Does a Dual-Mobility Cup Offer Better Stability than Conventional Bearings in Hip Arthroplasty Following Femoral Neck Fracture?

Instability following total hip arthroplasty (THA) remains a challenging complication. Dual-mobility (DM) hip components are aimed at improving joint stability by increasing the head-neck ratio and jump distance. However, data regarding the efficacy of these implants in the trauma setting are scarce. This study aimed to compare the dislocation rates of DM bearings with conventional THA in patients undergoing primary THA for the treatment of hip fractures. We retrospectively reviewed all patients who underwent THA for hip fractures between the years 2010-2022 and had a minimum follow-up of two years. Patient demographics and radiographic parameters, including cup version, leg length discrepancy (LLD) and femoral horizontal offset, were compared between patients who received DM bearings and patients who received conventional THA. Dislocation and revision surgery rates were also compared between the groups. The study included 570 patients who met inclusion criteria, of which 82 patients were in the DM bearings group and 488 patients were in the conventional THA group. Baseline demographics and comorbidity profiles were comparable between the groups. Cup anteversion was significantly lower in the DM group (11.1° vs. 14.1°; = 0.006), while no significant differences were observed in LLD nor femoral offset between the groups ( = 0.38, = 0.69, respectively). Dislocation rates were similar between the DM and conventional THA groups (1.2% vs. 1.02%, respectively; = 0.54). Furthermore, revision rates were similar between DM and conventional THA (1.22% vs. 2.87%, respectively; = 0.387). While no significant differences in dislocation rates were observed between dual-mobility and conventional THA bearings, the significantly lower cup anteversion suggests a potential improvement in acetabular safe zone positioning, this could reflect a broader margin for error in implant positioning. Further prospective studies are needed to elucidate the biomechanical advantages of DM bearings in patients with hip fractures.