Inflammatory factors are crucial for the pathogenesis of post-traumatic osteoarthritis confirmed by a novel porcine model: “Idealized” anterior cruciate ligament reconstruction” and gait analysis

Abstract Background: The study was performed to determine whether idealized anterior cruciate ligament reconstruction (IACL-R) restores normal gait features, and whether inflammatory factors are involved in the pathogenesis of post-traumatic osteoarthritis (PTOA). Methods: Fourteen mature female minipigs were allocated to a sham group (n = 7) or an IACL-R group (n = 7). Load asymmetry during gait was recorded using a pressure-sensing walkway measurement system to evaluate the gait features of the right knee joint before and after surgery. Inflammatory factors (including interleukin [IL]-1α, IL-1β, IL-2, IL-6, IL-8, IL-18, tumor necrosis factor-α, and granulocyte–macrophage colony-stimulating factor) in synovial fluid were measured using Luminex assays before and after surgery. Cartilage integrity and the subchondral bone plate of the right knee were evaluated using histology and imaging at 3 months postoperatively. Results: Swing time and stance time returned to their preoperative values on day 31, while maximum force, contact area, peak force ,and impulse returned to their preoperative values on day 45 after the surgery in the IACL-R group (P = 0.073, 0.053, 0.107, 0.052, 0.152, and 0.059, respectively).Thus, IACL-R restored normal gait. Compared with their preoperative concentrations, all tested inflammatory factors showed significantly increased concentrations in the synovial fluid in the IACL-R group, especially at 3, 7, and 15 days postoperatively. X-ray, computed tomography, magnetic resonance imaging, and histological data showed severe cartilage damage in the IACL-R model. Conclusion: IACL-R restored normal gait features but caused significant cartilage damage, indicating that significantly elevated inflammatory factors maybe crucial for the pathogenesis of PTOA.