The patients who presents with either mechanical low back pain or segmental instability. Mechanical lower back pain is defined as pain that was induced by posture change, or that prevents the patient from sitting or standing for more than 30 minutes. Patients are considered to have segmental instability if they had isthmic spondylolisthesis, degenerative spondylolisthesis with more than 4 mm of translation or intervertebral angle reversal on dynamic radiographs.18 Surgical techniques