Arthroscopic Anterior Cruciate Ligament Transection for Osteoarthritis Induction in Rabbits: A Pilot Feasibility and Characterization Study.

Background and Objectives: Traditional open anterior cruciate ligament transection (ACLT) surgical models performed through arthrotomy may introduce capsular trauma and postoperative inflammatory responses that can interfere with the interpretation of post-traumatic osteoarthritis (OA). This study aimed to evaluate the feasibility of a minimally invasive, arthroscopic ACLT rabbit model performed entirely under arthroscopic visualization, without arthrotomy, using a 2.4-mm arthroscope and 2.5-mm shaver, and to provide preliminary structural, histological, synovial, and systemic biochemical characterization of the model for future therapeutic testing. Materials and Methods: Bilateral arthroscopic ACLT was performed in three skeletally mature New Zealand rabbits, followed by a supervised 12-week exercise protocol. Joint degeneration was evaluated macroscopically and histopathologically using the standardized Pritzker-Osteoarthritis Research Society International (OARSI) grading system. Collagen matrix remodeling was assessed via Picrosirius Red staining. Local intra-articular catabolism was quantified via Enzyme-Linked Immunosorbent Assay (ELISA) for matrix metallopeptidase 13 (MMP-13) and interleukin-1β (IL-1β) from synovial fluid. Systemic oxidative stress, including lipid peroxidation biomarkers, malondialdehyde (MDA), and nitric oxide (NO), was evaluated in serum. Results: The arthroscopic approach induced osteoarthritic changes, with severity varying across the cohort. Histopathology revealed vertical matrix fissures and disruption of the normal columnar chondrocyte organization, yielding a median comprehensive Pritzker-OARSI score of 6 (range 6-10), with horizontal degradation restricted to stage 2. Synovial fluid analysis demonstrated measurable concentrations of MMP-13 (188.77 ± 93.87 ng/mL) and IL-1β (174.93 ± 95.51 pg/mL). Furthermore, serum oxidative stress parameters at the 12-week endpoint included lipid peroxidation (MDA: 1.01 ± 0.03 nmol/mL) and NO levels (82.72 ± 0.32 µmol/L), presented descriptively in the absence of a comparator group. Conclusions: This study establishes the first multifaceted pathological baseline of a minimally invasive arthroscopic ACLT rabbit model before therapeutic intervention. The arthroscopic ACLT model produced structural cartilage degeneration alongside measurable intra-articular catabolic and systemic oxidative stress changes, establishing a baseline phenotype and a starting point for future therapeutic studies.