Cervical Pedicle Screw Insertion Using O-Arm-Based 3D Navigation: Technical Advancement to Improve Screw Accuracy

Presented at SMISS Annual Forum 2019
By Keiji Wada
With Ryo Tamaki , Tomohisa Inoue , Ken Okazaki ,

Disclosures: Keiji Wada None Ryo Tamaki None, Tomohisa Inoue None, Ken Okazaki None,


Posterior cervical pedicle screw (CPS) placement is widely used for cervical posterior reconstruction. However, CPS placement has remained technically demanding. O-arm navigation system improved the accuracy of CPS placement, though there were several technical pitfalls. As surgical instruments and techniques for O-arm based surgery have been advanced, the accuracy of CPS placement might have also improved. However, there have been no reports describing the accuracy of CPS placement using O-arm based navigation on advances in surgical instruments and techniques.


This study aimed to investigate the accuracy and technical advancement of CPS placement in the lower cervical spine using intraoperative O-arm navigation.


Forty patients who underwent lower cervical spine surgery with CPS using intraoperative O-arm navigation system between 2013 and 2018 were included in this study. Three different surgeons in our hospital performed the surgeries. We divided the above period into 3 phases according to the development of surgical techniques. In the first phase, we placed a reference frame onto the spinous process of the cranial vertebrae and used it for CPS placement at a maximum of 3 vertebral levels. The navigation guide sleeve was used to drill a screw hole, and then to tap and insert screws. A power drill was used to make the screw hole. In the second phase, we introduced a reference frame that can hold the spinous processes of 3 vertebrae, navigation tap, and navigation screw drivers. In the third phase, we developed a drill guide sleeve to minimize bending of the drill tip. We evaluated the accuracy of screw placement using postoperative computed tomography (CT). Screw placement accuracy was assessed using Neo’s classification: grade (G) 0, no perforation; G1, perforation <2 mm; G2, perforation 2-4 mm; G3, perforation >4 mm. Complications related to screw malpositioning were also evaluated.


Mean age at surgery was 67 years (range, 19-85). A total of 198 CPS were inserted: 68 in the first phase, 46 in the second phase, and 84 in the third phase. The total proportion of malpositioning was 5.6% (11 screws) and all were G1; 7.4% (5/68 screws) in the first phase, 10.9% (5/46 screws) in the second phase, and 1.2% (1/84 screws) in the third phase (p<0.05). There were no complications related to screw malpositioning.


O-arm use dramatically improved CPS placement accuracy with the advancement of techniques and instruments.

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