Foot morphology influences the change in arch index between standing and walking conditions

Abstract

Human foot morphology has been of interest to anatomists, clinicians, and paleontologists for a century due to its importance in bipedal walking. Foot shape changes as forces move through it from the body to the substrate. Although the arch of the foot has been extensively evaluated, the role of foot morphology in the change of the arch height in walking is less explored. To remedy this lacuna, the Arch Indices (AIs) of the left and right feet of 77 people were calculated in double and single stance standing and walking (dynamic) conditions. The feet were categorized into clinical foot types (cavus, normal, planus). The change in static AI between double and single stance was used to predict dynamic AI and the difference between predicted and observed dynamic AI was examined. As expected, AIs increased (i.e., arch height decreased) with increasing load on the foot for the entire sample and each foot type (p’s > .001), but the ability of change in static AIs to predict dynamic AI varied among foot types, implicating the possibility of variability in foot mechanics among foot types. While planus feet change stiffness during walking, presumably due to muscular action, cavus feet are more variable in their response to load. Static and dynamic AIs are effective in reflecting the changes in foot stiffness that occur in walking and future work should examine the role of extrinsic muscle activation in this stiffness change.

An exploratory study of dynamic foot shape measurements with 4D scanning system

“…For deformation of height dimensions (IH, BH): The arches collapse with increased loads upon the foot during walking 64 , 65 . Arch pads and metatarsal pads, which accommodate the morphological plantar deformation during locomotion can ensure the plantar fully contact the insole for better distribution of plantar pressure.…”

Classification of foot type from podography: correlation of results between six quantitative assessment methods

“…Only the AI has cut-off points established among the three methods in the group of indexes using area for classification. Therefore, although the FI and the TAI have similar scores to the AI, it is not possible to determine if the same cut-point from the AI can be used for the other two (31)(32)(33) .…”

Relationships of three arch height indices related to different foot lengths between sitting and standing postures

“…Arch height index (AHI) between sitting and standing is an important reference in assessing foot mobility and foot classification in clinic of podiatry (Cowan et al, 1993;Yen et al, 1998;Kaufman et al, 1999;Williams et al, 2001;Lees et al, 2005;Franettovich et al, 2007;Xiong et al, 2010;Kramer and Lautzenheiser, 2022). AHI is usually defined as the dorsal arch height normalized to the total foot length (TFL), that is, the height of the medial longitudinal arch normalized by the total foot length (called AHI-TFL).…”