Hx

• 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

LOOK

• Medial Swelling 

FEEL

• Tenderness at any point along the MCL

MOVE

• 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

• AP force test the ACL ("Lachman's test", "Anterior draw test")
• IR subluxation/reduction tests ACL ("Pivot shift test")

Exclude combined MCL + Medial meniscus

• True locking
• Medial joint line tenderness (away from the MCL!)

XRAYS

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

MRI

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

• Disruption of the MCL