Lateral wedges - a crossover study
DISCUSSION
Findings from this study indicate that the
addition of custom foot arch support to
5-degree lateral wedges may result in clinical
improvements in knee and foot symptoms, and
timed stair climb, in people with medial knee
OA and pronated feet. However, these changes
were generally not statistically significantly
better than those observed with treatment by
lateral wedges alone. Further, more participants
subjectively preferred the supported lateral
wedges overall, compared to lateral wedges
alone. Data from this study provide important
preliminary clinical information regarding
safety and efficacy of combined insoles for the
treatment of an important sub-group of patients
with knee OA, namely those with concomitant
pronated feet.
Although no other research has specifically
evaluated effects of insoles in a subgroup of
people with knee OA and concurrent pronated
feet, our findings are consistent with the limited
research investigating combined lateral wedge
insoles with arch supports in heterogeneous
samples of people with knee OA. Indeed, a
previous uncontrolled study investigating a
similar insole design showed improvements in
pain and function in 42 individuals with medial
knee OA and varus knee alignment. Skou et al
showed that an insole that combined a custom-
made arch support with an individualized
amount of lateral wedging produced significant
improvements in pain, function, and quality
of life after an average of 7.75 months of wear
[30]. Specifically, they found greater than 40%
improvement, on average, in knee pain intensity
(measured using a visual analog scale) with the
combined insole. In the present study, a 30%
32
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"Taken together, these studies
show the potential for greater
improvement in knee pain with
a combined insole than with a
lateral wedge alone in people
with knee OA."
improvement in WOMAC pain was observed
with our combined insole, compared to only 12%
with the lateral wedges alone. Similar findings
have been reported elsewhere, with Jones et
al showing more immediate improvement in
knee pain with a combined insole compared to
a standard lateral wedge alone in people with
knee OA [21]. Taken together, these studies show
the potential for greater improvement in knee
pain with a combined insole than with a lateral
wedge alone in people with knee OA.
Although the combined insole resulted in
clinical improvements across all measured
parameters, and we observed no significant
effect on outcomes when participants were
treated with lateral wedges alone, there was
generally no statistically significant difference
in outcomes when comparing between insole
conditions. A larger sample size may have
produced statistically significant differences,
and results from this study can now be used
to guide sample size calculations for future
clinical trials. Importantly, though the lateral
wedges plus arch support produced more
symptomatic benefits over a two-month
period, biomechanical data from the current
cohort taken at the initial baseline assessment
indicates that both insoles produced similar
KAM reductions (albeit slightly larger reductions
in the lateral wedges alone) compared to a