Inertial measurement unit-assisted implantation of thoracic, lumbar, and sacral pedicle screws improves precision of a freehand technique

Abstract Objective A method applying inertial measurement units (IMUs) was developed to implant pedicle screws in the thoracic and lumbosacral spine. This was compared with a freehand technique. Methods The study was done on 9 human cadavers. For each cadaver, a preoperative computed tomography (CT) scan was performed to measure the axial and sagittal tilt angles of the screw trajectories from T1 to S1. After the entry points were defined on the exposed spine, the IMU-equipped pedicle finder and screwdriver were used to reproduce these tilt angles and implant half of the screws. The other half were implanted with a freehand technique. Fluoroscopy was not used. The screw trajectories were analyzed on postoperative CTs. Results 162 screws were placed with use of the IMUs and 162 screws by freehand. The IMU-guided technique matched the planned trajectories significantly better than the the freehand technique (axial tilt p