Instrumented Footwear to Measure Plantar Tissue Properties

Abstract

The prevalence of diabetes is increasing in the United States, and the lack of a cure makes it imperative to manage symptoms to prevent overall health from worsening. Diabetes-related foot complications include peripheral neuropathy and ulceration. Greater understanding of the biomechanical changes to the foot soft tissue can help inform clinicians on better care and also guide the design of diabetic footwear and orthoses. To improve understanding, researchers have conducted various studies on diabetic feet. In vivo studies that used ultrasonography often had test subjects in static positions. In cases where test subjects ambulated, radiography was used to image soft tissue, exposing test subjects to ionization. To overcome these limitations, an instrumented shoe was designed and developed to capture the dynamic properties of plantar soft tissue during gait. The footwear, developed with additive manufacturing in mind, was equipped with a custom ultrasound probe and four load cells, which provided displacement and force data, respectively. The sensors went through validation tests that confirmed accurate data collection. A pilot study was done on a test subject walking on a treadmill. Several trials were conducted to collect data at the heel and forefoot. The displacement and force data were used to create force-deformation curves to help inform soft tissue deformation, peak force, tissue stiffnesses, and energy dissipation ratio. The data were comparable to the literature. Though the pilot study only used one test subject, the instrumented shoe demonstrated its ability to collect viable data. However, the footwear durability was in question. Improvements to the data collection process and further refinement of the footwear are necessary to make a reliable instrumented footwear.