经伤椎椎弓根螺钉置入内固定修复胸腰椎骨折：远期效果及生物力学分析

Pedicle screw fixation into the injured vertebra for thoracolumbar fractures: a long-term effect and biomechanical analysis

BACKGROUND: Pedicle screw fixation is a common repair method for thoracolumbar fractures. Of them, pedicle screw placement into the injured vertebra is an important method. However, the long-term effects and the related biomechanical properties deserve further analysis.OBJECTIVE: To analyze the long-term effect and biomechanical characteristics of the internal fixation of thoracolumbar fractures by pedicle screw implantation.  METHODS: A retrospective analysis was performed in 126 cases of thoracolumbar fractures. The patients were treated with pedicle screw implantation and the treatment was followed up regularly. Ten specimens of fresh calf chest and lumbar spines were obtained. Five specimens served as an experimental group to prepare models of anterior middle column fractures, and these specimens received pedicle screw fixation into the injured vertebra. The other five specimens served as the control group, and did not receive any treatment. In the two groups, along the sagittal axis, axial compression displacement, anterior flexion displacement, posterior extension displacement, torsion angle and pull-out strength were measured and recorded.  RESULTS AND CONCLUSION: (1) Clinical trial results: 126 patients were followed up for 10-36 months. Compared with pre-treatment, compression ratio of the injured vertebra, the height of intervertebral space, vertebral slip distance, visual analogue score and Cobb angle were significantly improved at 1 month after treatment and during final follow-up (all P < 0.05). No significant difference in above indexed was detected between 1 month and final follow-up (all P > 0.05). At the end of follow-up, Frankel spinal cord injury grade was significantly improved (Z=-4.127, P < 0.05). After operation, three patients suffered from pulmonary infection, four patients affected urinary tract infection, and one patient experienced delayed wound healing. (2) Biomechanical results: axial compression displacement, anterior flexion displacement, posterior extension displacement, torsion angle and pull-out strength were smaller in the experimental group than in the control group (all P > 0.05). (3) Above findings showed that pedicle screw fixation into the injured vertebra for thoracolumbar fractures obtained good long-term effects, and had good biomechanical properties.