Medial collateral ligament injury of the knee is the most common ligament injury of the knee and occurs in all age groups. It is more common in sportspersons especially in sports like football, hockey, wrestling, and other contact sports.
The medial collateral ligament is the ligament present on medial [inner] side of the knee and goes from femoral condyle to tibia. It has two parts –
- Superficial medial collateral ligament or tibial collateral ligament runs from the medial femoral epicondyle and inserts 4-5 distal to the tibial tubercle.
- The deep medial collateral ligament is at the capsule level and also has a meniscal attachment and thus getting names meniscofemoral ligament and the meniscotibial ligament for its upper and lower portions
The medial collateral ligament acts as a primary restraint to valgus and external rotation of the tibia.
Mechanism of Medial Collateral Ligament Injury
Medial collateral ligament injury may occur due to
It involves a direct valgus load to the knee. It may lead to a complete tear.
This is an indirect injury and is seen with deceleration, cutting, and pivoting movements. It usually causes partial tears.
This kind of injury is said to occur in swimmers due to repeated use of knee for stroking.
Classification of Medial Collateral Ligament Injury
- Isolated grade I MCL injury (mild) – MCL has few torn fibers but no loss of ligamentous integrity.
- Isolated grade II MCL injury (moderate) – MCL is partially torn. However, the fibers are still opposed. There might be mild pathological laxity, which may or may not be symptomatic.
- Isolated grade III MCL injury (severe) – Integrity of the MCL is completely disrupted. There is significant pathological laxity of the knee with valgus stress.
AMA Committee Classification
MCL injuries are classified based on the amount of medial joint opening when a valgus load is applied at 20° to 30° of knee flexion
- Grade I: 0 to 5 mm of opening
- Grade II: 5 to 10 mm of opening
- Grade III: >10 mm of opening
Presentation of Medial Collateral Ligament Injury
There is a history of trauma and usually popping sound. A detailed history would explain the mechanism of injury. The local examination would reveal the presence of swelling and tenderness. Contusions may point towards the injury site.
Sometimes, the medial collateral ligament may be associated with intra-articular injury of the knee which is indicated by large effusion.
Valgus Stress Test
This test is done to check the integrity of medial collateral ligament and is done in full knee extension and 30 degrees of flexion. The examiner supports the thigh with one hand applies a lateral force on the leg with the other hand. Comparison with the opposite knee is always done.
Tests for ruling out injuries to cruciate ligaments are done.
Associated injuries to look for are
- Anterior cruciate ligament – 20% [ grade 1 injuries] to 78% [grade 3 injuries]
- Medial meniscus[5-25%]
- Quadriceps extensor mechanism [9-21%]
Xrays are done to rule out bony injury or osteochondral defects. Routine AP, lateral and skyline views are sufficient for this purpose. Stress views may be added for confirming the grade of medial collateral ligament injury by measuring measure medial compartment opening.
MRI is indicated when associated injuries like ACL, PCL, and meniscal tears, osteochondral fractures, and bone bruises may also be identified.
Joint aspiration may be required if there is large joint effusion making evaluation difficult.
Treatment of Medial Collateral Ligament Injury
In the acute setting, the standard treatment for sprains is followed which includes rest, ice, compression, and elevation. The severity of the injury dictates further treatment.
Grade 1 and 2 Medial Collateral Ligament Injury
These injuries are treated nonoperatively. An appropriate knee orthosis is applied and protective weight-bearing is instituted with crutches. This is continued until a normal gait is obtained
Grade 3 Medial Collateral Ligament Injury
Most of the grade 3 injuries are also treated nonoperatively either in long leg cast or hinged knee orthosis and protective weight bearing for 1-2 weeks.
After that range of motion exercises are started which are followed in due course with quadriceps strengthening.
Walking without crutches is allowed when comfortable. Same goes for running but pivoting needs to be avoided initially.
Sports-specific exercises and drills are added and advanced until the athlete is ready to return to the sport.
People with grade 1 and 2 injuries usually return to play within 2-3 weeks but may take up to 3 months to return to preinjury levels. People with grade 3 injuries frequently require 6 or more weeks. Isolated grade 3 injuries still allow an excellent return to preactivity levels by 6-9 months.
Surgical Treatment of Medial Collateral Ligament Injury
Isolated medial collateral ligament injury rarely needs operative repair. Another indication for surgical intervention would be persistent instability, with surgery consisting of tissue repair and imbrication. Often, reinforcement with an allograft is necessary.
Combined ruptures of the medial collateral ligament and anterior or posterior cruciate ligament would require reconstruction.