Osteolysis in patients with a metal-on-metal hip arthroplasty

Background: Despite design and manufacturing improvements in contemporary metal-on-metal hip replacements, the problem of wear particles persists. The local and systemic biological consequences of this ionic debris have been the subject of much investigation and it has become clear that cell-mediated delayed-type hypersensitivity reactions are a discrete mode of osteolysis in susceptible patients. Methods: We have carried out a consecutive series of 125 primary hip replacements using the Metasul (Zimmer, Warsaw, IN, USA) bearing couple. The radiographs, periprosthetic tissue and retrieved implants of patients undergoing revision for osteolysis were analysed. Results: Three patients underwent revision procedures during a follow-up period of 3-9 years. Histological analysis showed a perivascular lymphocytic infiltrate of the pseudocapsule. Infection was excluded in each patient, there was no implant loosening and no evidence of impingement between trunion and acetabular component. Conclusion: We report a prevalence of 2.6% of patients displaying femoral osteolysis associated with characteristic clinical and histological findings.