Assessment of Sagittal Vertical Alignment in Individuals with Axial Spondyloarthritis and Its Association with Static Sway and Handgrip Strength

Background and Aims: Proper sagittal alignment and postural control are important for functional independence. This exploratory cross-sectional study evaluated the sagittal vertical axis (SVA), as measured by spinal radiography, in individuals with axial spondyloarthritis (iwaxSpA), and examined its associations with postural sway parameters, derived from plantar pressure via baropodometry, as well as with 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: In iwaxSpA, there are numerical trends toward poorer postural assessment and balance control, as measured via spinal radiography and baropodometry, though no significant differences remain after adjusting for multiple comparisons. No significant associations were found between spinal alignment (as assessed by spinal radiography), baropodometric parameters, and HGS. Due to the exploratory nature of the study and its limited statistical power, larger controlled multicenter trials are needed to better define the roles of spinal radiography and baropodometry in this population.