Comparative evaluation of CT-to-Fluoroscopy and Scan-and-Plan registration techniques in robot-assisted pedicle screw placement: a preliminary cadaveric faesibility study.

STUDY

DESIGN

Preliminary Cadaveric Faesibility study.

PURPOSE: To evaluate the preliminary faesibility, technical accuracy, and procedural metrics of CT-to-Fluoroscopy and Scan-and-Plan registration techniques in robot-assisted pedicle screw placement using the Mazor X robotic system.

BACKGROUND

Robot-assisted pedicle screw placement has been associated with improved accuracy and safety compared with conventional freehand techniques. However, direct comparisons between the two commonly used robotic registration workflows-CT-to-Fluoroscopy and Scan-and-Plan-remain limited. Evaluating their relative performance is important for optimizing surgical workflow and radiation utilization.

METHODOLOGY: Four fresh-frozen male cadavers were allocated to CT-to-Fluoroscopy (n = 2) or Scan-and-Plan (n = 2) registration groups. Eight experienced spine surgeons inserted a total of 32 pedicle screws bilaterally from L2 to L5. Screw accuracy was assessed using the Gertzbein-Robbins classification and trajectory deviation analysis in axial, sagittal, and coronal planes. Procedural time, surgeon-reported ease of use, and radiation exposure were also evaluated.

RESULTS

All 32 screws were clinically acceptable (Grade A + B), resulting in 100% overall accuracy in both groups. CT-to-Fluoroscopy demonstrated a higher proportion of Grade A screws than Scan-and-Plan (87.5% vs. 50.0%; p = 0.054). Scan-and-Plan showed significantly lower sagittal angular deviation (0.55 ± 0.71° vs. 1.66 ± 1.14°; p = 0.002), superior clearance (0.20 ± 0.16 mm vs. 0.45 ± 0.36 mm; p = 0.038), and lower coronal angular deviation (0.59 ± 0.76° vs. 1.99 ± 1.74°; p = 0.002). Planning, execution, and overall procedure times were comparable between groups, although Scan-and-Plan required shorter registration time. Surgeon satisfaction was identical (4.75 ± 0.46). Radiation exposure to surgeons was negligible in both groups, while cadaver radiation exposure was higher with CT-to-Fluoroscopy.

CONCLUSION

Both registration workflows achieved excellent accuracy. Scan-and-Plan demonstrated advantages in registration efficiency and patient-equivalent radiation exposure while maintaining comparable procedural performance, supporting its use when workflow optimization and radiation reduction are priorities.