Compressão nervosa e exercício físico resistido: efeitos sobre a morfologia da articulação talocrural de ratos

Abstract

An adequate activity of the sciatic nerve is essential for the morphofunctional integrity of the lower limb structures, including the ankle joint or talocrural, responsible for providing a stable base of support for the body, in addition to propel it effectively during locomotion. These motor functions may be affected by changes in the peripheral nervous system by various pathological conditions, such as sciatica, which can be generated through the sciatic nerve compression, leading to functional incapacities. Among the treatment modalities, the resistive exercise stands out, and despite of its widespread use, still shows divergences in literature as to the best type, its intensity and the most indicated period for its outset. Therefore, the objective of this research was to verify the effects of experimental model of nerve compression and treatment with resistive exercise on the morphology of the talocrural joint of Wistar rats. For this purpose, 32 rats were divided into 4 groups (n = 8 / group): G1 (control), G2 (injury), G3 (exercise) and G4 (injury and exercise). Three days after the sciatic nerve compression surgery, groups G3 and G4 were submitted to resistive exercise stair climbing during 21 days. After euthanasia, the talocrural joints followed the protocol for paraffin embedding. The slides were colored with hematoxylin-eosin and Safranin O-Fast Green, photomicrographed and analyzed using Image Pro Plus 6.0®. Data were presented in mean and standard deviation, and ANOVA one way with posttest t was used for comparison. No significant differences in the thickness of the articular cartilage in the tibia and the talus were found. As for the number of chondrocytes in the tibia, G2 and G3 presented more cells in the anterior region of articular cartilage compared to G1, condition reversed in G4 animals. In the talus, there was an increase in the number of chondrocytes in anterior and posterior articular region of G2 and G3, and in G4, this hypercellularity was maintained only in the posterior region. As the central region of the joint, all groups presented a higher cell density compared to G1. In the morphological analysis, in the injury group (G2), changes were observed in the tibia and talus with the presence of flocculation, invagination of the subchondral bone, tidemark discontinuity and presence of pannus in the talus. In the exercise group (G3), discrete alterations were found only in talus and, in G4, the cartilage presented similar characteristics to G1. As for the morphology of the synovial membrane, this showed to be fibrous in the injury group, while in the other groups tissue changes were not noticed. Thus, sciatica led to an increase of the number of chondrocytes mainly in the talus and also produced morphological changes in the cartilage and in the synovial membrane of the talocrural joint, and the resistive physical exercise proved to be effective in the recovery of morphological characteristics of the joint components.