Fig. 1

Planned versus placed screw trajectories in ExcelsiusGPS® assisted lumbar fusion. a Axial CT overlay reconstruction with placed screw and pre-planned 3D trajectory in Patient 1, who underwent L4 and (b) L5 instrumentation. c-d Sagittal and axial CT overlay reconstruction in Patient 2 demonstrating deviation of actual right L4 screw placement from pre-planned trajectory, but without medial or lateral cortical breach. e-f Left L4 screw placement with mild deviation from pre-planned trajectory on axial and sagittal projections. g-j Left and right L5 screw placement in Patient 2 demonstrating minimal deviation from planned trajectory