Optimization of rocker sole footwear
An optimal apex position was then identified, from
descriptive statistics, as that which minimized pressures
for the largest proportion of individuals with diabetes.
This optimal position was taken to be the group-
optimized design. Given our focus on two separate
rocker angles (RA) and concerns over the aesthetics of
the larger rocker angle, a group-optimized design was
defined separately for the 15° and the 20° RA.
In order to address our second research question,
we first compared peak pressures between the group
optimized design (defined above) and a personalized
design. This personalized design was identified on
an individual participant basis as the apex position
the personalized design. Again, this was carried out
separately for the two different rocker angles in each
anatomical region.
Finally, in order to understand whether footwear
responses were similar between people with diabetes
and healthy individuals, we repeated the ANOVA
analysis (described above) on the healthy control
subjects. We also determined the group optimized
design for the healthy group. In addition, to compare
characteristics of the two groups, the mean peak
pressures (across all eight rocker shoe designs) were
compared between the patients with diabetes and the
healthy control group using an independent t-test.
Results
A total of 102 individuals (52 male) with medically
confirmed diagnosis of diabetes were recruited.
These participant had a mean (SD) age of 57 (9
years), weight of 87 (18) Kg and height of 170 (9)
cm. Loss of sensation at one foot site was identified
in 25 participants with and at 2 or more sites in 17
participants (according to [20] ). A further 66 healthy
individuals (36 male) were recruited. There were no
differences in age, 56 (8) years or height, 173 (8) cm
between the healthy group and those with diabetes.
However, an independent t-test showed that the healthy
participants were of lower weight (p < 0.001, 74 (14)
Kg).
which corresponded to the minimum peak pressures
for that participant. This comparison, between group
optimized and personalized footwear, was carried out
separately for each rocker angle.
We then quantified the proportion of individuals
for which pressures were below the critical 200 kPa
threshold in both the group-optimized design and
42
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There was a clear trend for pressure to increase as
apex position was moved distally (Fig. 2a-c, Table 1).
This effect was consistent across the three anatomical
regions but was most pronounced in the 2-4th MTH
region, for which there were pairwise differences in
peak pressure between every apex position (Table 1).
There was also a significant main effect of rocker angle
in each anatomical region, with pressure decreasing
as rocker angle was increased from 15° to 20° (Fig.
2d-f, Table 1). No interactions were observed in either