Surgery of lumbar disc herniation is most common procedure in neurosurgical practice. However poor outcomes, recurrent disc herniation and recurrence of low back and leg pain which affect quality of life, are still challenging. Lumbar spine instability develops as a result of a gradual degenerative process and lumbar segmental instability is one of main reason of failed back surgery. Presence of lumbar segmental instability or potential secondary instability after surgery should not be overlooked. Accurate preoperative evaluation of patients with lumbar disc herniation needs to understand biomechanics of spinal stability and predict possible result of postoperative instability. Thus failure of treatment modalities can be avoided.