EFFECTS OF ANTERIOR SINGLE SEGMENT FIXATION ON SPINAL STABILITY IN TREATMENT OF THORACOLUMBAR BURST FRACTURE OF Denis TYPE B WITH PEDICLE INJURY

To investigate the effects of anterior single segment fixation on the spinal biomechanical stabilization in the treatment of thoracolumbar burst fracture of Denis type B with pedicle injury.Six fresh human cadaveric spine specimens (T11-L3) were harvested as normal control (group A). Then the L1 Denis type B fracture model was created by the hemi-corpectomy method. Each specimen was tested in 3 different scenarios: anterior single segment (T12, L1) fixation with the integrity of the pedicle (group B), anterior single segment fixation with the resection of the unilateral pedicle (group C), and anterior single segment fixation with the resection of the bilateral pedicles (group D). Range of motion (ROM) in flexion/extension, bilateral bending, and bilateral axial rotation was measured by spinal three-dimensional measuring system under pure moments of 8.0 N x m.The ROM values of T12, L1 in flexion, extension, and right/left lateral bending of groups B, C, and D were significantly lower than those of group A (P 0.05). The ROM values of T12, L1 in right/left axial rotation of groups B and C were significantly lower than those of groups A and D (P 0.05) between groups B and C and between groups A and D. The ROM values of L1,2 in flexion, extension, right/left lateral bending, and right/left axial rotation showed no significant difference between groups (P > 0.05).Resection of the unilateral pedicle has litter effects on the spine biomechanical stabilization of the anterior single segment fixation in the 6 degrees of freedom. However, the bilateral resection results show significant decrease in flexion, extension, lateral bending, and rotation motion stability by the single segment fixation devices, especially in the axial rotation aspect.