Pedicle screw accuracy assessment in ExcelsiusGPS® robotic spine surgery: evaluation of deviation from pre-planned trajectory

Abstract

Background: The ExcelsiusGPS® (Globus Medical, Inc., Audubon, PA) is a next-generation spine surgery robotic system recently approved for use in the United States. The objective of the current study is to assess pedicle screw accuracy and clinical outcomes among two of the first operative cases utilizing the ExcelsiusGPS® robotic system and describe a novel metric to quantify screw deviation. Methods: Two patients who underwent lumbar fusion at a single institution with the ExcelsiusGPS® surgical robot were included. Pre-operative trajectory planning was performed from an intra-operative CT scan using the O-arm (Medtronic, Inc., Minneapolis, MN). After robotic-assisted screw implantation, a post-operative CT scan was obtained to confirm ideal screw placement and accuracy with the planned trajectory. A novel pedicle screw accuracy algorithm was devised to measure screw tip/tail deviation distance and angular offset on axial and sagittal planes. Screw accuracy was concurrently determined by a blinded neuroradiologist using the traditional Gertzbein-Robbins method. Clinical variables such as symptomatology, operative data, and post-operative follow-up were also collected. Results: Eight pedicle screws were placed in two L4-L5 fusion cases. Mean screw tip deviation was 2.1 mm (range 0.8-5.2 mm), mean tail deviation was 3.2 mm (range 0.9-5.4 mm), and mean angular offset was 2.4 degrees (range 0.7-3.8 degrees). All eight screws were accurately placed based on the Gertzbein-Robbins scale (88% Grade A and 12% Grade B). There were no cases of screw revision or new post-operative deficit. Both patients experienced improvement in Frankel grade and Karnofsky Performance Status (KPS) score by 6 weeks post-op. Conclusion: The ExcelsiusGPS® robot allows for precise execution of an intended pre-planned trajectory and accurate screw placement in the first patients to undergo robotic-assisted fusion with this technology.

Feasibility and accuracy of a robotic guidance system for navigated spine surgery in a hybrid operating room: a cadaver study

“…We find a very high accuracy as shown in bone entry deviation data and angular errors (0.48 ± 0.44 mm, 0.94 ± 0.83° and 0.68 ± 0.58 mm, 0.87 ± 0.82°) in the axial and sagittal planes, respectively. This is in line with top performers among previously published material on bone entry deviation accuracy and superior in regard to angular errors (Table 3) [30][31][32][33][34][35][36] . This in turn resulted in a favorable simulated Gertzbein grading (100% accuracy), well in line with the vast majority of recent studies that typically report 98 -100% accuracy 34,[37][38][39][40][41] .…”

Initial Single-Institution Experience With a Novel Robotic-Navigation System for Thoracolumbar Pedicle Screw and Pelvic Screw Placement With 643 Screws

“…Recently, there was 1 small case series published examining the use of ExcelsiusGPS in 2 patients, demonstrating 100% accuracy in screw placement in 8 screws. 12 This finding is further confirmed with the present study demonstrating 100% accurate screw placement in the subgroup analysis of 66 screws. Similarly, a recent study examining the feasibility of another robotic-navigation guided system, Mazor X (Mazor Robotics Ltd) reported an accuracy rate of 98.7% examining 75 screws.…”

Robotic Spine Surgery: Current State in Minimally Invasive Surgery

“…In this study, placement of 4 additional screws was attempted robotically, but these attempts were aborted due to technical difficulties. 18,19 No prospective, randomized studies of the ExcelsiusGPS have been reported, although initial case reports and small case series indicate high accuracy and safety with rates similar to those of other robotic systems (Figure 2). 15,18,[28][29][30] Additionally, with spinal robotics, the accuracy of screw placement can be judged not only with the conventional GRS but also by measuring deviation from a pre-planned trajectory.…”

“…In this study, placement of 4 additional screws was attempted robotically, but these attempts were aborted due to technical difficulties. 18,19…”

“…The GRS evaluates pedicle/cortical breach based on an idealized and optimized trajectory. [17][18][19] As the first robotic system to be developed for spinal surgery, the Mazor robots remain the most well investigated to date. Several randomized controlled trials (RCTs) have been conducted to validate the accuracy of these systems.…”