Effects of total contact insoles on the plantar stress redistribution: a finite element analysis.
OBJECTIVE
To investigate the effects of total contact insoles on the plantar stress redistribution using three-dimensional finite element analysis.


METHODS
The efficacies of stress reduction and redistribution of two total contact insoles with different material combinations were compared with those of a regular flat insole used as a baseline condition.


BACKGROUND
Many specially designed total contact insoles are currently used to reduce the high plantar pressure in diabetic patients. However, the design of total contact insoles is mostly empirical and little scientific evidence is available to provide a guideline for persons who prescribe such insoles.


METHODS
To use three-dimensional finite element models of the foot together with insoles to investigate the effects of total contact insoles on the foot plantar pressure redistributions. Nonlinear foam material properties for the different insole materials and the contact behavior in the foot-insole interface were considered in the finite element analysis.


RESULTS
Results showed that the peak and the average normal stresses were reduced in most of the plantar regions except the midfoot and the hallux region when total contact insoles were worn compared with that of the flat insole condition. The reduction ratios of the peak normal stress ranged from 19.8% to 56.8%.


CONCLUSIONS
Finite element analysis results showed that the two sets of total contact insoles used in the current study can both reduce high pressures at regions such as heel and metatarsal heads and can redistribute the pressure to the midfoot region when compared with the flat insole condition.


CONCLUSIONS
It is possible to simulate foot deformities, change in material properties, different ambulatory loading conditions, and different orthotic conditions by altering the finite element model in a relatively easy manner and these may be of interests to the medical professionals who treat foot-related problems.
Chen
Weng-Pin
WP
Department of Biomedical Engineering, Chung Yuan Christian University, Chungli 320, Taiwan, ROC. wpchen@cycu.edu.tw
Ju
Chia-Wei
CW
Tang
Fuk-Tan
FT
D000328:Adult; D020342:Finite Element Analysis; D005528:Foot / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008422:Materials Testing; D011095:Polyethylenes; D011126:Polypropylenes; D011312:Pressure; D012775:Shoes; D013314:Stress, Mechanical
C016674:Plastipore; D011095:Polyethylenes; D011126:Polypropylenes