One-wayversusuniversal pedicle screw fixation for lumbar fractures：biomechanics / 中国组织工程研究

ABSTRACT

BACKGROUND:Previous studies have performed three-dimensional finite element analysis on lumbar fracture fixation. However, a few studies concerned three-dimensional finite element analysis of lumbar spinal pedicle screw fixation. OBJECTIVE:To analyze the biomechanical characteristics of one-way screw and universal screw fixation for lumbar fractures using finite element method. METHODS:Models of lumbar fractures treated with one-way screw and universal screw fixation were established. Three-dimensional finite element method was used to analyze and compare the maximum axial displacement, maximum bending degree, maximum stress on thepedicle screw fixation system and maximum stress of intervertebral disc in normal vertebral fracture model, one-way and universal pedicle screw fixation models. RESULTS AND CONCLUSION:(1) The maximum axial displacement at anteflexion, posterior extension, left lateral curvature and right lateral curvature was significantly lower in the one-way fixation group and universal fixation group than in the normal group (P< 0.05-0.01). The maximum axial displacement at above directions was lower in the universalfixation group than in the one-way fixation group. (2) The maximum bending degree was significantly lower in the one-way and universal fixation groups than in the normal group (P< 0.05-0.01). The maximum bending degree at various directions was lower in the universal fixation group than in the one-way fixation group. (3) The maximum stress on the pedicle screw fixation system at various directions was lower in the universal fixation group than in the one-way fixation group (P< 0.05-0.01). (4) The maximumstress of intervertebral disc was significantly lower in the one-way and universal fixation groups than in the normal group (P< 0.05-0.01). The maximum stress of intervertebral disc at various directions was lower in the universal fixation group than in the one-way fixation group. (5) Results suggested that one-way and universal screw fixation for lumbar fracture can bear most of the stress, obviously decrease the maximum axial displacement, maximum bending degree, maximum stress on the pedicle screw fixation system and maximum stress of intervertebral disc. The stability of universal screw fixation was better than that of one-way screw fixation.