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.

1. Lonstein, J. E., Denis, F., Perra, J. H., Pinto, M. R., Smith, M. D., & Winter, R. B. (1999). Complications associated with pedicle screws. Journal of Bone and Joint Surgery American, 81(11), 1519–1528.
2. Parker, S. L., Amin, A. G., Santiago-Dieppa, D. R., et al. (1976). Incidence and clinical significance of vascular encroachment resulting from freehand placement of pedicle screws in the thoracic and lumbar spine. Spine, 39(9), 683–687.
3. Mac-Thiong, J. M., Parent, S., Poitras, B., Joncas, J., de Guise, J. A., & Labelle, H. (2013). Neurological outcome and management of pedicle screws misplaced totally within the spinal canal. Spine, 38(3), 229–237.
4. Açikbaş, S. C., Arslan, F. Y., & Tuncer, M. R. (2003). The effect of transpedicular screw misplacement on late spinal stability. Acta Neurochirurgica, 145(10), 949–955.
5. Kosmopoulos, V., & Schizas, C. (2007). Pedicle screw placement accuracy: A meta-analysis. Spine, 32(3), E111–E120.
6. Castro, W. H., Halm, H., Jerosch, J., Malms, J., Steinbeck, J., & Blasius, S. (1976). Accuracy of pedicle screw placement in lumbar vertebrae. Spine, 21(11), 1320–1324.
7. Hu, X., Ohnmeiss, D. D., & Lieberman, I. H. (2013). Robotic-assisted pedicle screw placement: Lessons learned from the first 102 patients. European Spine Journal, 22(3), 661–666.
8. Khan, A., Meyers, J. E., Yavorek, S., Siasios, I., & Pollina, J. (2019). Comparing next-generation robotic technology with 3-dimensional computed tomography navigation technology for the insertion of posterior pedicle screws. World Neurosurgery, 123, e474–e481.
9. Khan, A., Meyers, J. E., Siasios, I., & Pollina, J. (2019). Next-generation robotic spine surgery: First report on feasibility, safety, and learning curve. Operative Neurosurgery, 17(1), 61–69.
10. Khan, A., Rho, K., Mao, J. Z., O'Connor, T. E., Agyei, J. O., Meyers, J. E., Mullin, J. P., & Pollina, J. (2020). Comparing cortical bone trajectories for pedicle screw insertion using robotic guidance and three-dimensional computed tomography navigation. World Neurosurgery, 141, e625–e632. https://doi.org/10.1016/j.wneu.2020.05.257
11. Bertelsen, A., Melo, J., Sánchez, E., & Borro, D. (2013). A review of surgical robots for spinal interventions. International Journal of Medical Robotics, 9(4), 407–422.
12. Wang, K., Li, H., Yan, L., Zhang, H., Zhang, X., & Hao, D. (2025). Clinical efficacy comparison of Mazor X robot-assisted and traditional freehand techniques in the treatment of atlantoaxial fracture and dislocation. European Journal of Medical Research, 30(1), Article 678. https://doi.org/10.1186/s40001-025-02959-9
13. Gubian, A., Kausch, L., Neumann, J. O., Kiening, K., Ishak, B., Maier-Hein, K., Unterberg, A., & Scherer, M. (2022). CT-navigated spinal instrumentations—Three-dimensional evaluation of screw placement accuracy in relation to a screw trajectory plan. Medicina, 58(9), Article 1200. https://doi.org/10.3390/medicina58091200
14. Keric, N., Doenitz, C., Haj, A., et al. (2067). Evaluation of robot-guided minimally invasive implantation of 2067 pedicle screws. Neurosurgical Focus, 42(5), E11.
15. Ringel, F., Stüer, C., Reinke, A., et al. (2012). Accuracy of robot-assisted placement of lumbar and sacral pedicle screws: A prospective randomized comparison to conventional freehand screw implantation. Spine, 37(8), E496–E500.
16. Onen, M. R., Simsek, M., & Naderi, S. (2014). Robotic spine surgery: A preliminary report. Turkish Neurosurgery, 24(4), 512–518.
17. Khan, A., Soliman, M. A. R., Lee, N. J., et al. (2022). CT-to-fluoroscopy registration versus scan-and-plan registration for robot-assisted insertion of lumbar pedicle screws. Neurosurgical Focus, 52(1), E8.