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

Tracy Wilson
Thunder Bay Regional Hospital, Ontario, Canada

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

Although polyethylene wear particles have been implicated in osteolysis and implant loosening, this study is the first to test whether chemical eluates extracted from ultra-high molecular weight polyethylene (UHMWPE) could also be involved in this process. Eluates were prepared from UHMWPE bar stock and examined for their effects on (3)H-thymidine incorporation by human foreskin fibroblasts grown in 96-well culture plates. Low concentrations of eluates stimulated (3)H-thymidine uptake; whereas, high concentrations inhibited uptake in a dose-dependent manner. Maximum inhibition of proliferation for eluates (87 ± 0.03% inhibition, n = 45 paired wells) was greater than that observed for particles (54 ± 0.07% inhibition, n = 45 paired wells). Ethylene oxide sterilization of UHMWPE reduced (3)H-thymidine uptake at low eluate concentrations relative to sterilization by gamma-irradiation. It was concluded that leachable eluates from UHMWPE implantse contribute to the osteolytic process at the bone-implant interface.

Key Words: polyethylene; fibroblast; proliferation; eluate; osteolysis