Abstract
OBJECTIVES: To clarify the histopathologic findings of the contracture mechanism, we conducted experiments to observe the histopathological changes in joint capsule and articular cartilage after joint immobility in rats. STUDY DESIGN: Three rats had their right knee joints immobilized with a casting fixator for 2 weeks. The fixation group was subjected to maximum hip joint extension, maximum knee joint flexion, and maximum ankle joint plantar flexion. Their left knee joints constituted the free control group. After sacrifice, the six knee joints from the rats were fixed in formalin, decalcified and embedded in paraffin. Staining was done with hematoxylin and eosin stain and elastica van Gieson stain and examination with a light microscope. RESULTS: The capsule thickness and the number of elastic fibers of the fixation group were less than those of the control group. The fibroconnective tissue of the fixation group was denser, and the surface layer of the articular cartilage showed fibrous proliferation, compared with the control group. CONCLUSION: These results suggest the possible occurrence of disuse atrophy in joint capsule and articular cartilage.
