Monitoring and assessment of diabetic patients by Intelligent Footwear System

Abstract

Diabetes mellitus has become a major issue in public health. Diabetic peripheral neuropathy and foot ulceration in particular are major complications that can cause significant morbidity and mortality. Prevention of foot ulceration development is better than cure. Therefore, it is highly desirable for patients to have an additional artificial sense of pressure and signal that will send them a signal to protect the foot when abnormally high plantar pressure conditions occur. The Intelligent Footwear System-developed and patented by The Hong Kong Polytechnic University, can fulfill this by providing both long-term monitoring and alarm function for diabetic patients. The Intelligent Footwear System is real-time, dynamic and specifically based on patented textile pressure sensing arrays that can be used during activities in daily life. It has been validated with satisfactory accuracy (7.7%), repeatability (6.4%) and wearing comfort. The aim of this research was to find the threshold value of peak plantar pressure using the Intelligent Footwear System so that overloading diabetic feet could be avoided. Subject selection and requirements were settled after the relevant research had been reviewed. All the subjects were assessed by foot dimension, plantar sensation measurement and the wearing comfort of the Intelligent Footwear System was assessed by the use of a perception questionnaire. Two clinical trials were conducted on the Intelligent Footwear System in Kwong Wah Hospital. The first clinical trial involved a H group of 10 healthy subjects (male, 56±9.5yrs, 167.4±5.0cm, 67.6±9.2kg) and a DM group of 10 diabetic patients without peripheral neuropathy (male, 55.8±10.3yrs, 165.2±4.4cm, 71.2±10.0kg). There were no significant differences in age, height, weight, or gender between the two groups. This trial explored and identified differences of plantar pressure between the healthy and diabetic subjects in dynamic daily activities. Level ground corridor walking, up-slope walking and down-slope walking, and climbing up and down stairs with "the Shoes" on are were tested. There were significant differences in the plantar pressure distributions among these activities. This trial identified plantar regions where the statistics showed a significantly higher plantar pressure between the DM group the H group (p<0.005): left lateral forefoot (in corridor, slope and stairs activities), right lateral forefoot (in slope and stair activities), and left central forefoot (in slope activities). These areas over the 1st and 5th metatarsal heads are common sites of ulcerations observed in clinical practice. The second trial involved five high-risk diabetic patients with-high pressures concentrated on their forefoot and heel regions, especially in Metatarsal 1 (Ls7 and Rs7), where there is a very high risk of developing a diabetic ulcer. Protection is needed to prevent these subjects from damage. A threshold value of peak pressure is taken as a warning signal of developing diabetic ulcer. The threshold value of average peak pressure was identified as 580kPa, the same as the clinically defined threshold value of neuropathy. The medical doctor who participated in the study commented that there were obvious beneficial effects of continually monitoring the normal feet of high-risk patients and those monitoring helped feet to recover from ulcers. In general, the Intelligent Footwear System can monitor plantar pressure distributions during normal activities of daily living in order to protect the feet of diabetics.