Prognosis of 1st time revision due to pain following primary total hip arthroplasty - a nationwide cohort study from the Danish Hip Arthroplasty Register

Revision total hip arthroplasty (THA) for persistent or unexplained pain remains controversial. Uncertainty remains regarding the subsequent risk of re-revision following revision THA for pain. The objectives of this study are to compare the risk of all-cause and cause-specific re-revision following first-time revision THA performed for pain versus aseptic loosening. This nationwide, register-based cohort study will use data from the Danish Hip Arthroplasty Register. Patients who underwent primary THA followed by first-time revision THA for pain or aseptic loosening between 1995 and 2025 will be included. Patients will be followed from the index revision until re-revision, death, emigration, or end of follow-up. The primary outcome is time to all-cause re-revision. Secondary outcomes are cause-specific re-revision due to pain, aseptic loosening, infection, or dislocation. Cumulative incidence will be estimated using competing-risk methods, and hazard ratios will be estimated using Cox proportional hazards regression. The study will provide nationwide evidence on the risk of re-revision following revision THA for pain and may inform clinical decision-making and patient counselling.