Osteolysis from a press-fit hydroxyapatite-coated implant. A case study.

The clinical and histological results of hydroxyapatite (HA) coating separation from a press-fit total hip arthroplasty 3.3 years after surgery are documented. Semiquantitative histological analysis showed grade 3+ mononuclear histiocytes and giant cells present in the retrieved capsule and periprosthetic tissues. Grade 3+ (titanium alloy, HA, and polyethylene) particles could be seen throughout the tissues. Backscattered electron and correlated elemental analysis confirmed that the HA coating had migrated to the articulating surface of the polyethylene insert causing third-body wear. The authors suggest that the orthopedic surgeon be cautioned in the routine use of HA-coated implants if osteolysis associated with HA separation and migration is to be avoided.