The relationship between the mechanical properties of heel-pad and common clinical measures associated with foot ulcers in patients with diabetes

Abstract Aim The present study aims at investigating the correlation between the mechanical properties of the heel-pad of people with type-2 diabetes and the clinical parameters used to monitor their health and ulceration risk. Methods A new device for the in-vivo testing of plantar soft tissues was built and pilot-tested. This device consists of an ultrasound probe connected in series with a dynamometer. Loading is applied manually using a ball-screw actuator. A total of 35 volunteers with type-2 diabetes were recruited and the thickness, stiffness of their heel-pads as well as the energy absorbed during loading were assessed. The participants with diabetes also underwent blood tests and measurements of Ankle Brachial Index and Vibration Perception Threshold. Results Pearson correlation analysis revealed strong correlations between triglycerides and heel-pad stiffness (r = 0.675, N = 27, p < 0.001) and between triglycerides and energy (r = − 0.598, N = 27, p = 0.002). A correlation of medium strength was found between Fasting Blood Sugar (FBS) and stiffness (r = 0.408, N = 29, p = 0.043). Conclusions People with type-2 diabetes and high levels of triglycerides and FBS are more likely to have stiffer heel-pads. Increased stiffness could limit the tissues’ ability to evenly distribute loads making them more vulnerable to trauma and ulceration.