Robot-assisted anterior screw fixation for fracture of odontoid process (Surgeon: Prof. TIAN Wei)


A 61-year-old female presented with upper neck pain after a fall for 3 days. She had no neurologic deficit on neurological examination. The cervical CT images demonstrated that there was a fracture of odontoid process and partially displacement (Figure 9).


The surgery was taken on October 14th, 2015. After general anesthesia, Mayfield tongs and patient’s position (supine) were placed to have a reduction by keeping the head in traction and a slight extension. After we placed the patient tracker and the Mayfield tongs, 3D C-arm scanning and robotic planning was carried out using TiRobot system. Virtual drill trajectories were planned on the 3-dimensional software (Figure 10).


Figure 10. Plan a trajectory intra-operatively

A left sided 2cm skin incision was made under the robotic guidance. Expose the anterior inferior side of the C2 vertebrae. Through the sleeve of the robotic arm, we drilled a Kirschner wire into the odontoid process, then inserted a 36mm in length, 4mm in diameter cannulated screw by the guidance of the K-wire. We found the placement of the screw was satisfied due to the intraoperative 3D C-arm fluoroscopy scan. The surgery took 5 hours 30 minutes. The blood loss was 50 ml.

There was no intraoperative complication. The patient had maintained full extremity strength and sensation. By postoperative CT images (0 days) (Figure 11), there was no perforation and loose of the screw.


Figure 11. Post-op CT showed good position of the screw


There have always been limits of precision and safety for spine surgery for a long time because of the limits of surgeons their own. The limits come from, on one hand, the vision of operation field, because it’s unable to see the inner structures directly during surgery. The risk of spine surgery is still at a high rate even with the assist of improving imaging technologies. The most popular intraoperative imaging technology can still only provide surgeons with overlapped 2-dimensional images, and could cause extra radiological damages to patients as well as surgeons. On the other hand, the limits also come from the manipulation of surgeons’ hands. Although surgeons’ control force, steadiness, and repeatability are under long-period strict practice, they maybe still insufficient enough to face the challenge of complicated difficult surgeries, or at least couldn’t keep at a sufficient level from the start to the end when such a surgery could last for a very long time. And it could be more difficult to train a young spine surgeon, because the learning curve for spine surgeries could be relatively shallower.

In order to break those limits in spine surgery, more and more researchers start to work on the study of surgical robot system since 1985, when Kwoh et al [1] designed the first neurosurgery robot arm that based on the industrial robot PUMA200. Surgical robots and other intelligent surgical equipment have been used a lot these years, like Da Vinci system (Intuitive surgical, U.S.) [2], and Robodoc system (Integrated Surgical Systems, U.S.)[3].

TiRobot system is a new surgical robot system that our hospital designed by our own. Surgeons use the system to make preoperative planning based on intraoperative 3-dimensional fluoroscopy images. It has a serial structured mechanical arm to guide the surgeon finding a proper entry point and trajectory as planned. It provides a trajectory and allows surgeons drill a K-wire into the marked point on pedicle. The drilling and screw insertion are still performed by the surgeon manually.

Case 1 is the first robot-assisted CAMISS surgery around the world. Case 2 is the first report on the usage of real-time intraoperative 3-dimensional robotic guidance for atlantoaxial transarticular screw fixation. The calculated deviation between planning and actual screw place was 0.8798 mm, and there was no cortex perforation of the screw due to the postoperative CT images. TiRobot system for surgical planning and guidance could be a useful tool in such challenging surgery.


1. Kwoh Y S, Hou J, Jonckheere E A, et al. A robot with improved absolute positioning accuracy for CT guided stereotactic brain surgery[J]. Biomedical Engineering, IEEE Transactions on, 1988, 35(2): 153-160.

2. Yang M S, Kim K N, Kim H, et al. Robot-assisted anterior lumbar interbody fusion in a Swine model in vivo test of the da vinci surgical-assisted spinal surgery system[J]. Spine, 2011, 36(2): E139-E143.

3. Bargar W L, Bauer A, Börner M. Primary and Revision Total Hip Replacement Using the Robodoc (R) System[J]. Clinical orthopaedics and related research, 1998, 354: 82-91.