Risk factors of inaccurate screw placement in robotic spine surgeries: why do robots make error and how to avoid them?

The study design is retrospective study. Robotic spine surgery has evolved rapidly over the past two decades, with growing adoption. However, research on error sources in robotic-assisted pedicle screw placement remains scarce. This study investigates the incidence, risk factors, and intraoperative error types linked to screw malposition. We retrospectively analyzed patients who underwent robotic-assisted thoracic and lumbar spine surgeries at our center since Oct 2023. The incidence of screw breaches, intraoperative errors, and risk factors, such as BMI, pathology, and surgical approach, were assessed. Screw malpositions were identified on postoperative O-arm scans and classified by error cause. Intraoperative revision protocols were documented. A total of 1060 patients (5644 pedicle screws) were included. Screw malposition occurred in 13 patients (1.2%) involving 22 screws (0.39%). The mean BMI of patients with malposition was 27.3 versus 26.5 overall. Among the 13 cases, 8 had lumbar degenerative pathology, 3 scoliosis, 1 high-grade listhesis, and 1 revision for proximal junctional failure. Skiving was the most frequent error (6 cases), followed by arm shift (4), patient movement (2), and registration error (1). Learning curve had a significant role with 12/22 screw malpositioning happening in the initial 50 robotic cases. No significant correlation was found between malposition and pathology type or surgical approach. Robotic systems improve pedicle screw accuracy but are not immune to errors. Skiving is the most common issue and can be minimized by selecting flat bony entry points and avoiding sloping surfaces. Other causes include arm shift, patient movement, and registration errors.