Medial Collateral Ligament Injuries
Injury to the medial collateral ligament (MCL) is common, occurring in both contact and non-contact injury mechanisms. It is the most common ligamentous injury of the knee, comprising 40% of all knee ligament injuries.
Anatomy and Pathophysiology
The MCL is located on the medial, or inner, aspect of the knee joint, and extends from the distal femur to the proximal tibia. It includes both superficial and deep MCL layers and has a good vascular supply via the superior medial and inferior medial geniculate arteries.
This ligament provides stability to valgus stress, and injury occurs most commonly when a hit or flow occurs to the outer aspect of the knee.
MCL Injury Grades (Hughston Modification)
- Grade I: mild stretch injury without loss of ligamentous integrity.
- Grade II: incomplete or partial MCL tear
- Grade III: complete MCL tear
Physical Examination and Work-up
On examination, tenderness may be elicited along the MCL. A knee effusion or ecchymosis may be present. Both ROM and knee stability are assessed, including determining the grade of injury.
Valgus Stress Test: this clinical test is used to evaluate the integrity of the medial collateral ligament (MCL). The knee is held in 20 degrees of flexion and loaded in valgus distally such that the MCL is placed on stretch. The examiner assesses the amount of opening/gapping at the medial joint space. The test is repeated with the knee in full extension.
In the setting of laxity on exam, additional “stress X-rays” may be performed to accurately quantify the medial gapping at the joint line compared to the non-injured side. Additionally, on X-ray, calcification at the medial femoral insertion site may be present, known as a Pellegrini-Stieda sign. MRI is the modality of choice to characterize extent of injury and the presence of concurrent injuries of the knee.
Management of MCL Injuries
The MCL has great healing potential in comparison to the anterior cruciate ligament (ACL). In the setting of Grade I injuries, nonoperative care of NSAIDs, rest and physical therapy often enable advancement to return to activity rather quickly.
Grade II and a subset of Grade III injuries may also be treated non-surgically with bracing, NSAIDs, activity modification and physical therapy. A gradual, criterion-based return to activity follows.
In the case of injuries with significant medial joint line gapping on stress X-ray and continued instability despite conservative care, ligamentous repair or reconstruction may be indicated. An MCL repair involved reattaching or repair the torn MCL, while MCL reconstruction utilizes autograft or allograft to replace the torn MCL. Post-operative rehabilitation is closely monitored and guided with criterion-based advancement based on regular exercise testing intervals at the COSMO Fit Lab.