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

Abstract

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 biomechanical test was performed in order as below:longsegment 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. Key words: Spinal fractures; Lumbar vertebrae; Fractures,compression; Index-level screws