• S Samuel Bederman, Peter Hahn, Vincent Colin, Douglas P Kiester, and Nitin N Bhatia.
• Department of Orthopaedic Surgery, University of California, Irvine, 101 The City Drive South, Pavilion III, Orange, CA.
• J Spinal Disord Tech. 2013 Jul 26.

Study Design:A retrospective cohort study of patients who underwent S2-alar-iliac (S2AI) screw insertion using robotic guidance in long constructs for spinal deformity correction extending to the sacrum performed at a single institution OBJECTIVE:: To assess and evaluate the feasibility and accuracy of robotic guidance for S2AI screw insertion.Summary Of Background Data:Pelvic fixation has become a common adjunct to long fusions extending to the sacrum. The S2AI method possesses advantages over the traditional Galveston technique. S2AI involves finding a pathway from S2 across the sacral ala and the sacroiliac joint into the ilium. Robotic guidance is a new modality for implant insertion that has shown high accuracy.Methods:We identified all patients who underwent robotic-guided S2AI screw insertion in long constructs extending to the sacrum. Cortical breaches and protrusions, assessed on postoperative imaging, and complications were recorded.Results:Fourteen patients (31 screws) underwent S2AI screw insertion using robotic guidance and free hand probing. Average screw length was 80 mm (range 65 to 90). All trajectories were confirmed as accurate (no proximal breaches). Screw insertion, performed manually, resulted in 10 protrusions less than 2 mm, 1 by 2-4 mm, and 6 by 4 mm or more. No screw was intrapelvic or risked any visceral or neurovascular structures and none required removal or revision. Longer screws (>80 mm) were associated with distal protrusion.Conclusions:Robotic-guided S2AI screws are accurate and a feasible option. While no complications from protrusion were identified, larger studies and instrumentation modifications are required to assess the clinical acceptance of robotic guidance in sacropelvic fixation.

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