Intraoperative simulator for navigated surgeries of the scoliotic spine: preliminary prototyping results

Aims To develop a prototype of an intraoperative simulator for the navigated surgery of a scoliotic spine. Materials and methods An instrumentation strategy (pedicle screw insertion, rod attachment and rotation) was numerically simulated on a synthetic model of a scoliotic spine by using the radiographs of the spine in standing position (simulating the preoperative conditions). A navigation system was used to acquire the replicated intraoperative geometry of the spine. This geometry was transferred to the simulator, enabling to update (1) the preoperative planning of the pedicle screw positioning, (2) the simulation of the surgical maneuvers, and (3) the measurement of several clinical indices (Cobb angles, etc.). Results The Cobb angle decreased from 34° to 24° between the simulated pre- and intraoperative geometries (before the instrumentation). Differences in pedicle screw positioning between the preoperative planning and the intraoperative situation were less than 0.5 mm. The new simulation of the rod attachment and rotation maneuvers resulted in a 12°-Cobb angle. Conclusion This study is a first step toward developing an integrated simulator for preoperative planning and intraoperative navigation of scoliotic spine surgeries. Significance When completed, the integrated simulator will enable to obtain real-time biomechanical feedback during the navigated surgery of a scoliotic spine, and could help to optimize instrumentation parameters (instrumented levels, surgical maneuvers, etc.) and the resulting correction. Acknowledgements Funded by the NSERC (Industrial Chair with Medtronic). Special thanks to Jeremie Theriault for his assistance.