Response of the knee’s joint structures in rats after immobilization

Abstract

Objective: The purpose of the study is to analyze the articular structures behavior of rats submitted to knee immobilization, through a histomorphometric analysis. Materials and Methods: In order to perform this study, 10 male Rattus navergicus albinus, Wistar variety, 3 to 4 months old were separated in two groups: one group for a 7-day-period of immobilization and the other for 14 days. After the immobilization period, the animals were euthanized and the articulations were histologically analyzed. The results were tested through a paired t test with a 5% significance level. Results: In both groups of immobilization (G7 and G14), a reduction on the cartilage (G7: p=0,0006; G14: p=0,006) and subchondral (G7: p=0,0003; G14: p=0,002) bone thickness were observed, as well as an increase of the epiphyseal cartilage thickness (G7: p=0,001;G14: p=0,05) and the number of chondrocytes in the articular cartilage (G7=0,004; G14=0,034). In the 14-day group of immobilization it was also observed an increase of isogenic group population. Conclusion: With the results of this study, we can conclude that both after 7 and 14 days of immobilization, structural alterations occurs in the knee articulation, for instance thickness reduction in the articular cartilage of the subchondral bone and an increase of the epiphyseal cartilage thickness, affecting negatively the articular integrity.