The posterior oblique ligament (POL) is the primary posteromedial static stabiliser of the knee, arising from the semimembranosus expansion and reinforcing the posteromedial capsule. It works with the superficial MCL to resist valgus stress and internal tibial rotation. The posteromedial corner reconstruction includes the POL when it is disrupted in combined valgus-rotation knee injuries.
| Origin | Semimembranosus tendon expansion at the posteromedial tibia |
|---|---|
| Insertion | Posterior knee capsule and lateral femoral condyle |
| Actions | Posteromedial knee stability; resists internal tibial rotation and valgus stress in extension; the primary static posteromedial stabiliser |
|---|
The POL is the key structure in posteromedial corner reconstruction — it is tightened or reconstructed using a semimembranosus advancement or a gracilis graft. MRI identifies POL disruption as posteromedial soft tissue oedema and ligament discontinuity. Combined MCL-POL tears produce valgus instability at both 0 and 30 degrees of flexion.
POL disruption requiring combined superficial MCL and POL reconstruction for valgus instability at full extension.
