Salvage total hip arthroplasty after internal fixation compared with acute total hip arthroplasty for fracture: a cohort study based on 32,960 cases from the Dutch Arthroplasty Register

BACKGROUND AND PURPOSE: Total hip arthroplasty (THA) is used as treatment of acute hip fracture and as a salvage procedure after failed internal fixation (IF). We aimed to assess revision rates of salvage-THA after IF of hip fracture compared with acute fracture-related THA. METHODS: Using the Dutch Arthroplasty Register, 32,960 procedures with fracture-related THAs of the proximal femur between 2007 and 2023 were selected. We performed competing risk survival analysis and adjusted multivariable Cox regression. RESULTS: 12,486 patients received salvage THA after failed IF, 744 (6.0%) needed revision THA; 18,450 patients received acute THA for fracture, 885 (4.8%) needed revision THA. Cumulative rates of revision THA after salvage THA at 1 and 5 years were 2.7% (95% confidence interval [CI] 2.4-3.1) and 4.5% (CI 4.1-4.9), respectively, comparable to 2.5% (CI 2.3-2.8) and 4.3% (CI 4.0-4.6), for revision THA after acute THA. Revision THA of salvage THA patients were more often younger, male, had higher BMI, lower ASA class, and were smokers. Posterolateral approach, reversed-hybrid fixation, and small femoral heads were more common, compared with revision after acute THA for fracture patients. In both groups, most common reasons for revision THA were infection, aseptic loosening, and dislocation. In the salvage THA, adjusted hazard ratios (HR) showed increased risk of revision THA for ASA class III-IV (HR 1.6), high BMI (BMI > 25, HR 1.6-2.1), reversed hybrid fixation (HR 1.3), and 22-28 mm femoral head size (HR 1.3). Cumulative second revision rates of salvage THA after IF at 1 and 5 years were 14.1% (CI 11.6-17.2) and 22.3% (CI 19.0-26.2), similar to the acute THA for fracture group. CONCLUSION: Revision rates after salvage THA following IF were comparable to those after acute THA for fracture. Hence, previous internal fixation does not seem disadvantageous. However, both groups differed clearly in case mix.