Effect of Daily 4-hour Joint Fixation with Hindlimb Unweighting on Joint Contractures of Rats

Abstract

[Purpose] The purpose of this study was to investigate whether a daily 4-hour continuous joint fixation with hindlimb unweighting induces joint contracture within a week in rats. [Subjects and Methods] The subjects of this study were 7 Wistar rats. On the first experimental day, the rats’ angles of ankle dorsiflexion were measured. The right hindlimbs of all the rats were fixed in full plantar-flexion, and the left hindlimbs of all the rats were left free as the control. In addition, hindlimb unweighting was performed for all the rats. The unweighting was performed daily for seven consecutive days with a 4-hour joint fixation of the right hindlimbs. On the last day, the angles of right ankle dorsiflexion, after the joint fixation was removed, and left ankle dorsiflexion of all the rats were measured. [Results] Statistically, there was no significant difference between the right and left angles of ankle dorsiflexion before the experiment. There was no significant difference between the first and last experimental day left hindlimb angles of ankle dorsiflexion. The right hindlimb angle of ankle dorsiflexion on the last experimental day showed a significant decrease from that of the first experimental day. [Conclusion] A daily 4-hour continuous joint fixation with hindlimb unweighting induces a joint contracture in rats.