Medial Collateral Ligament Injury

The medial collateral ligament has a superficial band, a deep band and the posterior oblique ligament. It resists valgus and external rotation. It is the most commonly injured knee ligament, typically from a valgus blow to the lateral knee or a non-contact twist in football and skiing.

Grading by medial joint opening on valgus stress at 30 degrees: grade I (pain, no laxity, under 5 mm), grade II (5 to 10 mm with a firm endpoint), grade III (over 10 mm with a soft endpoint). The ligament is extra articular and well vascularized, so over 90% heal without surgery. Associated injuries are anterior cruciate rupture (about 20%), medial meniscal tear and Pellegrini-Stieda calcification (chronic ossification at the femoral origin).

• Medial knee pain, localized tenderness and swelling over the ligament
• Pain and laxity with valgus stress at 30 degrees. Opening in full extension implies a cruciate or posterior oblique injury.
• Often no effusion because the capsule is torn
• Red flags: gross instability, hemarthrosis (suggests cruciate injury), displaced distal avulsion, and open physes in an adolescent (physeal fracture mimics ligament injury)

• Valgus stress test at 0 and 30 degrees with comparison to the other knee.
• Radiographs for avulsion fractures, physeal injury and Pellegrini-Stieda lesion.
• Stress radiographs: medial gap difference over 3.2 mm suggests grade II and over 9.8 mm grade III.
• MRI for grading, the site of tear (femoral, midsubstance, tibial), and associated cruciate and meniscal injury.

Differentials: medial meniscal tear, anterior cruciate tear, medial plateau fracture, pes anserine bursitis, medial patellofemoral ligament injury.

Grades I and II:

• Hinged knee brace for 2 to 6 weeks, early range of motion, weight bearing as tolerated.
• Ibuprofen 400 mg orally every 8 hours with food for 5 to 7 days, with paracetamol 1 g every 6 hours.
• Quadriceps and hamstring strengthening. Return to sport at 2 to 4 weeks for grade I and 4 to 8 weeks for grade II.

Grade III isolated: hinged brace for 6 weeks, early motion, return at 8 to 12 weeks.

Surgery:

• Acute grade III with an anterior cruciate tear: reconstruct the cruciate and consider repairing or reconstructing the collateral.
• Distal tibial avulsion displaced over the pes anserine (surgical, as the ligament cannot heal).
• Chronic symptomatic valgus laxity.
• Techniques: suture anchor repair within 2 weeks, or reconstruction with semitendinosus autograft or Achilles allograft.
• Complications: stiffness, residual laxity, saphenous nerve injury, Pellegrini-Stieda calcification.

Follow up at 2 and 6 weeks and 3 months. Counsel on functional bracing during pivoting sport for 6 to 8 weeks after return.