椎弓根螺钉置入对幼犬胸椎形态发育的影响

目的:通过动物实验观察椎弓根螺钉置入对胸椎形态发育的影响。方法:将16只2月龄幼犬随机分为3组,A组(3只)为空白对照组,自T7～T13后路切开,显露椎板;B组(5只)为对照组,以螺钉穿过神经弓中心软骨联合对目标椎椎弓根仅做隧道破坏,螺钉不置留;C组(8只)为实验组,螺钉穿过神经弓中心软骨联合并留置于椎弓根内。实验的目标椎设计为T8、T10、T12,目标椎的上下两个脊椎的各相应测量指标取平均值做为其自身对照。应用CT测量并观察脊椎的形态学指标变化。结果:术后3个月,C组目标椎椎管面积、椎管横径、椎管纵径、椎弓根长度与相邻脊椎平均值比较显著减少(P<0.05),而A组、B组间未发现明显差异;各组椎体横径、椎体纵径、椎体高度测量结果显示目标椎与相邻脊椎平均值无显著性差异(P>0.05)。结论:椎弓根螺钉内固定术对于幼犬胸椎椎管、椎弓的发育有显著影响,有可能导致医源性椎管狭窄;对于椎体发育无明确影响。

The effect of pedical screw insertion on the growth of the immature canine thoracic vertebra

Objective:To investigate the influence of the pedical screw insertion on the growth of the thoracic vertebra via animal model.Method:A total of 16 dogs(about 2-month age)were randomly assigned into 3 groups:group A,blank control group only exposing posterior lamellar;group B(control group),only penetrating the neurocentral cartilage structure with pedicle screws which were absent after this procedure;group C(test group),penetrating and leaving the pedicle screws in the neurocentral cartilage structure.The objective vertebras were defined as T8,T10,T12,and the rostral and caudal their counterparts were served as self control.Computerized tomography(CT)was used to measure the morphology of the vertebras.Result:Three months after operation,in group C,the spinal canal area,the transverse dimension,anterior-posterior dimension and pedicle length were significantly smaller than their self controls(P<0.05),while there were no remarkble differences between group A and group B.And in all the groups,there were no remarkable variety with respect to the transverse dimension,anterior-posterior dimension and height of vertebra body between the tested vertebra and it's control(P>0.05).Conclusion:Pedicle screw placement has significant effect on the growth of spinal canal and pedicle,which may lead to iatrogenic thoracic spinal stenosis,however it has no evident influence on the progression of vertebra body.