The Elbow and Its Disorders E-Book

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A must-have resource for any orthopaedic library, the latest edition of this technique-focused guide to the elbow has been revised and updated to give you even more coverage of trauma, arthroscopy, soft tissue injury, and joint replacement. The new full-color illustrations and online access to 43 video clips of exams and procedures performed by experts visually enhance an already great resource for both the novice becoming familiar with elbow anatomy and biomechanics and the seasoned surgeon treating difficult elbow problems.
  • Features a technique-focused style and emphasis so you can provide the best hands-on care for your patients.
  • Presents authoritative guidance from leading experts.
  • Covers basic science through practical clinical application for a comprehensive look at the elbow.
  • Features expanded coverage of key topics in trauma, soft tissue procedures, and joint replacement technique to keep you up to date on the latest advances.
  • Supplements the text with new full-color-photos, illustrations, and diagrams for a more instructive and visually appealing approach.
  • Includes 39 video clips (over 2 hours) of exams and procedures—such as calcific tendonitis and RCR margin convergence—performed by the experts online for step-by-step guidance.

Subjects

Books
Savoirs
Medicine
Médecine
Surgical incision
Seronegative arthritis
Nerve compression syndrome
Tenotomy
Screw
Complete
Liver
Disarticulation
Surgical suture
Arthrocentesis
Joint mobilization
Synovectomy
Olecranon bursitis
Continuous passive motion
Replacement
Golfer's elbow
Radial collateral ligament of elbow joint
Tendinosis
Osteochondritis dissecans
Joint replacement
Arthrodesis
Article (publishing)
Arthropathy
Bone grafting
Osteolysis
Epicondylitis
Ossification
Global Assessment of Functioning
Ankylosis
Distal radius fracture
Neoplasm
Inborn error of metabolism
Hip replacement
Muscle contraction
Traumatic brain injury
Acute pancreatitis
Tennis elbow
Internal
Allotransplantation
Orthopedics
Trauma (medicine)
Debridement
Bursitis
Regional anaesthesia
Juvenile idiopathic arthritis
Osteomyelitis
Swelling
Review
Osteoarthritis
Stiffness
Chemical engineer
Orthopedic surgery
Pain management
General anaesthesia
Arthralgia
Lesion
Congenital disorder
Shoulder problem
Soft tissue
Tendinitis
Healing
Medical imaging
Erythrocyte sedimentation rate
Arthroscopy
Rheumatology
Internal medicine
Spasticity
Sports injury
Carpal tunnel syndrome
Complex regional pain syndrome
Cementation
X-ray computed tomography
Cerebral palsy
Infection
Rheumatoid arthritis
Repetitive strain injury
Phylogenetics
Osteoporosis
General surgery
Arthritis
Fractures
Father
Contracture
Elbow
Athlete
Force
Viewpoint
Insight
Supination
Gout
Maladie des exostoses multiples
Release
Pronation
Dislocation
Manual
Fracture
Flexion
Inflammation
Surface
Copyright

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Published 25 November 2008
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EAN13 9781437720808
Language English
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THE ELBOW AND ITS
DISORDERS
Fourth Edition
Bernard F. Morrey, MD
Professor of Orthopedic Surgery, Mayo Medical School,
Department of Orthopedic Surgery, Mayo Clinic, Rochester,
Minnesota
Joaquin Sanchez-Sotelo, MD, PhD
Associate Professor, Department of Orthopedic Surgery, Mayo
Graduate School, Rochester, Minnesota
S A U N D E R SCopyright
SAUNDERS ELSEVIER
1600 John F. Kennedy Blvd.
Ste 1800
Philadelphia, PA 19103-2899
THE ELBOW AND ITS DISORDERS
ISBN: 978-1-4160-2902-1
Copyright © 2009 by The Mayo Clinic Foundation
All rights reserved. No part of this publication may be reproduced or
transmitted in any form or by any means, electronic or mechanical, including
photocopying, recording, or any information storage and retrieval system, without
permission in writing from the publisher. Permissions may be sought directly from
Elsevier’s Rights Department: phone: (+1) 215 239 3804 (US) or (+44) 1865
843830 (UK); fax: (+44) 1865 853333; e-mail: healthpermissions@elsevier.com.
You may also complete your request on-line via the Elsevier website at
http://www.elsevier.com/permissions.
Notice
Knowledge and best practice in this Aeld are constantly changing. As new
research and experience broaden our knowledge, changes in practice, treatment
and drug therapy may become necessary or appropriate. Readers are advised to
check the most current information provided (i) on procedures featured or (ii) by
the manufacturer of each product to be administered, to verify the recommended
dose or formula, the method and duration of administration, and
contraindications. It is the responsibility of the practitioner, relying on their own
experience and knowledge of the patient, to make diagnoses, to determine
dosages and the best treatment for each individual patient, and to take all
appropriate safety precautions. To the fullest extent of the law, neither the
Publisher nor the Editors assumes any liability for any injury and/or damage to
persons or property arising out of or related to any use of the material contained
in this book.
The Publisher
Previous editions copyrighted 2000, 1993, 1985 by The Mayo Clinic
Foundation.
Library of Congress Cataloging-in-Publication DataThe elbow and its disorders / [edited by] Bernard F. Morrey.–4th ed.
p.; cm.
Includes bibliographical references and index.
ISBN 978-1-4160-2902-1
1. Elbow–Surgery. 2. Elbow–Diseases. 3. Elbow—Fractures. I. Morrey,
Bernard F., [DNLM: 1. Elbow Joint–injuries. 2. Joint Diseases. WE 820 E383 2009]
RD558.E43 2009
617.5′74–dc22
2008012878
Acquisitions Editor: Daniel Pepper
Developmental Editor: Ann Ruzycka Anderson
Editorial Assistant: Kim DePaul
Design Direction: Louis Forgione
Marketing Manager: Lisa Damico
Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1#
#
Dedication
As I was preparing the front material for the Fourth Edition of The Elbow and Its
Disorders, my father passed away at age 91. It is with great humility as well as a
tremendous sense of loss, but also pride that I dedicate this fourth volume to my
father, Alfred E. Morrey, Jr. My dad was a chemical engineer and worked in the
petroleum industry all of his life. His professional background and skills were
instrumental in my formative years in teaching, observation, precision, accuracy,
practicality and problem solving. In many ways these features of engineering are
not dramatically di erent from the requirements of the orthopedic surgeon. But,
more importantly than this, my father was my role model. He was open-minded
and objective and strongly believed in the concept of service. He avoided assuming
information as being factual unless it had been demonstrated to be so. But
probably the most important characteristic was his desire and stimulus for myself
and my siblings to contribute to society and to “give a full days measure”. I have
thought of my father regularly throughout my career and with his passing on July
13, 2008, it seems . tting to dedicate this e ort to him. He had all three prior
volumes proudly displayed in his library.
Bernard F. Morrey, MDCONTRIBUTORS
Julie E. Adams, MD, Assistant Professor, Department of
Orthopaedic Surgery, University of Minnesota School of
Medicine, Minneapolis, Minnesota, Fractures of the
Olecranon
Robert A. Adams, MA, OPA-C, Adjunct Faculty Clinical
Coordinator, University of Wisconsin-La Crosse, La
Crosse, Wisconsin, Assistant Professor, Mayo College of
Medicine, Rochester, Minnesota, Physician Assistant,
Mayo Clinic, Rochester, Minnesota, Linked Total Elbow
Arthroplasty in Patients with Rheumatoid Arthritis; Total
Elbow Arthroplasty for Primary Osteoarthritis; Wear and
Elbow Replacement
Christopher S. Ahmad, MD, Associate Professor,
Orthopaedic Surgery, Center for Shoulder, Elbow and
Sports Medicine, Columbia University College of
Physicians and Surgeons, Attending, Orthopaedic
Surgeon, New York Orthopaedic Hospital, Columbia
University, New York, New York, Arthroscopy in the
Throwing Athlete; Diagnosis and Treatment of Ulnar
Collateral Ligament Injuries in Athletes
Gilberto J. Alvarado, MD, Orthopedic Sports Medicine
Fellow, Nirschl Orthopaedic Center for Sports Medicine
and Joint Reconstruction, Arlington, Virginia, Tennis
Elbow Tendinosis
Peter C. Amadio, MD, Professor of Orthopedics, Mayo
Clinic College of Medicine, Consultant in Orthopedic
Surgery, Mayo Clinic, Rochester, Minnesota, Congenital
Abnormalities of the Elbow
Kai-Nan An, PhD, Professor, and Director, Biomechanics
Laboratory, Mayo Clinic, Rochester, Minnesota,Biomechanics of the Elbow; Functional Evaluation of the
Elbow
Karen L. Andrews, MD, Assistant Professor of Physical
Medicine and Rehabilitation, College of Medicine, Mayo
Clinic, Rochester, Minnesota, Elbow Disarticulation
Amputation
Robert D. Beckenbaugh, MD, Professor of Orthopedics,
Mayo Clinic, Rochester, Minnesota, Arthrodesis
Richard A. Berger, MD, PhD, Professor of Orthopedic
Surgery and Anatomy, Mayo Clinic College of Medicine,
Consultant, Division of Hand Surgery, Department of
Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota,
Overuse Syndrome
Thomas H. Berquist, MD, FACR, Professor of Diagnostic
Radiology, Mayo Clinic College of Medicine, Rochester,
Minnesota, Consultant, Mayo Clinic – Jacksonville,
Jacksonville, Florida, Diagnostic Imaging of the Elbow
Allen T. Bishop, MD, Professor of Orthopedic Surgery,
Mayo Clinic College of Medicine, Consultant,
Department of Orthopedic Surgery, and Chair, Division
of Hand Surgery, Mayo Clinic, Rochester, Minnesota,
Soft Tissue Coverage of the Elbow; Flaccid Dysfunction of
the Elbow
Kenneth P. Butters, MD, Consultant, Hand Surgery,
Department of Orthopedic Surgery, University of
Oregon, Eugene, Oregon, Septic Arthritis
Andrea Celli, MD, Consultant Orthopaedic and
Traumatology Surgeon, Orthopaedic and Traumatology
Department, University of Modena e Reggio Emilia,
Modena, Italy, Triceps Insufficiency Following Total Elbow
Arthroplasty
Emilie Cheung, MD, Assistant Professor, Medical Center
Line, and Stanford Hospital and Clinics, StanfordUniversity, Stanford, California, Treatment of the
Infected Total Elbow Arthroplasty
Akin Cil, MD, Assistant Professor of Orthopaedics,
Department of Orthopaedic Surgery, University of
Missouri Kansas City, Attending Surgeon, Department of
Orthopaedic Surgery, Truman Medical Center, Kansas
City, Missouri, Synovectomy of the Elbow
Mark S. Cohen, MD, Professor, Director, Orthopaedic
Education, and Director, Section of Hand and Elbow
Surgery, Department of Orthopaedic Surgery, Rush
University Medical Center, Chicago, Illinois, Advanced
Techniques: Arthroscopic Management of Lateral
Epicondylitis
Patrick M. Connor, MD, Clinical Faculty, Shoulder and
Elbow Surgery/Sports Medicine, and Trauma Surgery,
Orthopaedic Surgery Residency Program, Carolinas
Medical Center, Charlotte, North Carolina, Total Elbow
Arthroplasty for Juvenile Rheumatoid Arthritis
William P. Cooney, MD, Professor of Orthopedics, Mayo
Clinic, Rochester, Minnesota, Elbow Arthroplasty:
Historical Perspective and Emerging Concepts
Ralph W. Coonrad, MD, Associate Clinical Professor,
Department of Orthopedic Surgery, Duke University,
Medical Director Emeritus, Lenox Baker Children’s
Hospital, Duke University, Durham, North Carolina,
Nonunion of the Olecranon and Proximal Ulna
Joshua S. Dines, MD, Clinical Instructor, Orthopedic
Surgery, Weill Cornell Medical College, Assistant
Attending, Sports Medicine and Shoulder Service, The
Hospital for Special Surgery, New York, New York,
Articular Injuries in the Athlete
James H. Dobyns, MD, Professor of Orthopedics, and
Emeritus Staff, Mayo Clinic College of Medicine,
Rochester, Minnesota, and University of Texas SanAntonio Health Science Center, San Antonio, Texas,
Congenital Abnormalities of the Elbow
Neal S. ElAttrache, MD, Associate Clinical Professor,
Department of Orthopaedics, Keck School of Medicine,
University of Southern California, Director, Sports
Medicine Fellowship, Kerlan-Jobe Orthopaedic Clinic,
Los Angeles, California, Arthroscopy in the Throwing
Athlete; Diagnosis and Treatment of Ulnar Collateral
Ligament Injuries in Athletes; Articular Injuries in the
Athlete
Larry D. Field, MD, Clinical Instructor, Department of
Orthopaedic Surgery, University of Mississippi School of
Medicine, Director, Upper Extremity Service, Mississippi
Sports Medicine and Orthopaedic Center, Jackson,
Mississippi, Diagnostic Arthroscopy: Indications, Portals,
and Techniques; Management of Loose Bodies and Other
Limited Procedures; Arthroscopic Management of the Stiff
Elbow
Gerard T. Gabel, MD, Clinical Associate Professor,
Department of Orthopedic Surgery, Baylor College of
Medicine, Houston, Texas, Medial Epicondylitis
David R.J. Gill, MD, ChB, FRACS, Joondalup Health
Campus, Joondalup, Western Australia, Australia,
Linked Total Elbow Arthroplasty in Patients with
Rheumatoid Arthritis
E. Richard Graviss, MD, Professor of Radiology, St. Louis
University School of Medicine, Pediatric Radiology,
Cardinal Glennon Children’s Hospital, St. Louis,
Missouri, Imaging of the Pediatric Elbow
G. Dean Harter, MD, Associate, Department of
Orthopaedic Surgery, Chief, Shoulder and Elbow
Institute, Program Director, Orthopaedic Surgery
Residency, Geisinger Health System, Danville,
Pennsylvania, Ectopic Ossification About the ElbowAlan D. Hoffman, MD, Associate Professor of Radiology,
Mayo Clinic College of Medicine, Consultant in
Radiology – Pediatric Radiology, Mayo Clinic,
Rochester, Minnesota, Imaging of the Pediatric Elbow
Terese T. Horlocker, MD, Professor of Anesthesiology
and Orthopedics, Mayo Clinic, Rochester, Minnesota,
General and Regional Anesthesia and Postoperative Pain
Control
Jeffery S. Hughes, MB, FRACS, Orthopaedic Consultant,
North Shore Private Hospital, Sydney, Australia, Injury
of the Flexors of the Elbow: Biceps Tendon Injury;
Unlinked Arthroplasty: Distal Humeral Hemiarthroplasty
Srinath Kamineni, MBBCh, FRCS-Ed, FRCS-Orthopaedics
and Trauma, PhD, Professor of Bioengineering, Brunel
University – School of Engineering and Design,
Consultant Elbow, Shoulder, Upper Limb Surgeon, and
Clinical Lead, Upper Limb Unit, Cromwell Hospital,
London, United Kingdom, Distal Humeral Fractures–Acute
Total Elbow Arthroplasty
Graham J.W. King, MD, MSc, FRCSC, Professor,
Department of Surgery, University of Western Ontario,
Chief of Orthopaedic Surgery, St. Joseph’s Health
Centre, London, Ontario, Canada, Unlinked Arthroplasty:
Unlinked Total Elbow Arthroplasty; Unlinked Arthroplasty:
Convertible Total Elbow Arthroplasty; Revision of Failed
Total Elbow Arthroplasty with Osseous Integrity
Sandra L. Kopp, MD, Assistant Professor of
Anesthesiology, Mayo Clinic, Rochester, Minnesota,
General and Regional Anesthesia and Postoperative Pain
Control
Tomasz K.W. Kozak, FRACS, West Perth, Western
Australia, Australia, Total Elbow Arthroplasty for Primary
Osteoarthritis
Mikko Larsen, MD, Research Fellow, MicrovascularResearch Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, Rochester, Minnesota, Resident in
Training, Department of Plastic and Reconstructive
Surgery, V.U. Medical Center, Amsterdam, The
Netherlands, Flaccid Dysfunction of the Elbow
A. Noelle Larson, MD, Resident in Orthopedics,
Department of Orthopedics, Mayo Clinic, Rochester,
Minnesota, Hinged External Fixators of the Elbow;
Interposition Arthroplasy of the Elbow
Susan G. Larson, MS, PhD, Professor, Department of
Anatomical Sciences, School of Medicine, Stony Brook
University Medical Center, Stony Brook, New York,
Phylogeny
Brian P. Lee, MD, Orthopaedic Associates, Singapore,
Singapore, Wear and Elbow Replacement
Robert L. Lennon, DO, Associate Professor of
Anesthesiology, Mayo Medical School, Supplemental
Consultant, Mayo Clinic, Rochester, Minnesota, General
and Regional Anesthesia and Postoperative Pain Control
R. Merv Letts, MD, MSc, FRCSC, FACS, Consultant
Pediatric Orthopaedic Surgeon, Sheikh Khalifa Medical
City, Abu Dhabi, United Arab Emirates, Dislocations of
the Child’s Elbow
Harvinder S. Luthra, MD, Professor of Medicine,
Department of Rheumatology, Mayo Clinic, Rochester,
Minnesota, Rheumatoid Arthritis
Alex A. Malone, MBBS, MRCS (Eng), FRCS (Tr & Orth),
Consultant Orthopaedic Surgeon, Christchurch Hospital,
Canterbury, New Zealand, Senior Lecturer in
Orthopaedics with an interest in Upper Limb Surgery,
Christchurch School of Medicine, Otago University, New
Zealand, Honorary Consultant, Shoulder and Elbow
Unit, The Royal National Orthopaedic Hospital,
Stanmore, United Kingdom, Honorary Lecturer,Department of Surgery, University College London,
London, United Kingdom, Phylogeny
Pierre Mansat, MD, PhD, Professor of Orthopedics and
Traumatology, Faculté Medecine Toulouse/Purpan,
Université Paul Sabatier, and Service
d’Orthopedie/Traumatologie, Unité du Membre
Superieur, Centre Hospitalier Universitaire Purpan,
Toulouse, France, Extrinsic Contracture: Lateral and
Medial Column Procedures
Thomas G. Mason, MD, Associate Professor of Internal
Medicine and Pediatrics, Mayo Clinic College of
Medicine, Consultant in Adult and Pediatric
Rheumatology, Mayo Clinic, Rochester, Minnesota,
Seronegative Inflammatory Arthritis
Glen A. McClung, II, MD, Commonwealth Orthopaedic
Surgeons, Lexington, Kentucky, Diagnostic Arthroscopy:
Indications, Portals, and Techniques
Amy L. McIntosh, MD, Associate Clinical Professor, Mayo
Clinic, Rochester, Minnesota, Complications of
Supracondylar Fractures of the Elbow
Steven L. Moran, MD, Assistant Professor of Orthopedics
and Plastic Surgery, Mayo College of Medicine, and
Mayo Clinic, Rochester, Minnesota, Soft Tissue Coverage
of the Elbow
Bernard F. Morrey, MD, Professor of Orthopedic Surgery,
Mayo Medical School; Department of Orthopedic
Surgery, Mayo Clinic, Rochester, Minnesota, Anatomy of
the Elbow Joint; Biomechanics of the Elbow; Physical
Examination of the Elbow; Functional Evaluation of the
Elbow; Surgical Exposures of the Elbow; Principles of
Elbow Rehabilitation; Splints and Bracing at the Elbow;
Proximal Ulnar Fractures in Children; Dislocations of the
Child’s Elbow; Post-Traumatic Elbow Stiffness in Children;
Radial Head Fracture: General Considerations,
Conservative Treatment, and Open Reduction and InternalFixation; Radial Head Fracture: Prosthetic Radial Head
Replacement; Nonunion of the Olecranon and Proximal
Ulna; Coronoid Process and Monteggia Fractures; Complex
Instability of the Elbow; Chronic Unreduced Elbow
Dislocation; Ectopic Ossification About the Elbow;
Extrinsic Contracture: Lateral and Medial Column
Procedures; Hinged External Fixators of the Elbow; Injury
of the Flexors of the Elbow: Biceps Tendon Injury; Rupture
of the Triceps Tendon; Complications of Elbow
Arthroscopy; The Future of Arthroscopy of the Elbow;
Medial Epicondylitis; Surgical Failure of Tennis Elbow;
Elbow Arthroplasty: Historical Perspective and Emerging
Concepts; Unlinked Arthroplasty: Radiohumeral Arthrosis:
Anconeus Arthroplasty and Capitellar Prosthetic
Replacement; Linked Elbow Arthroplasty: Rationale,
Indications, and Surgical Technique; Linked Total Elbow
Arthroplasty in Patients with Rheumatoid Arthritis; Total
Elbow Arthroplasty for Juvenile Rheumatoid Arthritis;
Semiconstrained Elbow Replacement: Results in Traumatic
Conditions; Total Elbow Arthroplasty as a Salvage for the
Fused Elbow; Total Elbow Arthroplasty for Primary
Osteoarthritis; Complications of Elbow Replacement
Arthroplasty; Treatment of the Infected Total Elbow
Arthroplasty; Triceps Insufficiency Following Total Elbow
Arthroplasty; Wear and Elbow Replacement; Revision of
Failed Total Elbow Arthroplasty with Osseous Integrity;
Revision of Failed Total Elbow Arthroplasty with Osseous
Deficiency; Nonimplantation Salvage of Severe Elbow
Dysfunction; Synovectomy of the Elbow; Interposition
Arthroplasty of the Elbow; Primary Osteoarthritis:
Ulnohumeral Arthroplasty; Septic Arthritis; Neoplasms of
the Elbow; Loose Bodies; Bursitis; The Elbow in Metabolic
Disease
Matthew Morrey, MD, Senior Orthopaedic Resident,
Department of Orthopaedic Surgery, Mayo Clinic,
Rochester, Minnesota, Hinged External Fixators of the
Elbow
Scott J. Mubarak, MD, Clinical Professor, Department of
Orthopedics, University of California, San Diego,Director of Orthopedic Program, Children’s Hospital,
San Diego, California, Complications of Supracondylar
Fractures of the Elbow
Robert P. Nirschl, MD, MS, Associate Clinical Professor,
Georgetown University School of Medicine, Washington,
DC, Director, Sports Medicine Fellowship Programs,
Nirschl Orthopaedic Center for Sports Medicine and
Joint Reconstruction, Arlington, Virginia, Attending
Orthopedic Surgeon, Virginia Hospital Center,
Arlington, Virginia, Tennis Elbow Tendinosis
Shawn W. O’Driscoll, PhD, MD, Professor of Orthopedic
Surgery, Mayo Clinic, Rochester, Minnesota, Continuous
Passive Motion; Current Concepts in Fractures of the Distal
Humerus; Elbow Dislocations; Complex Instability of the
Elbow
Nicole M. Orzechowski, DO, Instructor of Internal
Medicine, Mayo Clinic College of Medicine; Mayo Clinic,
Rochester, Minnesota, Seronegative Inflammatory
Arthritis
Panayiotis J. Papagelopoulos, MD, DSc, Associate
Professor of Orthopaedics, Athens University Medical
School, Consultant, First Department of Orthopaedics,
Attikon University General Hospital, Athens University
Medical School, Athens, Greece, Nonunion of the
Olecranon and Proximal Ulna
Hamlet A. Peterson, MD, MS, Emeritus Professor of
Orthopedic Surgery, Mayo Medical School, Emeritus
Consultant in Orthopedic Surgery, Mayo Clinic,
Rochester, Minnesota, Physeal Fractures of the Elbow
Douglas J. Pritchard, AB, MS, MD, Orthopedic Surgery,
Retired, Mayo Clinic, Rochester, Minnesota, Neoplasms
of the Elbow
Matthew L. Ramsey, MD, Associate Professor of
Orthopaedic Surgery, Thomas Jefferson University, andRothman Institute, Philadelphia, Pennsylvania, Total
Elbow Arthroplasty for Distal Humerus Nonunion and
Dysfunctional Instability
William D. Regan, MD, FRCS(C), Associate Professor,
Department of Orthopaedics, University of British
Columbia, Associate Head, Department of Orthopaedics,
and Head, Division of Upper Extremity Surgery,
University Hospital, Vancouver, British Columbia,
Canada, Physical Examination of the Elbow; Coronoid
Process and Monteggia Fractures
Anthony A. Romeo, MD, Associate Professor, and
Director, Section of Shoulder and Elbow, Department of
Orthopaedic Surgery, Rush University Medical Center,
Chicago, Illinois, Advanced Techniques: Arthroscopic
Management of Lateral Epicondylitis
Joaquin Sanchez-Sotelo, MD, PhD, Associate Professor of
Orthopedics, Mayo Clinic College of Medicine,
Consultant in Orthopedic Surgery, Department of
Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota,
Nonunion and Malunion of Distal Humerus Fractures;
Lateral Collateral Ligament Insufficiency; Total Elbow
Arthroplasty for Distal Humerus Nonunion and
Dysfunctional Instability; Revision of Failed Total Elbow
Arthroplasty with Osseous Deficiency; Hematologic
Arthritis
Felix H. Savoie, III, MD, Lee Schlesinger Professor,
Shoulder, Elbow and Sports Surgery, Department of
Orthopaedic Surgery, Tulane University, Chair, Division
of Sports Medicine, Tulane Institute of Sports Medicine,
New Orleans, Louisiana, Diagnostic Arthroscopy:
Indications, Portals, and Techniques; Management of
Loose Bodies and Other Limited Procedures; Arthroscopic
Management of the Stiff Elbow; Advanced Techniques:
Arthroscopic Radial Ulnohumeral Ligament Reconstruction
for Posterolateral Rotatory Instability of the Elbow; The
Future of Arthroscopy of the ElbowAlberto G. Schneeberger, MD, Privatdozent, University
of Zurich, Consultant, Shoulder and Elbow Surgery,
Zurich, Switzerland, Semiconstrained Elbow Replacement:
Results in Traumatic Conditions
William J. Shaughnessy, MS, MD, Associate Professor of
Orthopedic Surgery, Mayo Medical School, Member,
Division of Pediatric Orthopedics, Mayo Clinic,
Rochester, Minnesota, Osteochondritis Dissecans
Alexander Y. Shin, MD, Professor, Orthopaedic Surgery,
Mayo Clinic School of Medicine, Consultant,
Orthopaedic Surgery, Mayo Clinic, Rochester,
Minnesota, Flaccid Dysfunction of the Elbow
Thomas C. Shives, MD, Professor of Orthopedics, Mayo
Clinic, Rochester, Minnesota, Elbow Disarticulation
Amputation
Jay Smith, MD, Associate Professor of Physical Medicine
and Rehabilitation, Mayo Clinic College of Medicine,
Consultant, Department of Physical Medicine and
Rehabilitation, Mayo Clinic, Rochester, Minnesota,
Principles of Elbow Rehabilitation
Robert J. Spinner, MD, Professor, Departments of
Neurosurgery, Orthopedics and Anatomy, Mayo Clinic
College of Medicine, Consultant, Department of
Neurologic Surgery and Orthopedics, Mayo Clinic,
Rochester, Minnesota, Nerve Entrapment Syndromes
Anthony A. Stans, MD, Assistant Professor, and Chair,
Division of Pediatric Orthopedics, Mayo Clinic,
Rochester, Minnesota, Supracondylar Fractures of the
Elbow in Children; Fractures of the Neck of the Radius in
Children; Proximal Ulnar Fractures in Children;
PostTraumatic Elbow Stiffness in Children
Scott P. Steinmann, MD, Consultant, Professor of
Orthopedics Mayo Clinic College of Medicine,
Rochester, Minnesota, Fractures of the OlecranonJ. Clarke Stevens, MD, Professor of Neurology, Mayo
Medical School, Rochester, Minnesota, Neurotrophic
Arthritis
Kristen B. Thomas, MD, Assistant Professor of
Radiology, Mayo Clinic College of Medicine, Consultant
in Radiology – Pediatric Radiology, Mayo Clinic,
Rochester, Minnesota, Imaging of the Pediatric Elbow
Nho V. Tran, MD, Assistant Professor of Plastic Surgery,
Mayo College of Medicine, and Mayo Clinic, Rochester,
Minnesota, Soft Tissue Coverage of the Elbow
Stephen D. Trigg, MD, Associate Professor, Orthopaedics
and Hand Surgery, Mayo Clinic Medical School Hand
Surgery, Mayo Medical School, Rochester, Minnesota,
Hand Surgeon, Department of Orthopaedics, and
Medical Director, Outpatient Surgery Center, Mayo
Clinic, Jacksonville, Florida, Pain Dysfunction Syndrome
K. Krishnan Unni, MD, Emeritus Professor of Pathology,
Departments of Anatomic Pathology, Orthopedic
Oncology, and Orthopedic Surgery, Mayo Clinic,
Rochester, Minnesota, Neoplasms of the Elbow
Francis Van Glabbeek, MD, PhD, Professor of Functional
Anatomy and Orthopaedics, University of Antwerp, Vice
Chair, Department of Orthopaedics and Traumatology,
University Hospital Antwerp, Antwerp, Belgium, Radial
Head Fracture: General Considerations, Conservative
Treatment, and Open Reduction and Internal Fixation
Ann E. Van Heest, MD, Professor, Department of
Orthopaedic Surgery, University of Minnesota,
Minneapolis; Gillette Children’s Specialty Healthcare,
St. Paul, Minnesota, Spastic Dysfunction of the Elbow
Roger P. van Riet, MD, PhD, Orthopaedic Surgeon,
Elbow Surgery, Monica Hospital, Deurne, Antwerp,
Belgium, Radial Head Fracture: General Considerations,
Conservative Treatment, and Open Reduction and InternalFixation
Ilya Voloshin, MD, Assistant Professor, University of
Rochester, Director, Shoulder and Elbow Service,
University of Rochester Medical Center, Rochester, New
York, Complications of Elbow Replacement Arthroplasty
Ken Yamaguchi, MD, Sam and Marilyn Fox
Distinguished Professor of Orthopaedic Surgery, and
Chief, Shoulder and Elbow Service, Washington
University School of Medicine, St. Louis, Missouri,
Treatment of the Infected Total Elbow Arthroplasty
Mark E. Zobitz, MS, Assistant Professor, Biomechanics
Laboratory, Mayo Clinic, Rochester, Minnesota,
Biomechanics of the Elbow



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PREFACE
Since the rst edition of The Elbow and Its Disorders in 1983 I am extremely
proud to hear such comments regarding the original and previous e orts such as
“the de nitive word in elbow surgery”. Such statements and con dence is a source
of tremendous pride and also motivation to continue to improve. In the spirit of
the original goal of providing a source of reliable information that will im-prove
patient care, we continue to be focused on this initial desire to provide clear,
concise, current, accurate, relevant and intelligible information that is easily
accessible.
I have a simple personal requirement for the timing of subsequent editions of
this book. This is to wait until I feel as though there has been su cient additional
information to justify another volume. This requirement has been met with this
particular effort.
Thus, I am very pleased along with my co-authors to have completed the
current volume. The overall organization, hope and e ort to be a comprehensive
reference has been maintained with an increased emphasis on surgical technique
which is an ever growing and relevant need of the orthopedic community. We are,
therefore, speci cally pleased to o er video clips in a number of chapters that do
complement and enhance the practical and useful learning experience.
The exciting advances in elbow arthroscopy are more extensively explored in
the current volume. Innovative opportunities with regard to prosthetic joint
replacement are also discussed in the current volume, along with nonprosthetic
options such as anconeus arthroplasty. In fact we are pleased to observe
considerable enhancement in the majority of chapters. As always I am deeply
appreciative and humbled by those who have contributed material, thoughts, and
insights over the years, particularly Doctors O’Driscoll, Steinmann, Sanchez-Sotelo
and my other partners at the Mayo Clinic.
Finally, I should note that this edition is an opportunity to introduce my partner
and colleague, Joaquin Sanchez-Sotelo, who has assisted me in the preparation of
the current volume, and who has shown an insightful and substantive
commitment to the practice of elbow surgery. It remains our hope that the reader
will continue to nd this text relevant both from the perspective of arriving at a
diagnosis of a di cult problem, understanding the options and potential outcome
of various interventions, as well insight with regard to how surgical techniquesmight be executed.
Bernard F. Morrey, MD#
(
#
A c k n o w l e d g m e n t
I wish to acknowledge with genuine appreciation all the input and insight I
received from orthopedic colleagues around the world, especially my colleagues,
residents and fellows at the Mayo Clinic. I also wish to express my most sincere
appreciation to Professor Gerber for the thoughtful and gracious comments which he
made in the “forward” of this edition.
The administrative e orts of my associate of 30 years, Bob Adams, to help nd
that one unique patient or x-ray has always been a tremendous and an essential
asset, as is the secretarial and administrative e orts of my secretary, Sherry
Koperski, and the numerous details and competencies provided by Donna Riemersma
in the preparation of this manuscript.
Finally, and as always, I want to expressly acknowledge my wife, Carla, who
has now lived through and encouraged me in the preparation of four editions of
“Disorders”. I am deeply appreciative of all the support I have received from Carla,
our children, and from the profession throughout my career.0
0
FOREWORD
Via internet we can gain access to almost any medical data within a few
mouse clicks. The most recent Journal articles including illustrations are at hand
and most data banks allow us to get immediate access to related articles. If ever
we decide to review an older publication not yet available in PDF format, it can be
ordered within hours or very few days. Details of current surgical techniques are
now reviewed in top quality video and DVD productions coming from leading
international experts. The question is therefore inevitable whether the concept of a
textbook is out of date and in fact, out of place. Unfortunately, many current
textbooks are an assiduous compilation of more or less well digested original
articles allowing at best for a cookbook approach to orthopaedics. These many
textbooks may decorate a bookshelf but add nothing to the impressive number of
references they quote and are superfluous.
What could the value of a current textbook be and why would we use it? In
this period of time, which Kipling characterizes by the probably unassailable lead
of knowledge over wisdom, in a time where orthopaedics is taught in “training”
programs – although we know that training refers to dogs and education refers to
people – we, the upper extremity surgeons who all have a copy of the Third wait
for the Fourth (!) Edition of “The Elbow and its Disorders”. Our expectations are
living proof that there remains a role for a textbook, because there is a role for
education, for educators, as role models who teach medicine based on an immense
body of knowledge with wisdom, experience and compassion. There is a role for
an instrument which puts scienti c knowledge into perspective and helps us to
apply knowledge most effectively to our patients.
Dr. Morrey has spent decades observing, describing, and de ning elbow
problems. In a very systematic fashion, he has studied the identified problems with
collaborators and friends in the laboratory, and brought his insight back into
clinical practice. Subsequently not only he and his pupils but surgeons throughout
the world have validated and do validate the respective contributions in their
patients. This textbook incorporates the knowledge gained from these and many
other investigations. It discloses details which have taken the authors years to
understand and apply. Yes, this textbook is comprehensive andprecise and yes, it
certainly is the gold standard for elbow surgery on all continents.
But I see the unique value of this book elsewhere. I see it in sharing an
approach to clinical problem solving. Dr. Morrey shows how to identify a problem,0
5
0
how to evaluate a problem and nally how to solve it. The text may not be able to
impart the human qualities of the editor, which certainly are large contributors of
his success with very di cult patient problems. But the text unequivocally clearly
states that orthopaedic surgery is not a manual but an intellectual discipline and
that excellent orthopaedic care is an art based on science.
Bernie, this textbook is a further testimony to you as a physician – scientist,
educator and role model. It has been one of the privileges of my lifetime to meet
you early in my career and to bene t from your wisdom and advice. For my next
elbow problem, I – as many others – will consult this textbook and I am sure it will
not only give me data but it will give me understanding. For any other very
difficult problem, I hope I can continue to call you.
Christian Gerber, MD, FRCS(hon), Professor and Chair,
Department of Orthopaedics, University of Zürich,
Zürich, SwitzerlandTable of Contents
Instructions for online access
Copyright
Dedication
CONTRIBUTORS
PREFACE
Acknowledgment
FOREWORD
PART I: Fundamentals and General Considerations
Chapter 1: Phylogeny
Chapter 2: Anatomy of the Elbow Joint
Chapter 3: Biomechanics of the Elbow
PART II: Diagnostic Considerations
Chapter 4: Physical Examination of the Elbow
Chapter 5: Functional Evaluation of the Elbow
Chapter 6: Diagnostic Imaging of the Elbow
PART III: Surgery and Rehabilitation
Chapter 7: Surgical Exposures of the Elbow
Chapter 8: General and Regional Anesthesia and Postoperative Pain
Control
Chapter 9: Principles of Elbow Rehabilitation
Chapter 10: Continuous Passive Motion
Chapter 11: Splints and Bracing at the Elbow
PART IV: Conditions Affecting the Child’s Elbow
Chapter 12: Imaging of the Pediatric Elbow
Chapter 13: Congenital Abnormalities of the ElbowChapter 14: Supracondylar Fractures of the Elbow in Children
Chapter 15: Complications of Supracondylar Fractures of the Elbow
Chapter 16: Physeal Fractures of the Elbow
Chapter 17: Fractures of the Neck of the Radius in Children
Chapter 18: Proximal Ulnar Fractures in Children
Chapter 19: Osteochondritis Dissecans
Chapter 20: Dislocations of the Child’s Elbow
Chapter 21: Post-Traumatic Elbow Stiffness in Children
PART V: Adult Trauma
Section A: Fractures and Dislocations
Chapter 22: Current Concepts in Fractures of the Distal Humerus
Chapter 23: Nonunion and Malunion of Distal Humerus Fractures
Chapter 24: Radial Head Fracture
Chapter 25: Fractures of the Olecranon
Chapter 26: Nonunion of the Olecranon and Proximal Ulna
Chapter 27: Coronoid Process and Monteggia Fractures
Chapter 28: Elbow Dislocations
Chapter 29: Complex Instability of the Elbow
Chapter 30: Chronic Unreduced Elbow Dislocation
Chapter 31: Ectopic Ossification About the Elbow
Section B: Soft Tissue Considerations
Chapter 32: Extrinsic Contracture: Lateral and Medial Column Procedures
Chapter 33: Hinged External Fixators of the Elbow
Chapter 34: Injury of the Flexors of the Elbow: Biceps Tendon Injury
Chapter 35: Rupture of the Triceps Tendon
Chapter 36: Soft Tissue Coverage of the Elbow
PART VI: Sports and Overuse Injuries to the Elbow
Section A: Arthroscopy
Chapter 37: Diagnostic Arthroscopy: Indications, Portals, and Techniques
Chapter 38: Management of Loose Bodies and Other Limited ProceduresChapter 39: Arthroscopy in the Throwing Athlete
Chapter 40: Arthroscopic Management of the Stiff Elbow
Chapter 41: Advanced Techniques
Chapter 42: Complications of Elbow Arthroscopy
Chapter 43: The Future of Arthroscopy of the Elbow
Section B: Muscle and Tendon Trauma
Chapter 44: Tennis Elbow Tendinosis
Chapter 45: Medial Epicondylitis
Chapter 46: Surgical Failure of Tennis Elbow
Chapter 47: Diagnosis and Treatment of Ulnar Collateral Ligament Injuries
in Athletes
Chapter 48: Lateral Collateral Ligament Insufficiency
Chapter 49: Articular Injuries in the Athlete
Chapter 50: Overuse Syndrome
PART VII: Reconstructive Procedures of the Elbow
Section A: Joint Replacement Arthroplasty
Chapter 51: Elbow Arthroplasty: Historical Perspective and Emerging
Concepts
Chapter 52: Unlinked Arthroplasty
Chapter 53: Linked Elbow Arthroplasty: Rationale, Indications, and
Surgical Technique
Chapter 54: Linked Total Elbow Arthroplasty in Patients with Rheumatoid
Arthritis
Chapter 55: Total Elbow Arthroplasty for Juvenile Rheumatoid Arthritis
Chapter 56: Distal Humeral Fractures–Acute Total Elbow Arthroplasty
Chapter 57: Semiconstrained Elbow Replacement: Results in Traumatic
Conditions
Chapter 58: Total Elbow Arthroplasty as a Salvage for the Fused Elbow
Chapter 59: Total Elbow Arthroplasty for Distal Humerus Nonunion and
Dysfunctional Instability
Chapter 60: Total Elbow Arthroplasty for Primary Osteoarthritis
Chapter 61: Complications of Elbow Replacement ArthroplastyChapter 62: Treatment of the Infected Total Elbow Arthroplasty
Chapter 63: Triceps Insufficiency Following Total Elbow Arthroplasty
Chapter 64: Wear and Elbow Replacement
Chapter 65: Revision of Failed Total Elbow Arthroplasty with Osseous
Integrity
Chapter 66: Revision of Failed Total Elbow Arthroplasty with Osseous
Deficiency
Chapter 67: Nonimplantation Salvage of Severe Elbow Dysfunction
Section B: Nonprosthetic Reconstruction
Chapter 68: Synovectomy of the Elbow
Chapter 69: Interposition Arthroplasty of the Elbow
Chapter 70: Arthrodesis
Chapter 71: Flaccid Dysfunction of the Elbow
Chapter 72: Spastic Dysfunction of the Elbow
Chapter 73: Elbow Disarticulation Amputation
PART VIII: Septic and Nontraumatic Conditions
Chapter 74: Rheumatoid Arthritis
Chapter 75: Seronegative Inflammatory Arthritis
Chapter 76: Primary Osteoarthritis: Ulnohumeral Arthroplasty
Chapter 77: Septic Arthritis
Chapter 78: Hematologic Arthritis
Chapter 79: Neurotrophic Arthritis
Chapter 80: Nerve Entrapment Syndromes
Chapter 81: Pain Dysfunction Syndrome
Chapter 82: Neoplasms of the Elbow
Chapter 83: Loose Bodies
Chapter 84: Bursitis
Chapter 85: The Elbow in Metabolic Disease
INDEXPART I
Fundamentals and General
ConsiderationsCHAPTER 1
Phylogeny
Alex A. Malone, Susan G. Larson
INTRODUCTION
The human elbow forms the link between brachium and forearm, controlling
length of reach and orientation of the hand, and is one of our most distinctive
anatomical regions. An appreciation of elbow phylogeny compliments anatomic
knowledge in three ways: (1) it demonstrates how the elbow has evolved to
facilitate speci c functional demands, such as suspensory locomotion and
dexterous manipulation; (2) it explains the functional signi cance of each
morphologic feature; and (3) it assists in predicting the consequences of loss of
such features through disease, injury, or treatment.
Most of the characteristic features of the human elbow signi cantly predate the
appearance of modern Homo sapiens. In fact, current evidence suggests that this
morphology can be traced back to the common ancestor of humans and apes,
extant about 15 to 20 million years ago (mya).
EVOLUTION OF THE VERTEBRATE ELBOW
The distal humerus of pelycosaurs, the late Paleozoic (255 to 235 mya) reptiles that
probably gave rise to more advanced mammal-like reptiles, possessed a bulbous
capitellum laterally and medially. The articulation with the ulna was formed by
two distinct surfaces: a slightly concave ventral surface and a more . at dorsal
11surface (Fig. 1-1). The proximal articular surface of the ulna was similarly
divided into two surfaces separated by a low ridge. Reconstruction of the forelimb
of these reptiles suggests that they walked with limbs splayed out to the side. The
humerus was held more or less horizontal, the elbow . exed to 90 degrees, and the
forearm was sagittally oriented. Forward motion was brought about by rotation of
the humerus around its long axis, which propelled the body forward relative to the
xed forefoot. Elbow . exion and extension probably were useful only in
side-toside motions. The ulnohumeral joint, with its dual articular surfaces, was well
suited to resist the valgus/varus stress produced by humeral rotation, and the
proximal end of the radius was . at and triangular, precluding pronosupination. It
appears, therefore, that stability rather than mobility was the major functional
characteristic of the elbow of these late Paleozoic reptiles.FIGURE 1-1 The major evolutionary stages in the development of the elbow joint
from pelycosaurs to advanced mammals. The distal ends of the humeri are shown
on the left, and the corresponding radius and ulna are on the right. The form of the
pelycosaur elbow was designed to maximize stability. Subsequent evolutionary
stages show accommodations to increasing mobility.
(Adapted from Jenkins, F. A. Jr.: The functional anatomy and evolution of the
mammalian humeroulnar articulation. Am. J. Anat. 137:281, 1973.)
Cynodonts, the more immediate ancestors of mammals from the Permo-Triassic
period (235 to 160 mya), had their limbs underneath their bodies rather than at
the sides. The distal humeral articular surface consisted of radial and ulnar
condyles separated by a shallow groove (see Fig. 1-1). The proximal ulnar articular
surface was an elongate spoon shape for articulation with the humeroulnar
condyle. The lateral . ange on the ulna for articulation with the radius was
separated from this surface by a low ridge. This ridge articulated with the groovebetween the radial and ulnar condyles displaying some features in common with
the “tongue and groove” (trochleariform) type of humeroulnar articulation
characteristic of many modern mammals.
Early mammals from the Triassic (210 to 160 mya) and Jurassic (160 to 130
mya) periods also had radial and ulnar condyles. However, the radial condyle was
more protuberant than the ulnar, and the ulnar condyle was more linear and
obliquely oriented (see Fig. 1-1). The two condyles were separated by an
intercondylar groove. The ulnar notch had articular surfaces for both the ulnar and
the radial condyles, each matching the con guration of the corresponding humeral
surface. The oblique orientation of the humeroulnar joint resembled a spiral
con guration, which helped to keep forearm movement in a sagittal plane as the
humerus underwent a compound motion involving adduction, elevation, and
rotation during propulsion.
The trochleariform distal humeral articular surface in modern mammals largely
came about by widening the intercondylar groove and the development of a ridge
within it (see Fig. 1-1, bear). The articular surface on the proximal ulna is oblique
in orientation, and the distal half retains an articulation with the ulnar condyle.
This spiral trochlear con guration allows the forearm to move in a sagittal plane
while maintaining the stability of ulnohumeral contact through the cam e; ect of
the ulnar condyle during humeral rotation.
Most small noncursorial mammals have maintained the spiral con guration of
the trochlear articular surface observed in early mammals. In larger and more
cursorial mammals, the trochlea displays various ridges and is narrower to improve
stability, although at the expense of joint mobility. Only in the hominoid primates,
which include humans, chimpanzees, gorillas, orangutans, and gibbons, is the
medial aspect of the distal humeral articular surface truly trochleariform. In the
next section, we discuss the functional signi cance of the unique aspects of the
hominoid elbow joint.
COMPARATIVE PRIMATE ANATOMY OF THE ELBOW REGION
20,21Much of what follows is taken from the detailed studies of Rose. The humeral
21trochlea may be cylindrical, conical, or trochleariform in nonhuman primates.
The trochlea is conical in some prosimians, but a cylindrical trochlea seems to be
the most common shape and is observed in most prosimians and New World
monkeys. The trochlea is also cylindrical in most Old World monkeys but with a
pronounced medial . ange or keel that is best developed anterodistally (Fig. 1-2).
Only in apes and humans is the trochlea truly trochleariform, possessing medial
and lateral ridges all around the trochlear margins, which contribute to the
stability of the ulnohumeral joint, substituting for the radiohumeral joint, which is
11,20freed for pronosupination throughout the . exion range. In most species, thearticular surface of the trochlea expands posteriorly to the area behind the
capitellum. In larger monkeys, the lateral edge of the posterior trochlear surface
projects to form a keel that extends up the lateral wall of the olecranon fossa (see
Fig. 1-2). In hominoids, this keel is a continuation of the lateral trochlear ridge and
helps form a sharp lateral margin of the olecranon fossa, providing resistance to
20.21varus and internal rotation in extension.
FIGURE 1-2 Distal humeri of a baboon, a chimpanzee, and a human from
anterior, distal, and posterior aspects. The lateral trochlear ridge is well developed
in both the human and the chimpanzee but is largely nonexistent in the baboon.
The baboon humerus displays prominent . anges anteromedially and
posterolaterally. The lateral epicondyle is placed higher in the chimpanzee than in
the human and displays a more strongly developed supracondylar crest.
The trochlear notch of the ulna generally mirrors the shape of the humeral
trochlea. In humans and apes, the notch has medial and lateral surfaces separated
20,21by a ridge that articulates with the trochlear groove (Fig. 1-3).FIGURE 1-3 Proximal ulnae of a baboon, a chimpanzee, and a human. The
trochlear notch is wider in the chimpanzee and the human and displays a
prominent ridge for articulation with the trochlear groove. In addition, the radial
notch faces laterally in the chimp and human, unlike in the baboon, in which it
faces more anteriorly.
The di; erences seen in the con guration of the humeroulnar joint across primate
species re. ect contrasting requirements for stabilization with di; erent forms of
limb use. In most monkeys, the humeroulnar joint is in its most stable con guration
in a partially . exed position owing to the development of the medial trochlear keel
20anterodistally and the lateral keel posteriorly.
It is not surprising that this position of maximum stability is the one assumed by
the forelimb during the weight-bearing phase of quadrupedal locomotion. The
anterior orientation of the trochlear notch is a direct adaptation to weight bearing
with a partially . exed limb. However, such an orientation does limit elbow
extension to some degree.
The great apes (chimpanzees, gorillas, and orangutans) and the lesser apes
(gibbons) move about in a much less stereotypical fashion than do monkeys. To
accommodate this more varied form of limb use, the hominoid humeroulnar joint,
with its deeply socketed articular surfaces and well-developed medial and lateral
trochlear ridges all around the joint margins, is designed to provide maximum
20-22stability throughout the . exion-extension range. The use of overhead
suspensory postures and locomotion in apes has led to the evolution of the capacity
for complete elbow extension. Apes even keep their elbows extended during
quadrupedal locomotion. The ideal joint con guration for resistance of
transarticular stress with fully extended elbows during quadrupedal postures would
be to have a trochlear notch that was proximally directed. It could then act as a
cradle to support the humerus during locomotion. However, a proximal orientation
of the trochlear notch would severely limit elbow . exion by impingement of the
coronoid process within its fossa. The anteroproximal orientation of the trochlear
notch in apes thus represents a compromise that safely supports the humerus on theulna in extended elbow positions during locomotion without unduly sacri cing
1elbow flexion.
On the lateral side of the elbow, the articular surface on the capitellum extends
farther posteriorly in apes and humans than in monkeys, allowing the radius to
move with the ulna into full extension of the elbow. In addition, the capitellum of
apes and humans is uniformly rounded, re. ecting versatility rather than stereotypy
in forelimb usage (Fig. 1-4).
FIGURE 1-4 Distal humeri of a baboon, a chimpanzee, and a human from the
lateral aspect. The articular surface of the capitellum extends further onto the
posterior surface of the bone (small arrows) in humans and chimpanzees to permit
full extension at the humeroradial joint.
The gutter-like region between the trochlea and capitellum—the zona conoidea
—is a relatively . at plane that terminates distally in most monkeys. In the
20,21hominoids, it continues posteriorly (see Fig. 1-1). The zona conoidea
articulates with the bevel of the radial head, and di; erences in its con guration
reflect differences in the shape of the radial head.
The radial head of hominoid primates is nearly circular, and the peripheral rim is
symmetrical and beveled all around the circumference of the radial head for
articulation with the zona conoidea (Fig. 1-5). This con guration provides good
contact to resist dislocation of the radial head from the humerus under the varied
loading regimes experienced by the hominoid elbow and can stabilize the radial
20,21head in all positions of pronosupination.FIGURE 1-5 Diagrammatic anterior views of the right humeroradial joints of a
monkey and an ape in the prone and supine positions. In the monkey, the lateral
bevel of the radial head comes into maximum congruence with the zona conoidea
(hatched area) in the prone position, thereby creating a maximally stable joint
con guration. In the ape, the rim of the more symmetrical radial head maintains
good contact with the recessed zona conoidea in all positions of pronosupination.
This contributes to a con guration emphasizing universal stability at the ape elbow
rather than a position of particular stability, as seen in the monkey.
(Adapted from Rose, M. D.: Another look at the anthropoid elbow. J. Hum. Evol. 17:193,
1988.)
In most monkeys and prosimians, the radial head is ovoid and the proximal
radioulnar joint articulation is restricted to the anterior and medial surfaces; as a
result, the joint becomes close packed for stability in pronation (Fig. 1-6). In apes
and humans, on the other hand, this articular surface extends almost all the way
20around the head, implying a greater range of pronosupination. The radial notch
of the ulna in most monkeys and prosimians faces either anterolaterally or directly
20,21anteriorly, whereas in hominoids, it faces more laterally. The con guration
observed in apes and humans emphasizes a broad range of pronosupination with a
20,21nearly equal degree of stability in all positions.FIGURE 1-6 Diagrammatic view of the radioulnar joint in pronation and
supination in a monkey and an ape. A section through the radius and ulna in the
region of the radial notch is superimposed on an outline of the distal humerus. In
the monkey, the radial notch faces anterolaterally, whereas in the ape, it faces
more directly laterally. The radial head of the monkey with its lateral lip comes
into maximum congruence in the pronated position, conferring maximum stability
in this position. The ape radioulnar joint, on the other hand, displays no such
position of particular stability and instead emphasizes mobility.
(Adapted from Rose, M. D.: Another look at the anthropoid elbow. J. Hum. Evol. 17:193,
1988.)
In general terms, most of the di; erences in elbow joint morphology between
quadrupedal monkeys and the apes can be related to the development of a position
of particular stability in monkeys versus more universal stability in apes.
A few additional features of the human elbow are shared with apes, such as a
21more distal biceps tuberosity (longer radial neck) relative to their body size. In
apes, this is probably related to the demands for powerful elbow . exion to raise the
center of mass of the body during climbing and suspensory postures and
locomotion. Although the radial tuberosity faces more or less anteriorly in most
primates, it faces more medially in apes and humans, re. ecting their greater range
17of pronosupination. Extreme supination is an important component of
suspensory locomotion in apes, and the medially placed tuberosity provides
14,30maximum supination torque near full supination. Apes and humans share a
relatively short lever arm for triceps compared with that of most other primates,
which is generally attributed to the demands for rapid elbow extension during
suspensory locomotion. Finally, apes and humans are distinguished from otherprimate species in possessing a biomechanical carrying angle at the elbow.
22Sarmiento has argued that the evolution of a carrying angle in apes is related to
the need to bring the center of mass of the body beneath the supporting hand
during suspensory locomotion in a manner similar to that in which the valgus knee
of humans brings the foot nearer the center of mass of the body during the single
limb support phase of walking (Fig. 1-7).
FIGURE 1-7 Frontal view of an arm-swinging gibbon showing the skeletal
structure of the forelimb. The carrying angle of the elbow brings the center of mass
(i.e., center of gravity [cg]) more nearly directly under the supporting hand.
(Adapted from Sarmiento, E. E.: Functional Differences in the Skeleton of Wild and
Captive Orang-Utans and Their Adaptive Significance. Ph.D. Thesis, New York University,
1985.)
All of these features have been retained in humans because of their continued
advantages for tool use and other behaviors. Powerful . exion is clearly important.
The continued importance of the carrying angle is perhaps less obvious, but one
advantage that it does o; er is that . exion of the elbow is accompanied by
adduction of the forearm, thus bringing the hands more in front of the body, where
most manipulatory activities are undertaken.
The morphology of the modern human elbow is not identical to that of the ape
elbow, however. In some cases, the di; erences are simply a matter of degree. For
example, although both apes and humans are distinguished from other primates inthe medial orientation of the radial tuberosity, it is more extreme in position in the
ape; in the human it is typically slightly anterior to true medial. In addition,
although the olecranon is short in both humans and apes compared with most
monkeys, it is slightly longer in humans than in apes and also shaped to maintain
this length throughout the range of . exion—both of which are advantageous for
4powerful manipulatory activities.
Other di; erences between the elbow morphology of humans and that of apes can
be related to the fact that the human forelimb has no role in locomotion. These
di; erences include a less robust coronoid process and a relatively narrower,
proximally oriented trochlear notch in humans, indicating relative stability in
. exion rather than the need to support the weight of the body during quadrupedal
1,13locomotion in extension. Humans possess a smaller and more distally placed
lateral epicondyle and a less well-developed supracondylar crest than is seen in the
23-25apes, reflecting diminished leverage of the wrist extensors and brachioradialis.
Humans have no bowing of the ulna that is related to enhancing the leverage of the
1forearm pronators and supinators in apes. Finally, a diminution in the prominence
of the trochlear ridges and steep lateral margin of the olecranon fossa in humans
can be related to the overall reduction in stresses at the human elbow and the
concomitant relaxation on the demands for strong stabilization in all
20,21positions.
When exactly did the basic pattern for the hominoid elbow arise, and how old is
the morphology of the modern human elbow? For answers to these questions we
must turn to the fossil record.
FOSSIL EVIDENCE
Dendropithecus macinnesi, Limnopithecus legetet, and Proconsul heseloni (all from
Africa) are among the earliest known hominoid species dated to the early part of
the Miocene epoch (23 to 16 mya) for which postcranial material is known.
Overall, the distal humeri of the rst two of these forms resemble generalized New
World monkeys such as Cebus (capuchin monkeys). The trochlea does not display a
prominent lateral ridge, and the zona conoidea is relatively . at. The trochlear
notch faces anteriorly, and the head of the radius is oval in outline with a
welldeveloped lateral lip. These features generally are considered to be primitive for
8,9,20higher primates (monkeys, apes, and humans).
P. heseloni, on the other hand, does display some features characteristic of extant
hominoids. It has a globular capitellum, well-developed medial and lateral
trochlear ridges, and a deep zona conoidea forming the medial wall of a recessed
20gutter between the capitellum and trochlea. In general, the elbow region of
Proconsul resembles that of extant hominoids in features related to general stabilityand range of pronosupination; yet full pronation remained a position of particular
20stability.
The limited fossil material that is available from the late Miocene epoch (16 to 5
mya) suggests that many hominoid species, including members of the genera
Dryopithecus (from Europe), Sivapithecus (from Europe and Asia), and Oreopithecus
(from Europe), displayed the features characteristic of the modern hominoid elbow.
Although it is possible that these features arose in parallel in di; erent genera, the
more parsimonious explanation is that they inherited this morphology from an
16,29,31early to middle Miocene common ancestor, possibly similar to P. heseloni.
Assuming that the characteristic features of the hominoid elbow are shared derived
traits, that is, traits inherited from a single common ancestor, we can say that the
elbow morphology of modern apes and humans can be dated to roughly 15 to 20
mya.
The majority of paleoanthropologists agree that humans are most closely related
to the African apes (chimpanzees and gorillas) and that the two lineages arose in
8the late Miocene or earliest Pliocene period (between 10 and 4 mya). The earliest
known fossils of the human lineage (hominids) date from the early Pliocene era,
approximately 4 to 5 mya. There are three genera of these earliest hominids
currently recognized, Ardipithecus, Paranthropus, and Australopithecus. The latter is
the best known and most widespread genus, and includes the famous “Lucy”
5,12skeleton from Hadar, Ethiopia (A. afarensis). The genus Homo, to which our
own species belongs, rst appeared about 2.5 to 2 mya in East Africa with its
earliest member species, H. habilis.
All of the hominids from the Pliocene period were bipedal, although some
23-2628probably spent signi cant time climbing trees. The development of
bipedalism freed the upper extremity from the requirements of locomotion, placing
greater emphasis on increasing mobility. The ability to supinate and pronate was
an immense advantage to hominids in caring for their young, defending
themselves, and gathering food. It was also critical in eH cient tool handling, which
developed approximately 2 mya, at about the same time as H. habilis, although
there is debate about which species of early hominid was responsible for making
27them.
Several distal humeri are known from these early hominid species. All of the
early hominid distal humeri lack the steep lateral margin of the olecranon fossa
that is characteristic of chimpanzees and gorillas. However, they do show a
considerable amount of morphologic variation in other characteristics (Fig. 1-8).
On the basis of the contour of the distal end of the humeral shaft, the placement of
the epicondyles, and the con guration of the articular surface, the fossil distal
humeri have been divided into two groups. The rst group is characterized by aweakly projecting lateral epicondyle that is placed low, at about the level of the
23,24capitellum, and by a moderately developed lateral trochlear ridge. These are
features shared with modern humans, and consequently, this group generally is
referred to as early Homo. The second group includes the Australopithecus and
Paranthropus species and is characterized by a well-developed lateral epicondyle
that is high relative to the capitellum. These features are similar to those of modern
apes.
FIGURE 1-8 Distal humeri of Plio-Pleistocene hominids. Gombore IB 7594
represents early Homo on the basis of the moderate development of the lateral
trochlear ridge and low position of the lateral epicondyle. AL 288-1m (part of the
“Lucy” skeleton, Australopithecus afarensis) displays a more prominent lateral
trochlear ridge, a recessed, gutter-like zona conoidea, a high position of the lateral
epicondyle, and a well-developed supracondylar crest. Therefore, it resembles
living apes in many features of its elbow morphology. KNM-ER 739 has been
attributed to Paranthropus boisei and, like AL 288-1m, has a lateral epicondyle that is
positioned above the articular surfaces. However, it is more like Homo, with the
moderate development of the lateral trochlear ridge.
A number of fragments of early hominid proximal radii have been recovered
representing each of the currently recognized species. The proximal radial
fragments that have been attributed to early Homo display a much narrower bevel
around the capitellar fovea than that of the modern apes and the earlier hominin
group. This provides for articulation with a more shallow zona conoidea and a
more vertical and uniformly wide surface on the side of the head for articulation
with the ulna favoring pronosupination over stability. Other primitive hominoid
features include thick cortices, a relatively long and angulated radial neck (lower
neck shaft angle), and a more anteromedially (rather than medially) placed biceps
tuberosity. Many of these features are still present in a small percentage of modern
humans, limiting the functional conclusions that can be drawn and suggesting a
18,19mosaic pattern of evolution.
Some early hominid ulnae that have been recovered appear to retain manyprimitive features including a longer more curved shaft, greater mediolateral width
1,2,10proximally, and a nonprominent interosseous border. However, early human
ulnae attributed to the genus Homo are similar to those of modern humans in
having a prominent interosseous border, a supinator crest, and a well-marked
6,7,15hollow for the play of the tuberosity of the radius. It appears, therefore, that
many of the characteristics that distinguish the human elbow from that of the ape
can be found in the earliest members of our genus.
In overview, the combination of comparative anatomy and the fossil record
indicates that the modern human elbow owes its beginnings to our hominoid
ancestry. Current evidence suggests that many of the characteristic features of the
human distal humerus and proximal radius and ulna can be projected back
approximately 15 to 20 mya to a common ancestor of extant apes and humans.
Functional analysis suggests that this morphologic structure arose in hominoid
primates in response to the need for stabilization throughout the . exion-extension
and pronosupination ranges of motion to permit a more versatile form of forelimb
use. This morphology was still largely intact following the evolution of upright
posture and bipedal locomotion in the earliest known hominids. However, as the
forelimb became less and less involved in locomotion, the hominid elbow
underwent additional modi cations, relaxing some of the emphasis on stabilization
and increasing performance throughout the range of movement. The fossil record
indicates that the distinct form of the modern human elbow probably rst
appeared about 2 mya in our ancestor H. habilis. This morphology has changed
only subtly during all subsequent stages of human evolution.
Acknowledgments
SGL would like to thank Jack Stern and John Fleagle for helpful comments on
earlier versions of this chapter, and Luci Betti-Nash for the preparation of figures.
The references in this chapter which suggest the evolution of the human from a
lower form are not accepted by and do not express the views of all of the
contributors of this book.
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2 Churchill S.E., Pearson O.M., Grine F.E., Trinkaus E., Holliday T.W. Morphological
affinities of the proximal ulna from Klasies River main site: archaic or modern? J.
Hum. Evol. 1996;31:213.
3 Conroy G.C. Primate Evolution. New York: W. W. Norton & Co., 1990.
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5 Drapeau M.S., Ward C.V., Kimbel W.H., Johanson D.C., Rak Y. Associated cranial
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6 Day M.H. Functional interpretations of the morphology of postcranial remains of
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7 Day M.H., Leakey R.E.F. New evidence for the genus Homo from East Rudolf, Kenya
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8 Fleagle J.G. Primate Adaptation and Evolution, 2nd ed. New York: Academic Press,
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9 Harrison T. The phylogenetic relationships of the early catarrhine primates: a review
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10 Howell F.C., Wood B.A. Early hominid ulna from the Omo Basin, Ethiopia. Nature.
1974;249:174.
11 Jenkins F.A.Jr. The functional anatomy and evolution of the mammalian
humeroulnar articulation. Am. J. Anat.. 1973;137:281.
12 Johanson D.C., Lovejoy C.O., Kimbel W.H., White T.D., Ward S.C., Bush M.E.,
Latimer B.M., Coppens Y. Morphology of the Pliocene partial hominid skeleton
(A.L. 288-1) from the Hadar Formation, Ethiopia. Am. J. Phys. Anthropol..
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13 Knussmann R.. Humerus, Ulna and Radius der Simiae. Bibliotheca Primatologica,
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14 Larson S.G. Subscapularis function in gibbons and chimpanzees: implications for
interpretation of humeral head torsion in hominoids. Am. J. Phys. Anthropol..
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15 Leakey R.E.F. Further evidence of lower Pleistocene hominids from East Rudolf,
Northern Kenya. Nature. 1972;237:264.
16 Martin L., Andrews P.I. Cladistic relationships of extant and fossil hominoids. J.
Hum. Evol.. 1987;16:101.
17 O’Connor B.L., Rarey K.E. Normal amplitudes of radioulnar pronation and
supination in several genera of anthropoid primates. Am. J. Phys. Anthropol..
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18 Patel B.A. The hominoid proximal radius: re-interpreting locomotor behaviors in
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19 Pearson O.M., Grine F.E. Re-analysis of the hominid radii from Cave of Hearths
and Klasies River Mouth, South Africa. J. Hum. Evol.. 1997;32:577.
20 Rose M.D. Another look at the anthropoid elbow. J. Hum. Evol.. 1988;17:193.
21 Rose M.D. Functional anatomy of the elbow and forearm in primates. In: Gebo D.,editor. Postcranial Adaptation in Nonhuman Primates. DeKalb, IL: Northern Illinois
Press; 1993:70.
22 Sarmiento, E. E.: Functional Differences in the Skeleton of Wild and Captive
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23 Senut B. Outlines of the distal humerus in hominoid primates: application to some
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24 Senut B. Humeral outlines in some hominoid primates and in Plio-Pleistocene
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25 Senut B., Tardieu C. Functional aspects of Plio-Pleistocene hominid limb bones:
implications for taxonomy and phylogeny. In: Delson E., editor. Ancestors: The
Hard Evidence. New York: A. Liss; 1985:193.
26 Stern J.T.Jr., Susman R.L. The locomotor anatomy of Australopithecus afarensis. Am.
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27 Susman R.L. Fossil evidence for early hominid tool use. Science. 1994;265:1570.
28 Susman R.L., Stern J.T.Jr., Jungers W.L. Arboreality and bipedality in Hadar
hominids. Folia Primatol.. 1984;43:113.
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30 Trinkaus E., Churchill S.E. Neandertal radial tuberosity orientation. Am. J. Phys.
Anthropol.. 1988;75:15.
31 Ward C.V., Walker A., Teaford M.F. Proconsul did not have a tail. J. Hum. Evol..
1991;21:215.CHAPTER 2
Anatomy of the Elbow Joint
Bernard F. Morrey
This chapter discusses the normal anatomy of the elbow region. Abnormal and surgical
anatomy is addressed in subsequent chapters of this book dealing with the pertinent
condition.
TOPICAL ANATOMY AND GENERAL SURVEY
The contours of the biceps muscle and antecubital fossa are easily observed anteriorly.
Laterally, the avascular interval between the brachioradialis and the triceps, the so-called
column, is an important palpable landmark for surgical exposures (Fig. 2-1). Laterally,
the tip of the olecranon, the lateral epicondyle, and the radial head also form an
equilateral triangle and provide an important landmark for joint aspiration and for elbow
arthro-scopy (see Chapters 37 and 77). The ) exion crease of the elbow is in line with the
medial and lateral epicondyles and thus is actually 1 to 2 cm proximal to the joint line
when the elbow is extended (Fig. 2-2). The inverted triangular depression on the anterior
aspect of the extremity distal to the epicondyles is called the cubital (or antecubital)
fossa.
FIGURE 2-1 The palpable landmarks of the tip of the olecranon and the medial and
lateral epicondyles form an inverted triangle posteriorly when the elbow is ) exed 90
degrees but are colinear when the elbow is fully extended.
(Redrawn from Anson, B. J., and McVay, C. B.: Surgical Anatomy, Vol. 2, 5th ed. Philadelphia,
W. B. Saunders Co., 1971.)FIGURE 2-2 A line placed over the ) exion crease (A) is actually situated about 1 cm
above the elbow joint line (B).
The super, cial cephalic and basilic veins are the most prominent super, cial major
contributions of the anterior venous system and communicate by way of the median
cephalic and median basilic veins to form an “M” pattern over the cubital fossa (Fig.
23).FIGURE 2-3 The super, cial venous pattern of the anterior aspect of the elbow
demonstrates a rather characteristic inverted M pattern formed by the median cephalic
and median basilic veins.
(Redrawn from Anson, B. J., and McVay, C. B.: Surgical Anatomy, Vol. 2, 5th ed. Philadelphia,
W. B. Saunders Co., 1971.)
The extensor forearm musculature originates from the lateral epicondyle and was
37termed the mobile wad by Henry. This forms the lateral margin of the antecubital fossa
and the lateral contour of the forearm and comprises the brachioradialis and the extensor
carpi radialis longus and brevis muscles. The muscles comprising the contour of the
medial anterior forearm include the pronator teres, ) exor carpi radialis, palmaris longus,
and ) exor carpi ulnaris. Henry has demonstrated that their relationship and location can
be approximated by placing the opposing thumb and the index, long, and ring , ngers
over the anterior medial forearm. The dorsum of the forearm is contoured by the lateral
extensor musculature, consisting of the anconeus, extensor carpi ulnaris, extensor
digitorum quinti, and extensor digitorum communis.
Dermal innervation about the proximal elbow is rather variable being provided by the
lower lateral cutaneous (C5, C6) and medial cutaneous (radial nerve, C8, T1 and T2)
nerves of the arm. The forearm skin is innervated by the medial (C8, T1), lateral
(musculocutaneous, C5, C6), and posterior (radial nerve, C6-8) cutaneous nerves of the
forearm (Fig. 2-4).FIGURE 2-4 Typical distribution of the cutaneous nerves of the anterior (A) and
posterior (B) aspects of the upper limb.
(Redrawn from Cunningham, D. J.: In G. J. Romanes (ed.): Textbook of Anatomy, 12th ed.
New York, Oxford University Press, 1981.)
OSTEOLOGY
HUMERUS
The distal humerus consists of an arch formed by two condyles that contain the articular
surfaces of the trochlea and capitellum (Fig. 2-5).FIGURE 2-5 The bony landmarks of the anterior aspect of the distal humerus.
Medial to the trochlea, the prominent medial epicondyle serves as a source of
attachment of the medial ulnar collateral ligament and the ) exor-pronator group of
muscles. Laterally, the lateral epicondyle is located just proximal to the capitellum and is
much less prominent than the medial epicondyle. The lateral ulnar collateral ligament
and the supinator-extensor muscle group originate from the ) at, irregular surface of the
lateral epicondyle.
Anteriorly, the radial and coronoid fossae accommodate the radial head and coronoid
process during flexion. Posteriorly, the olecranon fossa receives the tip of the olecranon.
86In about 90% of individuals, a thin membrane of bone separates the olecranon and
coronoid fossae (Fig. 2-6). The medial supracondylar column is smaller than the lateral
and explains the vulnerability of the medial column to fracture with trauma and some
56surgical procedures. The posterior aspect of the lateral supracondylar column is ) at,
allowing ease of application of contoured plates (see Chapter 22). The prominent lateral
supracondylar ridge serves as attachment for the brachioradialis and extensor carpi
radialis longus muscles anteriorly and for the triceps posteriorly. It is also an important
landmark for many lateral surgical approaches especially for the “column procedure”
(see Chapters 7 and 32).FIGURE 2-6 The prominent medial and lateral supracondylar bony columns as well as
other landmarks of the posterior aspect of the distal humerus.
Proximal to the medial epicondyle, about 5 to 7 cm along the medial intramuscular
45,49,81septum, a supracondylar process is observed in 1% to 3% of individuals (Fig.
27). A , brous band termed the ligament of Strothers may originate from this process and
38attach to the medial epicondyle. When present, this spur serves as an anomalous
34insertion of the coracobrachialis muscle and an origin of the pronator teres muscle.
Various pathologic processes have been associated with the supracondylar process,
45 4 38including fracture and median and ulnar nerve entrapment (see Chapter 80).FIGURE 2-7 Typical supracondylar process located approximately 5 cm proximal to the
medial epicondyle with its characteristic configuration.
RADIUS
The radial head de, nes the proximal radius and articulates with the capitellum. It
exhibits a cylindrical shape with a depression in the midportion to accommodate the
capitellum. The disc-shaped head is secured to the ulna by the annular ligament (Fig.
28). Distal to the radial head, the bone tapers to form the radial neck, which, along with
83the head, is vulnerable to fracture. The radial tuberosity marks the distal aspect of the
neck and has two distinct parts. The anterior surface is covered by a bicipitoradial bursa
protecting the biceps tendon during full pronation (Fig. 2-9). However, it is the rough
posterior aspect that provides the site of attachment of the biceps tendon. During full
pronation the tuberosity is in a dorsal position and allows repair of a ruptured biceps
12tendon through a posterior approach (see Chapter 34) and is helpful to determine axial
26alignment of proximal radial fractures.FIGURE 2-8 Proximal aspect of the radius demonstrating the articular margin for
articulation with the olecranon, the radial neck, and tuberosity.
FIGURE 2-9 A deep view of the anterior aspect of the joint revealing the submuscular
bursa present about the elbow joint.
ULNA
The proximal ulna provides the greater sigmoid notch (incisura semilunaris), which
serves as the major articulation of the elbow that is responsible for its inherent stability
(Fig. 2-10). The cortical surface of the coronoid process serves as the site of insertion of
the brachialis muscle and of the oblique cord. Medially the sublime tubercle serves asinsertion site of the medial ulnar collateral ligament. The triceps tendon attaches to the
posterior aspect of the olecranon process.
FIGURE 2-10 A, Anterior aspect of the proximal ulna demonstrating the greater
sigmoid fossa with the central groove. B, Lateral view with landmarks.
On the lateral aspect of the coronoid process, the lesser semilunar or radial notch
articulates with the radial head and is oriented roughly perpendicular to the long axis of
the bone. Distal to this the supinator crest serves as attachment to the supinator muscle, a
tuberosity occurs on this crest, which is the site of insertion of the lateral ulnar collateral
52,56,66ligament.
ELBOW JOINT STRUCTURE
ARTICULATION
77The elbow joint articulation is classi, ed as a trochoginglymoid joint. The ulnohumeral
joint resembles a hinge (ginglymus), allowing ) exion and extension. The radiohumeral
and proximal radioulnar joint allows axial rotation or a pivoting (trochoid) type of
motion.
Humerus
The trochlea is the hyperboloid, pulley-like surface that articulates with the semilunar
42,73,77notch of the ulna covered by articular cartilage through an arc of 300 degrees
(Fig. 2-11). The medial contour is larger and projects more distally than does the lateral
portion of the trochlea (Fig. 2-12). The two surfaces are separated by a groove that
courses in a helical manner from an anterolateral to a posteromedial direction.FIGURE 2-11 Sagittal section through the elbow region, demonstrating the high degree
of congruity.
(Redrawn from Anson, B. J., and McVay, C. B.: Surgical Anatomy, Vol. 2, 5th ed. Philadelphia,
W. B. Saunders Co., 1971.)
FIGURE 2-12 Axial view of the distal humerus shows the isometric trochlea as well as
the anterior position of the capitellum. The trochlear capitellar groove separates the
trochlea from the capitellum.
The capitellum is almost spheroidal in shape and is covered with hyaline cartilage,
which is about 2 mm thick anteriorly. A groove separates the capitellum from the
trochlea, and the rim of the radial head articulates with this groove throughout the arc of
flexion and during pronation and supination.
In the lateral plane, the orientation of the articular surface of the distal humerus is
rotated anteriorly about 30 degrees with respect to the long axis of the humerus (Fig.
213). The center of the concentric arc formed by the trochlea and capitellum is on a line
58that is coplanar to the anterior distal cortex of the humerus. In the transverse plane,
the articular surface and axis of rotation is rotated inward approximately 5 degrees (Fig.43,47,802-14), and in the frontal plane, it is tilted approximately 6 degrees in valgus
(Fig. 2-15).
FIGURE 2-13 Lateral view of the humerus shows the 30-degree anterior rotation of the
articular condyles with respect to the long axis of the humerus.
FIGURE 2-14 Axial view of the distal humerus demonstrates the 5- to 7-degree internal
rotation of the articulation in reference to the line connecting the midportions of the
epicondyles.FIGURE 2-15 There is approximately a 6- to 8-degree valgus tilt of the distal humeral
articulation with respect to the long axis of the humerus.
Proximal Radius
Hyaline cartilage covers the depression of the radial head, which has an angular arc of
77about 40 degrees, as well as approximately 240 degrees of articular cartilage that
articulates with the ulna, hence approximately 120 degrees of the radial circumference is
16not articular and amenable to open reduction internal , xation (ORIF) for fracture (Fig.
42,772-16). The lesser sigmoid fossa forms an arc of approximately 60 to 80 degrees,
leaving an excursion of about 180 degrees for pronation and supination. The
anterolateral third of the circumference of the radial head is void of cartilage. This part
of the radial head lacks subchondral bone and thus is not as strong as the part that
supports the articular cartilage; this part has been demonstrated to be the portion most
83often fractured. The head and neck are not co-linear with the rest of the bone and form
an angle of approximately 15 degrees, with the shaft of the radius directed away from
28the radial tuberosity (Fig. 2-17).FIGURE 2-16 Hyaline cartilage covers approximately 240 degrees of the outside
circumference of the radial head, allowing its articulation with the proximal ulna at the
radial notch of the ulna.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
FIGURE 2-17 The neck of the radius makes an angle of approximately 15 degrees with
the long axis of the proximal radius.
Proximal Ulna
In most individuals, a transverse portion of non-articular cartilage divides the greater
sigmoid notch into an anterior portion comprising the coronoid and the posterior
olecranon (Fig. 2-18).FIGURE 2-18 The relative percentage of hyaline cartilage distribution at the proximal
ulna.
(Redrawn from Tillmann, B.: A Contribution to the Function Morphology of Articular Surfaces.
Translated by G. Konorza. Stuttgart, George Thieme, Publishers; P. S. G. Publishing Co.,
Littleton, Mass., 1978.)
74In the lateral plane, the sigmoid notch forms an arc of about 190 degrees. The
contour is not a true hemicircle but rather is elipsoid. This explains the articular void in
85the midportion.
The orientation of the articulation is oriented approximately 30 degrees posterior to the
long axis of the bone (Fig. 2-19). This matches the 30 degrees anterior angulation of the
distal humerus, providing stability in full extension (see Chapter 3). In the frontal plane,
43,47,73the shaft is angulated from about 1 to 6 degrees lateral to the articulation (Fig.
2-20). This angle contributes, in part, to the variation of the carrying angle, which is
discussed in Chapter 3.
FIGURE 2-19 The greater sigmoid notch opens posteriorly with respect to the long axis
of the ulna. This matches the 30-degree anterior rotation of the distal humerus, as shown
in Figure 2-13.FIGURE 2-20 There is a slight (approximately 4 degrees) valgus angulation of the shaft
of the ulna with respect to the greater sigmoid notch.
The lesser sigmoid notch consists of a depression with an arc of about 70 degrees and is
situated just distal to the lateral aspect of the coronoid and articulates with the radial
head.
CARRYING ANGLE
The so-called carrying angle is the angle formed by the long axes of the humerus and the
ulna with the elbow fully extended (Fig. 2-21). In men, the mean carrying angle is 11 to
3,43,6914 degrees, and in women, it is 13 to 16 degrees. Furthermore, the carrying angle
88is approximately 1 degree greater in the dominant than nondominant side.FIGURE 2-21 The carrying angle is formed by the variable relationship of the
orientation of the humeral articulation referable to the long axis of the humerus and the
valgus angular relationship of the greater sigmoid fossa referable to the long axis of the
ulna.
(Redrawn from Lanz, T., and Wachsmuth, W.: Praktische Anatomie. ARM, Berlin, Springer,
1959.)
JOINT CAPSULE
The anterior capsule inserts proximally above the coronoid and radial fossae (Fig. 2-22).
Distally, the capsule attaches to the anterior margin of the coronoid medially as well as to
the annular ligament laterally. Posteriorly, the capsule attaches just above the olecranon
fossa, distally along the supracondylar bony columns. Distally, attachment is along the
medial and lateral articular margin of the sigmoid notch. The greatest capacity of the
40,70 70elbow occurs at about 80 degrees of flexion and is 25 to 30 mL.FIGURE 2-22 Distribution of the synovial membrane from the posterior aspect,
demonstrating the presence of the synovial recess under the annular ligament and about
the proximal ulna.
(Redrawn from Beethman, W. P.: Physical Examination of the Joints. Philadelphia, W. B.
Saunders Co., 1965.)
The anterior capsule is normally a thin transparent structure but signi, cant strength is
23,56provided by transverse and obliquely directed , brous bands (Fig. 2-23). The
anterior structure is, of course, taut in extension but becomes lax in ) exion. The joint
capsule is innervated by highly variable branches from all major nerves crossing the
joint, including the contribution from the musculoskeletal nerve (Fig. 2-24).
FIGURE 2-23 There is a cruciate orientation of the , bers of the anterior capsule that
provides a good deal of its strength.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1978.)FIGURE 2-24 A typical distribution of the contributions of the musculocutaneous radial
median and ulnar nerves to the joint capsule.
(Redrawn from Gardner, E.: The innervation of the elbow joint. Anat. Rec. 102:161, 1948.)
LIGAMENTS
The collateral ligaments of the elbow are formed by specialized thickenings of the medial
and lateral capsules.
Medial Collateral Ligament Complex
The medial collateral ligament consists of three parts: anterior, posterior, and transverse
segments (Fig. 2-25). The anterior bundle is the most discrete component, the posterior
portion being a thickening of the posterior capsule, and is well de, ned only in about 90
degrees of ) exion. The transverse component (ligament of Cooper) appears to contribute
little or nothing to elbow stability.FIGURE 2-25 The classic orientation of the medial collateral ligament, including the
anterior and posterior bundles, and the transverse ligament. This last structure
contributes relatively little to elbow stability.
65The ligament originates from a broad anteroinferior surface of the epicondyle. The
ulnar nerve rests on the posterior aspect of the medial epicondyle but is not intimately
related to the , bers of the anterior bundle of the medial collateral ligament itself. This
has obvious implications with regard to the treatment of ulnar nerve decompression by
medial epicondylar ostectomy. A more obliquely oriented excision might be most
appropriate to both decompress the ulnar nerve and preserve the collateral ligament
origin. On the lateral projection, the origin of the anterior bundle of the medial collateral
ligament is precisely at the axis of rotation at the anterior, inferior margins of the medial
62epicondyle (Fig. 2-26). The posterior bundle inserts along the midportion of the medial
margin of the semilunar notch. The width of the anterior bundle is approximately 4 to 5
56mm compared with 5 to 6 mm at the midportion of the fan-shaped posterior segment.
Recently ultrasound assessment has proved helpful in further documenting the
61dimensions of these structures.FIGURE 2-26 The origin of the medial complex is at the axis of rotation, which is
located at the anterior inferior aspect of the medial epicondyle. This is the projected
center of the trochlea.
The function of the ligamentous structures is discussed in detail below. Clinically and
experimentally, the anterior bundle is clearly the major portion of the medial ligament
59complex and has been divided into anterior, posterior and deep medial
62subcomponents.
Lateral Ligament Complex
Unlike the medial collateral ligament complex, with its rather consistent pattern, the
lateral ligaments of the elbow joint are less discrete, and individual variation
30,31,40,75iscommon. Our investigation has suggested that several components make up
the lateral ligament complex: (1) the radial collateral ligament, (2) the annular ligament,
(3) a variably present accessory lateral collateral ligament, and (4) the lateral ulnar
collateral ligament. These observations have now been con, rmed by others. The current
thinking is to consider the complex to be roughly in the shape “Y,” the arms of which
13,72attach to the anterior and posterior aspect of the semilunar notch (Fig. 2-27).FIGURE 2-27 Dissection demonstrating the “Y” orientation of the lateral collateral
ligament complex.
Radial Collateral Ligament
This structure originates from the lateral epicondyle and is actually a complex of several
components (Fig. 2-28). Its super, cial aspect provides a source of origin for a portion of
the supinator muscle. The length averages approximately 20 mm with a width of
approximately 8 mm. This portion of the ligament is almost uniformly taut throughout
the normal range of ) exion and extension, indicating that the origin of the ligament is
very near the axis of flexion (Fig. 2-29).
FIGURE 2-28 Schematic representation of the radial collateral ligament complex
showing several portions, one of which, termed the radial collateral ligament, extends
from the humerus to the annular ligament. This is the portion that is implicated in clinical
instability.FIGURE 2-29 The lateral collateral complex originates at the center of the lateral
epicondyle.
Annular Ligament
A strong band of tissue originating and inserting on the anterior and posterior margins of
the lesser sigmoid notch forms the annular ligament and maintains the radial head in
contact with the ulna. The ligament is tapered distally to give the shape of a funnel and
52contributes about four , fths of the , bro-osseous ring. The structure is not as simple as
it appears because , bers arc medially and laterally to secure the annular ligament to the
72ulna. A synovial re) ection extends distal to the lower margin of the annular ligament,
76forming the sacciform recess. The radial head is not a pure circular disc ; thus, it has
been observed that the anterior insertion becomes taut during supination and the
88posterior aspect becomes taut during extremes of pronation.
Lateral Ulnar Collateral Ligament
56In 1985 Morrey and An , rst described the so-called lateral ulnar collateral ligament.
Before this, however, Martin haddescribed a lateral ligament complex including “…
additional , bers inserting from the tubercle of the supinator crest to the humerus.” This
structure subsequently has been demonstrated to be invariably present and critically
important clinically. It originates from the lateral epicondyle and blends with the , bers
66of the annular ligament arching super, cial and distal to it. The insertion is at the
tubercle of the crest of the supinator on the ulna. Although the origin blends with the
origin of the lateral collateral ligament complex occupying the posterior portion, the
insertion is more discrete at the tubercle (Fig. 2-30). The function of this ligament is to
provide stability to the ulnohumeral joint and was shown to be de, cient in posterolateral
64,65rotatory instability of the joint. As con, rmed by several subsequent assessments, the
key factor is that this ligament represents the primary lateral stabilizer of the elbow andis taut in flexion and extension (Fig. 2-31).
FIGURE 2-30 Artist’s rendition of lateral collateral complex noting the thickening of the
lateral ulnar collateral ligament with a more discrete insertion at the tubercle of the
supinator. In life, the supinator origin obscures the ligament, making it unnoticeable
unless the supinator muscle has been removed.
(From Pede.)FIGURE 2-31 The lateral ulnar collateral ligament complex has an origin at the axis of
rotation and thus is isometric, being taut both in extension (A) and in ) exion (B). Note
presence of the accessory ligament.
Accessory Lateral Collateral Ligament
This de, nition has been applied by Martin to the ulnar insertion of discrete , bers on the
tubercle of the supinator as described previously. Others have termed this the lateral arm
72of the “Y” ligament. Proximally, the , bers tend to blend with the inferior margin of the
annular ligament (see Fig. 2-27). Its function is to further stabilize the annular ligament
during varus stress.
Quadrate Ligament
A thin, , brous layer covering the capsule between the inferior margin and the annular
20,60ligament and the ulna is referred to as the quadrate ligament or the ligament of
76Denucè. Spinner and Kaplan have demonstrated a functional role for the structure,
describing the anterior part as a stabilizer of the proximal radial ulnar joint during full
76supination. The weaker posterior attachment stabilizes the joint in full pronation.
Oblique Cord
The oblique cord is a small and inconstant bundle of , brous tissue formed by the fasciaoverlying the deep head of the supinator and extending from the lateral side of the
tuberosity of the ulna to the radius just below the radial tuberosity (see Fig. 2-23).
53,76Although the morphologic signi, cance is debatable and the structure is not
31considered to be of great functional consequence, it has been noted to become taut in
full supination, and contracture of the oblique cord has been implicated in the etiology of
10idiopathic limitation of forearm supination. At this point, we consider this structure as
a curiosity.
Bursae
The bursae were , rst detailed by Monro in 1788, and several bursae have been described
55at the elbow joint. Lanz recognized seven bursae, including three associated with the
52triceps. On the posterior aspect of the elbow, the super, cial olecranon bursa, which
18develops around age 7 years, between the olecranon process and the subcutaneous
33tissue is wellknown (Fig. 2-32). A deep subtendinous bursa is present as the triceps
inserts on the tip of the olecranon. An occasional deep subtendinous bursa is likewise
present between the tendon and the tip of the olecranon. A bursa has also even been
36described deep to the anconeus muscle in about 12% of subjects by Henle, but we
have not appreciated such a structure during more than 500 exposures of this region. On
the medial and lateral aspects of the joint, the subcutaneous medial epicondylar bursa is
frequently present, and the lateral subcutaneous epicondylar bursa occasionally has been
observed. The radiohumeral bursa lies deep to the common extensor tendon, below the
extensor carpi radialis brevis and super, cial to the radiohumeral joint capsule. This
17,67entity has been implicated by several authors in the etiology of lateral epicondylitis
but is probably not a major factor. The constant bicipitoradial bursa separates the biceps
tendon from the tuberosity of the radius (see Fig. 2-9). Less commonly appreciated is the
deep cubital interosseous bursa lying between the lateral aspect of the biceps tendon and
the ulna, brachialis, and supinator fascia. This bursa is said to be present in about 20% of
75individuals. The clinical signi, cance of the relevant bursae about the elbow is detailed
in Chapter 85.FIGURE 2-32 Posterior view of the elbow demonstrating the super, cial and deep
bursae that are present about this joint.
VESSELS
BRACHIAL ARTERY AND ITS BRANCHES
The cross-sectional relationship of the vessels, nerves, muscles, and bones is shown in
Figure 2-33. The brachial artery descends in the arm, crossing in front of the
intramuscular septum to lie anterior to the medial aspect of the brachialis muscle. The
median nerve crosses in front of and medial to the artery at this point, near the middle of
the arm (Fig. 2-34). The artery continues distally at the medial margin of the biceps
muscle and enters the antecubital space medial to the biceps tendon and lateral to the
nerve (Fig. 2-35). At the level of the radial head, it gives oI its terminal branches, the
ulnar and radial arteries, which continue into the forearm.FIGURE 2-33 Cross-sectional relationships of the muscles (A) and the neurovascular
bundles (B). C, The region above the elbow joint. D, View taken across the elbow joint. E,
View just distal to the articulation.
(Redrawn from Eycleshymer, A. C., and Schoemaker, D. M.: A Cross-Section Anatomy. New
York, D. Appleton and Co., 1930.)FIGURE 2-34 Anterior aspect of the elbow region demonstrating the intricate
relationships between the muscles, nerves, and vessels.
(Redrawn from Hollinshead, W. H.: The back and limbs. In Anatomy for Surgeons, Vol. 3. New
York, Harper & Row, 1969, p. 379.)FIGURE 2-35 Illustration of the anterior extraosseous vascular anatomy demonstrating
the medial arcade and the relationship of the radial recurrent artery (RR) to the proximal
aspect of the radius. The inferior ulnar collateral artery (IUC) provides perforators to the
supracondylar region, medial aspect of the trochlea, and medial epicondyle before it
courses posteriorly to anastomose with the superior ulnar collateral (SUC) and posterior
ulnar recurrent (PUR) arteries. The radial recurrent artery provides an osseous perforator
to the radius as it travels proximally and posterior. B, brachial artery; R, radial artery.
(Redrawn from Yamaguchi, K., Sweet, F. A., Bindra, R., Morrey, B. F., and Gelberman, R. H.:
The extraosseous and intraosseous arterial anatomy of the adult elbow. J. Bone Joint Surg.
79A:1654, 1997.)
The brachial artery usually is accompanied by medial and lateral brachial veins.
Proximally, in addition to its numerous muscular and cutaneous branches, the large,
deep brachial artery courses posteriorly and laterally to bifurcate into the medial and
radial collateral arteries. The medial collateral artery continues posteriorly, supplying the
medial head of the triceps and ultimately anastomosing with the interosseous recurrent
artery at the posterior aspect of the elbow. The radial collateral artery penetrates the
lateral intermuscular septum and accompanies the radial nerve into the antecubital
space, where it anastomoses with the radial recurrent artery at the level of the lateral
epicondyle.
The detailed vascular anatomy of the elbow region has been nicely described recently
89in great detail by Yamaguchi et al. The major branches of the brachial artery are the
superior and inferior ulnar collateral arteries, which originate medial and distal to the
profunda brachial artery. The superior ulnar collateral artery is given oI just distal to the
midportion of the brachium, penetrates the medial intermuscular septum, and
accompanies the ulnar nerve to the medial epicondyle, where it terminates by
anastomosing with the posterior ulnar recurrent artery and variably with the inferior
ulnar collateral artery (Fig. 2-36).FIGURE 2-36 Illustration of the posterior collateral circulation of the elbow. There are
perforating vessels on the posterior aspect of the lateral epicondyle, in the olecranon
fossa, and on the medial aspect of the trochlea. The tip of the olecranon is supplied by
perforators from the posterior arcade in the olecranon fossa. The superior ulnar collateral
artery (SUC) is seen terminating in the posterior arcade. IUC, inferior ulnar collateral
artery; PUR, posterior ulnar recurrent artery; IR, interosseous recurrent artery, RR, radial
recurrent artery; RC, radial collateral artery; MC, middle collateral artery.
(Redrawn from Yamaguchi, K., Sweet, F. A., Bindra, R., Morrey, B. F., and Gelberman, R. H.:
The extraosseous and intraosseous arterial anatomy of the adult elbow. J. Bone Joint Surg.
79A:1655, 1997.)
The inferior ulnar collateral artery arises from the medial aspect of the brachial artery
about 4 cm proximal to the medial epicondyle. It continues distally for a short course,
dividing into and anastomosing with branches of the anterior ulnar recurrent artery, and
it supplies a portion of the pronator teres muscle.
RADIAL ARTERY
The radial artery typically originates at the level of the radial head, emerges from the
antecubital space between the brachioradialis and the pronator teres muscle, and
continues down the forearm under the brachioradialis muscle. A more proximal origin
54occurs in up to 15% of individuals. The radial recurrent artery originates laterally from
the radial artery just distal to its origin. It ascends laterally on the supinator muscle to
anastomose with the radial collateral artery at the level of the lateral epicondyle, to
which it provides circulation. For better visualization, the radial recurrent artery
sometimes is sacrificed with the anterior elbow exposure.
ULNAR ARTERYThe larger of the two terminal branches of the brachial artery is the ulnar artery. There is
relatively little variation in its origin, which is usually at the level of the radial head. The
artery traverses the pronator teres between its two heads and continues distally and
medially behind the ) exor digitorum super, cialis muscle. It emerges medially to
continue down the medial aspect of the forearm under the cover of the ) exor carpi
ulnaris. Two recurrent branches originate just distal to the origin of the ulnar artery. The
anterior ulnar recurrent artery ascends deep to the humeral head of the pronator teres
and deep to the medial aspect of the brachialis muscle to anastomose with the
descending superior and inferior ulnar collateral arteries. The posterior ulnar recurrent
artery originates with or just distal to the smaller anterior ulnar recurrent artery and
passes proximal and posterior between the super, cial and deep ) exors posterior to the
medial epicondyle. This artery continues proximally with the ulnar nerve under the
) exor carpi ulnaris to anastomose with the superior ulnar collateral artery. Additional
extensive communication with the inferior ulnar and middle collateral branches
constitutes the rete articulare cubiti (see Fig. 2-35).
The common interosseous artery is a large vessel originating 2.5 cm distal to the origin
of the ulnar artery. It passes posteriorly and distally between the ) exor pollicis longus
and the ) exor digitorum profundus just distal to the oblique cord, dividing into anterior
and posterior interosseous branches. The interosseous recurrent artery originates from the
posterior interosseous branch. This artery runs proximally through the supinator muscle
to anastomose with the vascular network of the olecranon (see Fig. 2-36).
NERVES
Speci, c clinical and pertinent anatomic aspects of the nerves in the region of the elbow
are discussed in subsequent chapters as appropriate. A general survey of the common
anatomic patterns is given here (see Fig. 2-33).
MUSCULOCUTANEOUS NERVE
The musculocutaneous nerve originates from C5-8 nerve roots and is a continuation of
the lateral cord. It innervates the major elbow ) exors, the biceps and brachialis, and
continues through the brachial fascia lateral to the biceps tendon, terminating as the
lateral antebrachial cutaneous nerve (Fig. 2-37). The motor branch enters the biceps and
48the brachialis approximately 15 and 20 cm below the tip of the acromion, respectively.FIGURE 2-37 The musculocutaneous nerve innervates the ) exors of the elbow and
continues distal to the joint as the lateral cutaneous nerve of the forearm.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
MEDIAN NERVE
Arising from the C5-8 and T1 nerve roots, the median nerve enters the anterior aspect of
the brachium, crossing in front of the brachial artery as it passes across the intermuscular
septum. It follows a straight course into the medial aspect of the antecubital fossa, medial
to the biceps tendon and the brachial artery. It then passes under the bicipital
aponeurosis. The , rst motor branch is provided to the pronator teres, through which it
2,39passes. It enters the forearm and continues distally under the ) exor digitorum
superficialis within the fascial sheath of this muscle.
There are no branches of the median nerve in the arm (Fig. 2-38). In the cubital fossa,
a few small articular branches are given oI before the motor branches to the pronator
teres, the ) exor carpi radialis, the palmaris longus, and the ) exor digitorum super, cialis.
Because all branches arise medially, medial retraction of the nerve during exposure of the
anterior aspect of the elbow is a safe technique.FIGURE 2-38 The median nerve innervates the ) exor pronator group of muscles about
the elbow, but there are no branches above the joint.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
The anterior interosseous nerve innervates the ) exor pollicis longus and the lateral
portion of the ) exor digitorum profundus. It arises from the median nerve near the
inferior border of the pronator teres and travels along the anterior aspect of the
interosseous membrane in the company of the anterior interosseous artery.
RADIAL NERVE
The radial nerve is a continuation of the posterior cord and originates from the C6, C7,
and C8 nerve roots withvariable contributions of the C5 and T1 roots. In the midportion
of the arm, the nerve courses laterally just distal to the deltoid insertion to occupy the
spiral groove in the humerus that bears its name. Before entering the anterior aspect of
the arm, it gives oI motor branches to the medial and lateral head of the triceps,
accompanied by the deep branch of the brachial artery. It then emerges inferiorly and
laterally to penetrate the lateral intermuscular septum. The nerve is at risk for injury
from surgery or fracture at this site. Two recent studies have placed the position of the
22radial nerve as 54% of the acromion/ulnar distance or 1.7% of the transcondylar
41distance. After penetrating the lateral intermuscular septum in the distal third of the
arm, it descends anterior to the lateral epicondyle behind the brachioradialis. It
innervates the brachioradialis with a single branch to this muscle. In the antecubitalspace, the nerve divides into the super, cial and deep branches. The super, cial branch is
a continuation of the radial nerve and extends into the forearm to innervate the
middorsal cutaneous aspect of the forearm (Fig. 2-39).
FIGURE 2-39 The muscles innervated by the right radial nerve.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
The motor branches of the radial nerve are given oI to the triceps above the spiral
groove except for the branch to the medial head of the triceps, which originates at the
entry to the spiral groove. This branch continues distally through the medial head to
terminate as a muscular branch to the anconeus. This accounts for the variability of the
11,44,68anconeus when rotated or reflected from its origin.
In the antecubital space, the recurrent radial nerve curves around the posterolateral
aspect of the radius, passing deep to the supinator muscle, which it innervates. During its
course through the supinator muscle, the nerve lies over a bare area, which is distal to
23and opposite to the radial tuberosity. The nerve is believed to be at risk at this site with
79fractures of the proximal radius. It emerges from the muscle as the posterior
interosseous nerve, and the recurrent branch innervates the extensor digitorum minimi,
the extensor carpi ulnaris, and occasionally, the anconeus. The posterior interosseous
nerve is accompanied by the posterior interosseous artery and sends further muscle
branches distally to supply the abductor pollicis longus, the extensor pollicis longus, the
extensor pollicis brevis, and the extensor indicis on the dorsum of the forearm. The nerve15is subject to compression as it passes through the supinator muscle or from synovial
25,28proliferation. Compression and entrapment problems are described in detail in
Chapter 81.
ULNAR NERVE
The ulnar nerve is derived from the medial cord of the brachial plexus from roots C8 and
T1. In the midarm, it passes posteriorly through the medial intermuscular septum and
continues distally anterior to the septum and under the medial margin of the triceps. It is
accompanied by the superior ulnar collateral branch of the brachial artery and the ulnar
collateral branch of the radial artery. Although supposedly there are no branches of this
nerve in the brachium, an occasional motor branch to the triceps is encountered (Fig.
240). The ulnar nerve passes into the cubital tunnel under the medial epicondyle and rests
against the posterior portion of the medial collateral ligament, where a groove in the
ligament accommodates this structure. The roof of the cubital tunnel recently has been
64de, ned and termed the cubital tunnel retinaculum. Retinacular absence accounts for
congenital subluxation of the ulnar nerve. Furthermore, the structure ) attens with elbow
64flexion, thus decreasing the capacity of the cubital tunnel (Fig. 2-41). This accounts for
the clinical observation of ulnar nerve paresthesia with elbow ) exion. Similarly, elbow
51instability can cause traction injury to the nerve.
FIGURE 2-40 Muscles innervated by the right ulnar nerve. There are no muscular
branches of this nerve above the elbow joint.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,W. B. Saunders Co., 1976.)
FIGURE 2-41 With ) exion the cubital tunnel ) attens, compressing the ulnar nerve (A
and B).
(Redrawn from O’Driscoll, S. W., Horii, E., Carmichael, S. W., and Morrey, B. F.: The cubital
tunnel and ulnar neuropathy. J. Bone Joint Surg. 73B:613, 1991.)
8A few small capsular twigs are given to the elbow joint in this region. As the nerve
enters the forearm between the two heads of the ) exor carpi ulnaris, it gives oI a single
nerve to the ulnar origin of the pronator and one to the epicondylar head of the ) exor
carpi ulnaris. Distally, the nerve sends a motor branch to the ulnar half of the ) exor
digitorum profundus. Two cutaneous nerves arise from the ulnar nerve in the distal half
of the forearm and innervate the skin of the wrist and the ulnar two digits of the hand.
MUSCLES
Relevant features of the origin, insertion, and function of the muscles of the elbow region
are covered in other chapters dealing with surgical exposure, functional examination,
and biomechanics. This information also is discussed in various chapters when dealing
with specific pathology. The following description will serve as a basic overview.
ELBOW FLEXORSBiceps
The biceps covers the brachialis muscle in the distal arm and passes into the cubital fossa
as the biceps tendon, which attaches to the posterior aspect of the radial tuberosity (Fig.
2-42). The constant bicipitoradial bursa separates the tendon from the anterior aspect of
the tuberosity, and the cubital bursa has been described as separating the tendon from
the ulna and the muscles covering the radius (see Fig. 2-9). The bicipital aponeurosis, or
lacertus , brosus, is a broad, thin band of tissue that is a continuation of the anterior
medial and distal muscle fasciae. It runs obliquely to cover the median nerve and
brachial artery and inserts into the deep fasciae of the forearm and possibly into the ulna
19as well.
FIGURE 2-42 Anterior aspect of the arm and elbow region demonstrating the major
flexors of the joint, the brachialis, and the biceps muscles.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
The biceps is a major ) exor of the elbow that has a large cross-sectional area but an
intermediate mechanical advantage because it passes relatively close to the axis of
6rotation. In the pronated position, the biceps is a strong supinator. The distal insertion
57,78may undergo spontaneous rupture, and this condition is discussed in detail later
(Chapter 34).
BrachialisThis muscle has the largest cross-sectional area of any of the elbow ) exors but suI ers
from a poor mechanical advantage because it crosses so close to the axis of rotation. The
origin consists of the entire anterior distal half of the humerus, and it extends medially
and laterally to the respective intermuscular septa (Fig. 2-43). The muscle crosses the
anterior capsule, with some , bers inserting into the capsule that are said to help retract
the capsule during elbow ) exion. The major attachment is to the coronoid process about
2 mm distal from its articular margin. More than 95% of the cross-sectional area is
50muscle tissue at the elbow joint, a relationship that may account for the high incidence
of trauma to this muscle and the development of myositis ossi, cans with elbow
84dislocation.
FIGURE 2-43 Anterior humeral origin and insertion of muscles that control ) exion of
the elbow joint.
The muscle is innervated by the musculocutaneous nerve. The lateral portion of the
muscle covers the radial nerve as it spirals around the distal humerus. The median nerve
and brachial artery are super, cial to the brachialis and lie behind the biceps in the distal
humerus.
Brachioradialis
The brachioradialis has a lengthy origin along the lateral supracondylar bony column
that extends proximally to the level of the junction of the mid and distal humerus (see
Fig. 2-43). The origin separates the lateral head of the triceps and the brachialis muscle.
The lateral border of the cubital fossa is formed by this muscle, which crosses the elbow
joint with the greatest mechanical advantage of any elbow ) exor. It progresses distally toinsert into the base of the radial styloid (Figs. 2-44 and 2-45). The muscle protects and is
innervated by the radial nerve (C5, C6) as it emerges from the spiral groove. Its major
35function is elbow flexion. Rarely, the muscle may be ruptured.
FIGURE 2-44 The musculature of the posterolateral aspect of the right forearm.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
FIGURE 2-45 Posterior view of the radius and ulna demonstrating the insertion of the
extensors of the elbow as well as the origin of the forearm musculature.
Extensor Carpi Radialis LongusThe extensor carpi radialis longus originates from the supracondylar bony column joint
just below the origin of the brachioradialis (see Fig. 2-44). The origin of this muscle is
identi, ed as the , rst ) eshy , bers observed proximal to the common extensor tendon. As
it continues into the midportion of the dorsum of the forearm, it becomes largely
tendinous and inserts into the dorsal base of the second metacarpal. Innervated by the
radial nerve (C6, C7), the motor branches arise just distal to those of the brachioradialis
muscle.
In addition to wrist extension, its orientation suggests that this muscle might function
as an elbow flexor.
Clinically, the origin of this muscle and its relationship with that of the extensor carpi
radialis brevis have been implicated in the pathologic anatomy of tennis elbow by Nirschl
(Chapter 44).
Extensor Carpi Radialis Brevis
The extensor carpi radialis brevis originates from the lateral superior aspect of the lateral
epicondyle (see Fig. 2-43). Its origin is the most lateral of the extensor group and is
covered by the extensor carpi radialis longus. This relationship is important as the most
commonly implicated site of lateral epicondylitis. The extensor digitorum communis
originates from the common extensor tendon and is just medial or ulnar to the extensor
carpi radialis brevis. At its humeral origin, the , bers of the extensor digitorum communis
32and brevis are grossly and histologically indistinguishable from one another (see Fig.
244). The longus and brevis shares the same extensor compartment as they cross the wrist
under the extensor retinaculum. The brevis inserts into the dorsal base of the third
metacarpal. The function of the extensor carpi radialis brevis is pure wrist extension,
1with little or no radial or ulnar deviation. The extensor carpi radialis brevis is
innervated by , bers of the sixth and seventh cervical nerves. The motor branch arises
from the radial nerve in the region of its division into deep and superficial branches.
Extensor Digitorum Communis
Originating from the anterior distal aspect of the lateral epicondyle, the extensor
digitorum communis accounts for most of the contour of the extensor surface of the
forearm (see Fig. 2-44). The muscle extends and abducts the , ngers. According to
Wright, the muscle can assist in elbow ) exion when the forearm is pronated. This
1observation is not, however, supported by our cross-sectional studies. Innervation is
from the deep branch of the radial nerve, with contributions from the sixth through
eighth cervical nerves.
Extensor Carpi Ulnaris
The extensor carpi ulnaris originates from two heads, one above and the other below the
elbow joint. The humeral origin is the most medial of the common extensor group (Fig.
246) (see also Fig. 2-43). The ulnar attachment is along the aponeurosis of the anconeus
and at the superior border of this muscle. It is a valuable landmark for exposures of the
lateral elbow joint. The insertion is on the dorsal base of the , fth metacarpal aftercrossing the wrist in its own compartment under the extensor retinaculum. The extensor
carpi ulnaris is a wrist extensor and ulnar deviator. Fibers of the sixth through eighth
cervical nerve routes innervate the muscle from branches of the deep radial nerve.
FIGURE 2-46 The extensor aspect of the forearm demonstrating the deep muscle layer
after the extensor digitorum and extensor digiti minimi have been removed.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
Supinator
This ) at muscle is characterized by the virtual absence of tendinous tissue and a complex
origin and insertion. It originates from three sites above and below the elbow joint: (1)
the lateral anterior aspect of the lateral epicondyle; (2) the lateral collateral ligament;
and (3) the proximal anterior crest of the ulna along the crista supinatoris. The form of
the muscle is approximately that of a rhomboid, because it runs obliquely, distally, and
radially to wrap around and insert diI usely on the proximal radius, beginning lateral
and proximal to the radial tuberosity and continuing distal to the insertion of the
pronator teres at the junction of the proximal and middle third of the radius (see Fig.
246). It is important to note that the radial nerve passes through the supinator to gain
access to the extensor surface of the forearm. This anatomic feature is clinically
signi, cant with regard to exposure of the lateral aspect of the elbow joint and the
76proximal radius and in certain entrapment syndromes.
The muscle obviously supinates the forearm but is a weaker supinator than the38biceps. Unlike the biceps, however, the eI ectiveness of the supinator is not altered by
the position of elbow ) exion. The innervation is derived from the muscular branch given
oI by the radial nerve just before and during its course through the muscle with nerve
fibers derived primarily from the sixth cervical root.
ELBOW EXTENSORS
Triceps Brachii
The entire posterior musculature of the arm is composed of the triceps brachii (see Fig.
239). The long head has a discrete origin from the infraglenoid tuberosity of the scapula.
The lateral head originates in a linear fashion from the proximal lateral intramuscular
septum on the posterior surface of the humerus. The medial head originates from the
entire distal half of the posteromedial surface of the humerus bounded laterally by the
radial groove and medially by the intramuscular septum. Thus, each head originates
distal to the other, with progressively larger areas of origin. The long and lateral heads
are super, cial to the deep medial head, blending in the midline of the humerus to form a
common muscle that then tapers into the triceps tendon and attaches to the tip of the
14olecranon with Sharpey’s fibers. The tendon usually is separated from the olecranon by
the subtendinous olecranon bursa. The distal 40% of the triceps mechanism consists of a
layer of fascia that blends with the triceps distally.
Innervated by the radial nerve, the long and lateral heads are supplied by branches
that arise proximal to the entrance of the radial nerve into the groove. The medial head is
innervated distal to the groove with a branch that enters proximally and passes through
the entire medial head to terminate by innervating the anconeus, an anatomic feature of
considerable importance when considering some approaches (e.g., Kocher, Bryan-Morrey,
Boyd, and Pankovitch) to the joint.
The function of the triceps is to extend the elbow. Lesions of the nerve in the
midportion of the humerus usually do not prevent triceps function that is provided by the
more proximally innervated lateral and long heads.
Subanconeus Muscle
The attachment of some muscle , bers of the medial head of the triceps to the
posteromedial capsule has been termed the subanconeus muscle. This may have some
functional relevance of stabilizing the fat pad to help cushion the elbow as it comes into
87full extension.
Anconeus
This muscle has little tendinous tissue because it originates from a rather broad site on
the posterior aspect of the lateral epicondyle and from the lateral triceps fascia and
inserts into the lateral dorsal surface of the proximal ulna (see Fig. 2-46). It is innervated
by the terminal branch of the nerve to the medial head of the triceps. Curiously, the
function of this muscle has been the subject of considerable speculation. Possibly the
most accurate description of function is that proposed by Basmajian and GriL n and by5,21DaHora, who suggest that its primary role is that of a joint stabilizer. The muscle
covers the lateral portion of the annular ligament and the radial head. For the surgeon,
the major signi, cance of this muscle is its position as a key landmark in various lateral
and posterolateral exposures and is emerging for usefulness reconstruction of the lateral
elbow.
FLEXOR PRONATOR MUSCLE GROUP
Pronator Teres
This is the most proximal of the ) exor pronator group. There are two heads of origin: The
largest arises from the anterosuperior aspect of the medial epicondyle and the second
from the coronoid process of the ulna, an attachment absent in about 10% of
39individuals (see Fig. 2-37). The two origins of the pronator muscle provide an arch
through which the median nerve passes to gain access to the forearm. This anatomic
characteristic is a signi, cant feature in the etiology of the median nerve entrapment
syndrome and is discussed in detail in Chapter 80. The common muscle belly proceeds
radially and distally under the brachioradialis, inserting at the junction of the proximal
and middle portions of the radius by a discrete broad tendinous insertion into a
tuberosity on the lateral aspect of the bone. Obviously, a strong pronator of the forearm,
1,7,82it also is considered a weak ) exor of the elbow joint. The muscle usually is
innervated by two motor branches from the median nerve before the nerve leaves the
cubital fossa.
Flexor Carpi Radialis
The ) exor carpi radialis originates just inferior to the origin of the pronator teres and the
common ) exor tendon at the anteroinferior aspect of the medial epicondyle (see Fig.
243). It continues distally and radially to the wrist, where it can be easily palpated before
it inserts into the base of the second and sometimes the third metacarpal. Proximally, the
muscle belly partially covers the pronator teres and palmaris longus muscles and shares a
common origin from the intermuscular septum, which it shares with these muscles. The
innervation is from one or two twigs of the median nerve (C6, C7), and its chief function
1,24is as a wrist flexor. At the elbow no significant flexion moment is present.
Palmaris Longus
This muscle, when present, arises from the medial epicondyle, and from the septa it
shares with the ) exor carpi radialis and ) exor carpi ulnaris (see Fig. 2-43). It becomes
tendinous in the proximal portion of the forearm and inserts into and becomes
continuous with the palmar aponeurosis. It is absent approximately in 10% of
71extremities. Its major function is as a donor tendon for reconstructive surgery, and it is
innervated by a branch of the median nerve.
Flexor Carpi Ulnaris
The ) exor carpi ulnaris is the most posterior of the common ) exor tendons originatingfrom the medial epicondyle (see Figs. 2-38 and 2-43). A second and larger source of
origin is from the medial border of the coronoid and the proximal medial aspect of the
ulna. The ulnar nerve enters and innervates (T7-8 and T1) the muscle between these two
sites of origin with two or three motor branches given oI just after the nerve has entered
the muscle. These are the , rst motor branches of the ulnar nerve, and therefore, they are
useful in localizing the level of an ulnar nerve lesion. The muscle continues distally to
insert into the pisiform, where the tendon is easily palpable, because it serves as a wrist
) exor and ulnar deviator. With an origin posterior to the axis of rotation, weak elbow
1extension also may be provided by the flexor carpi ulnaris.
Flexor Digitorum Superficialis
This muscle is deep to those originating from the common ) exor tendon but super, cial to
the ) exor digitorum profundus; thus, it is considered the intermediate muscle layer. This
broad muscle has a complex origin (Fig. 2-47). Medially, it arises from the medial
epicondyle by way of the common ) exor tendon and possibly from the ulnar collateral
38ligament and the medial aspect of the coronoid. The lateral head is smaller and thinner
and arises from the proximal two thirds of the radius. The unique origin of the muscle
forms a , brous margin under which the median nerve and the ulnar artery emerge as
they exit from the cubital fossa. The muscle is innervated by the median nerve (C7, C8,
T1) with branches that originate before the median nerve enters the pronator teres. The
action of the ) exor digitorum super, cialis is ) exion of the proximal interphalangeal
joints.
FIGURE 2-47 The ) exor digitorum super, cialis is demonstrated after the palmarislongus and ) exor carpi radialis has been removed. The pronator teres has been transected
and reflected. The important relationships of the nerves and arteries should be noted.
(Redrawn from Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia,
W. B. Saunders Co., 1976.)
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intraosseous arterial anatomy of the adult elbow. J. Bone Joint Surg.. 1997;79A:1653.CHAPTER 3
Biomechanics of the Elbow
Kai-Nan An, Mark E. Zobitz, Bernard F. Morrey
INTRODUCTION
Upper extremity use depends largely on a functional elbow joint. A complex joint, the
elbow serves as a link in the lever arm system that positions the hand, as a fulcrum of the
forearm lever, and as a load-carrying joint. Mobility and stability of the elbow joint are
necessary for daily, recreational, and professional activities. Loss of function in the elbow,
possibly more than that in any other joint, can jeopardize individual independence.
In our practice, a working knowledge of biomechanics has been extremely important
and rewarding. Clinical relevance includes elbow joint design and technique, the
rationale and execution of trauma management, and ligament reconstruction. In short, a
5clear understanding of biomechanics provides a scientific basis for clinical practice.
From the clinician’s perspective, we have found the topic of elbow mechanics best
discussed according to motion (kinematics), stability (constants), and strength (force
transmission).
KINEMATICS
The elbow is described as a trochoginglymoid joint. That is, it possesses 2 degrees of
freedom (motion): - exion-extension and supination-pronation. The articular components
include the trochlea and capitellum on the medial and lateral aspects of the bifurcated
distal humerus, and distally the upper end of the ulna and the head of the radius. Thus,
the joint is composed of three articulations: the radiohumeral, the ulnohumeral, and the
radioulnar.
FLEXION-EXTENSION
Because of the congruity at the ulnohumeral articulation and surrounding soft tissue
constraint, elbow joint motion is considered primarily a hinge type. Yet, two separate
three-dimensional studies of passive motion at the elbow revealed that the elbow does not
51,69function as a simple hinge joint. The position of the axis of elbow - exion, as
measured from the intersection of the instantaneous axis with the sagittal plane, follows
69an irregular course. A type of helical motion of the - exion axis has been demonstrated.
26,50,61This pattern was previously suggested and was attributed to the obliquity of the
52trochlear groove along which the ulna moves. An electromagnetic tracking device that
allows a three-dimensional measurement of simulated active elbow joint motion reveals
the amount of potential varus-valgus and axial laxity that occurs during elbow - exion toaverage about 3 to 4 degrees. This has been con6rmed with more advanced
101electromagnetic tracking technology.
CENTER OF ROTATION
The axis of motion in - exion and extension has been the subject of many
60investigations. Fischer (1909), using Reuleaux’s technique, found the so-called locus of
the instant center of rotation to be an area 2 to 3 mm in diameter at the center of the
34trochlea (Fig. 3-1). Subsequent experiments with the same technique described a much
32larger locus. In a three-dimensional study of passive motion of the elbow joint, the
69observations of Fischer were con6rmed by using the biplanar x-ray technique. Based
109on direct experimental study as well as analytic investigation, Youm and associates
concluded that the axis does not change during - exion-extension. In our study, however,
variations of up to 8 degrees in the position of the screw axis from individual to
individual have been shown. As seen from below, the axis of rotation is internally rotated
3 to 8 degrees relative to the plane of the epicondyles. In the coronal plane, a line
perpendicular to the axis of rotation forms a proximally and laterally opening angle of 4
105to 8 degrees with the long axis of the humerus. These data, coupled with the clinical
information regarding implant loosening, have inspired the development of less
constrained but coupled elbow joint replacement designs. It recently has been
demonstrated that these designs do function as semiconstrained implants and allow for
75the normal out-of-plane rotations noted earlier (see Chapter 49).
FIGURE 3-1 Con6guration and dimensions of the locus of the instant center of rotation
of the elbow. This axis runs through the center of the articular surface, as viewed on both
the anteroposterior (AP) and the lateral planes.<
<
<
From a practical point of view, despite the di erent 6ndings of various investigators,
the deviation of the center of joint rotation is minimal and the reported variation is
probably due to limitations in the experimental design. Thus, the ulnohumeral joint could
be assumed to move as a uniaxial articulation except at the extremes of - exion and
extension. The axis of rotation passes through the center of the arcs formed by the
56trochlear sulcus and capitellum.
The center of rotation can be identi6ed from external landmarks. In the sagittal plane,
92the axis lies anterior to the midline of the humerus and lies on a line that is colinear
69with the anterior cortex of the distal humerus. The coronal orientation is de6ned by the
19plane of the posterior cortex of the distal humerus. This axis emerges from the center of
the projected center of the capitellum and from the anteroinferior aspect of the medial
epicondyle (see Fig. 3-1).
Similarly, the e ect of altering the center of rotation on the kinematics of the forearm
has been recently studied. Alterations of as much as 5 mm proximally, distally,
anteriorly, or posteriorly have been shown to have only a slight e ect on elbow
kinematics (Fig. 3-2). This observation has great clinical relevance regarding the design
and insertion of prosthetic replacement and articulating external fixation devices.<
FIGURE 3-2 Experimental data using the electromagnetic tracking system reveals 5-mm
changes in the elbow axis site (A) and causes relatively small e ects in the kinematics of
the forearm (B).
FOREARM ROTATION
The radiohumeral joint, which forms the lateral half of the elbow joint, has a common
transverse axis with the elbow joint, which coincides with the ulnohumeral axis during
- exion-extension motion. In addition, the radius rotates around the ulna, allowing for
forearm rotation or supination-pronation. In general, the longitudinal axis of the forearm
is considered to pass through the convex head of the radius in the proximal radioulnar
joint and through the convex articular surface of the ulna at the distal radioulnar
34,97joint. The axis therefore is oblique to the longitudinal axes of both the radius and45the ulna (Fig. 3-3), and rotation is independent of elbow position.
FIGURE 3-3 The longitudinal axis of pronation-supination runs proximally from the
distal end of the ulna to the center of the radial head. The axis is at the ulnar cortex in the
distal one third of the forearm.
Mori has characterized the axis of forearm rotation as passing through the attachment
of the interosseous membrane at the ulna in the distal fourth of the forearm (see Fig.
36232). This may have particular applications with regard to the sensitivity of forearm
rotation to angular deformity in this particular portion of the bone. Clinically and
experimentally, less than 10% angulation of either the radius or the ulna causes no
91functionally significant loss of forearm rotation.FIGURE 3-32 A, Pressure distribution on elbow joint surface as external load P is
applied at the distal end of the ulna. Distribution of muscle force, F and F , in- uencese f
the magnitude, R, and the direction, F, of resultant force on the elbow joint. F represents
the “attempted displacement,” U, of the humerus relative to the direction of the ulna. B,
For the given loading condition, resultant joint force increased with increasing
involvement of extensor muscle, as represented by the ratio of extension force F to - exore
force F (top). Peak articular pressure and the direction of the attempted displacement off
the humerus also are affected by the level of involvement of extensor muscle (bottom).
(From An, K. N., Himeno, S., Tsumura, H., Kawai, T., and Chao, E. Y.: Pressure distribution on
articular surfaces: Application to joint stability evaluation. J. Biomech. 23:1013, 1990.)
106In the past, ulnar rotation was described as being coupled with forearm rotation.
This observation could not be reproduced in a subsequent study by Youm and
108associates. By using a metal rod introduced transversely into the ulna, extension,
lateral rotation, and then - exion of the ulna was described with rotation from pronation
to supination. The axial rotational movements of the ulna were also observed by
14,22,30,43,69,88,108others.<
88Ray and associates also suggested that varus-valgus movement of the ulna occurs if
the forearm rotates on an axis extending from the head of the radius to the index 6nger.
76Experiments from our laboratory have demonstrated external axial rotation of the ulna
with forearm supination. Internal rotation or closure of the lateral ulnohumeral joint
occurs with pronation.
67Finally, the radius has been shown to migrate 1 to 2 mm proximally with pronation.
This observation had not been reported previously but has been con6rmed by
82observations at the wrist.
CARRYING ANGLE
The carrying angle is de6ned as that formed by the long axis of the humerus and the long
axis of the ulna. It averages 10 to 15 degrees in men and is about 5 degrees greater in
1,18,53,97women.
However, uncertainty has arisen over the use of the term carrying angle in the dynamic
27setting. Dempster described an oscillatory pattern during elbow - exion, whereas
69Morrey and Chao reported a linear change, with the valgus angle being the greatest at
full extension and diminishing during - exion. The confusion arises because three
descriptions based on di erent reference systems have been adopted for the measurement
of carrying angle changes.
Definition 1
The carrying angle is the acute angle formed by the long axis of the humerus as the long
axis of the ulna projects on the plane containing the humerus (Fig. 3-4A).
FIGURE 3-4 A, Carrying angle between the humerus and the ulna as measured byviewing from the direction perpendicular to the plane containing the humeral and the
- exion axes. Conventionally, the acute angle instead of the obtuse angle shown is used as
the carrying angle measurement. B, Carrying angle between humerus and ulna as
measured by viewing from the direction perpendicular to the plane containing the ulnar
and - exion axes. Conventionally, the acute angle instead of the obtuse angle shown is
based as the carrying angle measurement.
(From An, K. N., Morrey, B. F., and Chao, E. Y. S.: Carrying angle of the human elbow joint. J.
Orthop. Res. 1:369, 1984.)
Definition 2
The carrying angle is described as the acute angle formed by the long axis of the ulna
and the projection of the long axis of the humerus onto the plane of the ulna (see Fig.
34B).
Definition 3
The carrying angle is de6ned analytically as the abduction-adduction angle of the ulna
with respect to the humerus when eulerian angles are being used to describe arm motion.
From an anatomic point of view, it is not diC cult to conclude that the existence of the
carrying angle is due to the existence of obliquities, or cubital angles, between the
proximal humeral shaft, the trochlea, and the distal ulnar shaft. By assuming that the
ulnohumeral joint is a pure hinge joint and that the axis of rotation coincides with the
axis of the trochlea, the change in the carrying angle during - exion can be de6ned as a
function of anatomic variations of the obliquity of the articulations according to simple
8trigonometric calculations. If the 6rst or second de6nition is accepted, the carrying
angle changes minimally during - exion. The speci6c varus/valgus relationship of the
forearm to the humerus during - exion therefore depends on the relative angular
relationship of the humeral and ulnar articulations (Fig. 3-5).
FIGURE 3-5 The positional relationship of the forearm referable to the humerus in thefrontal plane of the humerus (carrying angle) is dependent on the relative tilt of the
humeral and ulnar articulations referable to their long axes.
RESTRICTION OF MOTION
In normal circumstances, elbow - exion ranges from 0 degrees or slightly hyperextended
to about 150 degrees in - exion. Forearm rotation averages from about 75 degrees
(pronation) to 85 degrees (supination) (see Chapter 2). The cartilage of the trochlea forms
an arc of about 320 degrees, whereas the sigmoid notch creates an arc of about 180
97degrees. Generally, the arc of the radial head depression is about 40 degrees, which
articulates with the capitellum, presenting an angle of 180 degrees.
The signi6cance of the 30-degree anterior angulation of the trochlea with the
30degree posterior orientation of the greater sigmoid notch to - exion and extension and
stability of the elbow joint is discussed in detail in Chapter 1 (Fig. 3-6). Impact of the
olecranon process on the olecranon fossa and the tension of the anterior ligament and the
- exor muscles as well as tautness of the anterior bundle of the medial collateral ligament
40,52have been described as serving as a check to extension. The anterior muscle bulk of
the arm and forearm, along with contraction of the triceps, is also reported to prevent
52active - exion beyond 145 degrees. However, the factors limiting passive - exion
include the impact of the head of the radius against the radial fossa, the impact of the
coronoid process against the coronoid fossa, and tension from the capsule and triceps.
FIGURE 3-6 The distal humeral forward - exion is complemented by a 30-degree
posterior rotation of the opening of the greater sigmoid notch.
(With permission, Mayo Foundation.)
20For pronation and supination, Braune and Flugel found that passive resistance of the
stretched antagonistmuscle restricts the excursion range more than that of the
96ligamentous structures. Spinner and Kaplan, however, have shown that the quadrate
ligament does provide some static constraint to forearm rotation. Impingement of tissue
restrains pronation, especially by the - exor pollicis longus, which is forced against the
deep 6nger - exors. The entire range of active excursion in an intact arm is about 150
degrees, whereas when the muscles are removed from a cadaver specimen, the range
increases to 185 to 190 degrees. With cutting the ligaments, the range increased up to<
205 to 210 degrees.
CAPACITY AND CONTACT AREA OF THE ELBOW JOINT
The capacity of the elbow joint recently has been shown to average about 25 mL. The
78maximum capacity is observed to occur with the elbow at about 80 degrees of - exion.
This explains the clinical observation that sti elbows tend to have 6xed deformities at
63about 80 to 90 degrees of flexion.
Accurate measurement of the contact points of the elbow is extremely diC cult, and
99several techniques have been applied to this highly congruous joint. Silicone casting,
Fuji Prescale 6lm, and reversible cartilage staining are most commonly used. Each has
advantages and disadvantages. The contact area of the articular surface during elbow
joint motion has been investigated by Goodfellow and Bullough, using a staining
39technique. They found that the central depression of the radial head articulates with
the dome of the capitellum and that the medial triangular facet was always in contact
with the ulna. The upper rim of the radial head made no contact at all. At the
humeroulnar joint, the articular surfaces were always in contact during some phases of
107movement. Others have veri6ed these observations. The contact areas on the ulna
occurred anteriorly and posteriorly and tended to move together and slightly inward from
31,74each side from 0 to 90 degrees of - exion and with increasing load. Using a wax
casting technique, in full extension, the contact has been observed to be on the lower
medial aspect of the ulna, whereas in other postures, the pressure areas described a strip
37extending from posterolateral to anteromedial. The radiocapitellar joint also revealed
contact during - exion without externally applied load. Investigations in our laboratory
show that the contact areas of the elbow occur at four facets: two at the coronoid and two
at the olecranon (Fig. 3-7). Only a slight increase in total surface area occurred with
99elbow - exion and with a sevenfold increase in load. With a 10-N load, about 9%
contact of the articular surfaces occurs, and with 1280 N, the area increased to about
3173%.
FIGURE 3-7 Contact in the sigmoid fossa moves toward the center of the fossa duringelbow flexion.
(Redrawn from Walker, P. S.: Human Joints and Their Artificial Replacements. Springfield, IL,
Charles C. Thomas, 1977.)
When varus and valgus loads are applied to the forearm, the contact changes medially
and laterally. This implies a pivot point about which the radioulnar articulation rotates
on the humerus in the anteroposterior (AP) plane in extension with varus and valgus
stress. In vivo experiments have demonstrated the varus-valgus pivot point of the elbow
to reside in the midpoint of the lateral face of the trochlea (Fig. 3-8).
FIGURE 3-8 The line of action in the muscles produces a compression force at the radial
head when situated just lateral to the middle of the lateral face of the trochlea, and a
tension force on the radial head is situated just medial to this point. This indicates that the
varus-valgus pivot point in the elbow lies at that point on the AP plane.
(From Morrey, B. F., An, K. N., and Stormont, T. J.: Force transmission through the radial head.
J. Bone Joint Surg. [Am.] 70:250-256, 1988.)
ELBOW STABILITY
The elbow is one of the most congruous joints of the musculoskeletal system and, as such,
is one of the most stable. This feature is the result of an almost equal contribution from
the soft tissue constraints and the articular surfaces.
The static soft tissue stabilizers include the collateral ligament complexes and the
anterior capsule. Studies from our laboratory regarding the anatomy of the lateral
68,77 36,79,95collateral ligament and others have been discussed previously (see Chapter
2). The lateral collateral ligament and the anterior bundle of the medial collateral
ligament originate from points through which the axis of rotation passes. Furthermore,
66,93the medial collateral ligament has two discrete components. The anterior bundle
has been shown to be taut in extension; the converse is true for the posterior 6bers of the
anterior bundle. Because elbow joint motion occurs about a nearly perfect hinge axis
through the center of the capitellum and trochlea, the posterior bundle of the medial<
<

collateral ligament complex will be taut at di erent positions of elbow - exion (Fig. 3-9).
The lateral collateral ligament and the anterior bundle lying on the axis of rotation will
assume a rather uniform tension, regardless of elbow position. Furthermore, the lateral
ulnar collateral ligament has inserts on the ulna and, as such, helps to stabilize the lateral
23,66,77,81ulnohumeral joint (Fig. 3-10). In experiments performed in our laboratory,
O’Driscoll and associates have demonstrated that the lateral ulnar collateral ligament is
essential to control the pivot shift maneuver (see Chapter 4). Further evidence of the
contribution of the lateral ligament complex to elbow stability is o ered by S∅jbjerg and
94associates. These investigators also attributed a major role in varus and valgus stability
to the annular ligament. Although our work suggests that the major component in the
varus and rotatory stability is the structure termed the lateral ulnar collateral ligament,
the parallel 6ndings of these investigators suggest that the lateral complex is, in fact, a
major valgus stabilizer of the elbow joint and functions with or without the radial
80head.
FIGURE 3-9 The anterior medial collateral ligament remains more taut during elbow
- exion than does the posterior segment of the ligament. The radial collateral ligament
originates at the axis of rotation for elbow - exion; hence, the ligament has little length
variation during flexion and extension.
(With permission, Mayo Foundation.)FIGURE 3-10 The orientation and attachment of the lateral collateral ligament
stabilizes the ulna to resist varus and rotatory stresses just as the medial ligament resists
valgus stress.
ARTICULAR AND LIGAMENTOUS INTERACTION
The in- uence of the ligamentous and articular components on joint stability are usually
studied with the use of the materials testing machine by imparting a given and controlled
47,65,87displacement to the elbow. The relative contribution of each stabilizing structure
can be demonstrated by sequentially eliminating each element and observing the load
recorded by the load cell for the constant displacement imparted, usually 2 to 5
95degrees (Fig. 3-11).FIGURE 3-11 Force displacement curves demonstrate relative contribution of elements
to elbow stability in extension (A) and flexion (B).
(From Morrey, B. F., and An, K. N.: Articular and ligamentous contributions to the stability of
the elbow joint. Am. J. Sports Med. 11:315, 1983.)
A simpli6ed summary of the observations from such an experiment is shown in Table
3-1. In extension, the anterior capsule provides about 70% of the soft tissue restraint to
distraction, whereas the medial collateral ligament assumes this function at 90 degrees of
- exion. Varus stress is checked in extension equally by the joint articulation (55%) and
the soft tissue, lateral collateral ligament, and capsule. In - exion, the articulation
provides 75% of the varus stability. Valgus stress in extension is equally divided between
the medial collateral ligament, the capsule, and the joint surface. With - exion, the
capsular contribution is assumed by the medial collateral ligament, which is the primary
stabilizer (54%) to valgus stress at this position. Furthermore, for all practical purposes,
the anterior portion of the medial collateral ligament provides virtually all of the
structure’s functional contribution.
TABLE 3-1 Percent Contribution of Restraining Varus-Valgus Displacement<
Limitations of this experimental model have resulted in an overestimation of the role of
47,65,90the radial head inresisting valgus load. This has prompted the development of an
experimental technique that allows simultaneous and accurate measurement of
threedimensional angular and translational changes under given loading conditions (Fig.
312). Using the electromagnetic tracking device, an accurate technique for measuring the
70function of the articular and capsuloligamentous structures was developed. More
70accurate and relevant data were generated. Valgus stability is resisted primarily by the
medial collateral ligament. With an intact medial collateral ligament, the radial head
does not o er any signi6cant additional valgus constraint. With a released or
compromised medial collateral ligament, the radial head does resist valgus stress. This
important experiment documents that the radial head is a secondary stabilizer for
resisting valgus stress, whereas the medial collateral ligament is the primary stabilizer
against valgus force (Fig. 3-13). In a laboratory investigation, the hyperextension trauma
produces lesions of the anterior capsule, the avulsion of proximal insertions of both
103medial and lateral collateral ligaments. The degree of extension increased by 17
degrees and induced signi6cant joint laxity in forced valgus internal-external rotation,
103but not varus.
FIGURE 3-12 The arrangement of the electromagnetic tracking device allows
varusvalgus stresses applied to the elbow during simulated motion with the - exor and extensor
muscles. Real-time simultaneous three-dimensional motion of the forearm may be<
<
<
monitored with reference to the humerus.
FIGURE 3-13 The stabilizing role of the radial head to valgus stress with the collateral
intact resection of the radial head has little e ect on valgus stability (A). However, if the
medial collateral ligament (MCL) has been sectioned, the absence of a radial head
markedly increases valgus displacement (B). The fact that the radial head is important
only when the medial collateral ligament is released de6nes the radial head as the
secondary stabilizer against valgus stress.
It has been recently observed that the valgus and varus laxity of the elbow is
86dependent on forearm rotation. Increased valgus/varus laxity with forearm pronation,
particularly in medial collateral ligament de6cient elbows, implies a possible additional
factor in throwing kinematics that might put professional baseball pitchers at risk of
medial collateral ligament injury due to chronic valgus overload. The forearm rotation
should be considered during the clinical examination of elbow instability. The stabilizing
e ects of monoblock and bipolar designs of radial head replacements in cadaver elbows
85with a de6cient medial collateral ligament were studied. The constraint mechanism
inherent in the implant design signi6cantly a ected the mean valgus laxity. The implants
all performed similarly except in neutral forearm rotation, in which the elbow laxity
associated with the Judet implant was signi6cantly greater than that associated with the
other two implants.
Comminuted radial head fractures associated with an injury of the medial collateralligament can be treated with a radial head implant. However, lengthening and
shortening of the radial neck by 2.5 mm signi6cantly alters the kinematics and contact
pressure through the radiocapitellar joint in the medial collateral ligament-de6cient
104elbow (Fig. 3-14). Radial neck lengthening caused a signi6cant decrease in
varusvalgus laxity and ulnar rotation, with the ulna tracking in varus and external rotation.
Shortening caused a signi6cant increase in varus-valgus laxity and ulnar rotation, with
the ulna tracking in valgus and internal rotation. Therefore, a radial head replacement
should be performed with the same level of concern for accuracy and reproducibility of
component position and orientation as is appropriate with any other prosthesis.
FIGURE 3-14 Average varus (-) or valgus (+) position of the ulna under different radial
neck shortening and lengthening conditions, with the application of valgus (top line) or
varus (bottom line) gravitational stress.
(From Van Glabbeek, F., Van Riet, R. P., Baumfeld, J. A., Neale, P. G., O’Driscoll, S. W.,
Morrey, B. F., and An, K. N.: Detrimental effects of overstuffing or understuffing with a radial
head replacement in the medial collateral-ligament deficient elbow. J. Bone Joint Surg. [Am.]
86:2629, 2004.)
Total elbow arthroplasty has been a valuable procedure for treating patients with
rheumatoid arthritis, post-traumatic arthritis, osteoarthritis, and failed reconstructive
procedures of the elbow. The development of elbow prostheses diverged into two general
types: linked and unlinked. The main concern with such development of unlinked elbow
replacements is instability, which is attributable to numerous factors including prosthesis
design, ligament integrity, and position of the prosthesis. A series of laboratory studies
have been performed to examine the intrinsic constraint of various total elbow
6arthroplasty designs, as well as the joint laxity after implantation in cadaveric specimens
(Fig. 3-15).<
<
FIGURE 3-15 Joint laxity for human elbow and with total elbow replacement including
the Souter-Strathclyde, Sorbie-Questor, Pritchard ERS, Ewald Capitellocondylar, GSB III,
Norway Elbow, and Coonrad Morrey implants.
(From An, K. N.: Kinematics and constraint of total elbow arthroplasty. J. Shoulder Elbow Surg.
14:168S, 2005.)
The contribution of the articular geometry to elbow stability was further evaluated by
13serial removal of portions of the proximal ulna, as shown in Figure 3-16. Valgus stress,
both in extension and at 90 degrees of - exion, was primarily (75% to 85%) resisted by
the proximal half of the sigmoid notch, whereas varus stress was resisted primarily by the
distal half, or the coronoid portion of the articulation, both in extension (67%) and in
flexion (60%).
FIGURE 3-16 Removal of successive portions of the proximal ulna was studied for its
e ect on various modes of joint stability. A linear decrease of combined stability is
observed, with removal of the olecranon. Note a similar e ect for both the extended and
the 90-degree flexed positions.
As demonstrated in subsequent chapters, the central role of the coronoid to provide<
elbow stability is emerging. As serial portions of the coronoid are removed, the elbow
becomes progressively more unstable. If the radial head has been resected, as little as
25% resection causes elbow subluxation at about 70 degrees of - exion. Our preliminary
studies indicate at least 50% of the coronoid is necessary for elbow stability if the radial
head is removed (Fig. 3-17).
FIGURE 3-17 Ulnohumeral instability increases as increasing amounts of coronoid are
removed. Resection of 50% of the coronoid can still be stable, but not if the radial head is
excised.
FORCE ACROSS ELBOW JOINT
Study of the force across the elbow joint is not an easy task. The analysis can be
performed at various degrees of sophistication. It can be either two-dimensional or
threedimensional, static or dynamic, with or without the hand activities. The clinical
implications of these forces are obvious, but the magnitudes are not common knowledge.
Consequently, in this section, the factors that a ect the force passing through the elbow
joint will 6rst be analyzed in detail based on two-dimensional considerations. Then, more
realistic data based on three-dimensional analysis will be presented.
TWO-DIMENSIONAL ELBOW FORCE ANALYSIS
In sagittal plane motion, the elbow joint is assumed to be a hinge joint. Forces and
moments created at the joint, due to the loads applied at the hand, are balanced by the
muscles, tendons, ligaments, and contact forces on the articular surfaces. The amount of
tension in the muscles and the magnitude and direction of the joint forces are determined
by the external loading conditions as well as the responses of muscles-that is, force
distribution among these muscles.
To calculate these forces, a free-body analysis of the forearm and hand isolated at the
elbow joint is required. From this analysis, a set of equilibrium equations is obtained:
[1]
thin which | F | = magnitude of the tension in i muscle;if , f = components in x and y direction for the unit vector along the line of action ofxi yi
muscle;
R , R = x and y components of the joint contact force;x y
P, P , P = magnitude of the applied forces on the forearm and its associatedx y
components; and
r , r = moment arms of the muscle force and the applied force to the elbow jointi p
center, respectively
2,8,84The lines of action of muscles crossing the joint have been reported. In the
sagittal plane, based on the magnitude of moment arms, the major elbow muscles consist
of biceps, brachialis, brachioradialis, extensor carpi radialis longus, triceps, and anconeus
(Table 3-2). The other forearm muscles for the hand and wrist provide various but
limited contributions to elbow - exion-extension. Unfortunately, the contributions of these
forearm muscles are not consistently reported in the literature.
TABLE 3-2 Physiologic Cross-Sectional Area (PCSA), Unit Force Vector (Fx, Fy), and
Moment Arm (r) of Elbow Muscles in Sagittal Plane
Assuming that friction and ligament forces are negligible, the resultant joint constraint
force vector should be perpendicular to the arc of the articular surface and pass through
the center of curvature of this arc. Thus, the problem of elbow force analysis may be
reduced to one of solving the unknown variables R , R , and | F | in equation [1].x y i
However, in reality, even for a simple task, multiple muscles are involved, making the
force calculation an indeterminate problem. Methods for resolving these indeterminate
problems are thus required.
Single-Muscle Analysis<
The simplest case is to consider only one single muscle involved in resisting external
force. This type of consideration has been used widely in the literature for
twodimensional force analysis of the musculoskeletal system. The magnitude of the muscle
force, f, and the magnitude and orientation of the joint reaction force, R, can be obtained
by solving equation [1] with i = 1.
[2]
where , θ and are the angles between the forearm axis and the applied force, P,
muscle pull, M, and resultant joint force, R, respectively.
Thus, an intimate relationship between the joint force and muscle forces in balancing
the externally applied force on the forearm (Table 3-3) exists. The magnitude of muscle
force required for balancing the external force re- ects the changes of the muscle’s
moment arm, or mechanical advantage, with changes of the joint configuration.
Muscle and Joint Forces with Single Muscle*TABLE 3-3
Effect of Muscle Moment Arm
The e ect of a changing muscle moment arm on the resultant joint force is demonstrated
graphically in Figure 3-18. If the loading con6guration does not change, both the muscle
force and the joint reaction force decrease as the muscle moment arm increases. The
orientation of the resultant force also changes from the middle portion of the trochlear
notch toward the border of the articular cartilage.<
<
<
<
FIGURE 3-18 E ect on the muscle and joint forces by changing the moment arm of the
muscle force. For a given externally applied force, the longer moment arm decreases the
muscle and joint forces. Also, the resultant joint force and orientation (R1, R2, R3) are
affected by the magnitude of the muscle moment arm.
Clinically, the concept of increasing the moment arm of the biceps muscle by moving
the insertion distally has been adopted for increasing weak - exion force of the elbow in
72patients with brachial plexus injury.
Effect of Orientation on Muscle Line of Action
Under the same loading condition, the e ect of changing the orientation of the muscle
line of action under a constant moment arm is demonstrated (Fig. 3-19). The applied
force is again assumed to be perpendicular to the forearm. Both magnitudes of muscle
and joint reaction forces change slightly with the change of the muscle’s line of action.
However, the orientation of the resultant joint force is sensitive to changes in the muscle
force line. The orientation of the resultant joint force, therefore, moves from the central
portion of the trochlea toward the rim as the direction of muscle pull relative to the
forearm changes from vertical to parallel. This is especially true for the resultant joint
force in the trochlear notch brought about by the contraction of the upper arm muscles,
whose direction relative to the forearm axis changes with the elbow joint - exion angle.
On the other hand, the directions of forearm muscles with respect to the resultant joint
forces are thus reasonably constant. When considering the direction of resultant joint
forces applied on the trochlea, the e ects of upper arm and forearm muscles are just
reversed. These changes have been con6rmed and directly measured with a force
transducer at the proximal radius and di erent orientation of the line of action of the
67flexors and extensors.<
<
FIGURE 3-19 E ect of changing the orientation of the muscle line of action on the
muscle and joint force under a given load. The magnitudes of both muscle and joint forces
are not changed, but their orientations are.
Effect of the Moment Arm of External Force
With the orientations and moment arms of the muscles kept constant, the magnitude of
muscle force and joint force created to resist the externally applied force decrease
proportionally, with the decrease of the moment arm of the external force. This is true,
simply because the resultant segmental moment created at the elbow joint due to
externally applied load decreases when the moment arm decreases. It should be noticed
that the direction of resultant joint force also changes slightly. From the aforementioned
results, it is also easy to realize that the magnitude of the muscle and joint force increases
proportionally with increases in the magnitude of external force. Therefore, in general,
these results are usually expressed in terms of ratio to the external load.
Effect of the Direction of the Externally Applied Force
When the force applied at the wrist changes direction from vertical to horizontal, the
e ective moment arm of this applied force changes. The resultant segmental moment
about the elbow joint center due to this force changes as well (Fig. 3-20). Furthermore,
when the resultant segmental moments change from - exion to extension, the required
muscles also change from flexors to extensors.<
<
<
FIGURE 3-20 E ect of changes in the orientation of the applied force (χ), where 90
degrees is perpendicular to the long axis of the forearm.
Effect of Change in Axis of Rotation
The sensitivity of the muscle moment arm to the axis of rotation is a critically important
consideration in the clinical setting. Altering the axis by 1 cm anterior, posterior,
proximal, and distally has a surprisingly small e ect on the muscle moments at the
elbow. Such axis changes result in less than 10% change in muscle moment arm values
(Fig. 3-21).
FIGURE 3-21 A 1-cm alteration in the axis of - exion shows little e ect on muscle
moment arms.
In summary, the parametric analysis demonstrates that the magnitude and orientationof the resultant joint forces in the trochlear notch depend very much on whether the
upper arm or forearm muscles are used, as well as the location and orientation of the
external load applied on the forearm and the joint - exion angle that alters the moment
arm and orientation of the muscle line of action. However, alterations of the - exion axis
have little impact on muscle moment arm.
Multiple Muscle Analysis
In reality, when external loads are applied on the forearm, multiple muscles are involved,
and this makes the analyticdetermination of muscle and joint forces diC cult. Because the
magnitude and orientation of the resultant joint force are two unknown variables, if more
than one muscle force is involved the number of unknown variables exceeds the number
of available equations (three). This makes the problem indeterminate, and a nonunique
solution will result.
Several methods have been employed to resolve the indeterminate problem.
Electromyographic (EMG) data and the physiologic cross-sectional area may be used to
35,49provide an additional equation. The most commonly adopted techniques are
analytic reduction and optimization methods.
In the reduction method, the redundant unknown variables are systematically
eliminated, making the remaining system uniquely solvable. In a two-dimensional
analysis, this method is more or less the same as that which considers only one single
muscle, as described in the previous section. This method can usually provide the ranges
of magnitude and orientation of the resultant joint forces for a given task. However, the
technique may give physiologically unreasonable solutions, such as using one single
forearm muscle to resist the forearm load. Additional judgment and screening are thus
required.
With the use of the optimization method, a unique solution to an indeterminate
11problem is obtained by minimizing a preselected objective function or cost function.
Although the solution to the problem is still nonunique, each solution generally is
associated with some physiologic phenomenon or condition on which the objective
function is constructed and selected. This technique has been described in more detail
9elsewhere. Recently, the results based on various object functions have been compared
with EMG data regarding the muscles. The dependence of muscle coordination is related
21more to the degree of freedom considered, and less to the cost function selected.
The most commonly used objective functions for resolving the indeterminate force
analysis problem include linear and nonlinear weighted combinations of the unknown
variables. An analytic model for the determination of muscle force across the elbow joint
10during isometric loading has been developed. In addition to the equilibrium equations
obtained from free-body analysis, constraints for muscle tensions based on the
physiologic considerations of muscle length-tension and velocity-tension relationships
were included:
[3] in which F is the magnitude of muscle tension, is the normalized muscle force as
adjusted by the muscle length, PCSA represents the muscle physiologic cross-sectional
area, and σ is the upper bound of muscle activation level. The maximum stress could be
generated by the muscle. The word activation is used to describe both the number of
active units (recruitment) and their degree of activity (6ring frequency). The muscle
force distribution was then determined by using the optimization method of
[4]
in which σ is taken as the upper bound value of overall activation of all muscles. In this
analysis, the effects of muscle architecture on the muscle force were examined.
Major Elbow Muscles
We are now in a position to consider several muscles in the solution; these include biceps,
triceps, brachialis, and brachioradialis.
For the loading case of force applied nonperpendicularly at the wrist, the solutions of
two types of optimization procedures are shown in Table 3-4. The magnitude (R) and
direction ( ) of the resultant joint forces correspond to various loads. The resultant joint
force shows more variation along the articular surface with changes of joint - exion (Fig.
3-22). This is because the line of action of the upper arm muscle undergoes a tremendous
change in direction with respect to the ulnar axis during flexion, as discussed earlier.
Muscle and Joint Forces in Resisting Flexion Moment by Three Major Flexors*TABLE 3-4<
FIGURE 3-22 Joint force magnitude and direction from an applied load at the wrist at
various elbow - exion angles. Family of solutions by using di erent muscle combinations
and solution techniques.
59,71The maximum elbow - exion strength occurs at 90 degrees (see Chapter 5). From
the measured lifting strength data, the maximal muscle force per unit of cross-sectional
2area can be calculated to be in the range of 10 to 14 kg/cm . About one third to one half
of the maximum lifting force can be generated with the elbow in the extended or
30degree - exed position. At these positions, a force almost three times the body weight can
be encountered in the elbow joint during strenuous lifting at about 30 degrees of - exion
(Table 3-5).
TABLE 3-5 Muscle and Joint Forces Under Maximum Flexion Forces
During strenuous actions, the maximum tension that could possibly be provided by
each individual muscle is usually considered to be proportional to the physiologic cross-8sectional area. This has been carefully measured for muscles crossing the elbow. The
potential moment contribution of each muscle at the elbow joint can thus be estimated
by multiplying its moment arm by its physiologic cross-sectional area. The moment
contributions for all of the muscles crossing the elbow joint have been calculated (Fig.
323). Of note, the potential moment in varus appears to be balanced by the valgus
moment under all of the functional con6gurations. When - exed, the - exion potential
moment seems to be balanced by the extension moment. However, the extension moment
exceeds the flexion moment when the elbow is extended.
FIGURE 3-23 The potential moment contribution of each muscle at the elbow joint was
estimated by multiplying the moment arm (cm) of the muscle by its physiologic
crosssectional area (cm2). These diagrams show the contributions to - exion-extension and
varus-valgus rotation about the joint center at six elbow and forearm con6gurations. A,<
Extended/supinated. B, Extended/neutral. C, Extended/pronated. D, Semi- exed/neutral.
E, Flexed/neutral.
(From An, K. N., Hui, F. C., Morrey, B. F., Linscheid, R. L., and Chao, E. Y.: Muscles across
the elbow joint: A biomechanical analysis. J. Biomech. 14:659, 1981.)
In constructing these moment potential diagrams, it is assumed that all muscles
simultaneously and maximally contract to their optimal lengths. To apply these data for
more general conditions, consideration should be given and adjustment made for
lengthtension and force-velocity relationships. In addition, when activities involve submaximal
contraction, a proper scaling system based on experimental measurements, such as
3,28,33,35,61EMG, is required. In more re6ned models, themuscle physiology, including
10,38the length-velocity-tension relationship, should be considered. In an analytic
modeling, the e ect of distal humeral shortening on the triceps force production and thus
48the elbow extension strength has been demonstrated (Fig. 3-24).
FIGURE 3-24 Length-tension relationship for the triceps with the elbow at 30 degrees of
flexion.
Electromyographic Activities of Elbow Muscles
EMG analysis is used to provide scaling systems for the muscle force calculations during
submaximal contraction and to show the phasic distribution of muscular activities for a
given task.
Flexors
100Surface electrodes along the belly of the biceps were 6rst used to record electrical
activity during dynamic - exion and extension, with and without load. This early study
showed a decrease in biceps activity in pronation compared with supination, and that the
biceps acted in extension to “brake” the forearm.
Subsequent studies have presented inconsistent data, but in almost all investigations,
16the biceps demonstrates no or decreased activity when - exion occurs in
35,58,98pronation. As expected, little in- uence is re- ected in the brachialis muscle with
35,98forearm rotation. The brachioradialis demonstrates electrical activity with - exion,
17,29 35,54,98especially with the forearm rotated to the neutral position or in pronation.<
These data are summarized for the 90-degree - exion position, because this is the
15,54position of maximum strength and of greatest electrical activity of the elbow
35flexors (Fig. 3-25).
FIGURE 3-25 Electrical activity of the major elbow - exors at 90 degrees of - exion in
different forearm rotation positions.
(From Funk, D. A., An, K. N., Morrey, B. F., and Daube, J. R.: Electromyographic analysis of
muscles across the elbow joint. J. Orthop. Res. 5:529, 1987.)
Extensors
EMG investigations of the elbow extensor muscles were 6rst completed by Travill in
1021962. The medial head of the triceps and anconeus muscles were found to be active
during extension; the lateral and long head of the triceps acted as auxiliaries. The
anconeus also was active during resisted pronation and supination. In fact, the anconeus
has been demonstrated to be active during - exion and abduction-adduction resisted
35,83motions. Thus, the anconeus may be considered a stabilizer of the elbow joint, being
active with almost all motions.
In 1972, Currier studied the same muscles at 60, 90, and 120 degrees of elbow - exion.
The greatest electrical activity occurred at the 90-degree and 120-degree positions,
24 55consistent with the position of greatest strength. Others found there was no
difference between position and muscular electrical activity.
EMG data of the elbow muscles have thus provided the following information: (1) the
biceps is generally less active in full pronation of the forearm, probably owing to its
secondary role as a supinator; (2) the brachialis is active in most ranges of function and is
believed to be the “workhorse” of - exion; (3) there is an increase of electrical activity of
the triceps with increased elbow - exion, probably secondary to an increased stretch
re- ex; (4) the anconeus shows activity in all positions and, hence, is considered a
dynamic joint stabilizer; and (5) generally speaking, the di erent heads of the triceps and
biceps are active in the same manner through most motion.Forearm Muscles
Some of the forearm muscles originating at the medial and lateral aspects of the distal
humerus had been considered in stabilizing the elbow joint. Flexor carpi ulnaris and
- exor digitorum super6cialis muscles, because of their positions and proximities over the
medial collateral ligaments, were potentially the muscles best suited to provide medial
25elbow support. However, in the EMG investigations, no signi6cant activities of these
35muscles were noted when valgus and varus stresses were applied. In a recent study of
baseball pitchers with medial collateral ligament insuC ciency, the data did not
42demonstrate increased electrical activity of these muscles. These 6ndings suggested
that the muscles on the medial side of the elbow do not supplement the role of medial
42collateral ligaments.
Distributive Forces on the Articular Surfaces
Joint compressive forces on various facets of the elbow joint have been reported in the
3,73literature. During the activities of resisting - exion and extension moments at various
elbow joint positions, the components of force along the mediolateral direction, causing
varus-valgus stress, are small compared with those acting in the sagittal plane directed
anteriorly or posteriorly. The resultant joint forces on the trochlea and capitellum have
been described in the sagittal plane for - exion (Fig. 3-26) and extension (Fig. 3-27)
isometric loads. With the elbow extended and axially loaded, the distribution of stress
across the joint has been calculated to be approximately 40% across the ulnohumeral
41,107joint and 60% across the radiohumeral articulation (Fig. 3-28). More recently,
46,57based on a cadaveric study, it has been noted that with the elbow in valgus
realignment, only 12% of the axial load is transmitted through the proximal end of the
ulna, but with the elbow in varus alignment, 93% of the axial force is transmitted to
proximal ulna. Because of the poor mechanical advantage with the elbow in extension,
3,49the largest isometric - exion forces occur in this position (see Fig. 3-27). Isometric
extension produces a posterosuperior compressive stress across the distal humerus. These
analytic calculations have undergone experimental con6rmation. Using a force
transducer at the proximal radius, the greatest force was transmitted across the
radiohumeral joint in full extension, a position in which the muscles have poor
68mechanical advantage.FIGURE 3-26 Orientation and magnitude of forces at the humeral articular surface
during flexion, per unit of force at the hand.
(From Amis, A. A., Dowson, D., and Wright, V.: Elbow joint force predictions for some
strenuous isometric actions. J. Biomech. 13:765, 1980.)
FIGURE 3-27 Orientation and magnitude of forces at the humeral articulating surface
during extension, per unit of force at the hand.
(From Amis, A. A., Dowson, D., and Wright, V.: Elbow joint force predictions for some
strenuous isometric actions. J. Biomech. 13:765, 1980.)FIGURE 3-28 Static compression of the extended elbow places more force on the
radiohumeral than the ulnohumeral joint.
When the elbow is - exed, inward rotation of the forearm against resistance imposes
large torque to the joint. The magnitudes have been calculated as approaching twice
body weight tension in the medial collateral ligament and three times body weight at the
4radiohumeral joint. Experimental data from the force transducer study suggest that the
analytic estimate is probably too high. The greatest force on the radial head from the
transducer data occurs with the forearm in pronation (Fig. 3-29). Even in this position,
however, the maximum possible force transmission at the radiohumeral joint was
67measured as approximately 0.9 times the body weight.
FIGURE 3-29 Consistently greater force transmission occurs with the forearm inpronation than in supination. This indicates that a screw-hole mechanism exists with the
proximal radial migration occurring during this maneuver.
(From Morrey, B. F., An, K. N., and Stormont, T. J.: Force transmission through the radial head.
J. Bone Joint Surg. [Am.] 70:250, 1988.)
Considerably less knowledge is available regarding the distributed forces at the elbow
73during use. Nicol and associates have demonstrated signi6cant forces with daily
activities that not only occur at the radiohumeral and ulnohumeral joints but also are
generated in the collateral ligaments. An example of such a force pattern is shown in
Figure 3-30. The actual distributive forces occurring at this joint with daily activity
constitute an important avenue of further investigation.
FIGURE 3-30 Distribution of articular and soft tissue forces across the elbow for a
selected activity.
(From Nicol, A. C., Berme, N., and Paul, J. P.: A biomechanical analysis of elbow joint function.
In Joint Replacement in the Upper Limb. London, Institute of Mechanical Engineers, 1977, p.
45.)
Contact Stress on the Joint Articular Surface
With the magnitude, direction, and point of application of the resultant joint force
84available, the stress on the articular cartilage can now be determined. Because the joint
is not a simple geometric shape, a method based on the concept of a rigid body spring
11model was adopted for solution. In the results, it was found that if the line of action of
the resultant force is at the middle of the articular surface, the stress is almost equally
distributed throughout the entire articular surface (Fig. 3-31A). On the other hand, as the
resultant force is directed toward the margin of the articulation anteriorly or posteriorly,
the weight-bearing surface becomes smaller, the maximum compressive stress becomes
elevated, and the stress distribution over the joint surface becomes more uneven (see Fig.
3-31B). It should be further noted that the position of maximum stress does not
necessarily correspond with the point of intersection of the resultant joint force through<
the articular surface. Based on this model, the role of antagonistic muscles on the
magnitudesand directions of the resultant joint forces, and thus the articulating pressure
7distribution and joint stability, were extensively examined (Fig. 3-32).
FIGURE 3-31 The contact pressure depends on the direction and magnitude of the
resultant compressive force. A, When the resultant force is oriented toward the center of
the trochlear notch, a more uniform distribution of pressure is observed. B, When the line
of action of the resultant joint force is directed to the rim of the trochlear notch, the
weight-bearing surface becomes smaller, and maximum compressive stresses increases.
Finite Element Analysis of Composite Fixation for Total Elbow Prosthesis
In total elbow arthroplasty implant loosening remains a challenging complication.
Achieving rigid 6xation using a combination of bone ingrowth and cementing should
improve the implant longevity. The semiconstrained Coonrad-Morrey elbow prosthesis
employs this philosophy. It has shown generally satisfactory clinical results for a variety
44,89of cases including in- ammatory arthritis and distal humerus fracture. The humeral
component of the implant incorporates an anterior - ange that has the theoretical bene6t
of transferring stress from the elbow to the humeral bone and relieving stress
concentrations at the vulnerable distal humerus cement interface. Finite element analysis
was used to evaluate the biomechanical e ects of bone graft between the anterior - ange
and the bone cortex.
Models were created that consisted of the humeral component of the Coonrad/Morrey
elbow prosthesis, bone cement surrounding the implant stem, simulated distal humerus,
and bone graft between the distal humerus and anterior - ange of the prosthesis. Material
properties were prescribed as linear elastic with Poisson ratio of 0.3 and elastic modulus
values of implant (E = 114 GPa), humerus (E = 17 GPa), bone cement (E = 3 GPa),
and bone graft (E = 0.65 GPa). Perfect bonding between the bone-cement and cement-implant interfaces was assumed.
Permutations of the stem size (4, 6, and 8 inch), graft size (50% of flange length, 100%
of - ange length, and 150% of - ange length), and distal humerus (normal and simulated
defect) were evaluated. Loading to the implant was applied for cases of anterior (45 N),
posterior (45 N), axial (45 N), 45 degrees posterior (45 N), and torsion (1 N-m) load.
Finite element analysis shows that stress and strain in the distal humerus and distal
cement mantle can be reduced 10% to 30% when using a bone graft compared with no
bone graft between the anterior - ange and the bone cortex (Fig. 3-33). Furthermore,
when the distal humerus had a simulated defect of 2 cm, extension of the bone graft more
proximally than the anterior - ange reduced the stress and strain up to 17% compared
with bone graft just under the - ange. Finally, when selecting the stem size, there was up
to a 15% reduction in distal cement stress and strain when choosing a 6-inch stem over a
4-inch stem or when choosing an 8-inch stem over a 6-inch stem. These 6ndings
con6rmed the clinical experience that rigid 6xation and stress relief due to the anterior
- ange of the implant reduce the complication rate for primary and revision total elbow
arthroplasty.
FIGURE 3-33 Stress transmission through 6nite element model of elbow prosthesis
before (A) and after (B) placement of bone graft between anterior - ange and distal
humerus. The bone graft and humerus are cut away to show the internal stress
transmission.
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Rec. 1962;144:373.
103 Tyrdal S., Olsen B.S. Combined hyperextension and supination of the elbow joint
induces lateral ligament lesions. An experimental study of the pathoanatomy and
kinematics in elbow ligament injuries. Knee Surg. Sports Traumatol. Arthrosc. 1998;6:36.
104 Van Glabbeek F., Van Riet R.P., Baumfeld J.A., Neale P.G., O’Driscoll S.W., Morrey B.F.,
An K.N. Detrimental effects of overstuffing or understuffing with a radial head
replacement in the medial collateral-ligament deficient elbow. J. Bone Joint Surg. [Am.].
2004;86:2629.105 Von Lanz T., Wachsmuth W. Praktische Anatomie. Berlin: Springer-Verlag, 1959.
106 Von Meyer H., Steindler A. Kinesiology of the Human Body Under Normal and
Pathological Conditions. Springfield, IL: Charles C. Thomas, 1955;490.
107 Walker P.S. Human Joints and Their Artificial Replacements. Springfield, IL: Charles C.
Thomas, 1977;182.
108 Youm Y., Dryer R.F., Thambyrajah K., Flatt A.E., Sprague B.L. Biomechanical analyses
of forearm pronation-supination and elbow flexion-extension. J. Biomech. 1979;12:245.PART II
Diagnostic Considerations&



CHAPTER 4
Physical Examination of the Elbow
William D. Regan, Bernard F. Morrey
INTRODUCTION
This chapter deals with the basics of a general comprehensive physical examination of
the elbow. Speci c and focused features of the examination are pictured with the various
conditions described below.
HISTORY
Without question the value of a precise history cannot be overstated. Pain is the most
common complaint. The severity of the pain and whether it is intermittent or constant,
the quantity and type of analgesia used, and the association of night pain are all
important characteristics. The functional compromise experienced, whether it be
recreational activity or activities of daily living, should be discussed. Frequently, the
patient who has lived with chronic pain, such as that accompanying rheumatoid arthritis,
has learned certain accommodative activities that have assisted in lessening or
eliminating pain from a conscious level. When considering intervention, it is extremely
helpful to determine if the pain is getting better, getting worse, or remaining constant.
Functionally, the elbow is the most important joint of the upper extremity, because it
places the hand in space away from or toward the body. It provides the linkage, allowing
the hand to be brought to the torso, head, or mouth. Because of this, the examiner must
be aware of the interplay of shoulder and wrist function as they complement the
usefulness of the elbow. However, a considerable limitation of elevation and abduction
function can exist at the shoulder complex without producing an appreciable compromise
in most activities of daily living. This is true because only a relatively small amount of
shoulder exion and rotation is necessary to place the hand about the head or posteriorly
about the waist or hip, and scapulothoracic motion can compensate for glenohumeral
motion loss. Full pronation and supination can be achieved only when both the proximal
6,25and distal radioulnar joints are normal.
Conditions involving the lateral joint, that is, the radiocapitellar articulation, generally
evoke pain that extends over the lateral aspect of the elbow with radiation proximally to
the midhumerus or distally over the forearm. The pain may be super cial, directly over
the lateral epicondyle or radial head, for example, or deep, localized poorly in the area of
the proximal common extensor muscle mass supplied by the posterior interosseous nerve.
For reasons that remain unclear, the posterior lateral ulnohumeral joint appears to be a
“watershed” referral point for a spectrum of remote conditions. Less commonly,
nonspeci c symptoms poorly localized to the medial aspect of the elbow can represent
ulnar nerve pathology, medial epicondylitis or arthrosis.
As is well known, symptoms from cervical radiculopathy can usually be distinguished
by a speci c radicular distribution of pain and associated neurologic abnormality of the
upper extremity. Today, a suspicion of cervical etiology is readily resolved with the
magnetic resonance imaging (MRI) scan.
PHYSICAL EXAMINATION
INSPECTION
Considerable information can be ascertained from careful visual inspection of the elbow
joint. Because much of the joint is subcutaneous, any appreciable alteration in the
skeletal anatomy is usually obvious. Gross soft tissue swelling or muscle atrophy is also
easily observed.
AXIAL ALIGNMENT
Axial malalignment of the elbow, when compared with the opposite side, suggests prior
trauma or a skeletal growth disturbance. To determine the carrying angle, the forearm
and hand should be supinated and the elbow extended; the angle formed by the humerus
and forearm is then determined (Fig. 4-1A). Although there is considerable variation with
race, age, sex, and body weight, an average of 10 degrees for men and 13 degrees for
3,4,13,14women has been calculated as the mean carrying angle from several reports.
FIGURE 4-1 A, The carrying angle is a clinical measurement of the angle formed by the
forearm and the humerus with the elbow extended. B and C, The normal 10- to 15-degree
carrying angle can be altered by injury about the elbow, causing a varus carrying angle,
or so-called gunstock deformity.&
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Angular deformities, such as cubitus varus or valgus, are also easily identi able (see
Fig. 4-1B and C). The elbow moves from a valgus to varus alignment as with exion. In a
post-traumatic condition, however, abnormalities in the carrying angle cannot be
accurately assessed in the presence of a signi cant exion contracture (see Chapter 3).
Rotational deformities following supracondylar or other fractures of the humeral shaft
may be difficult to perceive.
LATERAL ASPECT
Fullness about the infracondylar recess just inferior to the lateral condyle of the humerus,
the “soft spot,” suggests either an increase in synovial uid, synovial tissue proliferation,
or radial head pathology, such as fracture, subluxation, or dislocation (Fig. 4-2). Subtle
evidence of effusion can be determined by observing fullness in this area.
FIGURE 4-2 A normal depression in the contour of the skin in the intracondylar recess
(arrowhead) (A) becomes obliterated in the presence of synovitis or effusion (B).
Thin, taut, adherent skin over the lateral epicondyle may be indicative of excessive
cortisone injections in this area for refractory lateral epicondylitis (see Chapter 44). A
prominence involving the lateral triangle often indicates a posteriorly dislocated radial
head (Fig. 4-3; see Fig. 4-22A and B).<
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FIGURE 4-3 Developmental posterior dislocation of the radial head (A) is associated
with obvious prominence (B). Typically, this problem is associated with only minimal
limitation of function.
FIGURE 4-22 A, The patient has done a push-up with hands in neutral and his arms
wider than shoulder (valgus) and is at a terminal extension (axial load) of his una ected
elbow. He has apprehension in his a ected left elbow (axial load + valgus). B, A close-up
of the posterolateral dislocation.
POSTERIOR ASPECT
A prominent olecranon suggests a posterior subluxation or migration of the forearm on

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the ulnohumeral articulation. Occasionally, marked distortion is associated with
surprisingly satisfactory function (Fig. 4-4). Rupture of the triceps tendon at its insertion
should be suspected if this nding is accompanied by loss of active extension. Loss of
terminal passive extension of the elbow is a sensitive but nonspeci c indicator of
intraarticular pathology. Loss of active motion with full passive extension suggests either
mechanical (triceps avulsion) or neurologic conditions.
FIGURE 4-4 Gross deformity of the elbow from a malunion of a condylar fracture. The
excellent function is typical of condylar but not T-Y type malunions.
The prominent subcutaneous olecranon bursa is readily observed posteriorly when it is
in amed or distended (Fig. 4-5). Rheumatoid nodules frequently are found on the
subcutaneous border of the ulna (see Chapter 74).&
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FIGURE 4-5 An in amed or enlarged olecranon bursa is one of the more dramatic
diagnoses made by observation in the region of the elbow.
(From Polley, H. G., and Hunder, G. G.: Rheumatologic Interviewing and Physical Examination
of the Joints, 2nd ed. Philadelphia, W.B. Saunders Co., 1978.)
MEDIAL ASPECT
On occasion the ulnar nerve may be observed to displace anteriorly during exion with
8recurrent subluxation of the ulnar nerve. Otherwise, few landmarks are observable from
the medial aspect of the joint. The prominent medial epicondyle is evident unless the
patient is obese.
ASSOCIATED JOINTS AND NEURAL FUNCTION
No examination of the elbow is complete without a review of the cervical spine and all
other components of the upper extremity. If the elbow pain has a radicular pattern, it is
important to review the patient’s cervical spine alignment and range of motion and
perform neurologic testing of the entire upper extremity. The main nerve roots involved
with elbow function are C5-7 (Fig. 4-6). There is considerable overlap in the sensory
dermatomes of the upper extremity. The general distribution of sensory levels includes
C5, the lateral arm; C6, the lateral forearm; C7, the middle nger; and C8 and T1, the
medial forearm and arm dermatomes, respectively.
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FIGURE 4-6 The biceps, brachioradialis, and triceps re exes allow evaluation of the C5,
C6, and C7 nerve roots, respectively.
Biceps function from innervation of C5-C6 is a exor of the elbow and forearm
supinator. The re ex primarily tests C5 and some C6 competency. The C6 muscle group
of most interest is the mobile wad of three, consisting of the extensor carpi radialis longus
and brevis and the brachioradialis muscles. These also are known as the radial wrist
extensors and should be assessed for strength and re ex integrity. The re ex is primarily
a C6 function, with some C5 component. The primary elbow muscle innervated by C7 is
the triceps, which should always be assessed for strength and re ex. Wrist exion and
nger extension also are primarily supplied by C7, with some C8 innervation (see Fig.
46).
Elbow pain may be referred from the shoulder; therefore, a visual inspection of the
shoulder for muscle wasting and appearance should be made, followed by an appropriate
functional assessment. Speci c attention should be directed toward motion and the
spectrum of impingement tendinitis or rotator cu pathology which often is manifested
by pain in the brachium.
For normal forearm rotation, there must be a normal anatomic relationship between
the proximal and distal radioulnar joint. In ammatory changes involving either the
elbow or the wrist or both will cause a loss of forearm rotation. Disruption of the normal
relationship of the distal radioulnar joint will cause dorsal prominence of the distal ulna
exaggerated by pronation and is lessened by supination. Because pronation is the
common resting position of the hand, dorsal subluxation of the ulna at the wrist is often
identifiable by inspection.
PALPATION
OSSEOUS LANDMARKS
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Inspection and palpation of the medial and lateral epicondyles and the tip of the
olecranon form an equilateral triangle when the elbow is exed (Fig. 4-7). Fracture,
malunion, unreduced dislocation, or growth disturbances involving the distal end of the
humerus can be assessed clinically in this fashion.
FIGURE 4-7 With the elbow exed to 90 degrees, the medial and lateral epicondyles
and tip of the olecranon form an equilateral triangle when viewed from posterior. When
the elbow is extended, this relationship is changed to a straight line connecting these
three bony landmarks (A). The relationship is altered with displaced, intra-articular distal
humeral fractures (B).
LATERAL ASPECT
The lateral supracondylar region, which we call the lateral column, is readily palpable
and is a valuable landmark during lateral surgical exposures (Fig. 4-8) (see Chapters 7
and 32). The de nition of the location of the extensor carpi radialis brevis is carefully
sought and is enhanced by radial wrist and elbow extension. Examination of the radial
head is easily performed provided a joint e usion is not present. Digital pressure over the&
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peripheral articular surface of the radial head, when combined with pronation and
supination of the forearm in varying degrees of elbow exion, will o er valuable
information about this bony structure and the status of the synovium. If painful, this
examination should be performed gently. Radial head or capitellar fracture thus may be
suspected even when the radiographic results are negative. An e usion of the elbow is
most easily identi ed by palpation over the lateral borderof the radial head or about the
posterior recess located just between the radial head and the lateral border of the
olecranon (Fig. 4-9). A radio/humeral plica is appreciated by palpating the snapping of
the plica with exion and extension. As with other joints, signi cant e usions of
hemarthrosis will limit extremes of motion, especially extension. If tense, the elbow will
19assume a position of maximum joint capacity, which is 80 degrees. Palpation of the
arcade of Froshe, located approximately 2 cm anterior and 3 cm distal to the lateral
epicondyle, locates the posterior interosseous nerve.
FIGURE 4-8 The lateral supracondylar interval is an avascular area that can be readily
palpated and serves as an important landmark in many surgical exposures to the elbow.
(From Hoppenfeld, S.: Physical Examination of the Spine and Extremities. New York,
AppletonCentury-Crofts, 1976.)&
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FIGURE 4-9 The radial head may be readily palpated. The contour and integrity of the
structure may be further appreciated by pronating and supinating the forearm during this
examination.
MEDIAL ASPECT
Because of the tight ligament and capsule present on the medial side of the olecranon,
great diG culty is encountered in assessment of the soft tissues in this area. Palpation of
the cubital tunnel is easily performed to assessthe status of the ulnar nerve (Fig. 4-10). A
subluxing nerve is identi ed with exion and extension. Entrapment is assessed by
performing a Tinel test proximal to, at, or distal to the cubital tunnel.
FIGURE 4-10 Palpation of the cubital tunnel. The ulnar nerve is identified proximal and
distal to the medial epicondyle.
The exor-pronator muscles consist of four muscles taking origin from the medial
epicondyle. Wrist exion and pronation against resistance often accentuate the pain and
is consistent with a diagnosis of medial epicondylitis.
The medial collateral ligament is the elbow’s primary stabilizer to valgus strain. It takes
its origin slightly anterior and inferior to the medial epicondyle and fans out to attach
along the greater sigmoid fossa of the ulna with both an anterior and a posterior
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24thickening. With the elbow in 30 to 60 degrees of exion, it should be palpated for
tenderness along its course. Valgus stress is painful if the ligament is injured.
POSTERIOR ASPECT
The olecranon bursa overlies the triceps aponeurosis, which inserts on the olecranon. This
area should be palpated for thickening and pain. On occasion, a spur or bony prominence
may be readily palpable at the tip of the olecranon (see Chapter 84).
With elbow exion, the olecranon fossa may be identi ed in a thin person by careful
palpation. A tense e usion is likewise detectable from this aspect. The posteromedial
olecranon and ulnohumeral joint should be carefully palpated. This is a common site for
olecranon spur formation and is painful with forced extension. To accentuate this pain,
the elbow is snapped into full extension. The subcutaneous border of the olecranon and
proximal ulna also are readily appreciated by palpation.
ANTERIOR ASPECT
The cubital fossa is bordered laterally by the brachioradialis and medially by the
pronator teres muscles. There are four signi cant structures passing through the cubital
fossa from lateral to medial, including (1) the musculocutaneous nerve, (2) the biceps
tendon, (3) the brachial artery, and (4) the median nerve.
The musculocutaneous nerve supplying lateral forearm sensation is located deep to the
brachioradialis between it and the biceps tendon and is not readily palpable. The biceps
tendon is readily palpable with resisted forearm supination. The tendon should be
assessed for tenderness and for continuity distally. A medial expansion, the lacertus
brosus, is noted, which covers the common exor muscle group as well as the brachial
artery and median nerve and may be the source of compression of the median nerve. The
pulse of the brachial artery is easily located, lying deep to the lacertus brosus (Fig.
411).
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FIGURE 4-11 The lacertus brosus is easily palpable at its medial margin, and this
covers the brachial artery, median nerve, and becomes attenuated with the distal biceps
tendon disruption.
MOTION
Perhaps no portion of the physical examination is more important than the assessment of
motion. Loss of full extension is the rst motion altered by most pathology. As a matter of
fact, in a trauma situation, the likelihood of signi cant joint pathology in the face of
15normal elbow motion is so small as not to require radiographic analysis!
Normally, the arc of exion-extension, although variable, ranges from about 0 to 140
1,7,26degrees plus or minus 10 degrees (Fig. 4-12). This range exceeds that which is
17normally required for activities of daily living. Pronation-supination may vary to a
greater extent than the arc of exion-extension. Acceptable norms ofpronation and
supination are 75 and 85 degrees, respectively (Fig. 4-13). In assessing motion, the
examiner should record both active and passive values. The humerus is placed in a
vertical position when evaluating the arc of forearm rotation. Patients will tend to
accommodate for loss of pronation by abducting the shoulder. Any signi cant di erence
between active and passive ranges of motion suggests pain or motor function as the
cause. In patients with a exion or extension contracture, the examiner should
concentrate on solid or soft end points, pain or crepitus during the arc and at the end&

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points.
FIGURE 4-12 The normal exion and extension of the elbows is from zero to
approximately 145 degrees. The functional arc of exion and extension about which most
daily activities are achieved is 30 to 130 degrees.
FIGURE 4-13 Normal pronation and supination is about 80 and 85 degrees,
respectively. The functional arc of forearm rotation consists of approximately 50 degrees
of pronation and 50 degrees of supination.
The examiner should then make a careful assessment of any compromised motion at
the shoulder or wrist. Often, the disability will arise from a combination of factors, but it
should be stressed that a full range of motion at the elbow is not essential for
performance of the activities of daily living. The essential arc of elbow exion-extension
17required for daily activities ranges from about 30 to 130 degrees. Because the loss of
extension up to a certain degree only shortens the lever arm of the upper extremity,
exion contractures of less than 45 degrees may have little practical signi cance,
although patients sometimes are concerned about the cosmetic appearance (Fig. 4-14).&
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FIGURE 4-14 Illustration of the marked functional limitation associated with an
ankylosed elbow at 90 degrees. Notice the shoulder poorly compensates for the overall
e ect of limited exion and extension in both the sagittal (A) and the transverse (B)
planes.
To perform 90% of required daily activity, 50 degrees of pronation and supination are
17required (see Fig. 4-13). For most individuals, pronation is the most important function
on the dominant side for eating and writing, and loss of pronation is compensated by
shoulder abduction. On the other hand, a loss of supination of the nondominant side may
signi cantly hinder personal hygiene needs, accepting objects, and opening of door
handles. These tasks are poorly compensated by shoulder or wrist function.
STRENGTH
Only gross estimates of strength are attainable in the clinical setting. Flexion and
extension strength testing (Fig. 4-15) is conducted against resistance, with the forearm in
neutral rotation and the elbow at 90 degrees of exion. Extension strength is normally
270% that of exion strength and is best measured with the elbow at 90 degrees of
10,22,23,27exion, and with the forearm in neutral rotation. Pronation (Fig. 4-16),
supination, and grip strength are also best studied with the elbow at 90 degrees of exion
and the forearm in neutral rotation. Supination strength is normally about 15% greater
2than pronation strength. The dominant extremity is about 5% to 10% stronger than the
2nondominant side, and women are 50% as strong as men (see Chapter 5).<
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FIGURE 4-15 Flexion strength is best assessed with the elbow exed to 90 degrees and
the forearm in neutral rotation. Flexion resistance is assessed while the examiner attempts
to extend the elbow (A). To test extension strength, the examiner applies resistance to the
patient’s ability to extend the elbow with the joint in approximately 90 degrees of exion
and the forearm in neutral (or pronated) position (B).
(From Hoppenfeld, S.: Orthopedic Neurology. Philadelphia, J. B. Lippincott Co., 1977.)
FIGURE 4-16 Pronation strength is evaluated with the patient comfortable and the
elbow at 90 degrees of exion. Pronation strength is usually measured by grasping the
wrist or, less commonly, the hand with the forearm in neutral position or in
supinationrotation (A). To test supination strength, the forearm is in neutral position or pronation
(B).
INSTABILITY
In the absence of articular cartilage loss, the mechanical integrity of the radial and ulnar
collateral ligaments is diG cult to assess because of the intrinsic stability o ered by the
closely approximated surfaces of the olecranon and trochlea and the buttressing e ect of
the radial head against the capitellum. However, when articular cartilage has been
destroyed, as in rheumatoid arthritis, or removed, as with radial head excision, collateral&
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ligament stability can be determined by the application of varus and valgus stresses.
Medially, the bers become taut in an ordered sequential fashion, proceeding from
22anterior to posterior as the elbow is exed. Accordingly, a portion of the complex is
24always in tension throughout the arc of flexion (see Chapter 3).
The radial collateral ligament resists varus stress throughout the arc of elbow exion
with varying contributions of the anterior capsule and articular surface in extension (see
Chapter 3). The lateral collateral ligament complex consists of the radial collateral
ligament (RCL) and the lateral ulnar collateral ligament (LUCL). The RCL maintains
24consistent patterns of tension throughout the arc of exion. To properly assess
collateral ligament integrity, the elbow should be exed to about 15 degrees. This relaxes
the anterior capsule and removes the olecranon from the fossa. Varus stress is best
applied with the humerus in full internal rotation. Valgus instability is best measured
with the arm in 10 degrees of exion (Fig. 4-17). In recent years, we have used the
uoroscan routinely to assess all elbows in where a possible instability exists (see Fig.
417C).
FIGURE 4-17 A, Varus instability of the elbow is measured with the humerus in full
internal rotation and a varus stress applied to the slightly exed joint. B, Valgus
instability is evaluated with the humerus in full external rotation while a valgus stress is
applied to the slightly exed joint. C, Examination under uroscopy readily reveals
medial ligament insufficiency.
ROTATORY INSTABILITY
The lateral collateral complex also includes a narrow but stout band of ligamentous tissue
blending with the distal and posterior bers of the capsule to insert distally on the crista
20,24supinatoris of the ulna. This is the lateral ulnar collateral ligament.
InsuG ciency of the lateral collateral ligament is responsible for posterolateral
20instability of the elbow. Posterolateral instability is elicited in two ways (see Chapter&
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44). The more sensitive is by exing the shoulder and elbow 90 degrees, with the patient
supine. The patient’s forearm is fully supinated, and the examiner grasps the wrist or
forearm and slowly extends the elbow while applying valgus and supination movements
and an axial compressive force (Fig. 4-18). This produces a rotatory subluxation of the
ulnohumeral joint; that is, the rotation dislocates the radiohumeral joint posterolaterally
by a coupled motion. As the elbow approaches extension, a posterior prominence (the
dislocated radiohumeral joint) is noted with an obvious dimple in the skin proximal to
the radial head (Fig. 4-19). Additional exion results in a sudden reduction as radius and
ulna visibly snap into place on the humerus (Fig. 4-20). Alternatively, simply asking the
patient to rise from a chair may also reproduce the symptomatology (Fig. 4-21). Finally,
having the patient do a push-up places the elbow in the at-risk position (Fig. 4-22). These
latter two tests are active apprehension signs.
FIGURE 4-18 The pivot shift maneuver consists of extending the elbow with a valgus
axial stress while the forearm is supinated and the elbow is being extended. The elbow
tends to sublux toward full extension. A palpable snap or pop is felt with exion and
represents reduction.&
FIGURE 4-19 Gross appearance and radiograph of a patient with the positive pivot
shift maneuver. Note the dimple in the skin.
(From O’Driscoll, S. W.: Posterolateral rotatory instability of the elbow. J. Bone Joint Surg.
73A:440, 1991.)
FIGURE 4-20 With partial exion or sometimes simple pronation of the forearm, the
elbow is reduced and the dimple is obliterated.
(From O’Driscoll, S. W.: Posterolateral rotatory instability of the elbow. J. Bone Joint Surg.
73A:440, 1991.)FIGURE 4-21 Using the arms to rise from a chair can replicate the instability pattern of
posterolateral rotatory instability (PLRI).
References
1 American Academy of Orthopedic Surgeons. Joint Motion: Method of measuring and
recording. Chicago: American Academy of Orthopedic Surgeons, 1965.
2 Askew L.J., An K.N., Morrey B.F., Chao E.Y. Functional evaluation of the elbow: normal
motion requirements and strength determination. Orthop. Trans. 1981;5:304.
3 Atkinson W.B., Elftman H. The carrying angle of the human arm as a secondary symptom
character. Anat. Rec. 1945;91:49.
4 Beals R.K. The normal carrying angle of the elbow. Clin. Orthop. 1976;119:194.
5 Beetham W.P.Jr., Polley H.F., Slocumb C.H., Weaver W.F. Physical Examination of the
Joints. Philadelphia: W. B. Saunders Co., 1965.
6 Bert J.M., Linscheid R.L., McElfresh E.C. Rotatory contracture of the forearm. J. Bone Joint
Surg. 1980;62A:1163.
7 Boone D.C., Azen S.P. Normal range of motion of joints in male subjects. J. Bone Joint Surg.
1979;61A:756.
8 Childress H.M. Recurrent ulnar nerve dislocation at the elbow. Clin. Orthop. 1975;108:168.
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Examination, 2nd ed. Philadelphia: W. B. Saunders Co., 1946.
10 Elkins E.C., Ursula M.L., Khalil G.W. Objective recording of the strength of normal
muscles. Arch. Phys. Med. Rehabil. 1951;33:639.
11 Hoppenfeld S. Physical Examination of the Spine and Extremities. New York:
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12 Johansson O. Capsular and ligament injuries of the elbow joint. Acta Chir. Scand. Suppl.
1962;287:1.
13 Keats T.E., Teeslink R., Diamond A.E., Williams J.H. Normal axial relationships of the
major joints. Radiology. 1966;87:904.
14 Lanz T., Wachsmuth W. Praktische Anatomie. Berlin: ARM, Springer-Verlag, 1959.15 Lennon R.I., Riyat M.S., Hilliam R., Anathkrishnan G., Alderson G. Can a normal range of
elbow movement predict a normal elbow x-ray? Emerg Med J. 2007;24:86.
16 McRae R. Clinical Orthopedic Examination. London: Churchill Livingstone, 1976.
17 Morrey B.F., Askew L.J., An K.N., Chao E.Y. A biomechanical study of normal functional
elbow motion. J. Bone Joint Surg. 1981;63A:872.
18 Morrey B.F., Chao E.Y. Passive motion of the elbow joint. A biomechanical study. J. Bone
Joint Surg. 1979;61A:63.
19 O’Driscoll S.W., Morrey B.F., An K.N. Intra-articular pressuring capacity of the elbow.
Arthroscopy. 1990;6:100.
20 O’Driscoll S.W., Morrey B.F., An K.N. Intra-articular pressuring capacity of the elbow. J.
Bone Joint Surg. 1991;73A:440.
21 O’Neill O.R., Morrey B.F., Tanaka S., An K.N. Compensatory motion in the upper
extremity after elbow arthrodesis. Clin. Orthop. 1992;281:89.
22 Provins K.A., Salter N. Maximum torque exerted about the elbow joint. J. Appl. Physiol.
1955;7:393.
23 Rasch P.J. Effect of position of forearm on strength of elbow flexion. Res. Q. 1955;27:333.
24 Regan W.D., Korinek S.L., Morrey B.F., An K.N. Biomechanical study of ligaments about
the elbow joint. Clin. Orthop. 1991;271:170.
25 Schemitsch E.H., Richards R.R., Kellam J.F. Plate fixation of fractures of both bones of the
forearm. J. Bone Joint Surg. 1989;71B:345.
26 Wagner C. Determination of the rotary flexibility of the elbow joint. Eur. J. Appl. Physiol.
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27 Williams M., Stutzman L. Strength variation through the range of motion. Phys. Ther. Rev.
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28 Youm Y., Dryer R.F., Thambyrajahk K., Flatt A.E., Sprague B.L. Biomechanical analysis of
forearm pronation-supination and elbow flexion-extension. J. Biomech. 1979;12:245./
/
CHAPTER 5
Functional Evaluation of the Elbow
Bernard F. Morrey, Kai-Nan An
INTRODUCTION
Involvement of the upper limb accounts for about 10% of all compensation paid in the
47,67United States for disabling work-related injuries. In addition, dysfunction of the
66upper extremity cost about 5.5 million lost work days in 1977. Elbow function consists
of three activities: (1) allows the hand to be positioned in space, (2) provides the power
to perform lifting activities, and (3) stabilizes the upper extremity linkage for power and
ne work activities. The essential joint functions are motion, strength, and stability.
However, ultimately, the nal determinant of function and the ability to perform
activities of daily living is pain.
ELBOW MOTION
NORMAL MOTION
Normal 3exion and forearm rotation at the elbow are adequately measured clinically
with the handheld goniometer. Forearm rotation is measured with the elbow at 90
degrees of 3exion, often with the subject holding a linear object, such as a pencil, to
79make the measurement more objective. In spite of obvious limitations, investigators
have concluded that a standard handheld goniometric examination by a skilled observer
allows measurement of elbow 3exion-extension and pronation-supination with a margin
35,95of error of less than 5%. In fact, the 3exion-extension intraobserver reliability
78correlation coe6 cient is 0.99. Di9erent trained observers also provide measurements
30,78that are statistically equivalent.
1,11,44,79Normal passive elbow 3exion ranges between 0 and 140 to 150 degrees.
Greater variation of normal forearm rotation has been described but averages about 75
1,11,44,91degrees pronation and 85 degrees supination.
INVESTIGATIVE TECHNIQUES OF MEASURING COMPLEX ACTIVE
MOTION
To measure the three-dimensional joint motion in daily activities, any one of several
1,95rather sophisticated experimental techniques can be used. For experimental studies,
2,16,63the triaxial electrogoniometer can simultaneously measure three-dimensional
motion of more than one joint system with a high degree of reproducibility and
58,71reliability (Fig. 5-1). Video telemetry, computer-simulated motion, andelectromagnetic sensors have also been developed to study three-dimensional kinematic
2,71,87measurement. Most recently, robotic techniques and miniature accelerometers
and gyroscopes have been adopted to study complex upper extremity compensatory
49,56motion. For the elbow, the complex inter-relationship of shoulder and wrist
function, both motion and motor activity, remains a complex and poorly understood area
32of investigation.
FIGURE 5-1 The elbow electrogoniometer may be used to measure activities of daily
living. A, Elbow 3exion and forearm rotation to reach the back of the head. B, The
subject is sitting at the activities table.
(From Morrey, B. F., Askew, L. J., and Chao, E. Y.: A biomechanical study of normal functional
elbow motion. J. Bone Joint Surg. 63A:872, 1981.)
FUNCTIONAL MOTION
For most activities, the full potential of elbow motion is not needed or used. Loss of
terminal 3exion is more disabling than is the same degree of loss of terminal
14,70extension. Using the electrogoniometer just described, a study of 15 activities ofdaily living established that most functions can be performed using an arc of 100 degrees
of 3exion between 30 and 130 degrees (Fig. 5-2) and 100 degrees of forearm rotation
equally divided between pronation and supination (Fig. 5-3). This has become the
accepted standard for functional elbow motion.
FIGURE 5-2 Normal elbow 3exion positions for activities of hygiene and those
requiring arcs of motion are demonstrated. Most functions can be performed between 30
and 130 degrees of elbow flexion.
FIGURE 5-3 Routine daily activities requiring pronation and supination or arcs of
motion are performed between 50 degrees pronation and 50 degrees supination.The motion requirements of the elbow joint needed for daily activities are really a
measurement of the reaching ability of the hand. The extent to which this function is
impaired by loss of elbow 3exion or extension can be estimated analytically (Fig. 5-4).
When motion is limited from 30 to 130 degrees, the potential area reached by the hand is
reduced by about 20%. Thus, the range of elbow 3exion between 30 and 130 degrees
corresponds with about 80% of the normal reach capacity of the forearm and hand in a
selected plane of shoulder motion. The functional impact of further loss of the 3exion arc
is also not equally distributed between 3exion and extension. Our clinical experience
indicates that 3exion is of more value than extension in a ratio of about 2:1. Hence, a
10degree further loss of 3exion (120 degrees) is roughly equivalent to 20 degrees further
loss of extension (Fig. 5-5).
FIGURE 5-4 The reaching area of the hand in the sagittal (A) and transverse (B)
planes, with simultaneous movement of the elbow and shoulder. If the elbow is held at
approximately 90 degrees of 3exion, marked reduction of reach potential occurs. Note
also that the circumduction motion of the shoulder does not compensate for the hinged
type motion of the elbow joint.
FIGURE 5-5 The further loss of motion from the ideal 30 to 130 degree arc is better
tolerated as extension loss than as flexion loss./
/
/
/
The optimal position of elbow fusion to accomplish activities of daily living has been
86accepted as 90 degrees. To further assess this issue, we hypothesized that the optimal
position would be associated with a minimal amount of compensatory shoulder
71motion. It was surprising to observe that for discrete and xed positions of the elbow,
increasing the amount of shoulder motion did not provide greater use or increased
function. It was also noted that for greater degrees of xed elbow 3exion, e9orts to
perform daily functions were accompanied by a tendency of the humerus to assume a
less elevated and more lateral circumduction position (Fig. 5-6). This is consistent with
the mechanical functions of these two joints; a ball-and-socket joint providing rotatory
motion does not provide compensatory motion for hinge-type motion that occurs only in
a single plane. This investigation did con rm the accepted tenant that 90 degrees is the
optimum position or “least worse” for most activities.
FIGURE 5-6 As the fixed position of elbow fusion increases toward 90 degrees, activities
of daily living are accomplished with the humerus less elevated and more laterally
circumducted.
STRENGTH
To understand the value and limitations of clinical strength assessment, it will be helpful
to brie3y review the physiology of muscle contraction and major factors a9ecting
15strength.
TYPES OF MUSCLE CONTRACTION
There are several types of muscle contraction classi ed according to changes in length,
5,31,60force, and velocity of contraction (Fig. 5-7)./
/
/
/
FIGURE 5-7 Types of muscle contractions classi ed according to change in muscle
length. An isometric contraction results in no change of muscle length with a constant
load and velocity. The concentric contraction is de ned as a shortening of the muscle,
whereas the eccentric contraction occurs with lengthening of the muscle. These latter two
contractions may be subclassi ed according to whether a constant load (isotonic) or a
constant velocity (isokinetic) condition is met.
If there is no change in muscle length during a contraction, it is called isometric. When
the external force exceeds the internal force of a shortened muscle and the muscle
lengthens while maintaining tension, the contraction is called an eccentric, or
lengthening, contraction. In contrast, if the muscle shortens while maintaining tension, a
concentric contraction occurs. For elbow 3exion, eccentric force exceeds isometric force
by about 20%, and isometric force exceeds concentric force by about 20% (Fig.
523,858). However, it is known that eccentric exercise is associated with muscle ber
damage. This may lead to alterations in muscle receptors that can alter joint position
13sense.FIGURE 5-8 Comparison of isometric, concentric, and eccentric 3exion and extension
contraction strength for di9erent positions of elbow 3exion. Note that approximately
20% greater strength may be generated with an eccentric than with an isometric
contraction; the isometric contraction, on the other hand, is approximately 20% greater
than the concentric type of contraction.
(Modified from Singh, M.: Isotonic and isometric forces of forearm flexors and extensors. J.
Appl. Physiol. 21:1436, 1966.)
FORCE CONSIDERATIONS
If the muscle produces a constant internal force that exceeds the external force of the
resistance, the muscle shortens, and the contraction is further characterized as isotonic.
Energy use in this case is larger than that required to produce tension, which will balance
the load, and the extra energy is used to shorten the muscle. If the speed of rotation of an
exercising limb is predetermined and held constant, changes occur in the amount of
tension developed in the muscles causing the motion. This is called an isokinetic
contraction. This may be of either the concentric or eccentric type defined earlier.
Speed of Contraction
A rapidly contracting muscle generates less force than one contracting more slowly. In an
isometric contraction, the velocity is zero because the resistance exceeds the ability of the
muscle to move the joint. In sports, rates of motion exceeding 300 degrees per second are
common. One recent study has shown that isometric training at maximum strength is
more e9ective to increase power production than no load training at maximum
88velocity.
FACTORS AFFECTING MAXIMUM MUSCLE TENSION
Muscle Length at Contraction/
The relationship of muscle tension to muscle length is recognized by most clinicians and
is presented graphically in the form of a length tension curve of an isolated muscle (Fig.
275-9). Recent studies suggest this concept is applicable to muscle systems at di9erent
89anatomic sites. The exact nature of the relationship varies from muscle to muscle and
from joint to joint, depending on the speci c function. For example, a study in our
laboratory demonstrated the relationship of triceps strength as a function of muscle
shortening. A somewhat linear relationship with 1-, 2-, and 3-cm length change
39associated with 17%, 40%, and 63% strength reduction, respectively (Fig. 5-10). The
length of elbow rotators change considerably over the full range of motion. The percent
74change at the wrist is 8; at the elbow, 55; and at the shoulder, 200.
FIGURE 5-9 An idealized length tension curve during isometric contraction
demonstrates the maximal force for active muscle contractility. A greater amount of force
may be attained if the muscle is stretched to some optimal point. Excessive stretching,
although theoretically increasing the muscle force, in fact reduces the strength of
contraction owing to loss of the ability of the contractile elements to function optimally.
FIGURE 5-10 Effect of the change in triceps length on extension strength.
TECHNIQUE OF STRENGTH MEASUREMENT
When evaluating strength, either the torque created about the joint or the force
generated in the hand and forearm in resisting joint rotation is measured. Either static or
dynamic measuring devices may be used./
In the clinic, the most common study is that of static or isometric 3exion-extension
17,52strength using a simple tensiometer, or spring device (Fig. 5-11). For more accurate
documentation or for investigative purposes, more sophisticated devices such as a strain
25 21,64,76gauge tensiometer and dynamometer also have been used.
FIGURE 5-11 A simple spring tensiometer, which is used in the clinical setting to
estimate elbow flexion strength.
Isokinetic strength is a more speci c measurement of dynamic elbow 3exion-extension
function and is used more frequently today, especially for the assessment of athletic or
occupational injuries. In an isokinetic muscular movement, the speed of rotation of the
limb is held constant despite changes in the amount of tension developed. This isokinetic
movement can be measured by means of an accommodating resistance dynamometer.
Because of the accommodating load cell, the velocity of an exercising limb cannot be
60,72increased. As more force is exerted against the lever arm of the dynamometer, more
resistance is encountered by the limb, and rotation occurs only at the predetermined
constant speed. These devices accurately measure peak torque, the joint angle position at
6peak torque, the range of motion, and endurance. This technique is becoming
increasingly useful for the measurement of elbow strength and endurance, and for more
84accurate study of the role of fatigue in arriving at disability estimates. This has proven
particularly useful in assessing patients with biceps tendon reattachment.
ELBOW STRENGTH
STATIC MEASUREMENTS
Flexion Extension
9Although the general tends are relatively consistent, absolute strength measurements are
not exactly comparable owing to variations in study technique and even greater
10,41differences between individual subjects, especially correlated to body size and age.On the average, the maximum isometric torque created at the elbow joint is about 7
4kg-m for men and 3.5 kg-m for women. Isometric muscle power is greatest during
25,933exion at joint positions between 90 and 110 degrees. At elbow angles of 45 and
135 degrees, only about 75 percent of the maximum elbow 3exion strength is
43,45,94generated. Maximum 3exion strength is generated in forearm supination;
18,43forearm pronation is associated with the weakest 3exion strength. Most of the
28torque occurs from contributions of the biceps, brachialis, and brachioradialis.
The mean di9erence in isometric 3exion force among the three forearm positions at
25various 3exion angles is about 5% for women and 10% for men. Strengths at the
neutral forearm position were slightly greater than those at the supinated and pronated
25,43,76,80positions.
For elbow extension, the average maximum torque strength is about 4 kg-m for men
4and 2 kg-m for women (Fig. 5-12). Observations for 14 female and 10 male subjects
showed a gradual increase in strength as the elbow was extended and the 90 degree
20,28,53,76position generates the greatest isometric extension force.
FIGURE 5-12 Mayo Clinic Biomechanics Laboratory study of normal elbow strength.
Notice that men are approximately twice as strong as women and that a 5% to 10%
difference is noted between the dominant and nondominant extremities.
In general, the dominant extremity is about 5% to 10% stronger than the nondominant
side, and men are about twice as strong as women in most positions (see Fig. 5-12). The
isometric force of the 3exors is about 40 percent greater than the isometric force of the
4,45extensors.
Supination and Pronation
The greatest supination strength is generated from the pronated position; the converse
17,55relationship is also true. In the majority of shoulder elbow positions, the average
torque of supination exceeded that of pronation by about 15 to 20 degrees for males and
females. This was particularly marked when the elbow was extended. On the average,
isometric pronation and supination strengths for men are 80 kg-cm and 90 kg-cm,
respectively, and for women are 35 kg-cm and 55 kg-cm, respectively. The dominant and/
/
/
/
nondominant strength di9erence in these two types of function averaged about 10% (see
83Fig. 5-12). In one study, it was found that isometric elbow strengths of rheumatoid
arthritis patients decreased in proportion to an increase in the severity of x-ray ndings.
The 3exion and supination strengths after total elbow replacement were about two times
greater than before operation.
DYNAMIC FUNCTION
Fatigue is an important consideration in altered function because routine activities
22require repetitive actions, some of which may exceed one million cycles per year.
The relative value of static and dynamic testing modalities is a debated issue. Motzkin
65and colleagues studied the relationship between isometric and isokinetic fatigue and
found no consistent relationship. One reason for this is the marked variation even in
test33retest studies of the same function. The one reliable association is that the eccentric
contracture provides the greatest torque strength for both isometric and isokinetic testing
33,65modes.
4The relationship between strength and speed of movement is unde ned. Many
investigations support the hypothesis that maximum strength and the rate of movement
68,73 29are independent of each other. In a recent study, isokinetic peak torque and work
were greater at the slower speed, as opposed to power, which was signi cantly greater at
the faster speed.
ADDITIONAL VARIABLES OF STRENGTH ASSESSMENT
In addition to the factors discussed, other confounding variables to strength testing
51,59,81include motivation, the learning e9ect of repetitive tests, the psychological
37,54 58bene t derived from repetitive testing, and the in3uence of the time of day, age,
10,41and even body size. The motivation factor is a variable that is well recognized but is
19,50,85di6 cult to control, quantitate, or eliminate. The rate of attaining maximum
strength during repetitive exertion has been suggested as a possible objective criterion for
judging whether a subject is voluntarily exerting full muscular strength or is not giving
50an honest e9ort. The eccentric:concentric strength ratios as well as the di9erence
between these ratios at the high and the low speeds were highly e9ective in
24distinguishing maximal from submaximal e9orts, and we do currently use this
information clinically to assess for “functional” behavior.
STABILITY
By virtue of the inherent stability a9orded by the joint articulation, clinical instability of
the elbow may be a perplexing problem (see Chapters 28 through 30). Ligamentous
42,82injury most commonly occurs in association with radial head fracture or elbow
54dislocation. Recurrent dislocations, however, occur in only 1% to 2% of patients. In
fact, recurrent instability at the elbow is most commonly a rotatory instability due to/
/
/
/
69insu6 ciency of the lateral ulnar collateral ligament and is discussed at length in
Chapter 48. The clinical concept of complex instability is becoming more recognized. The
“unhappy triad” refers speci cally to fractures of the radial head and coronoid in
association with collateral ligament injury. Quanti cation of instability is di6 cult;
studies are being conducted to understand instability, but no well-de ned standard exists
8to clinically grade this parameter (see Chapter 4).
FUNCTIONAL EVALUATION OF THE ELBOW
PERFORMANCE INDICES
An objective and reproducible means of evaluating the elbow by considering all of these
features of function is obviously desirable. A tradeo9 exists between a complex but
detailed assessment protocol and one that is simple but not su6 ciently thorough. A
complete and comprehensive assessment that might be useful in a research facility is not
practical clinically. For a clinician, a meaningful rating system should be both complete
and readily amenable to an o6 ce practice (Table 5-1). A single parameter or index
composed of all pertinent variables should accurately re3ect the gradation of objective
function, as discussed earlier. To be of further value, the rating system should include
consideration of the presence of pain and speci c daily functions that serve as surrogates
to several functional variables as they apply to a discrete activity. Finally, it is also
realized that no index or system is capable of discriminating changes in function of the
full spectrum of pathology. A tool to describe the state of an athlete with tennis elbow is
not adequate to describe the dysfunction of rheumatoid arthritis.
TABLE 5-1 Characteristics and Implications of Patient Assessment Tools
Trait Implication
Short High compliance
Reflects reality Valid to draw conclusions
Easy Nonambiguous questions
Reliable
• Accurate for all respondents
• Effective in person or by communiqué
Universal Addresses broad spectrum of conditions
Validated
Variation Believable data
Reliable Make decisions
Accurate Based on outcome/
/
To date, most proposed rating systems consider both objective function and subjective
77features (motion, strength, stability, pain, and the ability to perform daily activities).
Most systems have been developed to document the e9ectiveness of surgical intervention
26,40,75 12(Table 5-2). Broberg and Morrey rst described a system designed to be
applicable not only to joint replacement but also to other reconstructive procedures.
However, as noted earlier, it is obvious that no single rating system is both simple and
also sensitive enough to distinguish the status and change of function of the person
crippled by rheumatoid arthritis and of the professional tennis player with epicondylitis.
Nonetheless, I (B.F.M.) have found that a modi cation of the simple system reported by
Broberg has met my clinical needs over the last several years. The currently employed
62system is termed the Mayo Elbow Performance Score (MEPS) (Tables 5-2 and 5-3).
Any discussion of a system or index to summarize function should be subjected to (1) test
and retest reliability, (2) internal consistency, and (3) validity.
TABLE 5-2 Functional Assessment and Rating Schemes for the Elbow
TABLE 5-3 Mayo Elbow Performance Score
Function Points Definition (Points)
Pain 45
None (45)
Mild (30)
Moderate (15)
Severe (0)
Motion 20
Arc >100 degrees (20)
Arc 50–100 degrees (15)
Arc <50 degrees="">
Stability 10/
/
Stable (10)
Moderate instability (5)
Gross instability (0)
Function 25
Comb hair (5)
Feed (5)
Perform hygiene (5)
Don shirt (5)
Don shoe (5)
Total 100
Classification: excellent, >90; good, 75–89; fair, 60–74; poor,
Furthermore, it is highly desirable to be able to determine the index from patient input
above, either in person or by questionnaire. The characteristics of an e9ective functional
26,75evaluation scheme are shown in Table 5-1. In most systems, pain accounts for the
majority of the overall score. Because pain improvement is the most common outcome of
intervention, one can bias the appearance of the success of a procedure by overweighing
pain in the index calculation. Furthermore, I believe that it is important for the speci c
functional index used in a clinical practice to represent all functions of the elbow joint as
accurately as possible. Thus, those indexes that do not consider strength and stability,
except as how they relate to activities of daily living, may not be as comprehensive as
23those that consider these speci c joint functions. The functions of motion, strength,
and stability are also tested and, hence, duplicated by the ability to perform activities of
daily living. Thus, this latter category is really a surrogate for the other three. The issue of
a reliable, comprehensive, and yet simple method of determining functional assessment
remains unanswered for the elbow and, at the present time, is the subject of discussion
and investigation by the American Shoulder and Elbow Surgeons. Turchin and
90colleagues recently conducted an extensive assessment of the published elbow rating
scores. Although there is a lack of agreement in the aggregate scores, there is good
correlation with the individual raw aggregate scores. The most important message is that
which reinforces the observation made earlier; there is no one system that accurately
re3ects therapeutic value for all conditions: athletic, arthritic, traumatic, and the like. In
fact, a self administered questionnaire to assess ulnar nerve function has recently been
61demonstrated to be reproducible and valid.
OUTCOME MEASURES
In recent years, an increased emphasis has been placed on the subjective status or the
“outcome” of intervention./
/
/
/
The 3urry of activity over the last decade has been productive in rst producing useful
43,46,92general tools of assessment such as the Short Form-36 and the Western Ontario
and McMaster University Osteoarthritis Index (WOMAC). The WOMAC is designed
33principally to asses hip and knee function. More speci c to the elbow and upper
extremity, the American Shoulder and Elbow Surgeons described a patient- and
48physician-administered assessment tool, and a global strategy of documenting upper
extremity function including the shoulder, elbow and hand (DASH) has been
38developed by the American Academy of Orthopedic Surgeons in conjunction with the
38Canadian Institute for Work and Health. The DASH continues to be assessed and
7refined to further enhance its relevance.
36Ultimately, the goal is to measure disease and intervention impact on function and
3quality of life. The Patient-Related Elbow Evaluation is a short form using the Visual
57Analogue Scale to describe pain and daily function. The goal is to include
patientspeci c symptoms as well as components of the functional status including physical,
social, and psychological aspects to determine the impact of treatment. The value of
3speci c intervention on quality of life has also been undertaken recently. As implied
earlier, accurately demonstrating this relationship is surprisingly complex, but by
carefully using existing metrics, investigators have objectively documented the positive
3impact of elbow joint replacement. What remains is to also demonstrate the cost
e9ectiveness of interventions and ultimately be in a position to compare selection factors,
techniques, implants, and the like by objective and subjective outcome standards.
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Correct. Ther. J. 1979;33:188.CHAPTER 6
Diagnostic Imaging of the Elbow
Thomas H. Berquist
INTRODUCTION
Imaging technology has expanded dramatically over the past decade (Box 6-1). However,
evaluation of the elbow still relies heavily on routine radiographs or computed
radiography (CR) images. Optimal hard copy radiographs, or CR images, are essential to
properly select additional studies and are required for accurate interpretation of other
7modalities such as magnetic resonance (MR) imaging.
BOX 6-1 Imaging Techniques for Evaluation of the Elbow
Radiography/CR imaging
AP, lateral, oblique, radial head, and axial views
Stress views
Computed tomography (CT)
Arthrography
Conventional single- or double-contrast techniquee
CT with coronal and sagittal reformatting
MRI with axial, coronal, and sagittal images
MRI
Ultrasonography
Radionuclide scans/PET
Angiography
AP, anteroposterior; CR, computed radiography; CT, computed tomography; MRI,
magnetic resonance imaging; PET, positron emission tomography;
Conventional tomography is rarely performed today. However, computed tomography
(CT) has increased in utility with new multidetector systems that provide rapid
3evaluation of numerous bone and soft tissue disorders. Arthrography also can be an
important tool in the diagnosis of intra-articular disorders of the elbow. Today,
conventional, CT, and MR arthrography play important roles for evaluating the articular
7cartilage, intra-articular anatomy, and supporting structures of the elbow.
Magnetic resonance imaging (MRI) frequently is used to evaluate subtle osseous andsoft tissue abnormalities. Soft tissue contrast is superior to that achieved with CT. MRI
scans can be obtained in any plane, which is an additional advantage. Intravenous or
intra-articular injection of gadolinium provides additional information in selected
23cases.
Within the scope of this chapter, the indications for diagnostic imaging options as well
as their utility in given clinical situations are discussed. Su4 cient background
information to aid in determining the best modality for a given situation also is presented.
RADIOGRAPHY/COMPUTED RADIOGRAPHY IMAGING
An understanding of the process by which routine radiographs or CR images are obtained
is essential. Factors such as the type of equipment, patient positioning, and radiation dose
must be kept in mind when determining the necessary views in a given clinical setting. In
obtaining views of the elbow, we routinely use a 48-inch target 9lm distance with 50 to
60 kVp, 600 ma, and an exposure time of 0.0125 seconds. Reusable CR or regular
1,4,5cassettes measuring 10 × 12 inches are routinely employed.
A minimum of two projections is necessary for evaluation of the elbow. Anteroposterior
(AP) and lateral views of the elbow are taken at 90-degree angles and ful9ll these
1,5criteria. In trauma patients, we routinely obtain oblique views as well.
CR uses phosphor plate technology, which is designed to be used in a 9lmless
environment. This technology is replacing conventional screen-9lm radiography.
Regardless of the method of distribution (9lm or electronic), the techniques for patient
positioning and other factors discussed are similar.
ANTEROPOSTERIOR VIEW
The AP view (beam enters the patient anteriorly and the 9lm is posterior) is obtained by
placing the patient adjacent to the radiographic table in a sitting position (the supine
position may be used if the patient is injured). The patient should be positioned with the
extended elbow at the same level as the cassette so that the extremity is in contact with
1,4the full length of the cassette. The hand is supinated, and the beam is centered
perpendicular to the elbow (Fig. 6-1A). The AP view demonstrates the medial and lateral
epicondyles and the radiocapitellar articular surface (Fig. 6-1B). Assessment of the
trochlear articular surface and at least a portion of the olecranon fossa is also possible.
The normal carrying angle (5 to 20 degrees, average 15 degrees) can be measured on the
1,5AP view.?
FIGURE 6-1 A, Patient positioned for the anteroposterior (AP) view of the elbow. The
arm is level with the cassette, with the hand positioned palm up. The central beam
(pointer) is perpendicular to the elbow. B, Radiograph of the elbow in the AP projection
with anatomic labels.
LATERAL VIEW
The lateral view is obtained by exing the elbow 90 degrees and placing it directly on the
cassette. The hand is positioned with the thumb up so that the forearm is in the neutral
position; the beam is perpendicular to the humerus (Fig. 6-2A). This view provides good
detail of the distal humerus, elbow joint, and proximal forearm. The coronoid of the ulna,
which cannot be readily seen on the AP view, and the olecranon are well visualized on
the lateral view (see Fig. 6-2B). Because the articular surface makes a valgus angle of
about 7 degrees to the long axis of the humerus (see Chapter 2), a lateral view of the arm
does not provide a lateral view of the joint. If the x-ray beam is parallel to the articular
5surface, three concentric arcs can be identi9ed (Fig. 6-3A-D). The smaller arc is the
trochlear sulcus, the intermediate arc represents the capitellum, and the largest arc is the
medial aspect of the trochlea. If the arcs are interrupted, a true lateral view has not been
obtained. Unfortunately, in patients with acute injury, true AP and lateral views are often?
?
di4 cult to obtain. Patients are frequently unable to extend or ex the elbow fully. In
these situations, the tube must be angled and the cassette positioned to simulate these
1,4,5views as closely as possible.
FIGURE 6-2 A, Patient positioned for the lateral view with the elbow exed 90 degrees
and the beam (pointer) perpendicular to the joint. The shoulder is at the same level as the
cassette. This position is required to obtain a true lateral view. B, The projected image.FIGURE 6-3 A, Dried bone specimen demonstrating the points used for the three
concentric arcs. A, capitellum; B, trochlear sulcus; C, medial aspect of trochlea. A true
lateral view of the joint requires the beam to be directed distally about 7 degrees. B, On
the true lateral view, the three arcs are perfectly aligned. C and D, With slight lateral (C)
and medial (D) rotation of the elbow, the arcs are no longer aligned, indicating that the
view is not a true lateral.
OBLIQUE VIEWS
Oblique views are obtained by initially positioning the arm as if one were taking the AP
view. For the medial oblique projection (Fig. 6-4A and B), the arm is positioned with the
forearm and arm internally rotated approximately 45 degrees (see Fig. 6-4A). This view
allows improved visualization of the trochlea, olecranon, and coronoid (see Fig. 6-4B).
The radial head is obscured by the proximal ulna. The lateral oblique view is taken with
the forearm, hand, and arm rotated externally (Fig. 6-5A). This projection providesexcellent visualization of the radiocapitellar joint, medial epicondyle, radioulnar joint,
1,4,5and coronoid tubercle (see Fig. 6-5B).
FIGURE 6-4 Medial oblique view. A, The patient’s arm is internally rotated and the
hand pronated. The central beam pointer is perpendicular to the elbow. B, Radiograph of
the medial oblique view. The radial head is obscured by the ulna. Note the constant
relationship of the radial head and the capitellum.FIGURE 6-5 Lateral oblique view. A, The patient is positioned with the arm externally
rotated, the forearm supinated, and the central beam (pointer) perpendicular to the
elbow. B, Radiograph of the lateral oblique view. Note the visualization of the radial head
and capitellum, medial epicondyle, and radioulnar joint.
RADIAL HEAD VIEW
Radial head fractures are a common clinical problem and are often di4 cult to visualize
on radiographs or CR images. The radial head view may de9ne the fracture more
16,17,28clearly. This view (Fig. 6-6A and B) is easily accomplished by positioning the
patient as one would for the routine lateral view. The tube is angled 45 degrees toward
the shoulder joint (see Fig. 6-6A). The radial head view projects the radial head away
from the ulna, allowing subtle changes to be more easily identi9ed (see Fig. 6-6B), and it
1,16,17also may allow better visualization of the fat pads.?
FIGURE 6-6 Radial head view. A, The patient is positioned as if a routine lateral view
(see Fig. 6-2A) were to be obtained. The tube is angled 45 degrees toward the humeral
head rather than perpendicular to the joint. B, Radial head view projects the radial head
(R) clear of the olecranon and clearly demonstrates the capitellum (C) and radiocapitellar
joint.
AXIAL VIEWS
Occasionally, suspected pathology of the olecranon or epicondyles prompts further
evaluation with axial views. Figure 6-7A and B demonstrate the axial projection used to
evaluate the epicondyles, olecranon fossa, and ulnar sulcus. The patient’s elbow is exed
approximately 110 degrees, with the forearm on the cassette and the beam directed
perpendicular to the cassette. This view is also helpful in detecting subtle calci9cation in
patients with tendonitis. The olecranon process may be better observed on the reverse
1,4,5axial projection (Fig. 6-8A and B).?
FIGURE 6-7 A, Patient positioned for the axial view of the distal humerus. The elbow is
exed approximately 110 degrees, with the forearm and elbow on the cassette. The
central beam (pointer) is perpendicular to the cassette and centered on the olecranon
fossa. B, The radiograph provides excellent visualization of the epicondyles, ulnar sulcus,
and radiocapitellar and ulnotrochlear articulations.?
FIGURE 6-8 A, The patient’s arm is placed on the cassette, with the elbow completely
exed. The central beam (pointer) is perpendicular to the cassette. B, The radiograph
demonstrates the olecranon, trochlea, and medial epicondyle. Contrast this view with that
of Figure 6-7B.
1,4,5Other views of the elbow also may be used, but those just discussed are usually
su4 cient. In fact, when questions arise regarding routine AP, lateral, and oblique views,
a CT scan with reformatting in the coronal and sagittal planes or an MRI scan is
frequently obtained instead of special views.
ASSESSMENT OF RADIOGRAPHS/COMPUTED RADIOGRAPHY
IMAGES
Assessment of the above-mentioned views should be complete and systematic. Certain
9ndings should be checked consistently and, if necessary, further views or techniques
employed.
The relationship of the radial head to the capitellum should be constant regardless of
5,26,28the view obtained (Fig. 6-9A-C). The radius is normally bowed at the level of the
tubercle. Therefore, the line should be drawn in the midpoint of the radial head, not
extended to include this portion of the radial shaft.?
?
FIGURE 6-9 The radiocapitellar relationship is constant regardless of the view. Oblique
views (A and B) demonstrating the constant relationship of the radial head (line) to the
capitellum (broken circle). Poorly positioned lateral view (C) with a normal
radiocapitellar relationship. Positive fat pad (arrowheads) sign due to a subtle fracture.
Careful evaluation of the fat pads and supinator fat stripe is essential. These structures
are best observed on the lateral (see Fig. 6-2) and radial head (see Fig. 6-6) views. The
5,8,10,26,28anterior and posterior fat pads are intracapsular but extrasynovial. The
anterior fat pad is normally visible on the lateral view. The posterior fat pad is obscured
owing to its position in the olecranon fossa (Fig. 6-10). Displacement of the fat pads,
particularly the posterior fat pad, is indicative of an intra-articular uid collection due to
5,8,10,26,28 26in ammation or hemarthrosis due to trauma. Norell reportedthat 90% of
children with displaced posterior fat pads had elbow fractures. This 9nding is less speci9c
in adults, but if present in patients following trauma (see Fig. 6-9C), a fracture is likely.
Cross-table lateral views may be more speci9c. A lipohemarthrosis, which is more speci9c
5,26,28for an intra-articular fracture, may be evident.FIGURE 6-10 Lateral illustration of the elbow, demonstrating the anterior and posterior
fat pads. These structures are intracapsular but extrasynovial.
The supinator fat stripe lies anterior to the radial head and neck on the surface of the
supinator muscle. Fractures of the elbow frequently displace or obliterate this structure,
28providing a clue to the underlying injury (Fig. 6-11). Rogers and MacEwan reported
changes in the fat stripe in 100% of fractures of the radial head and neck and in 82% of
other elbow fractures.
FIGURE 6-11 Anteroposterior (A) and lateral (B) radiographs of the elbow,
demonstrating displacement of the fat pads (arrows) and supinator fat stripe (open arrow)
due to a subtle impacted radial neck fracture.
The anterior humeral line helps detect subtle supracondylar fractures in children but is
not used as frequently for adults. This line, drawn along the anterior humeral cortex,
5should pass through the middle third of the capitellum (Fig. 6-12).?
FIGURE 6-12 Lateral view of the elbow in a child with a displaced physeal fracture of
the distal humerus. The anterior humeral line passes through the posterior capitellum.
Note the fat pads (small arrows) are displaced.
STRESS VIEWS
In patients with suspected ligament disruption or instability, varus and valgus stress views
are desirable and may be diagnostic. Ideally, these examinations should be performed
with uoroscopic guidance. This allows proper positioning of the elbows. Also,
visualization of subtle changes in the articular distance may be evident while stress is
being applied. Fluoroscopic images should be obtained in the neutral position and during
valgus and varus stress. Accuracy may be hindered by guarding and swelling following
acute injury. In this situation, anesthetic injection should be performed before the
examination. In the normal elbow, the joint should not open when stress is applied. We
have arbitrarily chosen an increase in the joint space of greater than 2 mm as being
abnormal (Fig. 6-13A and B). The relationship of the tip of the olecranon in the fossa is
also helpful in interpreting radiographic instability. The normal elbow carrying angle also
5may increase significantly if ligament instability is present.FIGURE 6-13 Anteroposterior views of the elbow in neural (A) and valgus (B) stress.
Note that the joint space (lines) has increased (arrow), indicating the presence of a
ligamentous injury.
COMPUTED TOMOGRAPHY
Conventional tomography is rarely performed today due to the improved utility of CT
and new fast multi detector CT systems. CT is useful in the evaluation of bone and soft
5,19tissue abnormalities. Articular deformities, complex fractures with multiple fragments
and other conditions can be evaluated quickly and reformatted into coronal and sagittal
planes. Three-dimensional reconstructions can also be obtained. Thin sections using
0.519to 1.0-mm slices can be easily reconstructed (Fig. 6-14A and B). We frequently use CT
in combination with arthrography to more clearly de9ne articular or capsular
5,30abnormalities.?
FIGURE 6-14 Coronal (A) and sagittal (B) reformatted CT images after elbow trauma
demonstrating radial head fractures (arrowheads) and a distal humeral avulsion (open
arrow).
ARTHROGRAPHY
Elbow arthrography provides valuable information about capsule size, the synovial
lining, supporting ligaments, and the articular surfaces of the joints. Needle access also
6permits uid aspiration for laboratory studies and diagnostic or therapeutic injections.
The most common indications for this procedure are the detection of possible loose
bodies, evaluation of articular cartilage, and the demonstration of capsular/ligament
injuries. Loose bodies may be osteocartilaginous, owing to osteochon dromatosis or
osteochondral fragments due to acute trauma, or osteochondritis dissecans. Less
commonly, arthrograms are performed to evaluate capsule size in patients with adhesive
5,7,12,14,20,32capsulitis.
TECHNIQUE
To obtain maximum information, arthrography should be performed by an experienced
physician with a thorough understanding of the patient’s clinical situation. Review of the
routine radiographs or CR images is essential. These images often provide clues that
dictate subtle changes that indicate which imaging technique (conventional, CT, MRI)
should be employed following the injection of the contrast material. The choice of
contrast material and indications for conventional, CT, or MR arthrography are highly
7,31dependent on the clinical setting (Table 6-1).
TABLE 6-1 Elbow Arthrography: Indications and Techniques?
?
Indication Technique
Conventional or CT arthrography
Loose bodies
Osteochondromatosis
Osteochondritis dissecans
Fracture fragments from acute trauma CT arthrography
Ligament and capsule tears MR arthrography
Synovitis Indirect or intravenous MR
arthrogram with gadolinium
Synovial cysts MR arthrography
Articular cartilage abnormalities MR or CT arthrography
Capsule size Conventional arthrography
Needle position before aspiration or Conventional arthrography
diagnostic/therapeutic injection
Postoperative Subtraction technique for total elbow
Total joint replacement arthroplasty
Other
Conventional arthrography with
subtraction technique
CT, computed tomography; MR, magnetic resonance.
Contrast agents include air, iodinated contrast material, or a combination of the two
for conventional or CT arthrography and gadolinium diluted in iodinated contrast and
anesthetic for MR arthrography. Radiographs or CR images are obtained immediately
following injection of contrast medium to avoid dilution thatreduces image quality. CT
and MR arthrography should be performed within 30 and 45 minutes following injection,
respectively. If longer delays are expected, this dilutional phenomenon can be prevented
5,7,31,32by combining 0.3 mL of 1:1000 epinephrine with the contrast agent.
The procedure can be performed with the patient positioned either sitting adjacent to
the radiographic table or lying prone on the table (Fig. 6-15). Determination of the best
position depends on the equipment available and the patient’s condition. In either
position, the elbow is exed 90 degrees, with the lateral aspect toward the examiner.
Before the injection of contrast agent, uoroscopic evaluation of range of motion and
5evidence of possible ligament stability or loose bodies should be accomplished.?
?
?
FIGURE 6-15 Patient positioned for lateral injection (A) and posterior injection (B),
sitting with the elbow exed and the metal marker over the needle entry sites. Patient
positioned prone (C) for radiocapitellar injection.
The elbow is then prepared using sterile technique. One of two injection sites may be
used. In most cases, a lateral approach into the radiocapitellar joint is selected. In
patients with previous radial head resection or suspected lateral ligament injury, a
posterior approach is more suitable. With the posterior approach, the elbow is again
exed 90 degrees, and the medial and lateral epicondyles and olecranon are palpated.
The needle is placed an equal distance between these points and is positioned
fluoroscopically (Fig. 6-16). If the needle is properly positioned, the contrast medium will
ow away from the needle tip as it is injected. If the needle is not properly positioned, the
contrast agent collects at the needle tip and significant resistance is encountered.?
FIGURE 6-16 Illustration of needle positioned for lateral (A) and posterior (B)
approaches.
Following the injection, the needle is removed and the elbow is studied
uoroscopically. This step is essential in evaluating stability of the joint and loose bodies.
Routine 9lms or CR images include AP, lateral, and both oblique views. Medial and
lateral cross-table lateral views provide additional information with double contrast
5,32technique. CT images are obtained using thin sections (1 mm) with reformatting in
the coronal and sagittal planes. MRI scans are also obtained in the axial, coronal, and
sagittal planes with fat-suppressed T1-weighted images and at least one T2-weighted
7,31series as periarticular cysts may not communicate with the joint.
NORMAL FINDINGS
In the normal conventional arthrogram (Fig. 6-17A-D), the radiocapitellar, ulnotrochlear,
and radioulnar joints can be identi9ed. The anterior (coronoid), posterior (olecranon),
and annular recesses also are visualized.?
?
FIGURE 6-17 Routine projections for single contrast arthrogram with normal anatomy
labeled. A, Anteroposterior view. B, Lateral view. C and D, Oblique views.
The normal joint capacity is 10 to 12 mL. This may increase to 18 to 22 mL in patients
with chronic instability, or it may be decreased in patients with capsulitis or exion
5contracture.
ABNORMAL FINDINGS
“Loose bodies” may be either attached to the synovium or actually free within the joint. If
they are free, they can be observed uoroscopically or demonstrated on images by
5,7,31contrast that completely surrounds the structure (Fig. 6-18). DiI erentiation of a
loose body in the olecranon fossa from the normal os supratrochlear dorsale is possiblebecause of the nature of the trabecular pattern and the cortical thickness. Most
symptomatic densities in the olecranon fossa have prominent trabeculae and sclerotic
cortical margins (Fig. 6-19B). The normal ossicle has sparse trabeculae and a thin cortical
5,27rim (see Fig. 6-19A).
FIGURE 6-18 Single-contrast conventional arthrogram image. The contrast medium
completely surrounds the lucent loose body (arrow) in the olecranon fossa.
FIGURE 6-19 Lateral tomograms of the elbow. A, Asymptomatic patient with an os
supratrochlear dorsale. Note the thin cortex and lack of trabeculae (arrow) . B,
Symptomatic patient with a density in the same region with thick cortex (large arrow)
representing a loose body. There is a second smaller density in the joint space inferiorly.MR arthrography is preferred to exclude ligament/capsular tears, although
conventional techniques may demonstrate the tear when they are complete (Figs. 6-20
and 6-21). Extravasation of contrast material on conventional images indicates a tear (see
Fig. 6-20). Care must be taken not to mistake extravasation at the needle site for a rent of
the capsule. Therefore, the needle should not be placed near the area of suspected injury
regardless of the imaging technique selected. If a lateral tear is suspected, a posterior
5approach should be used.
FIGURE 6-20 Elbow arthrogram in a patient with ligament and capsular tear with
contrast extravasation medially.
FIGURE 6-21 Coronal fat suppressed T2-weighted MR arthrogram demonstrates a
complete tear of the radial collateral ligament (arrow).
COMPLICATIONS?
?
?
?
13Complications due to elbow arthrography are rare. Freiberger reports an incidence of
infection of approximately 1 in 25,000 cases. EI usions may occur whether contrast
material or air is used; they usually occur within 12 hours and may result in pain and
5,13,31joint stiI ness. The joint uid may have a turbid appearance owing to the high
5eosinophil count.
The patient should be questioned about possible allergy to the contrast medium
13(iodinated or gadolinium). Although it is rare (0.1% of patients aI ected), this
complication must be kept in mind. Urticaria is the most common reaction experienced,
and often no treatment is necessary. In more severe cases, antihistamines may be
required. Most allergic reactions occur in the 9rst 30 minutes after the injection.
Premedication with an antihistamine may be used in patients with suspected allergy.
These patients should be observed for 1 or 2 hours following the procedure.
MAGNETIC RESONANCE IMAGING
MRI of the elbow can clearly de9ne numerous types of osseous and soft tissue pathology.
Improved soft tissue contrast and numerous image planes provide advantages over CT
7,31and other imaging techniques. Intra-articular contrast injection using gadolinium, as
described previously, aI ords advantages provided with conventional arthrography and
additional information regarding subtle synovial and cartilage abnormalities. Intravenous
gadolinium is useful for detection of early synovial in ammation and enhancement of
2,5,7other lesions such as osteomyelitis and neoplasms.
Surface coils generally are used to improve image quality. For patient comfort, the arm
should be placed at the side when possible. When the arm is raised above the head, there
5,7is often motion artifact resulting in image degradation.
MR pulse sequences are designed to demonstrate contrast diI erences between normal
and abnormal tissues. Multiple pulse sequences and image planes are required to identify
and stage pathology. Often, the axial plane is combined with sagittal (Fig. 6-22) or
5,7coronal images for initial screening. In certain situations, new fast-scan techniques are
used to allow motion (pronation-supination or exion-extension) studies to be performed.
Pronation-supination maneuvers (Fig. 6-23) are most easily performed, because MR
gantry size limits ranges of exion and extension. Newer open magnets provide more
7flexibility for motion.FIGURE 6-22 Patient with chronic muscle pain and weakness. (A) Oblique view of the
elbow shows several areas of soft tissue ossi9cation or avulsed fragments laterally
(arrowheads). Coronal (B) and axial (C) T1-weighted images (SE 500/11) show low signal
intensity changes in the fat and muscle (B) (arrows). Axial (D) and coronal (E)
T2weighted images demonstrate increased signal intensity in the muscles due to a muscle
tear.?
?
?
?
?
FIGURE 6-23 Sagittal gradient echo images in diI erent degrees of supination. A, The
biceps tendon (arrow) is in the image plane. B, The tendon is snapping over the ganglion
(arrows).
ULTRASONOGRAPHY
Ultrasound applications for musculoskeletal imaging have expanded dramatically from
the late 1970s. Improved technology and image quality permit more accurate depiction
of normal anatomy and pathologic lesions. Ultrasonography is also more readily available
5,21,24,25and less expensive than MRI.
Ultrasound uses mechanical vibrations whose frequencies are beyond audible human
perception (about 20,000 Hz or cycles per second). Imaging of most musculoskeletal
21,24structures is accomplished in the 7- to 12-MHz range. Doppler ultrasonography for
25peripheral vascular studies is performed in the 8-MHz range. New Doppler scanners
provide color ow data that allow diI erent ow rates (venous, arterial) to be easily
5,25demonstrated.
The central component of ultrasound instruments is the transducer, which contains a
piezoelectric crystal. The transducer serves as a transmitter and receiver of sound waves.
By applying the vibrating transducer to the skin surface (through an acoustic coupling
medium such as mineral oil or gel), the mechanical energy is transmitted into the
underlying tissues as a brief pulse of high-energy sound waves. Sound waves reach
diI erent tissue interfaces (acoustic impedances), resulting in re ection or refraction. The
re ected sound waves return to the transducer, where they are converted into electrical
5,21,24,25energy used to produce the image.
Ultrasound, once limited to evaluating solid and cystic soft tissue lesions, is now
commonly employed to evaluate articular and periarticular abnormalities. In the elbow,
ultrasonography is well suited for evaluating tendon (Fig. 6-24) and nerve (Fig. 6-25)
pathology. Tendon tears are demonstrated as gaps or areas of abnormal echo texture
compared with the normal tendon (see Fig. 6-24). Avulsed bone fragments or
21calci9cations are hyperechoic with posterior acoustic shadowing. Cost and exibility of
24this technique will, no doubt, result in increased orthopedic use.FIGURE 6-24 Longitudinal ultrasonographic image of a normal (right) and ruptured
(left) tendon.FIGURE 6-25 Ultrasound of ulnar nerve dislocation demonstrated on pre- (A), passive
(B) and active (C) resistance.
(Courtesy of Gina Hesley, Mayo Clinic, Rochester, Minnesota.)
RADIONUCLIDE SCANS/POSITRON EMISSION TOMOGRAPHY
There are numerous isotopes and indications for radionuclide imaging of the
5musculoskeletal system. Bone scans are typically obtained after intravenous injection of
10 to 20 mCi (370-740 MBq) of technetium-99m–labeled methylene diphosphonate.
Images are obtained 2 to 4 hours after injection. Common indications include primary or
metastatic bone lesions, subtle fractures, non-accidental trauma in children and other
5causes of suspected osseous related pain.?
?
?
Three-phase bone scans use the same isotope and dose, but images are obtained in the
initial 60 seconds after injection, followed by blood pool images at 2 to 5 minutes and
delayed images at 3 to 4 hours. Indications for three phase scans include diI erentiation
of cellulitis from osteomyelitis, bone infarction, re ex sympathetic dystrophy, and
5,29peripheral vascular disease.
Bone marrow scintigraphy is performed using 10 to 15 mCi (370-555MBq) of
technetium-labeled sulfur colloid. Images are obtained approximately 15 minutes after
injection. Lead shields are placed over the abdomen to delete counts from the liver and
spleen. Bone marrow imaging is most often performed to evaluate marrow replacement
5disorders and patients with joint prostheses.
Special approaches may be required in patients with suspected infection. A normal
bone scan or three-phase bone scan virtually excludes the possibility of infection. These
techniques are sensitive but not speci9c. Therefore, when there is a high index of
suspicion, more speci9c approaches are generally employed. White blood cells labeled
with indium-111 or technetium or technetium-labeled antigranulocyte antibodies provide
15,22more specificity.
Indium-111-labeled leukocyte scans are performed 18 to 24 hours after intravenous
injection of the isotope. Technetium-labeled leukocytes or antigranulocyte antibody
imaging is performed 2 to 4 hours after injection. Technetium is more readily available,
and image resolution is superior to Indium-111 studies. Gallium-67 citrate scans can also
be used to identify infection. Scanning is performed 24 to 72 hours after injection. This
9isotope is less commonly used today. Combined studies (i.e., technetium and white
blood cells or indium-111 and technetium sulfur colloid) may be required in chronic
5,9,22infections or in the presence of orthopedic implants or prostheses.
Positron emission tomography (PET) has provided a new physiologic approach to
11,18imaging musculoskeletal disorders, speci9cally infection and neoplasms.
Positronemitting agents include ourine-18-deoxyglucose, L-methyl-carbon 11, and oxygen 15.
Flourine-18 has a half life of 110 minutes compared with the shorter half life of 20 and
21 minutes respectively for the other agents. Therefore, ourine-18 is the clinical agent of
choice. Flourine-18-deoxyglucose imaging demonstrates increased glucose use seen with
active disease processes. Patients must be fasting for 4 hours before the study. No sugared
beverages should be taken, and blood sugar should be normal for optimal studies.
Scanning is performed 1 hour after injection. Early studies demonstrate that PET imaging
is more accurate than the studies described above for evaluating infection, chronic
infection, and infection associated with orthopedic 9xation devices or arthroplasty. PET is
also more useful than conventional isotopes for detection of tumor activity and
11,18metastasis.
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