Finite Element Approach Towards Selection of Appropriate Materials to Redistribute Peak Plantar Pressure in Diabetic Foot with Neuropathy

Objective: The aim of this study was to assess the effect of customized insole (CMI) variations on plantar pressure in diabetic foot with neuropathy, using finite element analysis (FEA).

Material and Methods: A three-dimensional foot model was constructed using FEA to study the peak contact pressure between the foot and the CMI. Nora® Lunalastike, Ethylene Vinyl Acetate (EVA), Amfit® and TPU were chosen for insole materials; and from these eight CMI models were created. The top surface of the tibia and fibula were fixed, and a displacement of 3 mm was exerted from the ground along with upwards Achilles tendon force.

Results: The peak contact pressure contour showed that a softer material, CMI-A (E = 1.04 MPa), resulted in a better reduction of peak contact pressure compared to a stiffer material; CMI-D (E = 11 MPa). In addition, it was shown that the use of a single material to fabricate the CMI resulted in higher peak contact pressure; with the exception of CMI-A, in comparison to a dual-layer material of CMI-E and CMI-F. Using FEA, can effectively enhance the insole material selection process, without need of a trial and error practice in a clinical setting.

Conclusion: The use of dual materials to fabricate CMIs, with the softer material as a top layer, is beneficial compared to a stiffer top layer material in the reduction of peak plantar pressure for diabetic foot with neuropathy.