肢体延长对肌间结缔组织超微结构及关节被动活动度的影响

Effects of limb lengthening on the ultrastructure of intramuscular connective tissues and the range of joint motion

目的探讨肢体延长中张应力对肌间结缔组织超微结构及关节被动活动度的影响。方法建立兔胫骨延长模型,延长速度为1mm/d和2mm/d,每12h一个增量,延长率为胫骨长度的10%和20%,在延长停止时和延长停止后4周取材,以扫描电镜观察肌束膜形态学上的变化,以自制的关节活动度测量器测量动物踝关节被动活动度的变化,并进行统计学处理。结果肌束膜胶原纤维集合成束带状,胶原纤维之间连接紧密,排列有序,成明显的波浪形结构。1mm/d10%延长率的肌束膜的胶原纤维变化不明显,关节活动度也无明显变化,而当延长率增加到20%的时候,波浪形的纤维出现了被拉直的趋势,关节活动度降低,等待4周后观察的结果也是一样的;2mm/d10%延长率的肌束膜的胶原纤维波浪形结构消失,胶原纤维已几乎被拉直,其次胶原纤维之间的排列松散,胶原纤维之间出现了较大的空隙,在经过4周的修复后其应有的波浪形结构仍未完全恢复;延长率增加至20%的时候,胶原纤维已经完全被拉直,4周后仍保持直线状态,2mm/d的延长速度下关节活动度明显下降。结论1mm/d的延长速度的方案下肌束膜胶原纤维的超微结构及关节被动活动度与正常最为接近,2mm/d的速度可致其超微结构及关节活动度的明显变化。

Objective To investigate the influence of the stress produced by limb lengthening on the ultrastructure of intramuscular connective tissues and the passive joint motion range. Methods Animal model of limb lengthening in rabbits was established. Distraction was initiated at a rate of 1 mm/d and 2 mm/d in two steps respectively, and both of them were preceded until 10% and 20% of the tibia length was achieved. Muscle samples were harvested at the end of distraction and at 28 days of consolidation after the distraction. Scanning electron microscopy was applied to observe the morphological variations of the perimysium and homemade goniometer was used to calculate the passive joint motion range. And data were subjected to statistical analyses. Results In the control group, the collagen fibers were partitioned in bundles, crimped and interconnected closely and orderly. In the lengthening profile of 1mm/d and 10%, no apparent variation of the collagen fibers or passive joint motion range was noted. When it was increased to 20% of the tibia length, the crimped fibers showed a tendency of being straightened while the range of joint motion was reduced. The pattern remained after 4 weeks of consolidation. In the lengthening profile of 2 mm/d and 10%, the crimped structure of the collagen fibers in the perimysium disappeared and the fibers were almost straightened. Additionally, the interconnection of the collagen fibers became loose and the interstice appeared among the fibers. After 4 weeks, the restoration to the original crimped structure had not been accomplished. When the lengthening ratio was elevated to 20%, the collagen fibers were straightened completely and the status remained throughout 4 weeks. Moreover, the passive joint motion range was dramatically reduced at the lengthening profile of 2 mmd. Conclusions The regime of lmm/d lengthening doesn＇t impair the perimysium ultrastructure and passive joint motion range, while 2 mm/d lengthening may cause a significant damage in the uhrastructure of the intramuscular connective tissues and passive range of joint motion.