Current concepts on the sagittal balance and classification of spondylolysis and spondylolisthesis

Treatment of spondylolysis and spondylolisthesis remains a challenge for orthopaedic surgeons, neurosurgeons and paediatrics. In spondylolisthesis, it has been clearly demonstrated over the past decade that spino-pelvic morphology is abnormal and that it can be associated to an abnormal sacro-pelvic orientation as well as to a disturbed global sagittal balance of spine. This article presents the SDSG (Spinal Deformity Study Group) classification of lumbosacral spondylolisthesis. The proper treatment of spondylolisthesis is dependent on recognizing the type of slip, sacro-pelvic balance and overall sagittal balance and its natural history. Although a number of clinical radiographic features have been identified as risk factors, their role as primary causative factors or secondary adaptative changes is not clear. The conservative treatment of adult isthmic spondylolisthesis results in good outcome in the majority of cases. Of those patients who fail conservative treatment, success with surgery is quite good, with significant improvement in neurologic function in those patients with deficits, as well as improvement in patients with back pain.