Trunk Lean Is Associated with the Magnitude of Forward Head Posture in Adolescents: A Cross-Sectional,...

Background: Forward head posture (FHP) is prevalent among adolescents and may occur as part of a broader pattern of three-dimensional (3D) postural alterations. Previous studies have primarily focused on isolated sagittal-plane measurements; therefore, the specific 3D postural characteristics associated with FHP remain unclear. This study investigated the 3D postural characteristics associated with FHP magnitude in adolescents. Methods: In this cross-sectional study, 256 adolescents were categorized into sample-based FHP tertiles (lower, middle, and upper) based on forward head displacement. Differences in postural variables among the tertiles were evaluated using age-adjusted multivariate analysis of covariance. Pearson correlation analyses with false discovery rate correction were used to examine associations among postural variables. Variables significantly associated with FHP were further examined using univariate and multivariable linear regression models. Results: After adjustment for age, shoulder protraction differed only between the lower and upper FHP tertiles, whereas trunk lean differed significantly across all tertiles. FHP was significantly correlated with trunk lean (r = 0.409) but not with shoulder protraction. In the multivariable regression analysis, trunk lean remained associated with FHP after adjustment for the other included variables (B = 0.408, BCa 95% CI: 0.279-0.526, p = 0.001), whereas the other postural variables did not. Conclusions: Among the evaluated 3D postural variables, trunk lean showed a consistent association with FHP magnitude in adolescents. However, this relationship should be interpreted cautiously because FHP and trunk lean share the shoulder landmark in their measurement definitions. These findings support consideration of sagittal trunk alignment when characterizing postural patterns associated with FHP in adolescents.