An observational study on the relationship between Foot posture index and lower extremity alignment in participants with asymptomatic pronated foot

Abstract

A pronated foot is a condition in which the medial longitudinal arch (MLA) collapses or becomes lowered. Previous studies have suggested that a pronated foot may cause malalignment of the lower extremities, resulting in structural deficits during weight-bearing activities. The study aimed to observe the relationship between the Foot Posture Index (FPI-6) and lower extremity alignment in participants with asymptomatic pronated foot. Fifty feet, 25 subjects (13 women and 12 men, average age 25.08 ± 4.47 years, weight 64.65 ± 12.22 kg, height 165.01 ± 8.22 cm, and BMI 23.52 ± 3.13 kg/m2) with asymptomatic pronated feet were included in the study. Participants with Foot Posture Index (FPI6) scores between 6 to 12 were recruited to the study. The lower extremities were assessed with the degree of deviation of forefoot, rearfoot, 1st metatarsal dorsiflexion (1st MTP-DF), 1st hallux valgus (1st HV), Tibial torsion, Craig’s test, and Q-angle by goniometer. Statistical analysis was performed with Spearman correlation to examine the relationship between the variables. The results revealed a correlation between FPI-6 with rearfoot alignment during weight-bearing (rs = 0.488, p < 0.001***), Q-angle (rs = -0.396, p = 0.004**), and Craig’s test (rs = -0.280, p = 0.049*). No significant correlations were found in forefoot alignment, 1st MTP-DF, 1st HV, and Tibial torsion. The present study demonstrated that foot pronation is associated with alterations in lower extremity alignment, particularly in rearfoot alignment during weight-bearing, as well as changes in the Q-angle and Craig’s test measures. Pronation of the foot appears to influence the alignment of the hip, knee, and ankle joints. The clinicians should be aware that when addressing biomechanical imbalances or increased risk of lower extremity injuries, foot alignment should be examined as a contributing factor.