Effects of Lumbar Fusion and Dual-Mobility Liners on Dislocation Rates Following Total Hip Arthroplasty in a Veteran Population.

BACKGROUND: Total hip arthroplasty (THA) is a common orthopedic procedure, particularly in the US veteran population. Dislocation is a significant complication, influenced by such factors as lumbar spinal fusion (LSF), which may be more prevalent in veterans due to service-related injuries. This 20-year retrospective study investigated the association between LSF and dislocation risk in veterans who underwent THA; it also explored the impact of dual-mobility liners on dislocation rates. METHODS: THA procedures performed by a single surgeon from 2003 to 2022 were reviewed. The primary outcome was dislocation within 1 year of primary THA; revision rates were a secondary measure. The study evaluated relationships between LSF, demographic variables, the Charlson Comorbidity Index, and lumbar levels that were fused. The study also reviewed whether the use of dual-mobility liners was linked to any protective effects in patients with THA who had previous LSF. RESULTS: The study included 967 THAs for 852 patients; 39 patients (42 THAs) had a prior LSF. Dislocation rates were 9.5% for those with LSF and 3.8% for those without LSF. Logistic regression analysis revealed 2 factors associated with a significantly increased risk of dislocation within 1 year of THA: female sex (odds ratio [OR], 5.84; 95% CI, 2.60-13.13; P < .001) and LSF (OR, 3.42; 95% CI, 1.12-10.47; P = .03). None of the 16 patients treated with a dual-mobility liner experienced dislocation. CONCLUSIONS: This 20-year retrospective study involving a veteran population and a single surgeon identified a heightened risk of postoperative dislocation within 1 year of THA among female patients and those with prior LSF. Findings also suggest that dual-mobility liners may be protective against postoperative dislocation in individuals with a history of LSF.