Pyrolytic carbon endoprosthetic replacement for osteonecrosis and femoral fracture of the hip: a pilot study.

UNLABELLED: Hemiarthroplasty in young patients has the potential for eliminating bearing wear, but has the disadvantage of cartilage wear. Low-temperature isotropic (LTI) pyrolytic carbon reportedly reduces cartilage wear in canine hemiarthroplasties. We therefore initiated a study in humans when it was released for human use. However, we observed failures in some patients. We therefore document and report the high failure rate observed in a subset of patients treated with an LTI pyrolytic carbon femoral head for osteonecrosis. We conducted a prospective pilot study of 17 patients treated with a titanium stem and an LTI pyrolytic carbon femoral head bearing surface for unipolar hemiarthroplasty for either femoral neck fracture (10 patients) or osteonecrosis (seven patients). One of 10 patients in the fracture group underwent conversion to THA as a result of arthritic progression compared with six of seven patients with osteonecrosis who underwent conversion to THA as a result of acetabular wear and severe groin pain. In this small series, patients with osteonecrosis had a higher rate of revision compared with the patients treated for femoral neck fracture. LEVEL OF EVIDENCE: Level III, therapeutic study.