Reduced wear in vitamin E-infused highly cross-linked polyethylene cups: 5-year results of a randomized controlled trial

Abstract

Background and purpose - Vitamin E-infused polyethylene is a relatively new material in joint arthroplasty; there are no long-term reports, and only few mid-term results. Using radiostereometric analysis (RSA), we primarily determined whether vitamin E-infused highly cross-linked polyethylene (HXLPE/VitE) acetabular cups show less wear than ultra-high molecular weight polyethylene (UHMWPE) acetabular cups at 5 years after total hip arthroplasty (THA). We also assessed whether wear rates correlate with increasing cup inclination angles or cup sizes.Patients and methods - This is a 5-year follow-up of our previously reported randomized controlled trial of 62 patients with 3 years' follow-up, who received THA with either an HXLPE/VitE or a UHMWPE acetabular cup. At 5 years, 40 patients were analyzed (22 in the HXLPE/VitE and 18 in the UHMWPE group).Results - HXLPE/VitE cups continued to show less cumulative femoral head penetration than UHMWPE cups (HXLPE/VitE: 0.24 mm, UHMWPE: 0.45 mm; p < 0.001). Distribution of wear was also more even with HXLPE/VitE cups than with UHMWPE cups (p = 0.002). Moreover, the difference in PE wear between 1 and 5 years in both groups showed no statistically significant correlation with increasing cup inclination angles or cup sizes. Finally, no osteolysis and implant loosening occurred, and no revision surgeries were required.Interpretation - Wear rates continue to be lower in HXLPE/VitE cups than in UHMWPE cups at 5 years of follow-up without correlation with increasing cup inclination angles or cup sizes. Finally, HXLPE/VitE cups may have the potential to prevent osteolysis and implant loosening.

Trial registration: ClinicalTrials.gov NCT02524587.

Figure 1.

Study enrollment. The reasons for the losses to follow-up—if known—are indicated in the corresponding boxes. HXLPE/VitE: Vitamin E-infused highly cross-linked polyethylene, RSA: radiostereometric analysis, UHMWPE: ultra-high molecular weight polyethylene.

Figure 2.

Creep and wear behavior of UHMWPE (n = 18, red line) and HXLPE/VitE (n = 22, blue line) over the first 5 years after implantation. HXLPE/VitE: Vitamin E-infused highly cross-linked polyethylene, UHMWPE: ultra-high molecular weight polyethylene.