Abstract
Highly cross-linked polyethylene (XLPE) has been introduced in total hip arthroplasty in an effort to reduce polyethylene wear and the associated periprohetic osteolysis. Cross-linking is a procedure in which irradiation and subsequent heating stabilize the internal structure of PE. Most of the conventional PE’s used, are gamma irradiated in air or an inert environment with a dose level of no more than 25 to 50 kGy. By irradiating PE at a higher dose, optimally around 95–100 kGy, a definite reduction in wear rate has been achieved. History already provided us some mixed in vivo results regarding altered PE. Therefore, present time surgeons are cautious when it comes down to using a new PE.
Some short follow up in vivo studies already suggested reduced wear rates with XLPE in comparison to conventional PE. Our aim was to demonstrate these reduced wear rates in a 2-dimensional head penetration model using the DICOMeasure™ computerized edge detection method (GreyStone, France) and to perform a clinical comparison of both groups using the Harris Hip Score and SF-36 questionnaire.
Sixty hips with a Trilogy XLPE liner (Zimmer Co.) were age and BMI matched with a control group of twenty conventional Trilogy PE liners (Zimmer Co.).
No differences in clinical performance were seen, but a statistically significant reduction of 67% in steady state wear rate was observed in the XLPE group.
It is clear that, due to the reduction and stabilization of free radicals in polyethylene, a reduction in annual wear can be achieved.
Correspondence should be addressed to Ms Larissa Welti, Scientific Secretary, EFORT Central Office, Technoparkstrasse 1, CH-8005 Zürich, Switzerland
