Relationship between sagittal spinal alignment and the incidence of vertebral fracture in menopausal women with osteoporosis: a multicenter longitudinal follow-up study.

Purpose: To investigate the relationship between sagittal spinal alignment and the incidence of vertebral fracture in patients with osteoporosis.

Methods: A cohort of 1,044 postmenopausal women with osteoporosis were prospectively observed for the incidence of lumbar vertebral fracture. Baseline characteristics of the subjects were recorded, including age, year post-menopause, body height and weight, lumbar spine BMD (LSBMD) and femoral neck BMD (FNBMD). Patients with radiologically diagnosed lumbar vertebral fractures were assigned to the fracture group, and 150 randomly selected participants were assigned to the non-fracture group. Parameters depicting sagittal spinal alignment, including sacral slope (SS), pelvic tilt, pelvic incidence (PI), thoracic kyphpsis, lumbar lordosis (LL), lumbar lordosis index (LLI) and sagittal vertical axis, were measured for both groups. Comparison between the two groups was carried out by Student's t test. Variables showing significant differences were entered into a logistic regression analysis to determine the independent risk factors.

Results: Patients with fracture events had significantly lower LSBMD as well as a significantly longer year post-menopause. Besides, patients with vertebral fracture were found to have significantly lower LL, LLI, SS and PI. Regression analysis showed that LSBMD (OR = 0.27), LL (OR = 0.3), LLI (OR = 0.43) and PI (OR = 0.67) had significant associations with the risk of vertebral fracture.

Conclusions: Osteoporosis patients with low LL, LLI, and PI could be at high risk of lumbar vertebral fracture. In addition to BMD, the abnormal sagittal spinal profile should also be taken into consideration when predicting the incidence of vertebral fracture in such patients.