Adipose-Derived Stromal Cells for the Treatment of Knee Osteoarthritis: A Retrospective Study of Clinical Outcomes and Predictive Factors

Background/Objectives: Knee osteoarthritis (OA) is a common degenerative joint disease for which conservative treatments often provide limited long-term benefit. Adipose-derived stromal cells delivered as stromal vascular fraction (SVF) represent a minimally invasive orthobiological approach with potential anti-inflammatory and regenerative effects. This study aimed to evaluate the clinical effectiveness and safety of intra-articular autologous SVF therapy and to explore patient- and treatment-related factors influencing outcomes over one year. Methods: This single-center retrospective study included 48 patients with knee OA Kellgren–Lawrence (KL) grade II–III treated with a single intra-articular injection of autologous SVF between June 2020 and February 2022. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline and at 3 and 12 months post-treatment. Associations between clinical outcomes and age, sex, body mass index (BMI), OA grade, and administered cell dose were analyzed. Results: Significant improvements were observed in all KOOS domains at 3 months post-treatment (p < 0.001). At 12 months, improvements remained significant across domains, although Symptom scores showed slight attenuation. Higher administered cell dose was associated with greater improvement in KOOS Quality of Life (CFU-F indicators, rs = 0.41–0.45, p < 0.01) and Sport and Recreation (TNC indicators, rs = 0.36–0.38, p < 0.05) at 12 months, while younger age predicted greater QoL improvement and normal BMI was associated with better Symptom outcomes. Radiographic OA severity did not significantly influence treatment response, and sex-related differences were minimal. No serious adverse events were recorded. Discussion: SVF therapy was associated with sustained functional improvement and demonstrated a favorable safety profile in patients with moderate knee OA. Although demographic and treatment-related factors showed limited influence, cell dose, BMI, and age may affect selected outcomes. Prospective controlled studies with larger cohorts and longer follow-up are required to optimize patient selection and treatment protocols. Conclusions: These findings suggest that autologous SVF therapy may represent a safe and effective complementary treatment option for patients with moderate knee osteoarthritis seeking alternatives to more invasive interventions; however, these results should be confirmed in prospective controlled studies.