Effects of a contoured foot orthosis and flat insole on plantar pressure and tibial acceleration while walking in defence boots

Daniel R Bonanno,Karl B Landorf,George S Murley,Ketharasarma Ledchumanasarma,Hylton B Menz,Shannon E Munteanu

doi:10.1038/s41598-018-35830-5

Abstract

This study investigated the effects of a contoured, prefabricated foot orthosis and a flat insole on plantar pressure and tibial acceleration while walking in defence boots. Twenty-eight adults walked along an 8-metre walkway in a: (i) defence boot (control condition), (ii) defence boot with a flat insole, and (iii) defence boot with a contoured foot orthosis. Plantar pressure data were collected using the pedar-X in-shoe system and tibial accelerations were measured with an accelerometer. In relation to plantar pressure under the rearfoot, the contoured foot orthosis, compared to the defence boot, decreased peak pressure and maximum force, and increased contact area. Under the medial midfoot, the contoured foot orthosis and flat insole increased peak pressure, maximum force and contact area. Under the medial forefoot, the contoured foot orthosis and flat insole increased maximum force. Under the lateral forefoot, the contoured foot orthosis and flat insole increased contact area, with the flat insole also increasing maximum force. In relation to tibial acceleration, the contoured foot orthosis, compared to the defence boot, decreased tibial peak positive acceleration. These findings provide novel biomechanical evidence for the effects of contoured foot orthoses in defence boots.

Highlights

Lower limb overuse injuries are common among physically active defence personnel[1,2,3], with the incidence reported to range from 10 to 47% during initial defence training[2,4]
The aim of this study was to investigate the immediate effects of a contoured, prefabricated foot orthosis and a flat insole on plantar pressure, tibial acceleration and comfort while walking in defence boots
Our findings indicate that, compared to the defence boot only condition, the contoured foot orthosis provided a medium to large reduction on plantar pressure under the rearfoot, medium to very large increases in contact area and plantar pressures under the medial midfoot, and small increases in force under the medial forefoot and hallux

Summary

Introduction

Lower limb overuse injuries are common among physically active defence personnel[1,2,3], with the incidence reported to range from 10 to 47% during initial defence training[2,4]. Laboratory-based studies have demonstrated that wearing defence boots can alter lower limb kinematics and have deleterious effects on lower limb tissue loads and impact forces when compared to athletic footwear[14,16]. Shock-absorbing insoles or foot orthoses are often used in defence boots to improve comfort[17], reduce impact forces[18], and to alter lower limb function[14,16,17,18]. A recent systematic review concluded that prefabricated foot orthoses, but not shock-absorbing insoles, can decrease the incidence of overall lower limb injuries and lower limb stress fractures during initial defence training[19]. The primary aim of this study was to evaluate the effects of a contoured, prefabricated foot orthosis on plantar pressure and tibial acceleration while walking in defence boots. Our objective was to provide insights into the possible mechanisms by which contoured foot orthoses may reduce the risk of lower limb overuse injury in defence personnel

Objectives

Results

Conclusion