Evidence showing the relationship between sagittal balance and clinical outcomes in surgical treatment of degenerative spinal diseases: a literature review

The measure of radiographic pelvic and spinal parameters for sagittal balance analysis has gained importance in reconstructive surgery of the spine and particularly in degenerative spinal diseases (DSD). Fusion in the lumbar spine may result in loss of lumbar lordosis (LL), with possible compensatory mechanisms: decreased sacral slope (SS), increased pelvic tilt (PT) and decreased thoracic kyphosis (TK). An increase in PT after surgery is correlated with postoperative back pain. A decreased SS and/or abnormal sagittal vertical axis (SVA) after fusion have a higher risk of adjacent segment degeneration. High pelvic incidence (PI) increases the risk of sagittal imbalance after spine fusion and is a predictive factor for degenerative spondylolisthesis. Restoration of a normal PT after surgery is correlated with good clinical outcome. Therefore, there is a need for comparative prospective studies that include pre- and postoperative spinopelvic parameters and compare complication rate, degree of disability, pain and quality of life.