The PCL is the strongest ligament in the knee, approximately twice the cross-sectional area of the ACL, and the primary restraint against the knee's tendency to sag posteriorly under gravity during weight bearing. It is the last knee ligament to fail in progressive knee instability. Isolated PCL tears often go undiagnosed because the posterior sag of the tibia is subtle and the patient complains only of vague posterior knee pain rather than the dramatic instability of ACL tears.
| Origin | Medial femoral condyle medial surface in the intercondylar notch |
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| Insertion | Posterior intercondylar area of the tibia approximately 1 cm below the articular surface (posterior tibial footprint) |
| Actions | Primary restraint against posterior tibial translation; also resists external tibial rotation and varus/valgus forces at high flexion |
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The posterior drawer test (applying a posterior force to the proximal tibia at 90 degrees of knee flexion) is the primary clinical test for PCL integrity. The posterior sag sign — the tibia visibly sagging posteriorly compared to the intact knee when both knees are held at 90 degrees of flexion — confirms PCL deficiency. Most isolated PCL tears are managed non-operatively with quadriceps rehabilitation, but high-grade tears (greater than 10 mm posterior translation) and combined ligament injuries benefit from surgical reconstruction.
Posterior tibial translation injury from a direct anterior blow to the proximal tibia (dashboard injury) or hyperflexion, confirmed by posterior drawer test, with most isolated tears managed non-operatively.
