Total hip arthroplasty compared with conservative treatment with a self-directed exercise programme in moderate-to-severe hip osteoarthritis: a randomized controlled trial

Aims: The aim of this study was to compare clinical, performance-based, and patient-reported outcomes between patients with moderate-to-severe hip osteoarthritis (OA) who were treated with total hip arthroplasty (THA) or conservative treatment with a self-directed exercise programme. Methods: We conducted a single-centre, randomized controlled trial including 120 participants with radiologically confirmed moderate-to-severe hip OA (Kellgren-Lawrence grades 2 to 4). Participants were randomly allocated (1:1) to receive either THA combined with postoperative rehabilitation or a self-directed exercise programme. The primary outcomes were changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Harris Hip Score (HHS) at 12 months. Minimal clinically important differences (MCIDs) were predefined as 11 points for WOMAC and 15.9 points for HHS. Secondary outcomes included WOMAC at six months, as well as WOMAC subscales, health-related quality of life (HRQoL) RAND 36-Item Health Survey 1.0 (RAND-36) domains, and physical performance tests (chair stand, 40 m walk, and stair climb). Results: At 12 months, the THA group demonstrated significantly greater improvements than the conservative group in WOMAC total score (-30.9 (95% CI -34.9 to -27.0) vs -3.7 (95% CI -8.2 to 0.9; between-group difference -27.1 points (95% CI -32.4 to -21.8)) and HHS (29.8 (95% CI 25.8 to 33.9) vs 5.7 (95% CI 2.4 to 9.0); difference 24.1 (95% CI 19.6 to 28.7)), both exceeding MCID thresholds. Overall, 23 participants (38%) in the conservative group underwent THA during the study; two participants in the THA group declined surgery. The THA group also showed superior gains across all performance-based tests and most RAND-36 domains. Conclusion: In patients with moderate-to-severe hip OA, THA combined with postoperative rehabilitation provides clinically meaningful improvements in pain, function, and HRQoL compared with a self-directed exercise programme alone. These findings reinforce THA as the preferred option for eligible patients.