四种下颈椎内固定技术初始稳定性的生物力学比较

A biomechanical comparison of four kinds of lower cervical stabilization system

目的比较四种下颈椎内固定技术在两种颈椎失稳模型中的初始稳定性,为其临床应用提供力学依据。方法应用6具新鲜人颈椎标本测定其正常值后,制成三柱损伤和前柱损伤模型。按顺序依次测四种内固定技术下的稳定性并进行比较:①后路侧块螺钉钢板(AP),②前路自锁钢板+后路侧块钢板(OP+AP),③前路自锁钢板(OP),④椎弓根螺钉钢板(TP)。结果三柱损伤模型中OP及AP在侧弯及旋转上达不到正常的稳定度。OP+AP及TP在各向运动上达到稳定。前柱损伤模型则四种技术在各向运动均能达到稳定。两种模型中,AP稳定性强于OP,而弱于OP+AP及TP,后两者间相似。结论OP可以稳定前柱缺损模型但不能稳定三柱损伤,不支持单纯前路钢板在临床颈椎三柱损伤中的应用;AP稳定性较高,但仍不能稳定三柱损伤模型;OP+AP稳定性最强;TP固定较单纯前路或后路稳定性更强,基本上达到OP+AP固定后稳定度。

Objectives To compare the constructive stabilities provided by f ou r internal fixations for lower cervical spine in clinically simulated 3-column injury and anterior column injury models to provide biomechanical basis for clin ical application. Methods 6 fresh human cervical spines (C3 to T1) were divided into 2 groups: 3-column injury model (Ⅰ) and vertebrae burst injury model (Ⅱ) . After the intact spine underwent tests, in each specimen the following structu res were tested successively: ①posterior lateral mass screw fixation (AP); ②co mbined anterior plating with locking fixation screws and posterior fixation (OP +AP); ③only anterior plating (OP); ④transpedicular screw fixation (TP). The d isplacement of C5 to C6 (or C4 to C6) segment and the moment in torsion test wer e measured and compared. Results In Group ⅠOP and AP could not provide effectiv e stabilization for the unstable cervical segment in lateral bending and axial r otation, while OP+AP and TP could. Then in Group Ⅱfour cervical internal fixat ions could provide the same stability as the intact specimens could. In the 2 gr oups, AP tended to provide greater stability than OP but less than OP+AP and TP . Conclusions Since OP could not provide more effective stabilization in the 3- column injury model, it is not wise to use only anterior plates in the clinical treatment of 3-column injury of cervical vertebrae. Although AP can provide gre ater stability than OP, it cannot provide enough stability for 3-column injury of cervical vertebrae. TP can offer the same stability as can be offered by OP+ AP.