Early, design-related failure in total knee arthroplasty. A case report

The analysis of retrieved implant devices can provide information unavailable through any other method. With the variety of implant designs rapidly increasing, retrieval and analysis of failed cases is an important means of evaluating existing designs, as well as suggesting modifications that might improve implant performance. This paper describes a case in which design considerations, rather than mechanical or material failure, appeared to be a major contributing factor. Sixteen months after insertion of a Howmedica Kinematic Rotating Hinge Knee, the patient complained of barometric pain in the knee. Roentgenograms at that time showed the metallic axle component to be protruding laterally. Upon retrieval the polyethylene bumper-lock component exhibited deep scalloping on its surface, which unlocked the axle and allowed it to slide out.