Assessment of static posture in individuals with axial spondyloarthritis and its association with body balance and peripheral muscle strength

Abstract

Introduction and Aims: Proper sagittal alignment and postural control are important for functional independence. This exploratory cross-sectional study evaluated sagittal vertical alignment (SVA) in individuals with axial spondyloarthritis (iwaxSpA) and examined its associations with plantar-pressure-derived postural sway parameters and handgrip strength (HGS). Methods: Twenty-one iwaxSpA and 20 controls underwent whole-spine lateral radiography for SVA measurement, baropodometric assessment, and HGS testing. Results: An SVA ≥50 mm was observed in 9/21 (42.8%) iwaxSpA and 4/20 (20.0%) controls. Median SVA was higher in iwaxSpA than in controls (31 [16–53] vs. 26.5 [9.50–36.7] mm), but the between-group comparison was not statistically significant after correction for multiple testing (adjusted p=0.802). No baropodometric parameter or mean HGS differed significantly between groups after multiplicity correction. Within the iwaxSpA group, SVA showed nominal positive correlations with age (ρ = 0.511, unadjusted p = 0.017) and maximal mediolateral displacement (ρ = 0.452, unadjusted p = 0.039), but neither association remained statistically significant after Benjamini–Hochberg adjustment (adjusted p = 0.356 and p = 0.395, respectively). Conclusions: Although iwSpA exhibit worse postural assessment and balance control values than controls—when measured via spinal radiography and baropodometry, respectively—there are no significant differences after adjusting for multiple comparisons. In iwSpA, the associations between postural assessment (via spinal radiography) and baropodometric parameters or HGS are weak and non-significant. Larger, adequately characterized studies with prespecified outcomes and adjustment for relevant confounders are needed.