Product development of a customized insole and midsole

Abstract

Orthotic insoles are shoe inserts that podiatrists often recommend to address a variety of biomechanical deficiencies such as knee osteoarthritis. This is usually done by adding extra cushioning and support features. However, traditional methods to produce these insoles are time consuming and costly. There is a lack of literature regarding how 3D printed insoles with auxetic structures providing cushioning in the midsole affect the knee adduction moment, plantar pressure distribution and ground reaction force during gait. Therefore, the objective of this study was to design a customized 3D printed insole and midsole that aims to delay the onset of knee osteoarthritis via the positive correction of the aforementioned parameters. A single participant was involved in this study. A 3D scan of the participant’s right foot was used to design the customized insole and midsole via Computer Aided Design. Various auxetic structures and their parameters were explored before one was chosen for the design of the midsole. The insole was generated by a third-party software known as LutraCAD. The final designs achieved poor results in the reduction of Ground Reaction Force, mixed results in the reduction and distribution of plantar pressures, and poor results for the knee adduction angles.