Performance and safety of the PYTHEAS Your Guided Trajectory^® for intra-pedicular screw placement in spine surgery

Safe and accurate pedicular screw placement in spine posterior approach may be a challenging procedure. Navigation systems help reduce pedicular screw mal-positioning. This study aimed to assess the safety and usability of the PYTHEAS Your Guided Trajectory^® angular assistance navigation device for pedicular screw placement.

This prospective, two-centre, single-arm, open-label, first-in-human study recruited 13 adult patients with indication for posterior arthrodesis of at least two lumbar or thoracic vertebrae with placement of pedicle screws at vertebral level. The primary outcome was the performance of the PYTHEAS medical device on the correct direction of pedicle aiming, allowing intrapedicular perforation, without false path. Calibration mode and surgery time were recorded. Surgeon satisfaction of the device was measured using custom questionnaires and usability was assessed according to the System Usability Scale (SUS) questionnaire. The operator defines levels of vertebrae, then per level, entry point and direction of screw, and calibration landmarks using a pre-operative standard CT scan. During surgery, the system is calibrated via specific or global mode according to surgeon preference. Pedicle is canulated using angular guided probe with a real-time display of its current versus planned orientation. Then screw is inserted using angular guided screwdriver.

All 83 cannulations were classed as having "good" placement according to the palpation technique and confirmed on screenshots of the trajectory taken versus that indicated by the device, and by CT scan. All screw placements were satisfactory on post-operative CT scan. No adverse events were recorded. Surgery time ranged from 50 min to 259 min, corresponding to 23.1 ± 14.7 min per pedicle operated in global calibration mode. Usability score was 74.2 ± 10.9, exceeding the threshold for satisfactory usability. Surgeons were very satisfied with the transfer time and ease of data transfer between the tablet and computer (84.6% and 76.9%, respectively).

The PYTHEAS device allowed accurate pedicular screws in thoracic, lumbar and sacral levels, with an excellent safety profile and user satisfaction. Trial registration NCT05565131, registered 30 September 2022.