纤维环针刺损伤大鼠模型的腰大肌被动拉伸张力变化研究

Changes of passive tensile stress of psoas major muscle in rat model with needling injury of fibre rings

目的 观察针刺损伤纤维环大鼠腰大肌被动拉伸张力变化及机理.方法 将20只Wistar大鼠随机分为模型组与假手术组,每组10只.模型组采用前入路腹膜手术法针刺损伤L4～5,L5～6两节段纤维环造模;假手术组仅切开腹部皮肤,肌肉暴露椎间盘后缝合.术后分别于第2周、第5周观察2组大鼠行为学表现.于术后5周取双侧腰大肌进行被动拉伸测试,并取L4～5,L5～6椎间盘,进行形态学观察.结果 术后5周大鼠垂直方向运动红外线计数模型组较假手术组减少,差异具有统计学意义（P＜0.05）.显微镜下可见模型组椎间盘形态学改变明显,纤维环排列轻度改变,髓核组织稀疏,分布不均,髓核中有大量不定形物质;假手术组椎间盘可见纤维环层次分明,与髓核界线明显,髓核组织呈中央密集分布,周围呈均匀分布,细胞数目较多.右侧腰大肌弹性模量模型组较假手术组减少,差异具有统计学意义（P＜0.05）.结论 针刺损伤腰椎间盘后可引发腰大肌被动拉伸张力降低,提示静力平衡结构损伤可能造成动力平衡结构变化.

Objective To observe the changes and mechanism of passive tensile stress of psoas major muscle in rat model with needling injury of fibre rings. Methods Wistar rats （n=20） were randomly divided into model group and sham-operation group （each n=10）. The model was established by needling in fibre rings of L4-5 and L5-6 by using anterior approach peritoneal surgery in model group, and sham-operation group was only given incision of skin and muscle for exposing intervertebral disc. On the 2nd week and 5th week after the surgery, the ethologic changes were observed in two groups. On the 5th week after the surgery, the samples of bilateral psoas major muscle were collected for passive tensile stress test, and samples of intervertebral disc of L4-5 and Ls-6 were collected for morphological observation. Results The infrared count of vertical motion decreased in model group compared with sham-operation group （P〈0.05） 5 weeks after surgery. The observation with microscope showed that morphological changes were significant including mild changes of fibre ring arrangement, sparse and uneven distribution of nucleus pulposus, and a lot of amorphous material in model group, and distinct fibre ring arrangement, clear boundary between fibre ring and nucleus pulposus, densely distribution in central nucleus pulposus and uniform distribution all around in sham-operation group. The elastic modulus of right psoas major muscle decreased in model group compared with sham-operation group （P〈0.05）. Conclusion Needling injury of intervertebral disc can induce the decrease of passive tensile stress of psoas major muscle, which indicates that damage of static equilibrium structure will lead changes of dynamic equilibrium structure.