O. O. Popoola, Zimmer Inc., Research Laboratory, Warsaw, IN; J. P. Anderson, Zimmer, Inc., Warsaw, IN; L. Gilbertson, Zimmer Inc., Warsaw, IN
Ultra high molecular weight polyethylene (UHMWPE) wear debris-induced osteolysis has been identified as one of the main causes of implant loosening and revision surgeries in patients with joint replacements. Several efforts are underway to reduce polyethylene wear by modifying the opposing metallic surfaces of medical implants. This study reports on the interfacial friction and wear of gamma-sterilized GUR 1050 UHMWPE pins articulated against diamond-like carbon coated and uncoated (controls) CoCrMo alloy discs surfaces. The applied load was 45kgf and the motion was a 25 x 25 mm2 square waveform at a frequency of 1Hz. The total sliding distance was 15km and the lubricant used was bovine calf serum. Diamond-like-carbon coated surfaces produced higher interfacial friction (m = 0.179) than untreated CoCrMo (m = 0.075) surfaces. The steady state serum lubricant temperature was 43oC and 31oC for diamond-like-carbon coated and untreated surfaces respectively. The wear of UHMWPE pins articulated against diamond-like carbon coatings was significantly higher than that of similar pins articulated against untreated control surfaces. Laser confocal microscopy studies of the pins and discs surfaces revealed significant differences in the wear mechanisms between the two surfaces. The uncoated disc surface had adhered polyethylene patches while the DLC-coated ones showed no evidence of attached polyethylene film. The wear mechanisms and orthopedic application implications of these surfaces will be discussed.
Summary: This presentation describes the friction and wear behavior of polyethylene GUR 1050 pins articulated against diamond-like-carbon coated cobalt-chromium alloy surfaces. The prevailing wear mechanisms and orthopedic applications are discussed.
