A quantitative comparison of plantar soft tissue strainability distribution and homogeneity between ulcerated and non-ulcerated patients using ultrasound strain elastography.

The primary objective of this study was to develop a method that allows accurate quantification of plantar soft tissue stiffness distribution and homogeneity. The secondary aim of this study was to investigate if the differences in soft tissue stiffness distribution and homogeneity can be detected between ulcerated and non-ulcerated foot. Novel measures of individual pixel stiffness, named as quantitative strainability (QS) and relative strainability (RS) were developed. Strain Elastography data obtained from 39 (nine with active diabetic foot ulcers) patients with diabetic neuropathy. The patients with active diabetic foot ulcer had wound in parts of the foot other than the first metatarsal head and the heel where the elastography measures were conducted. RS was used to measure changes and gradients in the stiffness distribution of plantar soft tissues in participants with and without active diabetic foot ulcer. The plantar soft tissue homogeneity in superior-inferior direction in the left forefoot was found to be significantly (p < 0.05) higher in ulcerated group compared to non-ulcerated group. The assessment of homogeneity showed potentials to further explain the nature of the change in tissue that can increase internal stress. This can have implications in assessing the vulnerability to plantar soft tissue damage and ulceration in diabetes.

Differences in the mechanical characteristics of plantar soft tissue between ulcerated and non-ulcerated foot.

AIMS: The purpose of this study was to investigate the differences in mechanical properties of the plantar soft tissue between the ulcerated and non-ulcerated feet in patients with diabetic neuropathy. METHODS: Thirty nine patients who met the inclusion criteria participated in this study. Ten out of 39 participants had an active ulcer at a site other than the plantar heel and the first metatarsal head. Real time ultrasound elastography was performed to measure the soft tissue thickness and stiffness of the heel pad and sub-metatarsal fat pad. To account for the qualitative nature of conventional real time elastography, relative tissue stiffness was assessed against that of a standardised ultrasound standoff material. RESULTS: The results indicated that the ulcerated group had a significantly lower heel pad relative stiffness (t (37)=2.559, P=0.015, η2=0.150) in the left foot. CONCLUSIONS: The observed difference in the stiffness of the heel pad between the ulcerated and non-ulcerated feet indicates a possible link between tissue mechanics and ulceration. Further analysis of the data proposed in this study provided a quantitative assessment of plantar fat pad deformability which can contribute to understanding the role of tissue biomechanics in ulceration.

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

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.