Letter: Image-Guided Navigation and Robotics in Spine Surgery.

Abstract

To the Editor: We really appreciated the manuscript by Kochanski et al1 entitled “Image-Guided Navigation and Robotics in Spine Surgery” published in January 2019 in Neurosurgery. The authors reported their experience with the application of innovative technologies in spine surgery such image guidance (IG) and robotics systems. There is a growing of data showing that IG and robotic systems decrease the incidence of mispositioned screws. The combination of robotic technology and IG can be very useful in cases with altered or complex anatomy. There is also a growing extension of the indications for the use of these systems reported in the literature, not only in guiding the correct positioning of the pedicle screws, but also in the cervical spine instrumented cases and in the spinal oncological surgery. Both of these techniques offer the possibility of reducing exposure to ionizing radiation for the patient and the technical-operating team, while offering reduced surgical times, less muscle dissection, in compliance with minimally invasive spine surgery. It is our pleasure to share with the international community our experience with the use of a new tool designed to improve accuracy in spinal navigation.2 At our institution, a new device has been designed and patented. In our daily practice after the classic reference frame placement, a new “screw-like” tool is screwed into the same or adjacent spinous process of the reference frame. The tool is composed by a lower portion with a threaded needle connected to a rectangular-shaped skin contact plate and an upper portion with a hexagonal nut and a 2 mm central pin (Figure 1).FIGURE 1.: Screw-like tool project template and complete equipment with screws of different sizes and T-shaped screwing system.A first 3-dimensional (3D) scan is acquired with O-arm (Medtronic Navigation, Medtronic Inc, Dublin, Ireland) and used by the StealthStation S7 surgical navigation system (Medtronic Navigation, Medtronic Inc) to create an automatic reconstruction of the spine. Navigation accuracy is intraoperative checked touching with the tip of the probe the pin surface of the screw-like tool (Figure 2).FIGURE 2.: System calibration verification is performed by evaluating the exact correspondence between the positioning of the probe tip and the new screw-like tool pin surface.The precise correspondence of these last 2 is considered as evidence of the absence of micromovements of the reference frame, conversely a mismatch suggested a loss of system calibration, so the execution of a new 3D acquisition and calibration is required. We evaluate pedicle screws’ placement accuracy using the new tool in adjunct to the classic reference frame, following the Gertzbein and Robbins classification, and the 98.9% are completely inside cortical bone (Grade A) and only the 1.1% with a breach of less than 2 mm (Grade B). Our experience demonstrates that the new “screw-like” tool coupled to the classic reference frame device could improve accuracy during navigated spine surgery and potentially reducing to zero the risks for screw mispositioning. In literature there are other reports navigation nuances with the aim to improve pedicle screw accuracy.3,4 We agree with Kochanski et al1 as they suggested that further research is necessary to better elucidate situations where these systems may be particularly beneficial in spine surgery. Funding This study did not receive any funding or financial support. Disclosures The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.