Pedicle Screw Instrumentation in Scoliosis Surgery

Study Design. Prospective experimental study with on-site simulation. Objective. To compare the accuracy and efficiency of different techniques for pedicle screw instrumentation (PSI). Summary of Background Data. Improving the safety and efficiency of PSI is a critical step to reduce the complication rates and the cost of scoliosis surgery. Innovative operative techniques for PSI have shown to safely improve efficiency, thereby reducing cost. Surgical simulation is a valuable tool to study different operative techniques. Methods. Five spine fellows instrumented 20 simulation models of a scoliotic spine with 10 pedicle screws per model. Four techniques were studied, including the conventional pedicle probe and the innovative sequential drilling technique, with or without computed tomography (CT)-based navigation. Our primary outcome measures were efficiency and accuracy of PSI. We analyzed the data with bivariate analyses using the Chi-square test for categorical variables and the Student t test or ANalysis Of VAriance with Bonferroni post-hoc tests for continuous variables. Results. The drilling techniques (free hand and navigated) were more efficient as compared with the pedicle probe techniques ( P < 0.01). The navigated techniques resulted in better accuracy as compared with the free hand techniques ( P = 0.036). Most pedicle breaches were medial (n = 32/52). The concave apical pedicle (T4 right side) had the highest incidence of breaches. There was no significant difference in efficiency comparing the free hand and the navigated pedicle probe techniques ( P = 0.261) or comparing the free hand drilling and the navigated drilling techniques ( P = 1.00). Conclusion. On site surgical simulation is a promising concept for teaching advanced procedural skills. Our findings suggest that navigation improves the accuracy of PSI while sequential drilling safely improves efficiency. Combining navigation with sequential drilling can significantly improve the accuracy and the efficiency of PSI in scoliosis surgery, as previously suggested with our published clinical data. Level of Evidence: 4