Sitting Position as an Alternative for Sagittal Balance Assessment: A Cross-Sectional Study

Abstract Background: The sagittal vertical axis (SVA) is used for spinal sagittal balance evaluation. Patients with sagittal imbalance are assessed by whole spine standing lateral radiography, with some patients demonstrating standing difficulty during the examination. We propose new positioning methods to facilitate SVA assessment in patients with sagittal imbalance who cannot tolerate the standing position.Methods: Thirty healthy subjects had their SVA evaluated by whole spine lateral radiography in four positions: standard position by standing with the hands on the clavicles with elbows touching the trunk (TC), standing with the hands holding on to a front stationary railing within arm’s reach (TS), sitting with the hands on the clavicles (IC), and sitting with the hands holding on to a stationary railing (IS). The SVA was evaluated for differences and correlations between the standard position (TC) and the new proposed positions.Results: The mean difference in the SVA between the TC and TS group was 1.55 mm, with a limit of agreement of -36.62 to 39.72 mm and Lin’s correlation of 0.63. The mean difference in the SVA between the TC and IC or IS positions indicated greater positive SVA difference with no correlation. The TS position had good regional spinal parameter correlation with the TC position, as well as pelvic parameter correlation. The IC and IS positions showed poor pelvic and other regional spinal parameter correlations. Conclusions: The TS position can be used as an alternative method in measuring the SVA in patients with standing difficulty during radiography. Though measurement using the sitting position can be conveniently performed, this position does not correlate well with the standard SVA measurement.