Summary
Definition
The medial collateral ligament (MCL) is a supporting structure on the medial part of the knee joint. 
[Figure caption and citation for the preceding image starts]: Medial collateral ligament (right knee)Created by Sanjeev Bhatia, MD; used with permission [Citation ends]. Its primary function is to resist valgus (twisting outwards away from the mid-line) and external rotation forces of the tibia in relation to the femur. The mechanism for MCL injury is typically a large valgus and/or external rotation force that is suddenly placed on the knee joint. Injuries to the MCL range in severity from a few torn fibres to complete disunity of the ligament.
History and exam
Key diagnostic factors
- presence of risk factors
- injury due to excessive or repetitive valgus loading of MCL
- medial knee pain
- joint effusion
- tenderness
- laxity on valgus stress testing
Other diagnostic factors
- ecchymosis
- audible pop or tearing sensation at time of injury
- difficulty walking
- instability symptoms of knee
- mechanical knee symptoms
- knee deformity
- positive anterior drawer test
- positive posterior drawer test
- positive Lachman's test
- positive pivot shift test
- joint line tenderness
- chronic pain
Risk factors
- participation in activities involving valgus stress at the knee joint
- age 20 to 35 years
- age 55 to 70 years
- weak muscles that cross the medial aspect of knee
Diagnostic investigations
1st investigations to order
- plain x-rays of knee
- stress x-rays of knee
Treatment algorithm
Contributors
Authors
Co-Director, Hip & Knee Joint Preservation Center
Northwestern Medicine Central DuPage Hospital
Northwestern University Feinberg School of Medicine
Warrenville
IL
Disclosures
SB receives royalties from the following Nova publication: Ligamentous Injuries of the Knee. SB has stock ownership in Vericel and Joint Preservation Innovations, LLC.
Professor
Department of Orthopedic Surgery
Section of Sports Medicine
Rush University Medical Center
Chicago
IL
Disclosures
NNV declares the following competing interests: American Orthopaedic Society for Sports Medicine: board or committee member; American Shoulder and Elbow Surgeons: board or committee member; Arthrex, Inc.: research support; Arthroscopy: publishing royalties, financial or material support; Arthroscopy Association of North America: board or committee member; Breg: research support; Cymedica: stock or stock options; Knee: editorial or governing board; Minivasive: paid consultant, stock or stock options; Omeros: stock or stock options; Orthospace: paid consultant; Ossur: research support; SLACK Incorporated: editorial or governing board; Smith & Nephew: IP royalties, research support; Vindico Medical-Orthopedics Hyperguide: publishing royalties, financial or material support; Wright Medical Technology, Inc.: research support.
Peer reviewers
Co-director of Orthopedic Sports and Shoulder Service
Department of Orthopedic Surgery
Naval Medical Center San Diego
San Diego
CA
Disclosures
DJS declares that he has no competing interests.
Professor
Chief of Physical Medicine and Rehabilitation
Ann Arbor VA Medical Center
Ann Arbor
MI
Disclosures
RW has been reimbursed by the University of Michigan for attending several conferences and has been paid an honorarium for speaking at the American Association of Neuromuscular and Electrodiagnostic Medicine national meeting. RW has been paid by the National Institute for Occupational Safety and Health, the American Dental Association, and SmartHealth as a consultant and has received grant funding from the UAW/GM Health and Safety Board (over US$1 million).
Assistant Director
Orthopaedic Shoulder and Sports Surgery
Naval Medical Center San Diego
San Diego
CA
Disclosures
MTP declares that he has no competing interests.
Clinical Assistant Professor of Medicine
Robert Wood Johnson Medical School
University of Medicine and Dentistry of New Jersey
Piscataway
NJ
Disclosures
PHC declares that he has no competing interests.
Orthopedic Surgeon
Department of Orthopedic Surgery
Seoul Veterans Hospital
Seoul
South Korea
Disclosures
JRY declares that she has no competing interests.
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