Treatment of the experimental scoliosis with external fixator

1.兔实验性脊柱侧弯的形态学研究本研究的目的是对实验性脊柱侧弯的形态变化进行实验研究。10只新西兰大白兔，在X线摄像下，将两根克氏针按一定的间隔插入椎间盘，左侧两根平行的克氏针。10只兔中有9只出现右侧凸胸腰椎或腰椎侧弯。3只兔在植入后8~12周拔除克氏针，脊柱侧弯不可逆。而术后不到8周拔除钢丝的4只兔，脊柱侧弯是可逆的。另2只兔术后虽然上克氏针松动，但仍有脊柱侧弯畸形。在这一实验性脊柱侧弯模型中，在组织形态上可见顶端凹侧的小关节软骨退行性改变。2.外固定架在实验性脊柱侧弯中的应用本实验研究目的是探讨脊柱外固定架在脊柱侧弯中的作用。部分切除生长期兔右侧2~4根肋骨。术后4~6周，出现中度右凸胸椎侧弯，7只兔用Kischner钢丝固定于T9/10和L1/2。外固定前Cobb角平均为27.1°，固定后初始矫正时Cobb角为13.6°。其中3例在术后8周以上取下固定器。取出固定器后，这些兔仅见轻微的进行性椎体弯曲，与对照组相比，具有相对较好的预防进展的效果。我们认为脊柱外固定架治疗脊柱侧弯的效果是由于矫正了顶椎的轴向旋转，而不是牵引力。

1.Morphological studies in experimental scoliosis in rabbitsThe prupose of this study was to investigate experimentally the morphological changes of scoliosis. In 10 rabbits, under X-ray imaging two Kirshner wires were inserted into intervertebral discs at regular intervals, together with two parallel wires on the left side. In 9 of these 10 rabbits, right convex thoracolumbar or lumbar scoliosis was produced. In 3 rabbits, the K-wires were removed between 8 and 12 weeks after insertion and the scoliosis was found to be irreversible. However in the 4 rabbits, from which the wires were removed at less than 8 weeks after the operation, then the scoliosis was foud to be reversible. In the other 2 rabbits, although the upper K-wire was loose after the operation, a scoliotic deformity remained. In this experimental scoliosis model, degenerative changes were seen in the facet cartilage on the apical concave side histomorphologically.2.External fixation in experimental scoliosisThe purpose of this experimental study was to investigate the effects of spinal external fixation in scoliosis. Two or four ribs on the right side of growing rabbits were partially resected. Between 4 and 6 weeks later, moderate right-convex thoracic scoliosis had developed.Then, in seven rabbits, a mini-Orthofix or fixano fixator was attached by Kischner wires to T9/10 and L1/2. The average Cobb angle was 27.1 degrees before external fixation, and was 13.6 degrees at initial correction just after attaching the fixator. In three of them, the fixators were removed at more than 8 weeks after the operation. Only slight progressive vertebral curvature was seen in these rabbits after removal of the fixator, with a relatively good effect of prophylaxis of progression compared to the controls. We propose that the effects of this spinal external fixation for scoliosis was due to correction of the axial rotation at the apical vertebra rather than to the traction force.