Accuracy and deviation analysis of robot-assisted spinal implants: A retrospective overview of 105 cases and preliminary comparison to open freehand surgery in lumbar spondylolisthesis

Background: Whether the accuracy of robot-assisted spinal screw placement is significantly higher than that of freehand and the source of robotic deviation remain unclear.

Methods: Clinical data of 105 patients who underwent robot-assisted spinal surgery was collected, and screw accuracy was evaluated by computed tomography according to the modified Gertzbein-Robbins classification. Patients were grouped by percutaneous and open surgery. Intergroup comparisons of clinical and screw accuracy parameters were performed. Reasons for deviation were determined. Thirty-one patients with lumbar spondylolisthesis undergoing open robot-assisted surgery and the same number of patients treated by open freehand surgery were compared for screw accuracy.

Results: Screw accuracy was not significantly different between the percutaneous and open groups in both intra- and postoperative evaluations. Tool skiving was identified as the main cause of deviation. The proportion of malpositioned screws (grade B + C + D) was significantly higher in the freehand group than in the robot-assisted group. However, remarkably malpositioned (grade C + D) screws showed no significant differences between the groups. No revision surgery was necessary.

Conclusions: Robot-assisted spinal instrumentation manifests high accuracy and low incidence of nerve injury. Tool skiving is a major cause of implant deviation.