OSTEOLYSIS IN ASSOCIATION WITH A TOTAL HIP-ARTHROPLASTY WITH CERAMIC BEARING SURFACES

The results of 103 total hip arthroplasties performed with insertion o f a ceramic femoral head and acetabular component in ninety-six patien ts were reviewed to determine the radiographic prevalence of osteolysi s. After a mean duration of follow-up of ninety-two months (range, six ty to 125 months), femoral osteolysis was observed in twenty-three hip s (22 per cent), in one of two distinct patterns: linear osteolysis (t welve hips) or scalloping expansile-type osteolysis (eleven hips). The most common locations of osteolysis in the femur were in zones I and VII as described by Gruen et al, Serial radiographs demonstrated that the extent of the osteolysis progressed over time. Osteolysis of the p elvis, noted in forty-nine hips, was always associated with migration of the acetabular socket. No focal osteolysis was observed in associat ion with the stable sockets. Ten patients (ten hips) had a revision be cause of loosening and migration of the acetabular component. In three of these patients, the femoral stem also was revised, Gross examinati on revealed evidence of wear of the ceramic bearing surface in all ten patients, Scanning electron microscopy showed cracking and wear marks on the weight-bearing surface. Histological evaluation of the tissue in the periprosthetic membrane demonstrated abundant ceramic wear part icles. The interface membrane was composed of a vascularized fibrous c onnective tissue with macrophages, Ultrastructurally, the macrophages contained numerous phagosomes of various sizes, with electron-dense ma terial within the cytoplasm of the cell, The mean size of the ceramic particles, as determined with scanning electron microscopy, was 0.71 m icrometer (range, 0.13 to 7.20 micrometers), This study supports the c oncept that ceramic wear particles can stimulate a foreign-body respon se and periprosthetic osteolysis.