IMPINGEMENT AFTER TOTAL KNEE ARTHROPLASTY CAUSED BY CEMENT EXTRUSION AND PROXIMAL TIBIOFIBULAR INSTABILITY

A 57-year-old patient with rheumatoid arthritis showed posterolateral impingement after total knee arthroplasty. The radiographs showed bone cement extrusion posterolateral to the tibial tray. Arthrotomy throug h a posterolateral approach revealed that the impingement was caused n ot only by cement extrusion against the fibular head bur also by proxi mal tibiofibular joint instability. It was speculated that rheumatoid arthritis had caused proximal tibiofibular instability, active knee mo tion had caused fibular head shift by tension of biceps femoris and th e fibular head had been impinged on the extruded cement. In cementing the tibial tray, especially in a rheumatoid patient, it is of paramoun t importance to take caution against posterolateral cement extrusion i n order to minimize the risk of fibular head impingement during total knee arthroplasty.