P117. Navigated robotic assistance improves pedicle screw accuracy in minimally invasive surgery of the thoracolumbar spine: 341 patients in a single institution

BACKGROUND CONTEXT As the field of robot-assisted spine surgery continues to progress and grow, radiographic evaluation of pedicle screw accuracy in a surgical setting is of high interest. Advances in medical imaging and technology have improved pedicle screw placement accuracy, from fluoroscope-guided placement to computer-aided navigation. PURPOSE The purpose of this study is to assess the pedicle screw accuracy of 341 consecutive cases in which navigated robotic assistance was used in a private practice clinical setting. STUDY DESIGN/SETTING Retrospective chart review. PATIENT SAMPLE A total of 341 consecutive patients. OUTCOME MEASURES Screw accuracy, screw offset, complications. METHODS A retrospective, Institutional Review Board-exempt review of 341 navigated robot-assisted spine surgery cases was performed at a single private institution. Radiographic evaluation of screw tip and screw tail offset distance and angulation from preoperative plan to actual final placement based on intraoperative computerized tomography (CT) images was analyzed and calculated. Additionally, pedicle screw malposition, reposition and return to operating room (OR) rates were reviewed. A CT-based Gertzbein and Robbins System (GRS) was used to classify pedicle screw accuracy. The GRS system classifies screws with the rating of A or B as accurate, and C, D, or E as inaccurate placement. The accuracy percentage was calculated by dividing the number of accurate screws placed with robotic navigation by the total cohort. RESULTS In the 341 cases analyzed, 1,929 thoracolumbar pedicle screws were placed. Thirty-one screws (6 patients) deviated from robot use due to surgeon discretion. Of the 1,929 pedicle screws inserted by navigated robotic guidance, only .005% (9/1929) were repositioned intraoperatively. The average age was 66.8 years, and 48% of the patients were male. Average body mass index was 29.31 kg/m2. The majority of the surgical diagnoses were degenerative disc disease (248) and adjacent segment disease (72). The average offset from preoperative plan to actual final placement was 1.7±1.3mm from the tip, 1.6±1.0mm from the tail, and 2.0±1.4° of angulation. Based on the GRS CT-based grading, 97.8% (1,886/1,928) screws were graded A or B, 2.0% (40/1,928) screws were graded C, and 0.2% (3/1,928) screws were graded D. A total of three complications that required a return to the OR were reported: interbody removal, deep wound infection, and wound vacuum-assisted closure. None were related to robotic guidance or pedicle screws. CONCLUSIONS This study demonstrated a high level of accuracy (97.8%) in the clinical use of navigated, robot-assisted surgery in 341 cases. FDA DEVICE/DRUG STATUS ExcelsiusGPS (Globus Medical) (Approved for this indication)