Femoral component failure in the Oxford unicompartmental knee arthroplasty: a case report

INTRODUCTION The present case report describes a patient who presented with an early complication after a unicompartmental knee arthroplasty. It is not the first case in this subject but the unique aspect of this case report rests on the timing in which the failure occurred. CASE PRESENTATION A 64-year-old Caucasian man received a medial unicompartmental knee arthroplasty (Oxford® Partial Knee) due to isolated anteromedial osteoarthritis of his right knee. His initial recovery was good, however, after 3 months he presented with acute pain and a locked knee. Radiographs showed a complete loosening and migration of the femoral component. During revision surgery no clear explanation was found for failure of the femoral component. CONCLUSIONS The most likely explanation for loosening is the combination of peak stresses on the posterior facet of the femoral components of a unicompartmental knee arthroplasty in a patient in a cross-legged knee position causing bone-cement or cement-implant interface failure. Further research is necessary in prosthetic designs and applications of the unicompartmental knee arthroplasty to determine the origin of this early complication.