Fig 4. K-wire placement under the assistance of the robot before and after reregistration.

A patient with lumbar spondylolisthesis received instrumentation from L3 to L5, and malpositioned bilateral L3 K-wires were noted initially. Fig 4A and 4B depict both left and right K-wire malpositions (Classification III) from the planned trajectory, as shown in the anteroposterior view (Fig 4A) and oblique view (Fig 4B). Fig 4C and 4D depict improved accuracy from classification type III to type I after the reregistration and adjustment of the K-wire placement.(Black arrow: planned trajectory; white star: implanted K-wire; green line: planned trajectory)