Does Sagittal Spinal Alignment Predict Future Fall-Related Fractures in Community-Dwelling Women with Osteoporosis?

Abstract

Introduction: Spinal alignment in women with osteoporosis tends to deteriorate with advancing age, and this misalignment may serve as an indicator of future fall-related fractures. Vertebral fractures, which commonly occur in patients with osteoporosis, have distinct characteristics compared with other fall-related fractures and should therefore be separately evaluated. This study aimed to investigate the association between future fall-related fractures and sagittal spinal alignment, excluding vertebral fractures.

Methods: A total of 333 women with osteoporosis were recruited and followed up between November 2013 and July 2024. At baseline, information on medication status and bone mineral density in the lumbar spine and femoral neck was obtained from the patients' medical record. Furthermore, the locomotive syndrome (LOCOMO) stage was assessed via risk tests, and sagittal alignment parameters, including sagittal vertical axis (SVA), thoracic kyphosis (TK), pelvic incidence (PI), and lumbar lordosis (LL), were evaluated. In addition, Cox proportional hazards regression analysis was conducted to determine the risk of fall-related fractures based on all variables.

Results: The mean follow-up period was 5.4 years. The final sample for assessing fall-related fracture incidence consisted of 214 participants. Fall-related fractures occurred in 31 of the 333 participants (9.3%). Cox proportional hazards regression analysis, adjusted for all variables, revealed that SVA (hazard ratio [HR]=1.011, 95% confidence interval [CI] 1.003-1.02), LL (HR=1.039, 95% CI 1.007-1.072), LOCOMO stage (HR=1.801, 95% CI 1.127-2.879), and presence of parathyroid hormone (HR=0.165, 95% CI 0.031-0.891) are independent risk factors for future fall-related fractures.

Conclusions: Awareness of fall-related fracture risks can be increased by monitoring the SVA, LL, and LOCOMO stage as well as administering parathyroid hormone medications. While the deterioration of sagittal spinal alignment is a well-known factor in vertebral fractures, this study suggests that future fall-related fractures, excluding vertebral fractures, are influenced by sagittal spinal alignment.

Keywords: Locomotive syndrome; Sagittal spinal alignment; fall; fracture; osteoporosis.

Figure 1.

Thoracic kyphosis (TK) is measured from the upper endplate of T12 to the lower endplate of T4. Lumbar lordosis (LL) is measured from the lower endplate of T12 to the upper endplate of S1. Pelvic incidence (PI) is measured as the angle between a line drawn from the center of the femoral head to the midpoint of the sacral endplate and a line perpendicular to the midpoint of the sacral endplate (S1). Sagittal vertical axis (SVA) is the distance from the vertical line passing through the center of C7 in the sagittal plane to the posterior upper endplate of S1.

Figure 2.

This baseline study included 333 women, of whom 98 and 26 were dropped from the study and 26 were excluded.