Wear factor comparison between single and dual mobility cup in total hip arthroplasty

The dual mobility cup (DMC) was developed to decrease wear, increase stability, and restore patients’ hip range of motion compared to the traditional single mobility cup (SMC) in total hip arthroplasty (THA). A rejuvenation of the THA population is increasing the risk of wear, and more personalised follow-up of patients is required. The aim of this study was to estimate DMC-THA wear during daily life activities based on 3D motion capture data. Using a musculoskeletal and a stem–liner contact model, a wear factor was computed for 16 participants with SMC-THA and compared to virtual DMC-THA. The force–velocity factor was estimated for slow, self-selected, and fast gait, as well as sit-to-stand and stand-to-sit activities. A significantly lower factor was found for DMC-THA than for SMC-THA during gait at the different speeds and during sit-to-stand. In the stand-to-sit task, the potential advantage of DMC-THA was not demonstrated, likely because the liner kinematics was simulated during intervals in the activity when hip contact force and sliding velocity were high. This study suggests the potential lower risk of wear of the DMC-THA, based on 3D motion capture data and multibody dynamics simulations. It also showed that an in vivo risk of wear can be estimated to help stratifying patients.