The biomechanically verified additive is used to manufacture special insole for diabetic foot

Contributor: Yue Yinheng wang Ling

Supplier: State Key Laboratory of Mechanical Manufacturing System Engineering

The Centers for Disease Control and Prevention reports that the rate of lower limb amputations (LEA) due to complications that first occur in the foot is 18.4% for every 1,000 people with diabetes.But LEA is preventable and can be prevented by treating shoes or orthotic insoles.Due to the individualized difference of the patient’s foot, the batch made orthotic insole cannot adapt to every patient, so the additive manufacturing method can solve this problem.

Recently, researchers at Kocaeli University in Turkey scanned the feet with a 3D scanner and obtained a personalized insole model based on the foot model. The fused deposition (FDM) process was used to make a special insole for diabetic feet.Of FDM technology used by E – SUN polymer wire print samples with traditional ethyl vinyl acetate (EVA) samples for mechanical properties test, and the traditional FDM process printing of insole and EVA insoles in the walking process under different gait (standing, heel strike, flat feet, standing, heel off the ground) in the finite element analysis, optimized the FDM printing process, to ensure that the FDM process under the biomechanical function of diabetes foot insoles.

Mechanical properties experiments showed that the tensile stress of each 3D printed sample with different filling densities varied between 6.5 and 12.5 MPa.The tensile stress of EVA foam was 2.1mpa, lower than that of any 3D printed sample.

The results of finite element analysis show that under the same external force, with the increase of the filling density of the insole model, the material displacement decreases at each gait stage, while the equivalent stress increases.The results show that the insole model with a filling density of 30% has the same finite element analysis results as the EVA foam insole model, thus ensuring the biomechanical function of the additive in manufacturing the insole.

The traditional processing cost of the insole is $31.92 and the processing time is 15h. The fused deposition (FDM) manufacturing cost of a pair of dedicated insole is $6.88 and the processing time is 8h, which greatly reduces the cost and time.

References:

Peker A, Aydin L, Kucuk S, et al. Additive Manufacturing and Biomechanical ical validation of A patient-specific diabetic insole. Polym Adv Technol. 2020;1-9. https://doi.org/10.1002/pat.4832.