Index—level螺钉短节段固定治疗下腰椎爆裂压缩骨折的生物力学研究

Biomechanical analysis of short-segment plus Index-level screw fixation for low lumbar burst fractures

目的通过对L4椎体爆裂骨折模型以及应用不同方法固定后的生物力学测试，探讨Index—level螺钉短节段固定方法在治疗下腰椎爆裂骨折中的意义。方法选取10具新鲜尸体腰骶椎标本，通过截骨、切断部分韧带的方法制作L4椎体爆裂骨折模型，然后依序进行长节段固定、短节段固定以及短节段＋Index-level螺钉固定并进行生物力学测试，比较不同固定方法腰椎活动度（range of motion，ROM）的差异。结果与短节段固定比较，短节段＋Index—level螺钉固定在前屈、轴向旋转和侧屈时ROM降低，差异有统计学意义（P〈0．05）。在后伸位时短节段＋Index—level固定稳定性提高，ROM降低32．7％，但差异无统计学意义。结论Index—level螺钉短节段固定较单纯短节段内固定平均提高32．5％的即刻稳定性，而且比长节段固定保留更大范围ROM。

Objective To establish L4 vertebrae burst fractures and take a biomechanical test of different internal fixations so as to discuss the significance of internal fixation using short-segment plus Index-level screws in treatment of low lumbar burst fractures. Methods Ten fresh human lumbosacral vertebrae specimens were used to establish models of L4 vertebrae burst fractures by corpectomy and partial removal of ligament. Thereafter, the biomeebanical test was performed in order as below： long- segment fixation, short-segment fixation and short-segment construction plus Index-level screw fixation. Differences of range of motion （ROM） of the lumbar after three different internal fixations were compared. Results Compared with short-segment fixation, short-segment plus Index-level screw fixation showed that ROM of the lumbar was decreased in front flexion, axial rotation and lateral bending （P 〈 0.05）, but stability was improved and ROM of lumbar was decreased by 32.7% in back extension （P 〉 0.05）. Conclusions Compared with short-segment fixation, the short-segment plus Index-level screw fixation can increase initial lumbar stability by average 32.5% in treatment of low lumbar burst fractures. In the meantime, short-segment plus Index-level screw fixation provides larger ROM of the lumbar than the long-segment fixation.