A new study presented at the Society for Minimally Invasive Spine Surgery Annual Forum in 2016 examines robotic pedicle screw placement for sacro-pelvic fixation with S2 alar-iliac screws.
The study authors retrospectively reviewed patients who underwent S2AI fixation with robotic guidance; there were 18 patients who underwent the operation between 2012 and 2014. The average age of the patient was 60 years old and average BMI was 26.6.
The researchers found:
1. There weren't any intraoperative complications related to S2AI screw placement and the robotic guidance was successful for all 35 screws.
2. All screw trajectories were accurate, according to a postoperative CT scan.
3. None of the screws violated the iliac cortex or breached the anterior sacrum.
4. One screw deviated from the preoperative plan by about 3 mm in the axial plane and 1.8 mm in the lateral plane. The screw deviated from the preoperative plan by 2.1 mm in the axial plane and 1.2 mm in the lateral plane.
5. The study authors attributed the deviation in the early entry point to ploughing of the screw during the correction maneuver or "skiving of the drill bit on the irregular surface of the sacrum."