An ozone injectable solution reduces structural cartilage degeneration in an ACLT rat model

Osteoarthritis (OA) is the leading cause of joint degeneration in the elderly, yet current treatment strategies remain inadequate. This study aimed to evaluate the chondroprotective effects of intra-articular Ozone Injectable Solution (OIS), a liposomal formulation containing ozone, hyaluronic acid, and 1% lidocaine, in a surgically induced knee OA model in rats. Forty male Sprague-Dawley rats underwent anterior cruciate ligament transection (ACLT) for OA induction. Random allocation yielded five groups: control, lidocaine, single-dose OIS (OIS-1), three weekly OIS injections (OIS-3), and five weekly OIS injections (OIS-5). Treatment began on postoperative day 14. Radiographic evaluations were performed before and after treatment. Histopathological assessment included modified Mankin scoring, cartilage degeneration scoring, and measurement of cartilage matrix loss width. Serum and synovial fluid levels of IL-6 and IL-1α were measured. Post-treatment radiographs showed better preservation of joint structure in OIS-3 and OIS-5, with lower scores for joint space narrowing and osteophyte formation than in controls (p ≤ 0.005). The OIS-3 group exhibited the lowest median modified Mankin score (1; range: 1-3; p < 0.001) and favorable cartilage architecture. Between-group differences were detected in cartilage matrix loss width and degeneration scores. For Zone 2 degeneration, the omnibus test yielded p = 0.001, and the OIS-3 score was lower than the control score in the pairwise comparison (p = 0.044). Serum cytokine concentrations also varied across groups, with p = 0.004 for IL-6 and p = 0.005 for IL-1α. Serum IL-6 and IL-1α levels differed significantly among groups (p = 0.004 and p = 0.005, respectively). Intra-articular OIS demonstrated chondroprotective effects in this experimental model of knee osteoarthritis, with favorable therapeutic responses observed particularly following three and five injections. These findings highlight OIS as a promising intra-articular therapeutic approach for osteoarthritis.