The effect of different subtalar joint pronation amounts on postural stability, function and lower extremity alignment in healthy individuals

Introduction: The prone foot posture has a negative effect on postural stability, function, and knee valgus, but to our knowledge, the contribution of the degree of pronation has not been examined. Methods: 39 participants aged 18–40, with Foot Posture Index (FPI) scores between 6–12 and without any pain complaints were included. Participants with 6–9 points were included in the pronation group (PG) (n = 19), and participants with 10–12 points were included in the hyperpronation group (HPG) (n = 20). Static and dynamic postural stability, Foot and Ankle Ability Measure (FAAM), and frontal plane projection angles (FPPA) were measured for all participants. Results: The initial data of the participants are distributed homogeneously. In the intergroup evaluation only FPI-1 (p = 0.001; p < 0.05), FPI-4 (p = 0.00; p < 0.05), FPI-5 (p = 0.00; p < 0.05) and FPI-T (p = 0.000; p < 0.05) scores were found significantly different. Conclusion: Pronation and hyperpronation of the subtalar joint did not lead to a difference in postural stability, function, and knee valgus in healthy individuals. It may be more beneficial to focus on the prone posture rather than the degree of pronation.