The authors retrospectively studied seven patients who had in situ fusion as adolescents for high-grade (IV, V) spondylolisthesis unresponsive to more conservative means. All patients achieved solid bony union; their pain was relieved; and hamstring whether crouch gait or any other abnormalities could be demonstrated in patients exhibiting clinical parameters of success. Each patient underwent gait analysis, radiographic analysis, and a physical slight degrees of forward trunk lean during varying phases of gait accompanied increased trunk extension accompanied by limited hip flexion. Two patients were essentially normal. The authors were unable to quantity residual crouch in these patients with solidly fused high-grade spondylolisthesis.