This 3D-printed prototype of self-offloading insoles shows the array of arches to offload the high-pressure areas.
Researchers in the Department of Mechanical Engineering, Indian Institute of Science (IISc), in collabvoration with the Karnataka Institute of Endocrinology and Research (KIER), have developed a set of self-regulating footwear for persons with diabetes. The footwear—a pair of specially-designed sandals—developed by the IISc-led team is 3D printed and can be customized to an individual’s foot dimensions and walking style. Unlike conventional therapeutic footwear, a ‘snapping’ mechanism in these sandals keeps the feet well-balanced, enabling faster healing of the injured region and preventing injuries from arising in other areas of the feet. The footwear can be especially beneficial for people who have diabetic peripheral neuropathy, which leads to a loss of sensation in the foot and irregular walking patterns.
For example, a healthy person usually places their heel first on the ground, followed by the mid-foot and toes, and then the heel again—this gait cycle distributes the pressure evenly across the foot. But due to the loss of sensation, persons with diabetes may not always follow this sequence, which means that the pressure is unevenly distributed. Regions of the foot where the pressure exerted is high are at greater risk of developing ulcers, corns, calluses and other complications.
Most of the therapeutic footwear available in the market is ineffective at off-loading the uneven pressure exerted by the ‘abnormal’ gait cycle of persons with diabetes, the researchers said. To address this challenge, they designed arches in their sandals that ‘snap’ to an inverted shape when a pressure beyond a certain threshold is applied. “When we remove the pressure, [the arch] will automatically come back to its initial position—this is what is called self-offloading,” explained Priyabrata Maharana, PhD student in the Department of Mechanical Engineering, IISc. “We consider the individual’s weight, foot size, walking speed, and pressure distribution to arrive at the maximum force that has to be off-loaded.” Multiple arches have been designed along the length of the footwear to off-load the pressure effectively.
