A modified protocol for mechanical extraction of stromal‑vascular fraction in combination with platelet‑rich plasma for osteochondral defects of the knee joint

Introduction Mechanical isolation of the stromal vascular fraction (SVF) from autologous adipose tissue represents a promising approach in regenerative treatment of osteochondral defects of the knee joint. However, intra-articular SVF administration may be associated with a post-injection synovial reaction, which decreases the tolerability of the procedure and complicates early clinical assessment. Therefore, optimization of the cell preparation protocol aimed at improving biological purity and reducing reactive intra-articular changes remains clinically relevant. Purpose To evaluate the impact of a modified mechanical SVF isolation protocol combined with highly concentrated platelet-rich plasma (P-PRP) on the severity and duration of post-injection synovial reaction in patients with osteochondral knee defects. Materials and Methods A retrospective-and-prospective comparative non-randomized study included 62 patients. Group I consisted of 41 patients treated using the standard mechanical SVF protocol. Group II included 21 patients treated with a modified protocol incorporating liposaspirate washing, mechanical emulsification through a 0.6 mm filter, and P-PRP preparation using double centrifugation with ACD-A anticoagulant. Comparative analysis was performed based on the severity and duration of post-injection synovial reaction using clinical and instrumental stratification and ultrasound assessment. Results In the standard protocol group, mild synovial reaction was observed in 4 (9.8 %) patients, moderate in 16 (39.0 %), and severe in 21 (51.2 %). In the modified protocol group, mild reaction was recorded in 11 (52.4 %) patients, moderate in 7 (33.3 %), and severe in 3 (14.3 %). The median duration of synovial reaction was 11 (9–12) days in the standard protocol and 5 (3–7) days in the modified protocol ( p < 0.001). Discussion The addition of liposaspirate washing and mechanical purification through a 0.6 mm filter in the protocol, along with double centrifugation using ACD-A, reduced the final injection volume and increased platelet concentration in PRP (> 1 × 10 6 /µL), which was associated with decreased severity and shorter duration of synovial reaction. Conclusion The modified mechanical SVF isolation protocol improves early post-injection tolerability by reducing the severity and duration of post-injection synovial reaction. The proposed technique is reproducible and may represent a promising approach for optimizing regenerative therapy in patients with osteochondral knee defects.