Monoaxial versus polyaxial pedicle screw fixation for thoracolumbar fractures

Aim
To compare short-segment monoaxial and polyaxial pedicle screw fixation in thoracolumbar fractures regarding their radiological and clinical outcomes.


Patients and Methods
A prospective case series was conducted on 50 patients with thoracolumbar fractures. The primary outcome was the sagittal index, while the secondary outcomes were the local kyphotic angle, regional kyphotic angle (Cobb’s angle), anterior vertebral height, middle vertebral height, posterior vertebral height, and interpedicular distance. Patients were followed up for a minimum duration of 1 year.


Results
Patients were divided into two groups according whether monoaxial or polyaxial screws were used. The mean postoperative radiographic parameters values improved in both groups. For the correction of kyphosis and correction loss, the mean values were statistically insignificant. Nevertheless, regarding the postoperative complications, none of the patients in the polyaxial had metal failure while four patients in the monoaxial group did.


Conclusion
There is no difference between monoaxial and polyaxial pedicle screws as regards reduction, correction of deformity and maintenance of correction in management of acute thoracolumbar fractures. However, polyaxial screws, have a statistically significant lower incidence of metal failure.