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Erschienen in:
01.02.2015 | Symposium: 2014 Hip Society Proceedings
The John Charnley Award: Highly Crosslinked Polyethylene in Total Hip Arthroplasty Decreases Long-term Wear: A Double-blind Randomized Trial
Erschienen in: Clinical Orthopaedics and Related Research® | Ausgabe 2/2015
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Background
The use of highly crosslinked polyethylene (HXLPE) is now commonplace for total hip arthroplasty. Hip simulator studies and short-term in vivo measurements suggest that the wear rate of some types of HXLPE is significantly less than conventional ultrahigh-molecular-weight polyethylene (UHMWPE). However, there are few long-term data to support its use.
Questions/purposes
The aim of this study was to measure the long-term steady-state wear of HXLPE compared with UHMWPE liners in a prospective, double-blind, randomized controlled trial using radiostereometric analysis.
Methods
Fifty-four patients were randomized to receive hip arthroplasties with either UHMWPE liners or HXLPE liners. Complete followup was available on 39 of these patients (72%). All patients received the same cemented stem and an uncemented acetabular component. Three-dimensional penetration of the head into the socket was determined at 10 years using a radiostereometric analysis system, which has an in vivo accuracy of < 0.1 mm. Oxford Hip Scores were compared between the groups.
Results
At 10 years there was significantly less wear of HXLPE (0.003 mm/year; 95% confidence interval [CI], ± 0.010; SD 0.023; range, −0.057 to 0.074) compared with UHMWPE (0.030 mm/year; 95% CI, ± 0.012; p < 0.001; SD 0.0.27; range, −0.001 to 0.164). The volumetric penetration from 1 to 10 years for the UHMWPE group was 98 mm3 (95% CI, ± 46 mm3; SD 102 mm3; range, −4 to 430 mm3) compared with 14 mm3 (95% CI, ± 40 mm3; SD 91 mm3; range, −189 to 242 mm3) for the HXLPE group (p = 0.01).
Conclusions
This study demonstrates that HXLPE has little detectable steady-state in vivo wear. This may result in fewer reoperations from loosening; however, careful clinical followup into the second decade still needs to be performed.
Level of Evidence
Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.