Significance of Preoperative Prone Position Computed Tomography in Free Hand Subaxial Cervical Pedicular Screwing

Abstract

The subaxial cervical pedicle screwing technique shows powerful biomechanical properties for posterior cervical fusion. When applying a pedicle screw using the freehand technique, it is essential to analyse cervical computed tomography and plan the surgery accordingly. Normal cervical computed tomography is usually performed in the supine position, whereas during surgery, the patient lies in a prone position. This fact leads us to suppose that radiological evaluations may yield misleading results. Our study aimed to investigate whether there is any superiority between preoperative preparation on computed tomography performed in the prone position and that performed in the supine position. Methods : This study included 17 patients (132 pedicle screws) who were recently operated on with cervical vertebral computed tomography in the prone position and 17 patients (136 pedicle screws) who were operated on by conventional cervical vertebral computed tomography as the control group. The patients in both groups were compared in terms of age, gender, pathological diagnosis, screw malposition and complications. A screw malposition evaluation was made according to the Gertzbein-Robbins scale. Results : No statistically significant difference was observed between the two groups regarding age, gender and pathological diagnosis. The screw malposition rate (from 11.1% to 6.9%, p<0.05), mean malposition distance (from 2.18 mm to 1.86 mm, p <0.05), and complications statistically significantly decreased in the prone position computed tomography group. Conclusion : Preoperative surgical planning by performing cervical vertebral computed tomography in the prone position reduces screw malposition and complications. Our surgical success increased with a simple modification that can be applied by all clinicians without creating additional radiation exposure or additional costs.