Acute Medial Collateral Ligament Injuries

As the principle stabilizer against valgus stresses the MCL is the most commonly injured ligament in the knee.



  • Significant valgus force
  • Significant twisting injury
  • Immediate pain +- "pop"
  • Gradual swelling if an isolated low grade injury
  • Immediate swelling if a high grade injury or in combination injuries causing haemarthrosis


  • Medial Swelling 


  • Tenderness at any point along the MCL


  • Reduced active movement due to pain
  • Valgus force tests the MCL
    • Normal laxity is 0
    • Grade 1: 0-0.5 cm of opening with an end point

(There may be no detectable opening in a Grade 1 injury)

    • Grade 2: 0.5-1.0 cm of opening with an end point
    • Grade 3: >1.0 cm of opening, usually there is no end point

Exclude combined MCL + ACL

Exclude combined MCL + Medial meniscus


AP and Lateral views

  • Usually reassuringly normal
  • Stress x-rays are not usually necessary, but would show abnormal joint opening in grade 2/3 injuries

Exclude combination injuries

  • Haemarthrosis
  • ACL: Segond fracture, Tibial spine avulsion
  • PCL: Distal avulsion


Only If there is clinical suspicion of a combination injury (and therefore all grade 3 injuries)

Emergency Room Treatment

Few of these patients will have multiligament injuries or associated meniscal detachment and will need an emergency orthopaedic referral.

Mr Gavin Holt :: :: Print this frame