EFFECTS OF STERILIZATION ON WEAR IN TOTAL KNEE ARTHROPLASTY

Twenty-nine Ortholoc(R) II ultrahigh molecular weight polyethylene tib ial components were retrieved from 27 patients at revision surgery fro m the same hospital, The polyethylene material grade, method of steril ization, and sterilization dosage for 26 of the tibial components were determined by tracing the material lot number for each component, Eac h tibial surface was scored for wear using a qualitative scoring syste m that evaluated delamination, pitting, scratching, cold flow; abrasio n, and burnishing, After the wear score analysis, 14 of the 26 compone nts were analyzed to determine the physical and mechanical properties of the polyethylene including toughness and elongation, Seven of these 14 components were sterilized using ethylene oxide and 7 were sterili zed using gamma radiation, Tibial components sterilized with gamma rad iation had significantly higher wear rates than those sterilized with ethylene oxide, Thirteen of the 18 components sterilized with gamma ra diation had delamination of the articular surface compared with 2 of 8 components sterilized with ethylene oxide, Mechanical properties were significantly affected by the sterilization method, Components steril ized with ethylene oxide had significantly higher toughness and percen t elongation than those sterilized with gamma radiation, These finding s suggest that ethylene oxide sterilization caused less microstructura l damage to the polyethylene and resulted in significantly less, year than was found in those components sterilized with gamma radiation.