Morphometric aspects of the articular cartilage of rats treated with low-level laser therapy and exercise in a rheumatoid arthritis model

Introduction: Rheumatoid arthritis (RA) is classified as an autoimmune, chronic disease affecting diarthrodial joints and periarticular structures. Objective: To evaluate whether low-intensity laser treatment (LLLT) and/or exercise reduce the deleterious effects of tissue in a rheumatoid arthritis model. Methods: 128 rats were divided into two inflammatory periods: acute (7 days) and chronic (28 days) and subdivided into control, injury and treatment. The protocol with Freund's Complete Adjuvant was used in two inoculations, one intradermal and one intraarticular in the tibiofemoral joint, the control animals received saline solution. For treatment, LLLT 660 nm, 5 J/cm² was used in the sensitized joint and climbing exercise in stairways with an overload of 100 grams. After the experimental period, the animals were euthanized and the joints were prepared for morphometric analysis of the total thickness, superficial, deep, and cellular density of the articular cartilage. Generalized Linear Models with Sidak post-test were chosen. Results: The control group was found to be different from the lesion group with greater joint cartilage thickness, and the animals treated with exercise alone increased the joint cartilage compared to the control group. Conclusion: The animals treated with laser association and exercise showed improvement in the morphometric aspects of the articular cartilage.