Measurement of early wear rates with X3 polyethylene and 36-mm femoral heads in young patients - A prospective study

Abstract

Background: Development of highly cross-linked polyethylene has allowed the use of larger femoral heads. We studied the wear rates of X3 polyethylene with 36-mm heads in younger patients to determine whether there was an increase in overall wear with these larger heads. Methods: This was a prospective study of 100 consecutive total hip arthroplasties. All received 36-mm heads with X3 polyethylene articulation. Follow-up averaged 2.3 (range, 1.99-2.87) years. Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score and High Activity Arthroplasty Score (HAAS) were measured preoperatively and postoperatively. Femoral head penetration was measured at 2 months, 1 year, 18 months, and 2 years using a validated edge-detecting software program by a blinded independent observer. Results: All patients had significant improvement in their functional scores (WOMAC and HAAS, P<0.001). Steady state twodimensional wear rate was -0.05 mm/year. There were no significant differences in two-dimensional, three-dimensional, or volumetric wear when compared with age, polyethylene thickness, or the acetabular position. Conclusions: This study showed extremely low steady state wear rates in X3, highly cross-linked polyethylene when used together with36-mm ceramic femoral heads for total hip arthroplasty at 2 years. At this early stage, these results offer reassurance to surgeons wishing to use larger femoral heads with X-3 polyethylene particularly in younger men. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.