[Effect of the sequence of intermediate instrumentation and distraction-reduction of the injured vertebra on the treatment of thoracolumbar burst fractures with high rate of spinal canal encroachment].

Objective: To investigate the effect of the sequence of intermediate instrumentation and distraction-reduction of the injured vertebra on the surgical efficacy of short-segment percutaneous pedicle screw fixation for thoracolumbar burst fractures with high rate of spinal canal encroachment.

Methods: From January 2016 to January 2022, 38 patients with thoracolumbar burst fractures with high rate of spinal canal encroachment (spinal canal encroachment rate >40%, complete posterior longitudinal ligament, no flipping bone block in the posterior marginal of the vertebra) without spinal cord injury who were were treated with short-segment percutaneous pedicle screw fixation were retrospectively analyzed. During the operation, 18 cases were used distraction-reduction first and then intermediate instrumentation on injured vertebral and sequential distraction-reduction again(the distraction-reduction first group) including 8 females and 10 males with a mean age of 46.5 (38.5, 50.0) years old, and the other 20 cases were used intermediate instrumentation on injured vertebral first and then direct distraction-reduction(the intermediate instrumentation first group) including 10 males and 10 females with a mean age of 46.0 (35.8, 50.8) years. The anterior height ratio of the injured vertebra, local Cobb's angle of the injured vertebrae, the spinal canal encroachment rate, and the improvement rate of spinal canal encroachment were compared and evaluated.

Results: All patients were followed up for more than 1 year, and no complications such as spinal cord and root injury, screw loosening and screw rod fracture were found. The anterior height ratio of the injured vertebra, local Cobb' angle of the injured vertebra in the two groups were significantly improved compared with preoperative data(<0.05), and those at 3 months and 1 year after operation was lost compared with that at the previous time point(<0.05). Although the spinal canal encroachment rate of the two groups 1 day and 1 year after operation was improved compared with that before operation(<0.05), the improvement of spinal canal volume in the distraction-reduction first group was significantly better than that in the intermediate instrumentation first group (<0.01).

Conclusion: In the treatment of patients with thoracolumbar fractures with high rate of spinal canal encroachment, short-segment percutaneous pedicle screw internal fixation with distraction-reduction first and then intermediate instrumentation and sequential distraction-reduction again can more effectively reduce the bony encroachment in the spinal canal and achieve indirect decompression effect better.