Plantar pressure distribution in the evaluation and differentiation of flatfeet.

Background: Although foot diseases are common, only a few studies have detailed the biomechanical and anatomical components of each disorder. The most reliable diagnostic tool for flatfoot is X-ray radiography. Achieving a similar accurate and objective diagnosis using another assessment tool, such as plantar pressure measurements, can be more convenient in clinical practice.

Research Question: To identify foot plantar pressure characteristics that primarily detect flatfoot based on X-ray, which addresses the use of such assessments for flatfoot diagnosis. In addition, to compare between the normal foot, flatfoot with positive Foot Posture Index-6 (FPI), and flatfoot with positive FPI and radiographic measures.

Methods: Sixty-two feet were examined from healthy female subjects aged 20.38 ± 1.10 years. According to the results of FPI and X-ray, each sample was assigned to one of the three groups (normal: negative FPI; FPI+: FPI ≥ +6; X-ray and FPI+: Arch Angle ≥ 165°, CP ≤ 12.3° and FPI ≥ +6) and compared using plantar pressure variables.

Results: As per normal group compared to X-ray and FPI+ group, there was a significant difference in the surface area (P-value: 0.01, 95 % CI: -26.58 to -3.62), force (P-value: 0.04, 95 % CI: -10.37 to -0.09), and pressure (P-value: 0.01, 95 % CI: -56.78 to -6.35) in the medial foot. Similarly, the arch index among the normal group and the X-ray and FPI+ group showed significant differences (Static AI; P-value: 0.003, 95 % CI: -0.21 to -0.04).

Conclusion: There was a significant difference in plantar pressure between the normal feet and flatfeet with positive FPI and X-ray in the medial foot area.

Significance: To attain a consensus among diagnostic approaches to identify flatfoot, the combined comparison of observational, foot pressure, and radiographic methods that have shown considerable reliability can be useful for clinical practice.