Imobilização prolongada e remobilização da articulação fêmoro-tíbio-patelar de ratos: estudo clínico e microscópico

Thirty-four rats were randomly allocated into one of four experimental groups: without immobilization (G1), immobilization of the right knee joint for 45 days (G2), immobilization and remobilization with free activity for 5 weeks (G3), and immobilization and remobilization with free activity and swimming program for 5 weeks (G4). The immobilization was prejudicial to march and flexibility articular. Animals from G4 showed a better march evolution on the first five days as compared to those from G3. After that periods, march evolution were similar in both G3 and G4. Animals from G2 showed rigid joint while in those from G3 and G4 the articular movement was close to normal. The histological analysis pointed out that immobilization led to increase in articular capsule thickness evidenced by the presence of fibrous connective tissue replacing adipose tissue in G2, but proportionally less in G3 and G4. It was observed that immobilization determined loss of proteoglycans from the cartilaginous matrix, increase in the number of regularly arranged condrocytes, increase in calcified cartilage thickness, irregularity in the articular surface, proliferation of connective tissue in the intra-articular space and increase in subchondral bone thickness. The animals from G3 showed a greater number of alterations in both articular cartilage and subchondral bone, as compared to those from G4. Immobilization degenerated synovial cells indicating decreased synovial fluid production and reduced nutritional supplying to the cartilage. The free cage activity and its association with swimming influenced positively the return of biomechanics and articular capsule morphologic conditions to those before immobilization.