Occurs when excessive valgus stresses or external rotation forces are placed on the knee joint.

Injuries to the MCL range in severity from a few torn fibres to complete disunity of the ligament.

Risk factors:

• Valgus stress to knee joint (e.g. in sports)
• Highest incidence in 20-35 year olds (most likely athletic-related)
• Age 55-70 (prone to MCL injuries during falls)

PC

• Medial knee pain

On examination:

• Joint effusion
• Tenderness - at adductor tubercle or proximal tibia
• Laxity on valgus stress testing
• Ecchymosis - Over the MCL, often develops 1-3 days after the injury

Investigations

• 1st line -
  • x-ray - may show associated fractures, calcification adjacent to the adductor tubercle in chronic cases
  • WB x-rays - Greater then normal medial gap
• MRI of the knee