Beyond the operating room: a simulator for sacroiliac screw insertion

Current teaching techniques for orthopedic screw insertions involve "learning by doing" in the operating room. Minimally invasive insertion of sacroilliac (SI) screws is a relatively uncommon operation, providing scant opportunity for training outside of a few major centers. As such, SI screw insertion is a prime candidate for simulator-based training. This work describes the development and implementation of a simulator for minimally invasive SI screw insertion using accurate 3-dimensional (3D) computed tomography (CT)-based visualization of the pelvic and upper sacral anatomy. The simulator was designed in Tool Command Language atop the Amira 3D visualization package. CT images of pelvic regions were automatically segmented to generate 3D surfaces. Using inlet and outlet 3D views, guidewire insertion can be performed followed by an appropriately sized SI screw. The simulator was found to provide a realistic representation of the pelvis, and test users reported increased understanding of the procedure of SI screw insertion following use. The 3D reconstructions of the pelvis allowed for visual correlations between CT slices and inlet and outlet x-ray views. Pilot work with surgical trainees suggests the tool's value in increasing the familiarity of surgical trainees to visualize the pelvis in 3D and perform SI screw insertion.