Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients

Abstract

Introduction Surgeons' interest in image and/or robotic guidance for spinal implant placement is increasing. This technology is continually improving and may be particularly useful in patients with challenging anatomy. Only through careful clinical evaluation can its successful applications, limitations, and areas for improvement be defined. This study evaluates the outcomes of robotic-assisted screw placement in a consecutive series of 102 patients. Methods Data were recorded from technical notes and operative records created immediately following each surgery case, in which the robotic system was used to guide pedicle screw placement. All cases were performed at the same hospital by a single surgeon. The majority of patients had spinal deformity and/or previous spine surgery. Each planned screw placement was classified as: (1) successful/ accurately placed screw using robotic guidance; (2) screw malpositioned using robot; (3) use of robot aborted and screw placed manually; (4) planned screw not placed as screw deemed non essential for construct stability. Data from each case were reviewed by two independent researchers to indentify the diagnosis, number of attempted robotic guided screw placements and the outcome of the attempted placement as well as complications or reasons for non-placement. Results Robotic-guided screw placement was successfully used in 95 out of 102 patients. In those 95 patients, 949 screws (87.5 % of 1,085 planned screws) were successfully implanted. Eleven screws (1.0 %) placed using the robotic system were misplaced (all presumably due to ''skiving'' of the drill bit or trocar off the side of the facet). Robotic guidance was aborted and 110 screws (10.1 %) were manually placed, generally due to poor registration and/or technical trajectory issues. Fifteen screws (1.4 %) were not placed after intraoperative determination that the screw was not essential for construct stability. The robot was not used as planned in seven patients, one due to severe deformity, one due to very high body mass index, one due to extremely poor bone quality, one due to registration difficulty caused by previously placed loosened hardware, one due to difficulty with platform mounting and two due to device technical issues. Conclusion Of the 960 screws that were implanted using the robot, 949 (98.9 %) were successfully and accurately implanted and 11 (1.1 %) were malpositioned, despite the fact that the majority of patients had significant spinal deformities and/or previous spine surgeries. ''Tool skiving'' was thought to be the inciting issue with the misplaced screws. Intraoperative anteroposterior and oblique fluoroscopic imaging for registration is critical and was the limiting issue in four of the seven aborted cases.

Robotic spine surgery: a preliminary report

“…duration of the process in patients who undergo multi-level instrumentation is reduced because of the decrease in the period typically lost during x-ray control and determination of screw location. The superiority of the system is evident in percutaneous interventions, in patients who undergo deformity surgery and in cases of recurrence (10,11,33). In our study, the mean surgical duration was 46.1 minutes in Group A patients as opposed to 73.2 minutes in Group B patients.…”

Current applications of robotics in spine surgery: a systematic review of the literature

“…In this subanalysis, 577 (89.3%) were GRS Grade A; 58 (9.0%) were GRS Grade B; 9 (1.4%) were GRS Grade C; and 2 (0.3%) were GRS Grade D. Hu and colleagues published a series of papers retrospectively assessing pedicle screw accuracy. [9][10][11] In their first paper, 10 accuracy was evaluated using fluoroscopy in 95 patients with 960 screws placed using the Mazor robot (note that accuracy was not graded in all 102 patients; in the other 7 the screw placement was aborted). Of these, 949 (98.9%) were deemed to be accurate.…”

“…5,10,12,15,22,24,27,29 Devito et al found that the ability to place screws robotically was 83.7% in their total cohort, but increased to a 90.8% execution rate when they looked at their most recent procedures. 5 In addition, time per screw placement decreased from 13.5 minutes for single-level cases (4 minutes per screw in multilevel cases) to 10.6 minutes (2 minutes in multilevel cases).…”

Robotics and the spine: a review of current and ongoing applications

“…Although measurement techniques are not standardized, the estimated malposition rates of conventional screw placement in studies such as those conducted by Kosmopoulos and Schizas and Hicks et al are much higher than those of current retrospective robotics studies. 9,12,20 Hu et al 14 conducted another important case series of 102 consecutive patients in whom the SpineAssist was used, which yielded similarly high accuracy rates. In their investigation 949 (98.9%) of 960 robotically placed screws were successfully positioned and 11 were malpositioned, presumably due to incorrect onset of trajectory.…”

“…Retrospective analyses of robot-assisted cohorts have overall demonstrated very high accuracy rates in large numbers of screw placements. 9,14,15 Furthermore, in 2013 Hu and Lieberman 13 contended that the successful placement of pedicle screws with robotic assistance follows a learning curve that increases with surgeons' experience. In a consecutive cohort study of 174 patients who underwent pedicle screw placement by the same surgeon, accuracy rates increased from 82% in the first 30 patients to 93%, 91%, and 95%, respectively, in the following groups of 30 patients.…”