The increased torque required to dislocate dual mobility (DM) components may increase peri-prosthetic femoral fracture (PPF) risk. Current literature often relies on revision as an endpoint and may underestimate PPF. This study aims to review PPF rate, risks and treatment following primary DM implantation.

Prospective cohort study of 549 patients following primary DM total hip arthroplasty (THA) between 2013 and 2021. Collected data included demographics, indication for surgery, cortical index and PPF.

549 patients were identified with primary DM THA. Mean age was 73 years (26–96). 446 (81.2%) patients had their index surgery following hip fracture. 18 patients (3.27%) sustained a PPF. Cumulative PPF rate was 1.5% at 1-year, 2.2% at 5-years and 3.27% overall. PPF was higher in patients undergoing surgery following hip fracture (4%) vs. other indications (1%). OR 4.04 (95% CI:0.53, 30.72), p=0.219. Mean cortical index was lower in patients with PPF 0.4 (95% CI:0.36, 0.45) compared to those without 0.46 (95% CI:0.45, 0.46) p=0.029. Treatment for PPF included 10 (55.6%) open reduction internal fixation (ORIF), 7 (38.9%) revision THA and 1 conservatively managed.

PPF rate following DM use is higher in our cohort than published rates. Our rates are comparable to some papers when subgroup analysis of older patients and cemented taper slip stems are considered. PPF risk with DM may be increased in patients undergoing surgery after hip fracture or with a lower cortical index preoperatively. Over half of PPF were managed with ORIF and may mask PPF risk studies that report using revision as an endpoint.