Comparison Of The Long Term Outcome Using Two Types Of UHMWP Liners In Total Hip Arthroplasty And Ultra-morphological Analysis Of Wear Particles

Ultra-high molecular weight polyethylene(UHMWPE),also known as non-cross-linked polyethylene,is a widely used material for joint arthroplasty.Aseptic loosening due to particulate debris generated by wearing is the most common mode of failure in total hip arthroplasty(THA).Hip simulator studies and clinical studies have suggested that non-cross-linked polyethylene liners have significantly higher wear rates compared to highly cross-linked polyethylene(XLPE)liners.However,there are very few in vivo studies describing the long-term survivorship of non-cross-linked polyethylene liners.Especially,there is a lack of cohort studies that compare different types of none-cross-linked polyethylene liners,thus,the literature is unclear concerning whether different types of none-cross-linked polyethylene liners have different clinical performance in vivo.Although highly XLPE liner is more widely used in recent years,many patients with none-cross-linked polyethylene liners are still alive and active,which makes the investigation of the wear characteristics of them still relevant and important.In this study,we hypothesized that different types of none-cross-linked polyethylene liners has different clinical performance,and it is related to the wear characteristics of polyethylene including the wear rate and the size of wear particles.We then evaluated the long-term(more than 10 years)outcome of patients who underwent THAs using two types of none-cross-linked polyethylene liners,Enduron(DePuy,Warsaw IN,USA)and Trilogy(Zimmer,Warsaw IN,USA).We also performed morphological analyses of wear particles in tissue samples which were harvested during revision surgeries.Purpose The aim of the present study was to investigate the long term outcome and the wear characteristics of two distinct types of ultra-high molecular weight polyethylene(UHMWPE)liners in total hip arthroplasty(THA).Methods We conducted a retrospective clinical study on patients which were treated with total hip arthroplasty using either Enduron polyethylene(Enduron PE)or Trilogy polyethylene(Trilogy PE)liners based on a minimum of 10-year follow up data.Morphological analyses of wear particles from tissue samples,which were harvested during revision surgeries,were also performed.Results 79 THAs in Enduron group and 55 THAs in Trilogy group were available for analysis.Kaplan-Meier survival with revision for wear-related complications as the endpoint of the Enduron PE liners was lower than that of Trilogy PE liners at 10 years(93.5% and 100%,P=0.03).Enduron group had higher mean linear wear rate than that of Trilogy group(0.20±0.09 and 0.09±0.03 mm/year,P<0.01).The incidence of osteolysis for Enduron group was higher than that of Trilogy group(33.3% and 12%,P=0.04).Under transmission electron microscopy,the Enduron group had more than 82% of the particles less than 1.0 ?m in size and more than 57% of the particles less than 0.5 ?m.Conclusion The long term performance of Enduron liners was worse than that of Trilogy liners.Further clinical follow-up may be necessary in patients with Enduron PE liners in order to avoid catastrophic complications.