Resistance Force and Limitation Factor up to the Joint's End-Range after Joint Immobility: An Experimental Study on the Rat Ankle

[Purpose] The purpose of this study was to investigate the resistance force and the limitation factor up to the joint's end-range after joint immobility. [Subjects] Eighteen adult female Wistar rats were used in this study. [Methods] Both their ankle joints were immobilized using casts for the duration of 1, 2, or 4 weeks. At the end of each period the casts were removed, and skin resection was carried out. For the right ankle joints, the resistance force up to the joint's end-range was measured. For the left ankle joints, the measurements were also performed after myotomy. [Results] The resistance force increased on both sides after 1 week of immobilization. The degree of the resistance increased after 2 and 4 weeks of immobilization. [Conclusion] There is a general tendency to presume that the arthrogenic factor is dominant over the muscular factor. Arthrogenic factors contributed to joint restriction up to the joint's end-range over 4 weeks immobilization.