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,

Introduction:

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.

Aims/Objectives:

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

Methods:

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.

Results:

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.

Conclusions:

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