A new prosthetic material, ultra-high molecular weight (UHMW) polyethylene graphite, was developed for use in total joint replacement and found to exhibit 1/7–1/30 lower wear rate than UHMW polyethylene bearing against Vitallium alloy.
A preliminary study was undertaken to test the biocompatibility of the new material. Specimens of 316L stainless steel, high-purity graphite, UHMW polyethylene, and the composite material were implanted in rabbits and cynomologous monkeys. The materials were evaluated in both solid and particulate forms after implantation in bone, joint cavities, and paravertebral muscles. The tissue reactions to the materials were noted at time intervals from 6 weeks to 1 year.
All materials showed good tissue acceptance in solid form. The UHMW polyethylene and the composite material were noted to be more reactive than either the high-purity graphite alone or the stainless steel when in particulate form.
The eventual use of the polyethylene graphite composite in total hip arthroplasties is suggested by virtue of its identical biocompatibility with UHMW polyethylene. In addition, its superior wear resistance, and hence low volume of wear debris particles presented to the surrounding tissues would offer an advantage in terms of longevity of the implant both mechanically and biologically.