The 10-Year Revision Risk of Dual-Mobility Versus Standard Cups in Primary Total Hip Arthroplasty for Osteoarthritis: A Population-Based Study from the Danish Hip Arthroplasty Register.

BACKGROUND: Dislocation is the leading cause of first-time revision following total hip arthroplasty (THA). Dual-mobility (DM) cups have been used to reduce this risk, but data on 10-year revision outcomes with DM compared with standard cups remain limited. We aimed to compare the 10-year risk of all-cause and cause-specific revision between DM cups and standard cups with 32 or 36 mm femoral heads.

METHODS: This was a nationwide register-based cohort study using data from the Danish Hip Arthroplasty Register and the Danish National Patient Register. We included patients who underwent primary THA for osteoarthritis (OA) between 2007 and 2019 receiving either a monoblock DM cup or a standard cup with a 32 mm (SC32) or 36 mm (SC36) femoral head. We identified 5,187 patients who have DM, 35,162 with SC36, and 15,702 with SC32. The primary outcome was revision within 10 years for any cause. The secondary outcomes included cause-specific revision within 10 years. We estimated standardized risk differences using direct standardization to the covariate distribution of the combined population.

RESULTS: The standardized 10-year risk of all-cause revision was 6.6% (95% confidence interval [CI] 5.7 to 7.4) for DM, 5.9% (95% CI 5.6 to 6.3) for SC36, and 6.9% (95% CI 6.4 to 7.4) for SC32. The standardized risk difference was -0.6 percentage points (95% CI -1.5 to 0.3; P = 0.16) for DM versus SC36 and 0.3 percentage points (95% CI -0.6 to 1.3; P = 0.50) for DM versus SC32.

CONCLUSION: The 10-year standardized risk of all-cause revision did not differ between DM and SC36 or SC32. The DM was associated with a lower standardized risk of revision due to dislocation, but a higher standardized risk of revision due to infection compared with both SC32 and SC36.