Trajectory tracking made simple: validating a low-cost IMU pedicle screw guide
摘要
Pedicle screw fixation is central to spinal stabilization, but its accuracy depends on precise trajectory alignment. Freehand placement has a steep learning curve, with breach rates of 1.7–6.2%. Navigation and template systems improve precision but are costly. This study aimed to validate a low-cost inertial measurement unit (IMU)–based guide for pedicle screw trajectory tracking using lumbosacral saw bone models.
MethodsA prospective experimental study was conducted on five lumbosacral saw bone models (60 screws). Pre-procedural CT planning determined ideal axial angles through the pedicle axis. A custom IMU assembly (MPU-925x™, Arduino Uno) provided real-time axial orientation. Screws were inserted at the superior facet–transverse process (SF–TP) junction under IMU guidance. Post-insertion CT assessed achieved angles and cortical breaches.
ResultsSixty pedicle screws were placed. Planned axial angles ranged 11°–30° (mean 22.6° ± 4.5°), while achieved angles averaged 25° ± 7.4°. The mean angular offset was 2.23° ± 6.5°. Pedicle containment was achieved in 54/60 screws (90%), with overall containment fidelity of 96.7% (58/60). Six screws (10%) exhibited cortical breaches, of which two (3.3%) were significant (> 2 mm). Trajectory fidelity (offset < 10°) was achieved in 83.3% (50/60) screws. Breach orientation correlated with offset magnitude, with medial breaches showing greater angular deviation.
ConclusionsIMU-guided pedicle screw insertion demonstrated high containment and trajectory fidelity in simulated models, supporting further cadaveric evaluation of low-cost orientation-tracking systems.