High grade Spondylolisthesis is reduction necessary? Advantage of reduction of fusion mass has biomechanical – fusion rate is better, less fusion segments, sagittal balance restored, canal stenosis treated and disadvantage is risk of neurological injury up to 75%. What is evidence saying? Mixed literature. Main concern is direct pressure on roots, extradural pressure on roots in reduced position, impingement of roots on iliolumbar ligaments, disc extruded in canal in canal. The ideal candidates for in situ fusion are no gait disturbance, no postural abnormalities, no radicular symptoms, balanced pelvis, preserved C7 plumbline. Ideal treatment for high grade spondylolisthesis controversial. Question needs to be answered whether need for reduction, number of levels to include in fusion, use of instruments, surgical approach.