History
Listen to the patient's description of the injury event. The force vector of injury to the knee indicates the most likely site of pathology. [10] For example, a football player who complains of medial knee pain after a valgus stress on the knee is likely to have an injury to the medial collateral ligament (MCL). Have the patient use the uninjured knee to explain precisely what he/she was doing when the incident occurred.
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MCL injury
Patients commonly have had recent excessive valgus force applied to a partially flexed knee (eg, a clipping injury in football). A common triad of injury (particularly in athletes) when a valgus force is applied to the knee involves injury to the MCL, the medial meniscus, and the anterior cruciate ligament.
Most patients are able to continue ambulating after an acute injury.
Pain and stiffness are localized to the medial knee.
Erythema may appear after several days.
The location of pain and swelling can be good indicators of which structure(s) may be damaged in the knee.
Instability or mechanical symptoms (eg, a locking or popping sensation) are uncommon.
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Lateral collateral ligament (LCL) injury
The patient commonly reports a history of varus force applied to the knee.
Most patients are able to continue ambulating after an acute injury.
Pain and stiffness are localized to the lateral knee.
Erythema may appear after several days.
Swelling is often present.
Instability or mechanical symptoms (eg, a locking or popping sensation) are uncommon.
Physical
Recognize that collateral ligament injuries often are seen in association with injury to other knee structures. A comprehensive musculoskeletal knee examination should be completed to direct further diagnostic testing and therapeutic interventions. A systematic review of the available literature revealed no articles that adequately assessed the diagnostic sensitivity and specificity of a physical examination in detecting medial and lateral collateral ligamentous injuries.
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Medial collateral ligament (MCL) injury
Palpate with the knee in 25-30 º of flexion.
Tenderness may be noted anywhere along the course of the MCL.
Isolated tenderness at the proximal or distal insertion sites may indicate an avulsion-type injury.
Swelling often is present and should alert the examiner to possible intra-articular injury.
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Lateral collateral ligament (LCL) injury
Palpate with the knee in 20 º of flexion.
Tenderness may be noted anywhere along the course of the LCL.
Isolated tenderness at the proximal or distal insertion sites may indicate an avulsion-type injury.
Swelling is common.
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Evocative testing of collateral ligaments
Valgus stress testing of the MCL
The patient is in the supine position with the knee flexed 25-30 º. The examiner places one hand on the lateral knee and grasps the medial ankle with the other hand. Then the knee is abducted. Pain and excessive laxity indicate stretching or tearing of the MCL.
Perform the same technique as above with the knee extended. If excessive knee joint laxity and pain are still noted, injury to the anterior cruciate ligament also may be present.
Varus stress testing of the LCL
The patient is in the supine position with the knee flexed 20-25 º. The examiner places one hand on the medial knee and grasps the lateral ankle with other hand. The knee is adducted. Pain and excessive laxity indicate injury to the LCL.
Then perform the same technique as above with the knee extended. If pain and laxity are still present, injury to the posterior capsule may be present.
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Injury severity
Grade I - Less than 5 cm laxity (partial tear)
Grade II - 5-10 cm laxity
Grade III - More than 10 cm laxity (complete tear)
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Physical examination under general anesthesia may be indicated if the patient is guarding due to pain symptoms.
Causes
See the list below:
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Injury to the medial collateral ligament (MCL) or lateral collateral ligament (LCL) may be caused by the following:
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Acute varus or valgus stress on the knee joint
Sports related (younger population)
Falls (elderly)
Other trauma
Overuse syndromes (for example, swimmers who use the breaststroke may repetitively stretch the MCL, leading to injury)
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A study by Lee et al reported that in children and adolescents with anterior cruciate ligament (ACL) tears, older age and contact injuries are risk factors for concomitant lateral and medial collateral ligament injuries. The study also found the proportion of chondral injuries in patients with concomitant collateral ligament trauma to be higher than in the rest of the group. [11]
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The medial and lateral collateral ligaments of the knee. Courtesy of Randale Sechrest, MD, CEO, Medical Multimedia Group.
