ABSTRACT Objective Gouty arthritis is characterized by painful inflammation due to the deposition of monosodium urate crystals in joint tissues. Despite available treatments, many patients experience ineffective management and adverse effects. This study evaluated a manual therapy protocol involving passive joint mobilization at the peak of inflammation in a gouty arthritis model using functional and inflammatory parameters. Methods Twenty male Wistar rats, 12 weeks old, were divided into two groups (n=10 each): Gouty Arthritis and Control Groups, which were further subdivided into treated and untreated groups (n=5 each). The Gouty Arthritis Group received intraarticular knee injection of 50µL of monosodium urate crystals, while the Control Group received 50µL of phosphate buffered saline. The treatment involved a 9-minutes session of grade III joint mobilization (according to Maitland). Nociception, grip strength, and edema were evaluated before induction (EV0), 7 hours after assessment (EV1), immediately after treatment (EV2), and 1 hour after treatment (EV3). The animals were euthanized, and synovial fluid was collected to analyze leukocyte migration. Results The model mimicked the signs of the Gouty Arthritis Group, with a decrease in the threshold of nociception and strength and an increase in edema and leukocyte count. The mobilization protocol significantly increased the nociceptive threshold and grip strength and reduced edema; however, it did not reverse the increase in leukocyte count. Conclusion Our results suggest that mobilization promotes analgesia and may modulate the inflammatory process owing to reduced edema and subtle attenuation of cell migration, which contributes to strength gain.

RESUMO JUSTIFICATIVA E OBJETIVOS: Os efeitos deletérios da artrite reumatoide nos tecidos periarticulares ainda não estão totalmente elucidados, sendo pertinente a busca por tratamentos que possam modular o perfil inflamatório e a remodelação tecidual. O presente estudo avaliou os efeitos do laser de baixa intensidade (LBI) na morfologia dos tecidos periarticulares e membrana sinovial de ratos submetidos à um modelo de artrite reumatoide. MÉTODOS: Para tanto, 64 ratos machos foram divididos em períodos inflamatórios agudo (7 dias) e crônico (28 dias), com 4 grupos (n=8) cada, sendo: GC (grupo controle), GL (grupo lesão), GCLa (grupo controle laser) e GLLa (grupo lesão laser). Os animais dos grupos lesão foram submetidos a duas inoculações de Adjuvante Completo de Freund na concentração de 50µL, sendo a primeira na base da cauda e a segunda no joelho direito. Os animais do grupo controle foram submetidos a injeções com solução isotônica de cloreto de sódio. Os grupos GCla e GLLa foram tratados com LBI 660nm, pontual no joelho direito, 5J/ cm2. Após o período experimental, os animais foram eutanasiados e os joelhos processados para análises em microscopia de luz. RESULTADOS: Na análise morfológica, GC e GCLa apresentaram aspectos normais. O GL apresentou sinovite, fêmur e tíbia com alterações no periósteo, com células inflamatórias e modificações ósseas. A membrana sinovial mostrou sinais de melhora no GLLa. No período crônico, o tecido ósseo apresentou aspectos morfológicos, denotando remodelação tecidual. CONCLUSÃO: O modelo experimental foi eficiente em simular os eventos inflamatórios teciduais, e o laser de baixa intensidade apresentou efeitos benéficos sobre a morfologia dos tecidos periarticulares.

ABSTRACT BACKGROUND AND OBJECTIVES: The deleterious effects of rheumatoid arthritis on periarticular tissues have not yet been fully elucidated. Therefore, the search for treatments that can modulate the inflammatory profile and tissue remodeling is pertinent. The present study evaluated the effects of low-level laser therapy (LLLT) on the morphology of periarticular tissues and synovial membrane of rats in a rheumatoid arthritis model. METHODS: Sixty-four male rats were divided into acute (7 days) and chronic (28 days) inflammatory periods, with four groups (n=8) each, being: CG (control group), LG (lesion group), CLaG (laser control group) and LLaG (laser lesion group). The animals of the lesion groups received two inoculations of Freund’s Complete Adjuvant at a concentration of 50µL, the first at the base of the tail, and the second at the right knee. The animals in the control groups were injected with isotonic sodium chloride solution. The ClaG and LLaG were treated with 660nm LBI, 5J/cm2 in the right knee. After the experimental period, the animals were euthanized, and the knees were processed for light microscopy. RESULTS: The CG and CLaG morphological analysis had normal aspects. The LG showed synovitis, femur, and tibia with changes in the periosteum, with inflammatory cells and bone modifications. In the LLaG, the synovial membrane showed signs of improvement. Bone tissue in the chronic period showed morphological aspects, denoting tissue remodeling. CONCLUSION: The experimental model was efficient in simulating inflammatory tissue events, and the low-level laser therapy showed beneficial effects on the morphology of the periarticular tissues.