Diagnostic criteria

AMA Committee on the Medical Aspects of Sports standard nomenclature of athletic injuries [2]

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: View image

• Grade I: 0 to 5 mm of opening

• Grade II: 5 to 10 mm of opening

• Grade III: >10 mm of opening.

O'Donoghue's classification [1]

MCL injuries are classified based on the amount of torn fibres:

• Grade I: few torn fibres, ligament is structurally intact

• Grade II: incomplete tear, no pathological laxity

• Grade III: complete tear, pathological laxity.