The Woodpecker variable-speed drilling protocol for robot-assisted subaxial cervical pedicle screw placement: technique and a consecutive series of 1027 screws.

摘要

Published descriptions of robot-assisted cervical pedicle screw placement remain limited, particularly for subaxial screws and for workflows integrating positioning, registration, and drilling. Small pedicle diameter, steep trajectories, and proximity to the vertebral artery magnify the consequences of minor technical error. This retrospective single-center case series included 117 consecutive patients undergoing robot-assisted subaxial cervical pedicle screw placement between November 2023 and June 2026. One workflow was applied across open, hybrid and percutaneous approaches, comprising rigid Mayfield fixation, thoracic and pelvic fixation to the table, table-mounted robotic guidance without patient-mounted pins, O-arm planning, and a standardized variable-speed drilling protocol. Screw position was graded on postoperative O-arm imaging using the Gertzbein-Robbins classification. Drilling was commenced at 1029 pedicles. Two trajectories were abandoned after bleeding raised suspicion of vertebral artery injury, and no screw was placed at either. Of 1027 placed screws, 1015 (98.8%) were Grade A or B and 12 (1.17%) Grade C, with no Grade D or E breach and no breach of the lateral pedicle wall. Mean blood loss was 288.8 mL, with no motor evoked potential loss. Both patients with suspected vascular injury remained free of clinical sequelae beyond 18 months. Robot-assisted subaxial cervical pedicle screw placement can be performed safely within a workflow that stabilizes the patient-table construct and standardizes drilling through the pedicle. Screw containment and procedural safety are distinct measures. The Woodpecker technique is one component of this workflow rather than a stand-alone intervention.