Does vitamin E highly-crosslinked polyethylene convey an advantage in primary total hip replacement? A systematic review and meta-analysis

BACKGROUND: Vitamin E highly cross-linked polyethylene (HXLPE) was developed to reduce wear in total hip replacement (THR). This formal systematic review and meta-analysis aimed to provide independent synthesis of wear characteristics of Vitamin E treated HXLPE compared to HXPLE/UHMWPE. Secondary outcome measures were differences in revision rates and functional scores.

METHODS: We performed a formal systematic review as per PRISMA guidelines; literature searches were conducted on 14 November 2017 (MEDLINE, Embase on Ovid, and the Cochrane Library). We included randomised controlled trials, analyses of joint registries, and case-controlled studies of primary THR comparing cups with a vitamin E HXLPE bearing with bearing surfaces made from other types of polyethylene. Initial screening was performed by 2 independent assessors; disagreement resolved in discussion with a third reviewer. Studies were evaluated using the Cochrane risk of bias tool. Data extraction permitted meta-analysis.

RESULTS: 372 studies were identified on initial screening, 5 studies met the eligibility criteria. There was no significant heterogeneity between studies. There was variable risk of bias. At a mean of 35 (range 20-60) months, Vitamin E HXLPE had significant advantages over highly cross-linked polyethylene with regards total femoral head penetration (p = 0.004). Given the RSA measurement errors this may not be clinically significant. There were neither significant differences in revision rates nor Harris Hip Scores (p = 0.06).

CONCLUSION: At a minimum of 3 years follow-up there was reduced total femoral head penetration for vitamin E HXLPE over HXLPE. This bearing surface does not, as yet, have clinically significant advantages in terms of revision rates or patient function over HXLPE.