Exploring the associations of femoral neck anteversion and alpha angle with dynamic muscle function patterns in soccer players: a functional principal component analysis.

In this exploratory cross-sectional study, the influence of femoral neck anteversion (FNA) and alpha angle on qualitative patterns of dynamic hip muscle function was investigated in male soccer players on qualitative patterns of dynamic hip muscle function was investigated in male soccer players. Twenty-six male field players underwent magnetic resonance imaging and isokinetic dynamometry (180°/s) to obtain hip torque-angle curves. Functional principal component analysis extracted principal patterns of variation (PCs), and Spearman's correlation determined associations between morphology and PC scores. FNA was significantly and negatively correlated with the third Principal Component (PC3) score during adduction of the preferred kicking leg (ρ = -0.57, p = .004). PC3 reflected the mathematical degree of bimodality; thus, higher anteversion (less retroversion) was associated with a more unimodal (smoother) pattern. No significant associations were found for the alpha angle. In conclusion, FNA shows a strong association with a qualitative hip adduction torque strategy in soccer players. The bimodal pattern linked to femoral retroversion is hypothesised to represent a neuromuscular adaptation to skeletal constraints. While this 'morphology-function linkage' offers a new theoretical perspective for understanding injury risk, longitudinal validation is strictly required before these findings can guide individualised clinical screening or training programmes.