Introduction: Hyaluronic acid (HA) is the major hydrodynamic component of synovial fluid. Thus, intra-articular injection of HA (IA-HA) has become the most widely accepted therapy for osteoarthritis. Growing interest has been seen recently in new uses for Botox in medicine, such as the treatment of osteoarthritis.
Aim of the work: This study was carried to investigate the effect of intra-articular injection of Botox, Hyaluronic acid and their combination on complete Freund's adjuvant (CFA) induced temporomandibular joint osteoarthritis (TMJ-OA) in rats.
Materials and Methods: 30 young adult male Albino rats weighing 250–300g were used in this study. Rats were divided randomly into 3 groups. Group I (control) in which animals received 3 doses of saline on days 7, 14 and 28. Group II (osteoarthritic) in which animals received single dose of CFA and left without treatment. Group III (treatment) was subdivided into 3 subgroups. In each subgroup, animals received 3 doses of high molecular weight hyaluronic acid in subgroup A, Botox in subgroup B, and combination of both in subgroup C on days 7, 14, and 28. After 35 days, the animals were sacrificed and the TMJs were dissected and examined histologically and immunohistochemically for tumor necrosis factor alpha.
Results: TMJ retained its normal histological structure after IA-HA. There was no improvement in osteoarthritic features by intra-articular injection of Botox. The combination improved osteoarthritic features more than Botox but did not reach the level of HA.
Conclusion: TMJ-OA could be treated with IA-HA, whereas Botox and their combination were ineffective.