CT Assessment of accuracy of lumbar pedicle screw insertion (An applied comparative evaluation of conventional and percutaneous techniques)

Overview of literature: Potential complications of screw misplacement and pedicle wall violation have focused attention on screw placement techniques. Moreover, evaluation of any new postoperative pain or neurological deficit should rule out the causal relation between the screws and neurological complication.

Purpose: The aim of the study is to evaluate the incidence and accuracy of pedicle screw placement comparing the conventional and percutaneous techniques of screw insertion. Study design: the study was done on 103 patients of both sexes and different ages. Patients are evaluated by postoperative C.T. scan with 2 mm axial slices with bone window performed.

Methods: Data were collected from the Department of neurosurgery, Kasr Al-Ainy, Cairo University Hospital. The valid patient sample was collected (n0=103). In addition to the standard study protocol evaluation, patients were evaluated for the presence or absence of pedicle breach generally comparing both techniques (hypothesis 1), and comparing the degree of deviation between both techniques (hypothesis 2). Blinded several observers CT assessment was done.

Results: Studying the presence of pedicle wall violation in general, there is no statistical difference between both techniques. However, at the S1 level, there is a statistical difference in favor of the percutaneous technique. Regarding the side of violation, there is a lower incidence of pedicle breach on the left side in favor of the percutaneous technique. Regarding the direction of pedicle breach, there is no statistically significant difference between both techniques.

Studying the extent of pedicle breach in general, we found no effect of technique or level on the extent of pedicle breach. However, percutaneous technique had a lower amount of pedicle breach taking the side into consideration. The amount of medial deviation is smaller with the percutaneous technique.

Conclusion: There is no statistical difference between open and percutaneous techniques, except at the S1 level, in favor of the percutaneous technique. Moreover, percutaneous technique had a lower amount of pedicle breach taking the side into consideration. The amount of medial deviation is smaller with the percutaneous technique.