The originality of our study is the diagram. We demonstrated that the rate of progression was linear, and it can be used to establish an individual prognosis. The diagrams visualized 2 main distinct types. There was a significantly faster rate of progression in type B. In type A, rotary subluxation occurs during progression of the curvature. In type B, it seems to be the initial event. Menopause is a period of deterioration in type B.

Purpose Degenerative scoliosis usually begins at menopause and lateral rotatory olisthesis (LRO) might be a triggering factor in the onset of degenerative scoliosis in postmenopausal women. We set out to evaluate the influence of hormone replacement therapy (HRT) on degenerative scoliosis and on LRO. Methods A cross-sectional study was conducted in 146 postmenopausal women: 75 women had received HRT for more than 1 year (HRT [ 1) and 71 women had never received HRT or less than 1 year (HRT \ 1). Scoliotic curve, LRO, sacral slope, lordosis, kyphosis were measured. The excess risk of LRO associated with age, BMI, isometric strength of brachial biceps, bone mineral density, lean mass and HRT was evaluated using a multiple logistic regression model. Results No difference was found in sacral slope, lumbar lordosis or thoracic kyphosis between both groups or in the presence of scoliosis. The prevalence of LRO was significantly lower in HRT[1 than HRT\1 (8 vs. 30%) while the risk was dependent on age, HRT and their interaction. LRO increased with age only in HRT \1 (11% when aged B66 years vs. 39% when aged [66 years, p = 0.013), whereas the prevalence of LRO remained stable in HRT[1.Conclusions LRO was significantly lower in women who received HRT. The excess risk of LRO was dependent on both age and HRT status. These findings suggest that HRT might prevent the onset of LRO, and therefore might contribute to the prevention of low back pain.