eMedicine Specialties > Sports Medicine > Upper Limb

Ulnar Collateral Ligament Injury

Author: Robert F Kacprowicz, MD, Program Director, San Antonio Uniformed Services Health Education Consortium Residency in Emergency Medicine
Coauthor(s): Eric Chumbley, MD, Consulting Staff, Department of Sports Medicine, Trover Clinic
Contributor Information and Disclosures

Updated: Sep 26, 2007

Introduction

Background

The ulnar collateral ligament (UCL) of the elbow is critical for valgus stability of the elbow and is the primary elbow stabilizer.1,2 As such, the UCL plays an important role in most throwing sports, including baseball and javelin, as well as racquet sports and ice hockey.

Elbow injuries in young athletes are generally chronic, with persistent pain and instability from repetitive overhead activities. In the athlete, ligamentous injury can also be heralded by an acute traumatic event such as an elbow dislocation. This can then lead to chronic pain and valgus instability. An understanding of the anatomy and biomechanics of the elbow in throwing sports is essential to the correct diagnosis and treatment of this potentially disabling injury.3

Functional Anatomy

The UCL originates at the posterior distal aspect of the medial epicondyle and inserts into the base of the coronoid process. At 90 º of flexion, it provides 55% of the resistance to valgus stress at the elbow. In full extension, the UCL, bony architecture, and anterior capsule equally maintain valgus stability.

The UCL is composed of 3 bands: anterior, posterior, and transverse. The anterior band, which arises from the anteroinferior surface of the medial epicondyle and inserts on the sublime tubercle of the ulna, provides the major contribution to valgus stability.

Sport-Specific Biomechanics

The acceleration phase of the overhead throw causes the greatest amount of valgus stress to the elbow.4 Extension occurs at a rate of up to 2500 º per second and continues to 20 º of flexion. During this phase, the forearm lags behind the upper arm and generates valgus stress while the elbow is primarily dependent on the anterior band of the UCL for stability. During the acceleration phase, valgus stress can exceed 60 Newton meters (Nm), which is significantly higher than the measured strength of the UCL in cadavers. The valgus force can, therefore, overcome the tensile strength of the UCL and cause either chronic microscopic tears or acute rupture.

Clinical

History

  • Medial elbow pain is the most common symptom in athletes who throw. Pain may be especially prominent during the acceleration phase of the overhead throw.
  • Pain is often chronic or recurrent, and it may lead to a slow erosion of the patient's throwing ability.
  • Athletes may report having had similar pain in previous seasons of throwing.
  • Rest generally helps to relieve the pain.
  • Occasionally, during a single throw, athletes may experience acute pain over the medial elbow, sometimes associated with a popping sensation, that causes them to immediately stop throwing.

Physical

  • Medial elbow tenderness and swelling are the most notable findings. Tenderness is commonly found approximately 2 cm distal to the medial epicondyle. UCL tenderness may occasionally be difficult to differentiate from flexor pronator tendinitis, but the pain of flexor pronator tendinitis is aggravated by resisting forearm pronation.
  • Loss of elbow range of motion (ROM) is occasionally observed.
  • With acute rupture, ecchymosis may be observed over the medial elbow.
  • Pain may be reproduced when the patient makes a clenched fist.
  • Valgus stress with the elbow in 25° of flexion (elbow abduction stress test) reproduces pain and may cause joint opening. The affected side should be compared with the contralateral elbow as a reference for baseline laxity.
  • Some throwing athletes have a baseline asymmetry; therefore, preseason documentation of baseline elbow laxity in elite athletes, especially pitchers, may be helpful for comparison if an injury occurs during the season.

Causes

  • Repetitive throwing motions are the most common cause of UCL injury in the athlete.
  • Traumatic valgus stress to the elbow during a fall or with the arm outstretched may lead to UCL rupture in association with elbow dislocation.

More on Ulnar Collateral Ligament Injury

Overview: Ulnar Collateral Ligament Injury
Differential Diagnoses & Workup: Ulnar Collateral Ligament Injury
Treatment & Medication: Ulnar Collateral Ligament Injury
Follow-up: Ulnar Collateral Ligament Injury
References
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References

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Further Reading

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Keywords

medial collateral ligament injury, little leaguer's elbow, UCL injury, elbow injury/trauma, elbow pain, valgus elbow instability

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Contributor Information and Disclosures

Author

Robert F Kacprowicz, MD, Program Director, San Antonio Uniformed Services Health Education Consortium Residency in Emergency Medicine
Robert F Kacprowicz, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Eric Chumbley, MD, Consulting Staff, Department of Sports Medicine, Trover Clinic
Eric Chumbley, MD is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, and Uniformed Services Academy of Family Physicians
Disclosure: Nothing to disclose.

Medical Editor

Craig C Young, MD, Associate Professor, Departments of Orthopedic Surgery and Community and Family Medicine, Medical Director of Sports Medicine, Sports Medicine Fellowship Director, Medical College of Wisconsin
Craig C Young, MD is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, American Medical Society for Sports Medicine, Phi Beta Kappa, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Henry T Goitz, MD, Chief, Sports Medicine, Associate Professor, Department of Orthopaedic Surgery, Medical College of Ohio
Henry T Goitz, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons and American Orthopaedic Society for Sports Medicine
Disclosure: Nothing to disclose.

CME Editor

Jon B Whitehurst, MD, Clinical Instructor of Surgery, University of Illinois College of Medicine; Partner and Executive Board Member, Rockford Orthopedic Associates; Orthopedic Chairman, Rockford Memorial Hospital
Jon B Whitehurst, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America
Disclosure: Nothing to disclose.

Chief Editor

Sherwin SW Ho, MD, Associate Professor, Department of Surgery, Section of Orthopedic Surgery and Rehabilitation Medicine, University of Chicago
Sherwin SW Ho, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America
Disclosure: Nothing to disclose.

 
 
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