Structural and functional predictors of regional peak pressures under the foot during walking

The objective of this study was to identify structural and functional facto rs which are predictors of peak pressure underneath the human foot during w alking. Peak plantar pressure during walking and eight data sets of structu ral and functional measures were collected on 55 asymptomatic subjects betw een 20 and 70 yr. A best subset regression approach was used to establish m odels which predicted peak regional pressure under the foot. Potential pred ictor variables were chosen from physical characteristics, anthropometric d ata, passive range of motion (PROM), measurements from standardized weight bearing foot radiographs mechanical properties of the plantar soft tissue, stride parameters, foot motion in 3D, and EMC during walking. Peak pressure values under the rearfoot, midfoot, MTH1, and hallux were measured. Heel pressure was a function of linear kinematics, longitudinal arch struct ure, thickness of plantar soft tissue, and age. Midfoot pressure prediction was dominated by arch structure, while MTH1 pressure was a function of rad iographic measurements, talo-crural joint motion, and gastrocnemius activit y. Hallux pressure was a function of structural measures and MTP1 joint mot ion. Foot structure and function predicted only approximately 50% of the va riance in peak pressure, although the relative contributions in different a natomical regions varied dramatically. Structure was dominant in predicting peak pressure under the midfoot and MTH1 while both structure and function were important at the heel and hallux. The predictive models developed in this study give insight into potential etiological factors associated with elevated plantar pressure. They also provide direction for future studies d esigned to reduce elevated pressure in ''at-risk" patients. (C) 1999 Elsevi er Science Ltd. All rights reserved.