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

Purpose: 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.

Materials and methods: 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.

Results: 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).

Conclusion: 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.