Objective      To evaluate the feasibility and accuracy of bovine lumber spine pedicle drilling assisted by X-ray fluoroscopy and O-arm based navigation system.       Methods      Sixty-one holes were drilled assisted by X-ray fluoroscopy at one side of pedicles in 4 to 5 lumbar segments from 15 bovine lumber spine specimens

and another 61 holes were drilled assisted by O-arm based navigation system at the other side. Then 122 K-wires were put into the holes in all. K-wire positions were evaluated by O-arm 3 dimensional reconstruction after intraoperative cone beam computed tomography scanning (CBCT) and postoperative CT scanning.       Results      Postoperative CT scanning revealed that there were 28(45.9%) K-wires in Grade Ⅰ (perfect within the pedicles)

24(39.3%) Grade Ⅱ (breaching the pedicle wall but not completely outside the pedicle boundaries)

and 9(14.8%) Grade Ⅲ (completely outside the pedicle boundaries) in fluoroscopy group

and 46(75.4%) in Grade Ⅰ

15(24.6%) in Grade Ⅱ

and none in Grade Ⅲ in O-arm group. The 2 groups had significantly difference in accuracy (P0.05). There was no significant difference in the accuracy between the assessment of intraoperative O-arm scanning and postoperative CT scanning (P0.05). Average hole drilling time was 6.5 min (ranging from 5.2 to 8.1 min) in fluoroscopy group and 3.9 min (ranging from 2.8 to 5.2 min) in O-arm group (P0.05).       Conclusion      O-arm based navigation system increases the accuracy of pedicle drilling and reduces the surgical time significantly.