title: Robot assisted navigated drilling for percutaneous pedicle screw placement: A preliminary animal study.
abstract: BACKGROUND
  There is much more radiation exposure to the surgeons during minimally invasive pedicle screws placement. In order to ease the surgeon's hand-eye coordination and to reduce the iatrogenic radiation injury to the surgeons, a robot assisted percutaneous pedicle screw placement is useful. This study assesses the feasibility and clinical value of robot assisted navigated drilling for pedicle screw placement and the results thus achieved formed the basis for the development of a new robot for pedicle screw fixation surgery.
  
  
  METHODS
  Preoperative computed tomography (CT) of eight bovine lumbar spines (L1-L5) in axial plane were captured for each vertebra, the entry points and trajectories of the screws were preoperatively planned. On the basis of preoperative CT scans and intraoperative fluoroscopy, we aligned the robot drill to the desired entry point and trajectory, as dictated by the surgeon's preoperative plan. Eight bovine lumbar spines were inserted 80 K-wires using the spine robot system. The time for system registration and pedicle drilling, fluoroscopy times were measured and recorded. Postoperative CT scans were used to assess the position of the K-wires.
  
  
  RESULTS
  Assisted by spine robot system, the average time for system registration was (343.4 ± 18.4) s, the average time for procedure of drilling one pedicle screw trajectory was (89.5 ± 6.1) s, times of fluoroscopy for drilling one pedicle screw were (2.9 ± 0.8) times. Overall, 12 (15.0%) of the 80 K-wires violated the pedicle wall. Four screws (5.0%) were medial to the pedicle and 8 (10.5%) were lateral. The number of K-wires wholly within the pedicle were 68 (85%).
  
  
  CONCLUSIONS
  The preliminary study supports the view that computer assisted pedicle screw fixation using spinal robot is feasible and the robot can decrease the intraoperative fluoroscopy time during the minimally invasive pedicle screw fixation surgery. As spine robotic surgery is still in its infancy, further research in this field is worthwhile especially the accuracy of spine robot system should be improved.
authors.affiliation: Department of Orthopedics, General Hospital of Shenyang Military Area Command of Chinese PLA, Liaoning, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Orthopedics, Xinqiao Hospital, The Third Military Medical University, Chongqing 400037, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Orthopedics, General Hospital of Shenyang Military Area Command of Chinese PLA, Liaoning, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Electronics, State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Science, Shenyang, Liaoning 110016, China.
authors.forename: Jianda
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Orthopedics, General Hospital of Shenyang Military Area Command of Chinese PLA, Liaoning, China.
authors.forename: Liangbi
authors.initials: L
authors.lastname: Xiang
keywords: Computer assisted orthopedic surgery; Computer assisted surgery; bone screws; lumbar spine; minimally invasive surgical procedures; pedicle screw; robot; robotics; spine