Failure of a metal-reinforced tibial post in total knee arthroplasty.

Failures of the polyethylene tibial post in posterior stabilized total knee arthroplasty are usually associated with pain and knee instability. We report an unusual presentation of a tibial post failure that occurred after the polyethylene insert was revised in a posterior-stabilized total knee. The tibial post on the revised insert broke off, exposing a metal reinforcing pin. During the resulting posterior subluxations of the tibia, the metal pin articulated against the cam on the femoral component, resulting in the generation of metallic debris in the knee joint.