eMedicine Specialties > Sports Medicine > Knee
Medial Collateral Knee Ligament Injury
Updated: May 30, 2006
Introduction
Background
Medial collateral ligament (MCL) injuries of the knee are very common sports-related injuries. The MCL is the most commonly injured knee ligament. Injuries to the MCL occur in almost all sports and in all age groups.
Frequency
United States
The incidence of MCL injuries is impossible to determine because of the wide spectrum of injury severity. Many MCL injuries are minor and may never be evaluated by a physician.
Functional Anatomy
The medial aspect of the knee has been divided into 3 distinct layers based on cadaver dissection. The first layer is the deep fascia, which consists of the sartorius fascia anteriorly and a thin fascial layer posteriorly. The thin posterior fascia covers the popliteal fossa and the heads of the gastrocnemius muscle. The second layer includes the superficial MCL, also known as the tibial collateral ligament. This ligament attaches proximally to the medial femoral epicondyle and to the tibia distally, approximately 4-5 cm distal to the joint line. The parapatellar retinaculum and patellofemoral ligament are within this layer.
The third layer is the knee joint capsule, which attaches proximally and distally at the articular margins. The capsule is divided into thirds from anterior to posterior. The anterior third of the capsule is the thinnest portion. It is attached to the anterior horn of the medial meniscus and is reinforced by the medial retinaculum. The middle third of the capsule consists of the deep medial collateral ligament. It is firmly attached to the mid body of the medial meniscus. Proximal to the meniscal attachment, it is termed the meniscofemoral ligament. Distal to its meniscal attachment, it is termed the meniscotibial ligament. The posterior third of the capsule includes the posterior oblique ligament (POL) and the oblique popliteal ligament. The POL has 3 arms, the superficial, tibial, and capsular.
Sport Specific Biomechanics
The superficial MCL has been shown through serial cutting studies to provide the primary restraint to valgus loads at all degrees of flexion. It is also an important restraint to anterior tibial translation when the anterior cruciate ligament is injured. The superficial MCL acts as a primary restraint to external rotation of the tibia.
Stability of the medial side of the knee is provided by dynamic and static restraints. The static restraints are the superficial MCL and the joint capsule, including the deep MCL and the POL. The semimembranosus muscle, the pes anserine muscles, and the vastus medialis muscle provide dynamic stability. The muscles of the pes include the sartorius, gracilis, and semitendinosus. These muscles flex and internally rotate the tibia. The semimembranosus has 4 attachments: direct, tibial, inferior, and capsular.
Clinical
History
A thorough history should be obtained prior to performing the physical examination. The following questions should be answered:
- How and when did the injury occur?
- What was the mechanism of injury?
- What was the position of the knee at the time of injury?
- Was the patient able to ambulate immediately after the injury? If so, is the patient still able to ambulate?
- Did the knee swell immediately or was swelling delayed?
- Did the patient experience a sensation of a tearing or hear an audible pop?
- Did any deformity occur? (Deformity may signify a patella subluxation or dislocation.)
- Have any prior injuries or fractures occurred?
- Where is the site of injury within the MCL?
Physical
A complete physical examination of the knee should be performed after a thorough history is obtained. Attention should be directed toward localizing the MCL injury and identifying any associated injuries.
- Inspection and palpation of the knee should identify the presence and location of point tenderness, localized soft tissue swelling, deformity, or ecchymosis. The region of injury within the ligament should be noted. A large joint effusion indicates an associated intra-articular injury. Outcome can be influenced by the location of the injury within the ligament.
- The integrity of the MCL is tested with a valgus stress. If any abnormal laxity is noted, the quality of the endpoint should be determined. Testing should be performed in full extension and at 30° of flexion. Grading of the injury is based on the amount of laxity. Any laxity is compared to the opposite knee.
- Rotation should be compared to the opposite knee when evaluating for associated posteromedial injuries.
- Anterior and posterior draw signs and a Lachman are performed to rule out associated injuries.
- Associated injuries include the following:
- Other structures within the knee may be injured in association with the MCL. The anterior cruciate ligament (ACL) is injured in approximately 20% of grade 1 injuries and as many as 78% of grade 3 injuries.
- The medial meniscus is injured 5-25% of the time; the incidence increases with severity of the MCL injury.
- The extensor mechanism, including the vastus medialis obliquus and retinacular fibers, is also injured in 9-21% of the cases.
- The PCL may be injured, but no incidence has been reported.
- Classification systems include the following:
- American Medical Association Committee on the Medical Aspects of Sports (1966)
- Grade 1 - 0-5 mm of opening
- Grade 2 - 5-10 mm of opening
- Grade 3 - Greater than 10 mm of opening
- O'Donoghue classification
- Grade 1 - Few torn fibers, structurally intact
- Grade 2 - Incomplete tear, no pathologic laxity
- Grade 3 - Complete tear, pathologic laxity
- American Medical Association Committee on the Medical Aspects of Sports (1966)
Causes
Contact, noncontact, and overuse mechanisms are involved in causing MCL injuries.
- Contact injuries involve a direct valgus load to the knee. This is the usual mechanism in a complete tear.
- Noncontact, or indirect, injuries are observed with deceleration, cutting, and pivoting motions. These mechanisms tend to cause partial tears.
- Overuse injuries of the MCL have been described in swimmers. The whip-kick technique of the breaststroke has been implicated. This technique involves repetitive valgus loads across the knee.
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References
Albright JP, Powell JW, Smith W, et al. Medial collateral ligament knee sprains in college football. Effectiveness of preventive braces. Am J Sports Med. Jan-Feb 1994;22(1):12-8. [Medline].
Fanelli GC, Edson CJ, Orcutt DR, et al. Treatment of combined anterior cruciate-posterior cruciate ligament-medial-lateral side knee injuries. J Knee Surg. Jul 2005;18(3):240-8. [Medline].
Halinen J, Lindahl J, Hirvensalo E, Santavirta S. Operative and Nonoperative Treatments of Medial Collateral Ligament Rupture With Early Anterior Cruciate Ligament Reconstruction: A Prospective Randomized Study. Am J Sports Med. Feb 1 2006;[Medline].
Lundberg M, Messner K. Long-term prognosis of isolated partial medial collateral ligament ruptures. A ten-year clinical and radiographic evaluation of a prospectively observed group of patients. Am J Sports Med. Mar-Apr 1996;24(2):160-3. [Medline].
Lundberg M, Messner K. Ten-year prognosis of isolated and combined medial collateral ligament ruptures. A matched comparison in 40 patients using clinical and radiographic evaluations. Am J Sports Med. Jan-Feb 1997;25(1):2-6. [Medline].
Reider B. Medial collateral ligament injuries in athletes. Sports Med. Feb 1996;21(2):147-56. [Medline].
Reider B, Sathy MR, Talkington J, et al. Treatment of isolated medial collateral ligament injuries in athletes with early functional rehabilitation. A five-year follow-up study. Am J Sports Med. Jul-Aug 1994;22(4):470-7. [Medline].
Warren LF, Marshall JL. The supporting structures and layers on the medial side of the knee: an anatomical analysis. J Bone Joint Surg Am. Jan 1979;61(1):56-62. [Medline].
Further Reading
Keywords
MCL injury, tibial collateral knee ligament injury, TCL injury, torn ligament, knee injury
