Differences in Postoperative Clinical Outcome and Quality of Life up to 2 Years Between Patients with Osteonecrosis of the Femoral Head and Osteoarthritis Undergoing Total Hip Arthroplasty

: Purpose Osteonecrosis of the femoral head (ONFH) often necessitates total hip arthroplasty (THA). This study compared clinical outcomes and quality of life (QOL) between patients with ONFH and osteoarthritis (OA) undergoing THA. Methods Among 558 hips with ≥2-year follow-up, with 30 hips per group were selected after propensity score matching based on age and sex. Outcomes were assessed preoperatively and at 6 months, 1 year, and 2 years postoperatively using the Oxford Hip Score (OHS), Japanese Orthopaedic Association (JOA) score, Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire, and the Short Form-12 Health Survey version 2 (SF-12v2). Results Both groups demonstrated significant postoperative improvements over time. OHS improved substantially after THA, with no significant differences in postoperative recovery trajectories between groups. Similarly, JOA Scores significantly improved in both groups, with no significant group effect or group-by-time interaction. Significant improvements over time were also observed in JHEQ and SF-12v2 scores. Although no statistically significant group-by-time interaction was observed, the SF-12v2 role component summary score showed a trend toward a group-by-time interaction ( p = 0.08). Conclusions Longitudinal analyses demonstrated that patients with ONFH achieved postoperative clinical and patient-reported outcomes comparable to those of patients with OA during the first 2 years after THA. These findings suggest that THA provides similarly favorable recovery irrespective of disease etiology.