ABSTRACT
BACKGROUND: Decompression-fixation-fusion is the key to spinal surgery since early effective fixation to achieve intervertebral fusion can restore spinal stability in lumbar degenerative disease. OBJECTIVE: To compare biomechanical stability of fusion segment and adjacent segments of bilateral pedicle screw fixation, unilateral pedicle screw fixation and unilateral pedicle screw combined with contralateral translaminar facet screw fixation under transforaminal lumbar interbody fusion. METHODS: Eighteen fresh calf L3-5 specimens were selected. Different forms of fixation were conducted under transforaminal lumbar interbody fusion. The specimens were divided into group A (complete specimens) and group B (bilateral pedicle screws), group C (unilateral pedicle screws), and group D (unilateral pedicle screw combined with contralateral translaminar facet screw). The range of motion of adjacent segment L3-4 and fusion segment L4-5 in six directions of backward extension, forward bending, left bending, right bending, left rotation and right rotation and the stiffness of fusion segment L4-5 were tested. RESULTS AND CONCLUSION: (1) For the range of motion of fusion segment L4-5, the stability was highest in the group B in six directions, followed by group D, which showed similar results in rotation in the group B (P > 0.05). The stability of right curvature and left rotation in group C was insufficient, and there was no significant difference in range of motion between group A and group C (P > 0.05). The range of motion in group A was largest and the stability was worst in the six motion directions. (2) For the stiffness value of fusion segment L4-5, the stiffness value of group B was largest in six directions, which was significantly different from other groups (P 0.05). There was no significant difference between group C and group A in the range of motion of six directions (P > 0.05). (4) The results showed that the motion ramge of unilateral pedicle screw fixation in the right and left rotation directions was large in the early stage, which was close to that of the complete specimen group. There is a shortage of stability, so we need to use it carefully and grasp the indications strictly. Unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation improves the disadvantages of asymmetric fixation of unilateral pedicle screw, increases the stability of rotation and lateral bending, and avoids the influence of bilateral pedicle screw fixation on adjacent segments, thus becoming an effective clinical surgical treatment.