Background: The extension of healthy life expectancy has become increasingly important because of rising health-care costs and decreases in the quality of life in the elderly population. Although reports have surfaced on an association between sagittal spinal alignment and physical performance, such studies on the healthy population are limited. This study investigated the relationship between sagittal spinal alignment and physical function in the general elderly population.

Methods: Registered citizens who were 50 to 89 years of age were targeted for this survey. We established 8 groups based on age (50 to 59 years, 60 to 69 years, 70 to 79 years, and 80 to 89 years) and sex (male and female) after random sampling from the resident registry of the town of Obuse in 2014. A total of 412 people (203 male and 209 female) were enrolled for the measurement and analysis of radiographic parameters of sagittal spinal alignment and physical performance tests.

Results: Physical function score values decreased with age, with moderate to strong correlations. Within age subgroups, worsened spinal alignment in standing whole-spinal radiographs indicated diminished physical performance results. The impact of the sagittal vertical axis was especially prominent; as the sagittal vertical axis was shifted forward by 1 standard deviation, 1-leg standing time became shortened by 3.8 seconds. Two-step scores were significantly associated with sagittal vertical axis, global tilt, cervical sagittal vertical axis, and pelvic tilt.

Conclusions: Our investigation of sagittal spinal alignment on physical function in a Japanese elderly cohort revealed significant negative correlations between spinal alignment and physical performance after excluding the influence of age and sex. Posture change in the community-dwelling elderly population is an important sign of physical function impairment.

Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.