Comparative Outcomes of Dual Mobility Cup versus Bipolar Hemiarthroplasty in Patients with Neurological Disorder with Femoral Neck Fractures

To compare the risk of periprosthetic and medical complications following dual mobility cup total hip arthroplasty (DMC-THA) and bipolar hemiarthroplasty (BHA) for femoral neck fractures in patients with neurological disorders. This retrospective study included patients with neurological disorders who underwent DMC-THA (n=1,153) or BHA (n=4,612) between 2016 and 2022, identified from the Korean Health Insurance Review and Assessment Service database. Propensity score matching was performed at a 1:4 ratio to adjust for baseline characteristics. The primary outcome was periprosthetic complications; the secondary outcome was medical complications. Compared with the BHA-matched group, the DMC-THA group showed a higher rate of early periprosthetic fracture (2.6% vs. 1.4%, P=0.02) and late dislocation (1.1% vs. 0.5%, P=0.03). No significant differences were observed in periprosthetic joint infection or revision. Regarding medical complications, DMC-THA was associated with more transfusions (63.1% vs. 57.6%, P<0.001) but fewer urinary tract infections (3.4% vs. 5.1%, P=0.01). Multivariable analysis identified DMC-THA as an independent risk factor for early periprosthetic fracture (odds ratio [OR] 3.01, 95% confidence interval [CI] 1.39-6.80, P=0.004) and late dislocation (OR 2.53, 95% CI 1.18-5.42, P=0.02). DMC-THA was not superior to BHA in preventing dislocation and was associated with a higher risk of periprosthetic fracture and late dislocation in neurologically impaired patients. Surgeons should recognize the risks of using DMC-THA implants as a sole strategy to prevent instability in this high-risk population.