Region-specific associations between Q-angle and plantar loading in physically active young adults

Quadriceps angle (Q-angle) is a static measure of lower-extremity alignment, but its relationship with dynamic plantar loading remains unclear. This study investigated the association between Q-angle and regional plantar pressure variables in physically active young adults. Ninety-two participants (34 males, 58 females; mean age 20.92 ± 1.42 years) were included. Bilateral Q-angle measurements were obtained three times using a standard goniometer, and plantar pressure variables were assessed with an Emed®-a50/D pedobarography system. Peak pressure, contact area, contact time, and maximum force (in Newtons and normalized to body weight) were analyzed for the toes, forefoot, midfoot, hindfoot, and total foot. Linear mixed-effects models were used to account for within-subject dependence between extremities, and false discovery rate correction was applied for multiple comparisons. Q-angle measurements showed excellent intra-rater reliability (ICC = 0.94 and 0.92 for the dominant and non-dominant sides, respectively). After multiple-testing correction, greater Q-angle was associated with lower contact area in the hindfoot, toes, and total foot; longer forefoot and toe contact times; lower absolute maximum force across all plantar regions; and lower toe peak pressure. No associations for maximum force normalized to body weight remained significant after correction. Sex-specific interaction analyses showed significant effects only for midfoot maximum force, whereas dominance-related interactions were not significant. Overall, the associations between Q-angle and plantar loading were region- and metric-specific rather than uniform across the foot. These findings should be interpreted cautiously given the cross-sectional design and the variability of associations across plantar-loading measures. Clinical trial registration: NCT07500597.