AB0088 MECHANICAL STIMULUS INDUCED BY CHIROPRACTIC MANIPULATION REDUCES CARTILAGE, SUBCHONDRAL BONE DAMAGE AND SYNOVIAL INFLAMMATION IN AN EXPERIMENTAL MODEL OF OSTEOARTHRITIS
Authors: Francisco Miguel Conesa-Buendía, Aránzazu Mediero-Muñoz, Ricardo Fujikawa, Paula Gratal Viñuales, Francisca Mulero, Juan Pablo Medina Giménez, Gabriel Herrero-Beaumont, Raquel Largo-Carazo, Arantxa Ortega DE Mues
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation, although both subchondral bone deterioration and synovial inflammation are also hallmarks of the disease. Chiropractic manipulation (CM) is a therapeutic approach focused on the diagnosis, treatment and prevention of musculoskeletal disorders. It is essentially manual, allowing the chiropractor to restore the normal range of motion and function of the joints, muscles, and ligaments. Clinical evidences suggest that CM might exert positive effects in OA patients. <h3>Objectives</h3> The aim of this study was to evaluate the effects of CM on cartilage, subchondral bone and synovitis state in an OA rabbit model. <h3>Methods</h3> Ten (4 months old) male New Zealand rabbits underwent knee surgery to induce OA by transection of anterior cruciate ligament. One week after the surgery, CM was performed using the chiropractic adjusting instrument ActivatorV as follows: Force 2 setting was applied onto the tibial tubercle of the right hind limb (true manipulation, TM-OA group), at an angle of approximately 90°, from medial to lateral, whereas the corresponding left hind limb received a false manipulation (FM-OA group) consisting of ActivatorV firing in the air and slightly touching the tibial tubercle. These procedures were repeated 3 times a week for 8 weeks. Three healthy animals were used as control. Following sacrifice, μCT and histological damage evaluation (Mankin score) were done in femur and tibiae. RANKL/OPG protein expressions were studied by immunohistochemistry in tibia samples. Sinovitis was assessed by Krenn score and immunohistochemistry for macrophages (RAM11) and angiogenesis (CD31) were done. Protein expression of VEGF, COX2, TNFa, IL-1b and MMP3 were determinated by Western Blot. <h3>Results</h3> In the OA rabbits, subchondral BMD decreased in relation to control, been partially reversed in the tibiae of TM-OA group. When subchondral trabecular bone structural parameters were analyzed by microCT, a significant decrease of bone volume/trabecular volume (BV/TV), trabecular number (Tb.N) and trabecular thickness (Tb.Th) was observed in the OA rabbits, while trabecular separation (Tb.S) increased compared to control animals. TM-OA group showed a significant improvement of these parameters compare to FM-OA group. FM-OA joints had higher Mankin score (cartilage damage) than control joints, and TM decreased Mankin score compare to FM-OA (<i>p&lt;</i><i>0.05</i>). The study of RANKL and OPG in cartilage and subchondral bone showed that the significant increase in the RANKL/OPG ratio observed in both tissues respect to controls, was partially reversed in TM-OA group. OA synovial membranes presented a total Krenn synovitis score higher than healthy animals; however, TM-OA rabbits exhibited scores lower than FM-OA (<i>p&lt;</i><i>0.05</i>). RAM11 immunostaining revealed lower expression in TM-OA synovial membranes compared to FM-OA (<i>p&lt;</i><i>0.05</i>). Finally, the significant increase in proinflammatory cytokines (COX2, TNFa and IL-1b) and MMP3 were observed in the synovial membranes of OA rabbits respect to controls, being partially reversed in TM-OA group. Likewise, VEGF and CD31 expression was higher in FM-OA synovium compared to TM-OA. <h3>Conclusion</h3> These results suggest that mechanical stimulus induced by CM may retard the pathologic progression of OA. The beneficial effects of CM might be associated with an improvement in bone and cartilage damage and also inflammatory state. <h3>Disclosure of Interests</h3> None declared