Influence of highly cross-linked polyethylene manufacturing characteristics on femoral head penetration in total hip arthroplasty : a ten- to 22-year follow-up study.

Abstract

Highly cross-linked polyethylene (HXLPE) has reduced wear and revision rates in total hip arthroplasty (THA) in the long term. However, the effect of HXLPE manufacturing characteristics on femoral head penetration has not yet been clearly defined. We report this single-institution study to investigate the clinical and radiological results of various HXLPE liners in THA. Between January 2001 and December 2013, 904 uncemented THAs using HXLPE liners were performed at our institution. Seven different HXLPE liner types were identified: remelted (n = 3), annealed (n = 2), sequentially annealed (n = 1), and vitamin E diffused (n = 1). A total of 746 hips were available for a minimum follow-up of ten years. The linear femoral head penetration rate was measured at six weeks and at one, five, ten, and 15 years, applying the Dorr criteria to digitized radiographs, using the Roman v. 1 70 software package for analysis. No patient was revised due to wear or osteolysis. The mean total femoral head penetration ten years after THA ranged from 0.14 mm (SD 0.06) to 0.20 mm (SD 0.17) for all groups (p = 0.649). Femoral head penetration > 0.40 mm at ten years was observed in 27 (3.6%) hips. From one to 15 years after surgery, mean total penetration was 0.21 mm (SD 0.13) in components with an acetabular inclination > 50° and 0.10 mm (SD 0.12) in those placed between 35° and 50° (p < 0.001). The radiological analysis did not detect osteolysis in any hip. Although HXLPE characteristics can result in different wear performance in patients undergoing THA at a mean follow-up of 15 years, the clinical and radiological results were excellent in all groups. The position of the acetabular component can influence the femoral head penetration of modern HXLPEs.