Background Data: In the late fifties of the last century, Boucher described posterior pedicle screw placement for the first time for treatment of a diversity of spinal pathologies. Currently, there are three methods for pedicle screw placement: the free hand, the fluoroscopy guided open and the percutaneous techniques. Despite being reported safe and accurate, percutaneous pedicle screw insertion is still being investigated in comparison to the traditional open technique.
Purpose: In this study, the authors are trying to find out if there was any superiority of one technique regarding accuracy of screw placement.
Study Design: This is a retrospective comparative study designed to assess the accuracy of screw placement in the sagittal plane in patients who underwent lumbar transpedicular fixation by open versus percutaneous techniques.
Patients and Methods: Patients were categorized into two groups: group A including patients who underwent open surgery and group B patients who underwent percutaneous fixation. Each screw was categorized according to the sagittal plane into one of the following classes: Class 0: with no cortical penetration at all, Class 1: with a single cortical penetration denoting accepted entry point and trajectory, Class 2: with 2 cortices penetration violating the lateral cortex of the pedicle and/or the vertebral body and Class 3: with 3 cortices penetration and a medially maldirected trajectory violating the roof and floor of the lateral recess.
Results: The current study included 51 patients distributed as 28 patients (55 %) in group A and 23 patients (45 %) in group B. A total of 262 screws were investigated with 134 (51.15 %) screws in group A and 128 (48.85 %) screws in group B. Cross tabulation of raw data of different screw type distribution among the two patients' groups preliminarily revealed a quite favorable screws position among group A patients with 94.77% of screws in class 1, 4.48% in class 2 and 0.75% of screws in class 3 compared to 81.25%, 12.5% and 6.25% respectively in group B of patients. However, statistical analysis using Chi Square test for individual screws' groups related to specific pedicles failed to show any significant difference with each one of the pertinent P-values>0.05. On the other hand, comparison of maldirected screws (classes 2 and 3 collectively) between the two groups confirmed a statistically high significant difference in the  number of maldirected screws per patient with a mean of 0.25 screw/patient in group A compared to 1.043 screw/patient in group B (P-value < 0.001).
Conclusion: Percutaneous pedicle screw insertion technique is an accepted technique regarding screw accuracy when properly indicated having the advantages of being less traumatic and more cosmetic with its inherent complications and drawbacks including financial issues, more radiation exposure and longer operative time. (2017ESJ144)