Does vitamin E-blended polyethylene reduce wear in primary total hip arthroplasty: a blinded randomised clinical trial.

Abstract

Some data indicate that first-generation highly cross-linked polyethylene (HXLPE) can oxidise in vivo and is associated with reduced mechanical properties. To overcome these limitations, a natural anti-oxidant vitamin E has been added to HXLPE to preserve the mechanical properties and decrease oxidative degradation whilst conserving high wear resistance. We hypothesised that after a minimal threeyears of follow-up the use of vitamin E-blended HXLPE would result in lower radiographic wear when compared with ultra-high molecular weight polyethylene (UHMWPE). One hundred patients were randomised to receive hybrid total hip arthroplasty (THA) using a monoblock cementless acetabular component made either of UHMWPE or vitamin E-blended HXLPE. All other parameters were identical in both groups. Complete follow-up was available for 74 of these patients. Femoral head penetration was measured using a validated computer-assisted method. The median creep measured 0.111mm (range, -0.576 - +0.444mm) in the vitamin E-blended group versus 0.170mm (range, -0.861 - +0.884mm) in the UHMWPE group (difference of medians, 0.059; p = 0.046). The median steady state penetration rate was -0.008mm/year (range, -0.88 - +0.64mm/year) in the vitamin E-blended group versus 0.133mm/year (range, -0.84 - +0.85mm/year) in the UHMWPE group (difference of medians 0.141, p = 0.043). This study demonstrated that femoral head penetration was lower when using vitamin E-blended HXLPE when compared with UHMWPE, with a steady-state penetration rate far below the osteolysis threshold. Longer-term follow-up is needed to warrant whether wear reduction will generate less occurrence of osteolysis and aseptic loosening.