1
Title: The relationship between the mechanical properties of heel-pad and common clinical
2
measures associated with foot ulcers in patients with diabetes
3 4
Authors:
5
Panagiotis E. Chatzistergos(1)(*), Roozbeh Naemi(1), Lakshmi Sundar(2), Ambadi Ramachandran(2) and
6
Nachiappan Chockalingam(1)
7 8
(1) CSHER, Faculty of Health Sciences, Staffordshire University, Stoke-on-Trent, United Kingdom.
9
(2) AR Diabetes Hospitals, Chennai, India
10 11
(*)
Corresponding author,
12
CSHER, Faculty of Health Sciences, Staffordshire University
13
Leek Road, Stoke on Trent ST4 2DF
14
tel.: +44 1782 295920
15
E-mail:
[email protected]
16 17 18 19 20 21 22 23 24 25 26 27
1
28
Abstract:
29 30
Aim: The present study aims at investigating the correlation between the mechanical properties of the
31
heel-pad of people with type-2 diabetes and the clinical parameters used to monitor their health and
32
also to assess ulceration risk.
33
Methods: A new device for the in-vivo testing of plantar soft tissues was built and pilot-tested. This
34
device consists of an ultrasound probe connected in series with a dynamometer. Loading is applied
35
manually using a ball-screw actuator. A total of 35 volunteers with type-2 diabetes were recruited and
36
the thickness, stiffness of their heel-pads as well as the energy absorbed during loading was assessed.
37
The participants with diabetes also underwent blood tests and measurements of Ankle Brachial Index
38
and Vibration Perception Threshold.
39
Results: Pearson correlation analysis revealed strong correlations between triglycerides and heel-pad
40
stiffness (r=0.675,N=27,p0.05).
Results
194 7
195
The results for both groups of volunteers are presented in table 1 while representative results in terms
196
of force/normalised deformation curves are shown in figure 3. As it can be seen the heel-pads of
197
volunteers of the two groups appear to exhibit different mechanical behaviour. In quantitative terms,
198
the heel-pads of the second group had a significantly higher stiffness (p=0.034, two-tailed) and a
199
significantly lower energy (p=0.007, two-tailed). Similar results were found for the normalised
200
stiffness and energy (p=0.001 and p=0.038 respectively). The participants of Group 1 showed a 38%
201
higher energy absorbed during loading (35% higher when normalised to the initial thickness) as
202
compared to Group 2. Furthermore Group 2 showed 36% higher stiffness (38% higher normalized
203
stiffness) as compared to Group 1. No statistically significant difference was found between the
204
groups in terms of thickness (p=0.985, two-tailed).
205 206
The Pearson correlation analysis revealed a medium strength positive correlation between stiffness
207
and FBS (r=0.408, N=29, p=0.043) (Figure 4a). Strong correlations were found between the level of
208
triglycerides of the volunteers with diabetes and the mechanical measurements (Figure 4b and Figure
209
4c). More specifically strong positive correlations were found between triglycerides and stiffness
210
(r=0.675, N=27, p
