An investigation of the relationship between plantar pressure distribution and the morphologic and mechanic properties of the intrinsic foot muscles and plantar fascia.

BACKGROUND: The purpose of this study was to investigate the relationship between plantar pressure distribution and the stiffness, thickness, and cross-sectional area of the plantar fascia (PF) and abductor hallucis (AbH), flexor hallucis brevis (FHB), and flexor digitorum brevis (FDB) muscles.
METHODS: The present study included a total of 41 healthy females between the ages of 20 and 34 years. Plantar pressure during static standing position was measured using a pedobarography system (MatScan, Tekscan, Inc., South Boston, Massachusetts, USA). Peak pressure, mean pressure, maximum force (Max-F), contact area (Con-A), pressure time integral, and force time integral (FTI) were measured. The thickness, cross-sectional area and stiffness of the intrinsic foot muscles and PF were measured using an ACUSON S3000 Ultrasound System and a 9L4 probe (4-9 MHz) (Siemens Medical Solution, Mountain View, CA, USA). Shear Wave Velocity (SWV) of the intrinsic foot muscles and PF was measured using a customized software program (Virtual Touch Imaging and Quantification; Siemens Medical Solution).
RESULTS: Con-A had a moderate correlation with the thickness and cross-sectional area of PF, AbH, FHB, and FDB. A fair to moderate correlation was found between heel Max-F and the thickness and cross-sectional area of PF, AbH, FHB, and FDB. There is no significant correlation between the SWV of the assessed tissues and plantar pressure distribution parameters. Body mass and BMI had a fair to good correlation with Mean-P, Con-A, heel Max-F, midfoot Max-F, metatarsal Max-F, FTI, thickness, and cross-sectional area of the PF and assessed muscles SIGNIFICANCE: The results suggest that abnormal force, contact area, and higher body mass may cause hypertrophy of the PF and foot intrinsic muscles.