Direct digital manufacturing of orthopedic insoles from thermoplastic polyurethane

Diabetic patients progressively lose their sensation in their feet and subsequently are prone to develop sores. To prevent this, individually designed insoles with soft and stiff areas are used to support the foot and prevent excoriations. Up to date, these insoles are made manually and the layout relies on the experience of the orthopedic shoemaker. With the surge in diabetic cases, the demands on the orthopedic industry will increase. The production process of these insoles should be cheap and traceable; in addition, an evidence-based layout of insoles is going to be required by the health care system. The most promising production process for additive manufacturing of soft polymers is the selective laser sintering because of the high material quality and the total freedom of form. Thermoplastic polyurethane, a new type of flexible material for selective laser sintering, has recently entered the market. This material will be used to design structures with different stiffness. Specimens made by selective laser sintering are compared to numerical simulations.