Correlation between Lumbar vertebral instability and severe degenerative spondylolisthesis

Background: Severe spondylolisthesis is related to high degenerative changes in verte-bral spine. Degenerative spondylolisthesis often is seen with high-sacral slope. This study was conducted to investigate the relationship between high degenerative spondyl-olisthesis and sacral slope.Methods: A cross-sectional prospective study was done in patients with low back pain in Shafa Yahyaian and Sina University Hospitals in Tehran, in 18 months (April 2010- October 2011). Intermittent or continuous low back pain for three months and history of two disable low back pain attacks since one year ago were inclusion criteria. Pregnant patients were excluded. Lumbar vertebra displacement to vertebra body size ratio was calculated in dynamic mode. The ratio higher than 8% was considered as a lumbar instability. Rotation angle more than 11 ° was considered abnormal.Results: In this study, 52 patients (30 men, 22 women) with 38.35±9.49 years old were enrolled. Mean body mass index was 23.01±4.59kg/m2. Thirty cases had abnormal verte-bral displacement. Angulation of the disc space more than 11 degrees was seen in 20 patients. No statistically significant difference in pelvic index between normal and abn-ormal lumbar vertebra displacement (P=0.443). The mean pelvic index in normal and abnormal angulation groups were 55.97° and 53.58°, respectively; the difference was not statistically significant (P=0.556).Conclusion: The results of the study showed disc degeneration had no association with sacral slope. High sacral slope can intensify spondylolisthesis but does not affect the incidence of degenerative spondylolisthesis. Additional research is required to find the other causes of degenerative spondylolisthesis