Spatiotemporal Gait Parameters and Static Balance Across Locomotor Conditions in Young Adults with Unilateral Flatfoot: A Cross-Sectional Comparative Study

Background/Objectives: Flatfoot (FF) may alter gait and postural control, but whether these differences vary across different locomotor conditions remains unclear. We compared gait and static balance in young adults with and without unilateral FF across locomotor conditions. Methods: This cross-sectional comparative study included 28 young adults classified into a unilateral FF group (n = 14) or a control group (n = 14). Spatiotemporal gait parameters, the primary outcomes, were assessed on an instrumented treadmill during preferred speed walking, running at 9 km/h, and uphill and downhill walking at ±10% grades. Static balance was assessed using center of pressure (COP) measures. Gait parameters were analyzed using a 2 × 4 repeated-measures ANOVA. Results: Group × condition interactions were significant for the involved single support phase (p = 0.042) and step width (p = 0.010). The involved single support phase was lower in the FF group during preferred speed walking (p = 0.003), and step width was greater during the three walking conditions (all p < 0.001) but not during running. Averaged across conditions, the FF group showed a greater uninvolved stance phase (p = 0.017) and shorter step and stride lengths (all p < 0.05). COP path length was greater in the FF group (p = 0.005). Conclusions: Gait differences in unilateral FF were observed across specific gait parameters and locomotor conditions rather than as a uniform pattern. These exploratory findings suggest that considering multiple locomotor conditions and both limbs may provide additional descriptive information when characterizing gait in unilateral FF.