AKate Y Wang, J Geoffrey Horne and Peter A Devane
Department of Surgery, Wellington School of Medicine, Wellington, New Zealand

John H Miller
School of Biological Sciences, Victoria University, Wellington, New Zealand

Periprosthetic osteolysis is a dominant factor in the success or failure of total hip prostheses. Polyethylene wear debris has been implicated in the process of bone resorption and subsequent implant loosening. The present study is the first to examine the effect of ultra high molecular weight polyethylene (UHMWPE) wear debris produced by a hip simulator on calvarial bone resorption in vitro. (45)Ca release was measured in cultured mouse calvarial bone samples. Although short-term exposure to UHMWPE particles (2 h) decreased (45)Ca release, longer-term exposure for 1–2 days increased release in a dose-dependent manner. After one-day exposure to 7.5 x 10 (6) particles per mL, 18% more (45)Ca was released from cultured calvarial bone than from control samples. It was concluded that UHMWPE wear particles either directly or indirectly stimulated osteoclasts to activate bone resorption. Polyethylene wear debris contributes to the osteolytic process at the bone-implant interface.

Key words: bone resorption; calcium; calvaria; hip simulator; mouse; polyethylene; osteolysise