The superficial MCL is the primary medial static stabiliser of the knee, providing valgus restraint throughout flexion and being the largest component of the medial capsular complex. It is the most commonly injured ligament in the knee from contact and non-contact valgus mechanisms. Grade III tears involving complete disruption have traditionally been managed non-operatively but combined MCL-ACL injuries benefit from surgical MCL repair.
| Origin | Medial femoral epicondyle (proximal attachment — large footprint) |
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| Insertion | Medial tibial condyle 4-5 cm distal to the joint line (broad distal attachment superficial to the pes anserinus) |
| Actions | Primary valgus stabiliser at 30 degrees of flexion; secondary restraint to anterior and posterior tibial translation |
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The valgus stress test at 30 degrees isolates the superficial MCL (deep MCL also in extension — positive test with knee in full extension indicates Grade III with additional posterior capsular or cruciate involvement). Grade I-III isolated MCL tears are managed non-operatively with functional bracing — healing rates approach 95%. Combined MCL-ACL tears require consideration of MCL repair at ACL reconstruction.
Valgus mechanism medial knee injury classified Grade I-III managed with functional bracing — Grade III combined with ACL may require surgical repair.
