Dual mobility bearings withstand loading from steeper cup-inclinations without substantial wear

Steep cup abduction angles with adverse joint loading may increase traditional polyethylene bearing wear in total hip arthroplasties. However, there have been few reports evaluating the effect of cup inclination on the wear of dual-mobility devices. In a hip joint simulation, we compared the short-term wear of two-sizes of modular highly cross-linked dual-mobility bearings (28mm femoral head diameter/42mm polyethylene insert outer diameter/54mm acetabular shell diameter; 22.2mm femoral head diameter/36mm polyethylene insert outer diameter/48mm acetabular shell diameter) at 50 and 65° of cup inclination with modular 28mm femoral head on 54mm cup diameter metal-on-highly cross-linked polyethylene bearings. Increasing inclination from 50-65° had no changes in volumetric wear of 28/42/54mm (mean, 1.7 vs. 1.2 mm3/million cycles, respectively; p=0.50) and 22.2/36/48mm (mean, 1.7 vs. 1.2 mm³/million cycles, respectively; p=0.48) dual mobility bearings. At 65°, 22.2/36/48mm dual-mobility bearings had lower volumetric loss (mean, 2.2 vs. 6.3 mm³; p=0.03) and wear rates (mean, 1.2 vs. 2.7 mm3/million cycles; p=0.02) compared to metal-onhighly cross-linked polyethylene bearings. Modern-generation dual-mobility designs with highly cross-linked polyethylenes may potentially withstand edge-loading from steeper cup-inclinations without substantial decreases in wear.