EXPERIMENTAL STUDY ON NERVE ELONGATION

本研究的目的是了解当兔股骨用外固定架逐渐加长时，坐骨神经在宏观和组织学上的伸长位置。新制造的兔股骨外固定架。在几种工业钉、1.6 mm克氏针和M-300皮质锥形半螺钉（Orthofix）中选择一种固定钉。由于股骨断裂或股骨弯曲，前两种方法无法使用。因此，使用M-300皮质锥形半螺钉（Orthofix）作为固定钉的引脚。以每天1mm的速度延长20天，股骨从15.9 mm延长至18.9 mm，即16.5%至18.5%，平均为健康侧的17.2%。在此延长期间，没有发现坐骨神经麻痹。坐骨神经用6-0型不锈钢丝标记1mm时，神经延长11.6 ~ 14.6 mm，平均12.9 mm，健康侧延长11.0 ~ 14.6%，平均12.7%。坐骨神经沿神经全程延长，虽然近端和远端比中枢延长，但无统计学差异。神经戏弄后，未见有髓神经纤维出现沃勒氏变性。Ranvier's结结构和长度正常，结间距离延长。这意味着神经在内部被拉长，而不是在肢体延长的朗维耶结。

The purpose of this study is to know where the sciatic nerve is elongated macroscopically and histologically when the rabbit femur is lenghthened gradually by an external fixator.An external fixator was newlly manufactured for a rabbit femur. A pin for fixation was selected among several industrial pins, 1.6 mm Kirschner wire and M-300 cortical tappered half screw (Orthofix). The first two were not usable as the femur was brokened or pin was bend. So, M-300 cortical tappered half screw (Orthofix) was used for the fixator's pin.When the femur wsa elongated as a rate of 1mm per day for 20 days, the femur was elongated from 15.9 to 18.9 mm, that is 16.5 to 18.5% with an average of 17.2% of the healthy side. During this elongation, there were no findings of sciatic nerve palsy.When the sciatic nerve was marked 1mm cach by 6-0 stenless steel wire, the nerve was elongated 11.6 to 14.6 mm with an average of 12.9 mm, that is 11.0 to 14.6% with an average of 12.7% of the helthy side. The sciatic nerve was elongated along the whole course of the nerve, although the proximal and distal part were more elongated than the central part with no statistical differences.After teasing of the nerve, no myelinated nerve fibers showed Wallerian degeneration. The Ranvier's node was normal in structure and length and the internodal distance was elongated. This means nerve was elongated internadally, not at the Ranvier's node during limb lengthening.