Intra-articular administration of autologous adipose-derived stem cells in hip osteoarthritis: Longitudinal treatment trajectories and prognostic factors.

Introduction: Evidence regarding the effectiveness of mesenchymal stem cells in improving hip function in patients with hip osteoarthritis (OA) remains inconsistent. Therefore, we aimed to estimate the longitudinal trajectories of treatment effects in individuals with hip OA following intra-articular administration of autologous adipose-derived stem cells (ASCs), both in the overall cohort and the cohort stratified by OA severity, and to explore the prognostic factors of treatment outcomes. Methods: This retrospective study included adults with hip OA who underwent magnetic resonance imaging (MRI) before treatment between 2020 and 2023. All patients underwent intra-articular ASC administration. The primary outcomes were the total scores on the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) at 1, 3, and 6 months after treatment. A linear mixed-effects model was used to estimate the marginally predicted JHEQ total score changes over time for all patients and compare these changes among subgroups categorized according to OA severity. Furthermore, models that included MRI findings were used to explore potential prognostic factors. Results: We identified 168 hips in 129 patients. In the analysis of all patients, the JHEQ total scores significantly increased at 1, 3, and 6 months after treatment compared with baseline. In the mixed-effects analysis, the predicted change in the JHEQ total score from the baseline to the 6-month follow-up was 10.6 points (95 % confidence interval, 8.3 to 12.8), with an increasing trend over time. The effect modification by OA severity on the JHEQ total score was observed over time after treatment (P = 0.016). Prognostic analysis revealed that patients with moderate hip OA had higher JHEQ total scores after treatment than those with mild hip OA (P = 0.028). Additionally, female patients had higher JHEQ total scores after treatment than male patients (P = 0.025). The presence of ligamentum teres abnormalities was associated with low JHEQ total scores after treatment (P = 0.011). Conclusions: Intra-articular ASC treatment enhanced patient-reported outcomes over 6 months, with differences observed across hip OA severities. Female sex and moderate hip OA were positive prognostic factors, whereas ligamentum teres abnormalities were negative prognostic factors for patient-reported outcomes after ASC treatment. These findings can be used to inform patients and clinicians about the expected course of treatment and aid clinical decision-making regarding the use of intra-articular ASC treatment for hip OA.