DUAL MOBILITY VS STANDARD BEARINGS: WHAT IS THE EFFECT ON THE TAPER JUNCTION?

IntroductionDual-mobility bearings increase the stable range of motion of total hip arthroplasty (THA) but are limited by the mechanical effects of a large diameter metal on polyethylene bearing which may cause high rates of wear from the surfaces of the polyethylene bearing and the head-stem taper. Improved polyethylene (PE) has reduced concern over bearing wear but the effects on the taper junction are unknown.We aimed to better understand the effect of dual mobility bearings on fretting-corrosion damage to the taper junction by comparison to standard bearings.Materials and MethodsWe collected and analysed retrieved hips of one design with either dual mobility (n= 39) or standard bearings (n=30). The bearing size in the dual mobility group was 42mm whereas in the standard bearing group it had a median of 36mm. Stem trunnions had V40 tapers. Time of implantation and body mass index were comparable between the two groups.Fretting and corrosion at the stem trunnions was quantified by: 1) visual scoring and...