Sagittal Alignment–Dependent Mechanical Interference during Robotic-Assisted S2 Alar–Iliac Screw Insertion

Introduction: Although robotic-assisted spinal instrumentation enables highly accurate screw placement, mechanical feasibility constraints remain underrecognized. During sacral instrumentation, a collision between the robotic arm and the patient' s body may prevent completion of S2 alar–iliac (S2AI) screw placement as planned. Alignment-related factors associated with failure of this procedure have not been clearly defined. The aim of this study was to identify spinopelvic alignment factors associated with mechanical interference during robotic-assisted S2 alar–iliac (S2AI) screw insertion.