The John Charnley Award: Highly Crosslinked Polyethylene in Total Hip Arthroplasty Decreases Long-term Wear: A Double-blind Randomized Trial

Abstract

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-molecularweight 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. Threedimensional 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, À0.057 to 0.074) compared with UHMWPE (0.030 mm/year; 95% CI, ± 0.012; p \ 0.001; SD 0.0.27; range, À0.001 to 0.164). The volumetric penetration from 1 to 10 years for the UHMWPE group was 98 mm 3 (95% CI, ± 46 mm 3 ; SD 102 mm 3

Accuracy of methods to measure femoral head penetration within metal-backed acetabular components

“…Due to the low in vivo wear being reported for XLPE liners, it is important to understand the differences in the accuracy of the software programs currently used to measure wear. The reported accuracy for each method in the literature varies due to studies using different reference measurements, different directions of wear investigated, diverse statistical presentation of the error, and continuously updated versions of the software methods that incorporate different methods to identify the ellipse.…”

“…The amount of polyethylene wear of THA articulations involving highly cross‐linked polyethylene (XLPE) is significantly less than that of articulations with conventional ultra‐high molecular weight polyethylene (UHMWPE) . With wear rates below 0.1 mm/yr now commonly being reported, it is important to identify the accuracy of the methods used to measure such small movements.…”

Silicon Nitride Bearings for Total Joint Arthroplasty

“…Due to differences in chemical affinities, elastic moduli, and hardness, Si 3 N 4 -on-XLPE bearings should not experience the same slip-stick behavior that was observed in the Si 3 N 4 -on-Si 3 N 4 couples, although additional simulator testing needs to confirm this supposition. Additionally, in vivo studies demonstrate excellent wear performance and survivability (currently >10 years) for ceramic-on-XLPE in comparison to ceramic-on-ceramic articulation [152][153][154][155]. Further XLPE improvements (e.g., vitamin E stabilization or phospholipid grafting) along with lower costs will build on these advances, favoring continued use and future growth of CoP bearings [47,[156][157][158].…”

Hip simulator testing of the taper‐trunnion junction and bearing surfaces of contemporary metal‐on‐cross‐linked‐polyethylene hip prostheses

“…The wear rates of metal‐on‐cross‐linked‐polyethylene (MoXLPE) bearing couples are typically less than 11 mm 3 /million cycles (Mc) compared with metal‐on‐non‐XLPE, which have reported wear rates ranging from 10 to 51 mm 3 /Mc . Clinical trials and mid‐ to long‐term follow‐up studies of XLPE have shown significantly reduced wear, less osteolysis, and a lower risk of revision than conventional non‐XLPE . A further point to note is that the revision rates for MoXLPE appear to vary according to the size of the femoral head, with 32‐mm femoral heads showing the lowest wear for MoXLPE in the AOANJRR…”