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[Purpose] The purpose of this study was to investigate whether the recovery period of joint contractures differ between treatments with joint fixation with unweighting of the hind limbs and joint fixation alone. [Subjects and Methods] Twelve 10-week-old male Wistar rats were divided into a group with joint fixation of the right ankle joints in full plantar flexion for 1 week (F) and a group with joint fixation and hind limb suspension (FS). Thereafter, the rats were removed from the joint fixation and hind limb suspension for 2 weeks. The ankle dorsiflexion angles during the recovery process of the joint contractures were measured. [Results] The ankle dorsiflexion angles of the F group from the day joint fixation was removed to the seventh recovery day were significantly lower than the pre-experiment values. The ankle dorsiflexion angles of the FS group from the day joint fixation and hind limb suspension were removed to the 10th recovery day were significantly lower than the pre-experiment values. [Conclusion] We found that the period required for the recovery of joint contractures treated with joint fixation with unweighting of the hind limbs was longer than that with joint fixation alone.

[Purpose] The purpose of this study was to investigate the change in soleus extensibility from a joint contracture caused by a reduction in joint movement with unweighted lower limbs and to interpret the results to aid in the treatment of human joint contractures. [Subjects and Methods] The subjects of this study were twenty-one 10-weeks-old male Wistar rats. Twenty-one rats were divided into one control (C) and two experimental groups. The first experimental group included fixed right ankle joints in full plantar flexion (F). The second experimental group’s hind limbs were suspended and the right ankle joints were fixed in full plantar flexion (FS). The period of this study was one week. On the first and last day of this study, all of the rats’ ankle dorsiflexion angles were measured. On the last day of this study, all of the rats’ soleus extensibilities were measured. [Results] On the last day of this study, the ankle dorsiflexion angles and the soleus extensibility in the FS group were significantly more decreased than those of the F group. [Conclusion] It was shown that the skeletal muscle extensibility from joint contracture caused by reduction of joint movement with unweighted lower limbs was more markedly decreased than that from joint contracture caused by reduction of joint movement.

[Purpose] The purpose of this study was to elucidate whether skin extensibility decreases when a contracture develops as a result of joint immobilization. [Subjects] This study was conducted on six female Wistar rats. [Methods] The rats were divided into two experimental groups. In the immobilized group, the right ankle joints were immobilized in complete plantar flexion by plaster casts for two weeks. In the control group, the left ankle joints had no intervention. On the final day, skin extensibility was determined from a length-tension curve by collecting skin from the posterior aspect of the ankle joint and using a tensile strength tester. [Results] Compared with the control group, the immobilized group showed a significant decrease in skin extensibility. [Conclusion] The results demonstrated that the extensibility of the skin itself decreases when joint contracture develops.

〔目的〕一日当たり12時間の関節固定がラット足関節拘縮発生に与える影響を検討することである．〔対象・方法〕8週齢のWistar系雌ラット14匹を，各7匹の2つに分けた．7匹は，左後肢の処置を施さない「正常肢群」とし，また右後肢を実験初日から最終日まで足関節最大底屈位で固定する「24時間固定肢群」とした．残り7匹は，右後肢を実験初日から最終日まで一日当たり12時間の足関節固定を行う「12時間固定肢群」とした．実験期間は1週間である．〔結果〕一日当たり12時間の関節固定は関節拘縮を発生させた．〔結語〕今後は，一日当たり12時間よりも短い関節固定で関節拘縮が発生するか調べる必要がある．

The effect of skin resection on joint contracture was determined by comparing the first measurement of range of motion after cast removal and the second measurement after the skin resection. This study aimed to verify that both the joint movement during the measurement and skin affect range of motion. [Subjects] Twelve female Wistar rats were used. [Methods] The right hind limb ankle of each rat was immobilized in complete plantar flexion in a cast. In the resection group (n = 6), the skin of the right hind limb ankle was removed surgically, but not in the non-resection group (n = 6). In the resection group, the first measurement of the dorsiflexion angle was obtained after the cast was removed, and the second measurement was obtained after skin resection. In the non-resection group, both measurements of the dorsiflexion angle were obtained soon after the cast was removed. [Results] Compared with the non-resection group, the resection group showed a significant increase between the first and second measurements of range of motion. [Conclusion] These results show that range of motion is substantially affected by skin, in addition to joint movement, during measurement.

[Purpose] The purpose of this study was to investigate whether there is an effect of ROM exercise on rats with denervation and joint contracture. [Methods] Fifteen female 8-week old Wistar rats were used. For seven out of the fifteen rats, the left hind limbs were used as control limbs (group 1), and the right hind limbs (group 2) were fixed continuously with white tape in full plantar flexion for one week. The remaining eight rats received bilateral sciatic neurectomies. The left hind limbs (group 3) were fixed continuously with white tape in full plantar flexion for one week. The right hind limbs (group 4) were fixed in full plantar flexion with white tape that was removed daily from the second through the seventh experimental days. After the tape was removed the foot was held in dorsiflexion by a spring balancer for 30 minutes. After the ROM exercise session was completed, the white tape was reapplied, again with the ankle fixed in full plantar flexion. [Results] Before the experiment, there were no significant differences among the groups. After the experiment: compared to group 1, ROM in group 2 and group 3 was significantly increased; compared to group 2, ROM in group 3 and group 4 was significantly decreased; and compared to group 3, ROM in group 4 was significantly decreased. [Conclusion] ROM exercise was effective for preventing ROM limitation. These results suggest that ROM exercise is effective for preventing joint limitation in rats with denervation and joint contracture.

[Purpose] It has been shown that an eight-hour joint fixation daily (i.e. for the remaining 16 hours, rats were set free in the cage without joint fixation) for one week induces a joint contracture. The purpose of this study was to investigate the difference between an 8 hours continuous joint fixation and an 8 hours intermittent joint fixation per day (two 4 hours joint fixations) in the development of joint contractures in rats. [Subjects and Methods] The subjects of this study were 34 Wistar rats. On the first day, all of the rats’ right ankle dorsiflexion angles were measured. The right hind limbs of all the rats were fixed in plantar flexion, and then the rats were divided into three groups as follows: Group 1 was in continuous fixation for 24 hours a day; Group 2 was in continuous fixation for 8 hours a day; Group 3 was in intermittent fixation for 8 hours a day. The fixation was performed daily for seven consecutive days. On the last day, ankle dorsiflexion angles of all the rats were measured after the casts had been removed. [Results] The development of joint contractures was statistically significant for Groups 1 and 2. [Conclusion] Our results indicate that 8 hours a day of continuous fixation induces a joint contracture, but 8 hours a day of intermittent fixation does not.