Medial collateral ligament (MCL) injury of knee

Medial collateral ligament (MCL) is the most commonly injured ligament in the knee (1)

MCL injuries can be seen in both contact and non contact sports. Examples include:

• valgus stress caused by lateral blows to the knee e.g. - in contact sports such as football, ice hockey and rugby
• external rotation of the foot with a flexed knee e.g. - in skiing injuries
• frank knee dislocations (1)

The American Medical Association has classified had graded MCL accoerding to the amount of joint space opening with valgus stress at 300 of knee flexion.

• grade I - amount of medial joint line opening <5 mm
• grade II - amount of medial joint line opening 5-10 mm
• grade III - amount of medial joint line opening >10 mm

Most MCL injuries are isolated

• there is an increase risk of injury to associated structures of the knee with increasing severity e.g - anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) etc
• a 78% rate of associated injury is seen in grade III sprains (1)

Reference:

• (1) Duffy PS, Miyamoto RG. Management of medial collateral ligament injuries in the knee: an update and review. Phys Sportsmed. 2010;38(2):48-54