Presence of macrophages at the bone-cement interface of stable hip arthroplasty components.

The bone cement interface of four clinically stable hip-joint prosthetic components was examined histologically for the presence of macrophages using routine staining and a histochemical technique for acid phosphatase. Macrophages were found in the absence of wear debris in all four cases. Because these cells are capable of bone resorption, their presence at a well-fixed interface must give cause for concern.