MECHANICAL CHARACTERISATION OF INSOLE MATERIALS USED FOR DIABETIC INSOLE ORTHOTICS

摘要

When podiatrists and orthopaedic technicians prepare individualised insoles for treating a patient with neuropathic foot ulcers they need to choose the different polymers available which basically can be grouped into polyurethane (PUR), ethylene vinyl acetate (EVA), polyethylene (PE) and polyvinylchloride (PVC), vulcanised rubber, etc. basing on their polymeric nature. All of them are foamed materials and the first three are the most frequently used. In many cases this choice is made subjectively because there is a lack of information on the mechanical properties of each material and even less information on their interaction. The functionality of the insole will depend on the mechanical properties of the combined materials used. Some of the targeted functions are cushioning, energy absorption, stiffness, adaptation to the foot sole, filling out empty spaces within the shoe and pressure relieve on the ulcered area. The purpose of this research was to provide objective criteria for selecting insole materials, basing on their mechanical characterisation. Therefore the mechanical properties (apparent density, Asker hardness, resilience, stiffness, compression set, compression fatigue, water vapour permeability and perspiration resistance) of many commercially available insole materials and of different usual combinations were quantified using standardised methods.