The impact of sterilization method on wear in knee arthroplasty

Sterilization by gamma irradiation in air has been shown to have the potential to accelerate the oxidation of polyethylene components resulting in reduced mechanical properties. In the hip, it has been reported that the occurrence of delamination and cracking in retrieved bearings is significantly different when comparing components sterilized with gamma irradiation in air with components sterilized with ethylene oxide. Using a collection of 1635 retrieved polyethylene knee bearings, this study pursues a similar comparison of sterilization method with clinical wear in the knee. It confirms that retrieved polyethylene knee components that were gamma irradiated in air have a high incidence of delamination and cracking, leading at times to complete wear through of the bearing. Knee components sterilized with ethylene oxide showed no evidence of fatigue damage even after in vivo durations in excess of 15 years.