A comparison of monoaxial pedicle screw versus polyaxial pedicle screw in short-segment posterior fixation for the treatment of thoracolumbar fractured vertebra

Background: Posterior pedicle screw fixation had been applied to maintain spinal stability and avoid further nerve damage in thoracolumbar fracture. This study aimed to evaluate the efficacy of short-segment posterior fixation with monoaxial pedicle screws versus polyaxial pedicle screws in treating thoracolumbar fracture. Methods: A total of 75 patients with thoracolumbar fracture who underwent short-segment posterior fixation with monoaxial pedicle screw (group A) or polyaxial pedicle screw (group B) were retrospectively enrolled. The patient demographic and radiological data were analyzed between the two groups. Results: A total of 63 patients with an average age of 44.7 +/- 11.5 years were finally recruited in this study. There were no significant differences in age, gender, fracture level, thoracolumbar injury classification and severity scale (TLISS) score, American Spinal Injury Association (ASIA) score, Arbeitsgemeinschaft fur Osteosynthesefragen (AO) classification, and hospital stay between the two groups (P>0.05). At the last follow-up, the prevertebral height ratio and normal-to-injured vertebral height ratio were significantly decreased in group A compared to group B (P=0.027 and P=0.007, respectively). Conclusions: Short-segment posterior fixation with monoaxial or polyaxial pedicle screw for fractured thoracolumbar vertebra can restore injured vertebral height. Compared with polyaxial pedicle screw, monoaxial pedicle screw endows stronger leverage which is more beneficial for restoring injured vertebral height and recovery of the damaged endplate in thoracolumbar short-segment posterior fixation.