Design and Analysis of Calibration Method for Universal Navigation Accessory in Image Guided Spine Surgeries

Precise navigation of pedicle screw placement instruments is crucial in Image Guided Spine Surgeries (IGSS), where a variety of pedicle screws and implants are utilized based on patient anatomy. Many Instrument manufacturers offer wide range of pedicle screws solely compatible with their placement instruments which is non-navigated. However, navigating these non-navigated instruments from different manufacturer is challenging. This issue is addressed by manufacturers through universal navigation adaptors. These adaptors, equipped with marker arrays and attachment mechanisms, enabling navigation by affixing them onto instruments and calibrating the tool tip intraoperatively. Existing adaptors lack axial rotation during screw placement, and their intraoperative calibration methods involve multiple steps for accurate tool tip calibration. To address these limitations, we propose two calibration methods for a newly developed universal accessory (UA). These system overcome the constraints of existing navigation adaptors, offering enhanced flexibility and simplified calibration processes. The proposed calibration methods employ a tracked template and patient reference marker (PRM) for intraoperative calibration. Extensive validation yielded a mean target registration error (TRE) below 0.85 mm (95% CI [1.244]), meeting the accuracy requirements for Image-guided spine surgeries. Notably, the mean TRE difference compared to pivot calibration was less than 0.3 mm, demonstrating significant precision.