Efeitos do exercício de alongamento mecânico passivo estático na morfologia da articulação talocrural de ratas wistar idosas

Abstract

The changes resulting from the aging process in the articular cartilage can be minimized by performing exercises, such as stretching, used to improve muscle-tendon length and range of joint motion. The aim of this study was to analyze the morphological and histomorphometric effects of an exercise protocol of static passive mechanical stretching in the talocrural joint of young and old Wistar rats. The study initially consisted of thirtyeight animals, randomly divided into four groups: old control (GJC; n = 8), old stretching (GJA; n = 10), young control (GIC; n = 10) and young stretching (GIA; n = 10). The stretching exercise was performed on the left pelvic limb and consisted of a series of 4 repetitions with duration of 60 seconds each repetition, three times a week for three weeks. After euthanasia, the joints were collected, fixed and followed protocol for paraffin embedding. The histological slides were stained with hematoxylin-eosin, photomicrographs with an increase of forty times and analyzed with the program Image Pro Plus 6.0® for the morphological and histomorphometric parameters. The histomorphometric data were analyzed with the program BioEstat 5.0 by ANOVA (Analysis of Variance) one-way with Tukey post hoc, and presented in mean and standard deviation (p < 0,05). The analysis of the results of the chondrocytes number did not present significant statistical differences in tibia and talus, in the comparation between groups of young animals (GJC – GJA) and old animals (GIC – GIA). In the thickness measurement of articular cartilage analysis was verified significant differences in the comparation between the young groups (GJC – GJA; p < 0,01), in tibia and talus, being that the GJA group presented higher values in the thickness of the articular cartilage. As for the morphological analysis, the groups GJC and GJA presented cartilage and synovial membrane with normal characteristics. The group GIC presented the deleterious effects of the aging process, with subchondral bone invagination, flocculation and presence of pannus covering cartilage. In the synovial membrane, was observed intense inflammatory process with cells arranged in their layers and in the joint cavity. Also were checked the thickening and increase in the synoviocytes number in the intima synovial, decrease in the number of fat cells and presence of connective tissue in the subintima. In the group GIA, the morphological findings showed an improvement in the chondrocytes and synovial membrane, similar to the morphology of the GJC and GJA. The present study shows that the elongation exercise protocol had a beneficial effect on the reversal of the morphological alterations due to aging, and may maintain or improve the morphology of the articular cartilage and especially of the synovial membrane in the ankle joint of elderly rats.