Navigated Robotic Assistance Improves Pedicle Screw Accuracy In Minimally Invasive Surgery of the Lumbosacral Spine: 600 Pedicle Screws in a Single Institution

Presented at SMISS Annual Forum 2019
By Arnold Vardiman MD
With David Wallace MD, Grant Booher MD, Neil Crawford PhD, Jessica Riggleman BS, Samantha Greeley BS, Charles Ledonio MD, CCRP,

Disclosures: Arnold Vardiman MD A; Globus Medical. C; Medtronic, Abbott. F; Globus Medical. David Wallace MD None, Grant Booher MD None, Neil Crawford PhD E; Globus Medical. F; Globus Medical., Jessica Riggleman BS E; Globus Medical, Samantha Greeley BS E; Globus Medical., Charles Ledonio MD, CCRP E; Globus Medical,


In the emerging field of robot-assisted spine surgery, radiographic evaluation of pedicle screw accuracy in the surgical setting is of high interest. Advances in medical imaging have improved the accuracy of pedicle screw placement, from fluoroscopic-guided to computer-aided navigation


This study describes pedicle screw accuracy of the first 106 consecutive cases in which navigated robotic assistance was used in a private practice clinical setting.


A retrospective, Institutional Review Board-exempt review of the first 106 navigated robot-assisted spine surgery cases was performed. 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 calculated. Additionally, pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. A CT-based Gertzbein and Robbins System (GRS) was used to classify pedicle screw accuracy. Screws with an A or B grade were deemed as accurate while screws with a C, D, or E grade were considered inaccurate. The number of accurate screws divided by the number of total screws placed with robotic navigation resulted in an accuracy percentage for the first 106 cases.


In the first 106 cases, 630 lumbosacral pedicle screws were placed. Thirty screws (5 patients) were placed without the robot due to surgeon discretion. Of the 600 pedicle screws inserted by navigated robotic guidance, only 1.5% (9/600) were repositioned intraoperatively. The average age of patients was 64.8 years, and 55% were female. The average body mass index of the patients was 31 kg/m2. The majority of the surgery diagnoses were degenerative disc disease (79) and adjacent segment disease (19). The average offset from preoperative plan to actual final placement was 1.7±1.3 mm from the tip, 1.8±1.2 mm from the tail, and 2.0±1.6 degrees of angulation. Based on the GRS CT-based grading, 98.2% (589/600) screws were graded A or B, 1.5% (9/600) screws were graded C, and 0.3% (2/600) screws were graded D. Two complications, interbody removal and wound vacuum-assisted closure, were reported as requiring a return to the OR, but these were not related to robotic guidance or pedicle screws.


This study demonstrated a high level of accuracy (98.2%) in the clinical use of navigated, robot-assisted surgery in the first 106 robotic cases, with only 2 non-screw-related complications requiring return to the OR.

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