shoe toe box shape and volume
background
Analysis of the effects footwear has on foot function
have previously focused on how changes in material
composition, design of heel counter, sole stiffness
and thickness and motion control alter whilst
wearing the shoe [1-4] . This body of research has
focused on running and athletic shoes and results
have highlighted that a stiffer heel counter reduces
rearfoot motion and improves comfort [5,6] . Sole
stiffness and thickness alter stability and balance [7-9]
and motion control has a varied impact on rearfoot
kinematics [6,10] . However, running and athletic shoes
are infrequently chosen by females for everyday use
[11]
. Current research suggests that footwear related
pain in the general population is dominated by
females who associate up to 60% of foot pain to the
shoes that have been worn with the elderly female
population reporting a high association between ill-
fitting footwear and foot pain [12] .
The concept of ill-fitting footwear for females within
published literature often leads to the assumption
that joint pathologies and deformities are caused
by wearing high heels. It is widely reported that
the use of a heeled shoe for a prolonged time can
have detrimental effects on foot health [13-15] . Studies
investigating the effects of heel height have primarily
focused on the influence of heel elevation on plantar
pressure and triceps surae function rather than
any other characteristics this shoe type imposes.
Furthermore, these reported changes in increased
forefoot pressure and altered triceps surae function
do not directly identify the impact high heeled
shoes have on toe deformities. Shoe toe box shape
and volume may have a similar impact on foot
health than the height of the heel. Reduced volume
in the toe box causing cramping of the toes has
been associated with foot deformities including the
development of joint pathologies and forefoot lesions
40
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. Hammer toe deformity where the interphalangeal
joint is often prominent, may cause pain and callus
due to irritation from shoe wear [16] . Increases in
forefoot plantar pressure have been associated with
the development of metatarsalgia, callus formation
and increased risk of ulceration under the metatarsal
heads [17-20] . Treatment of these lesions should provide
symptomatic relief and alleviate the underlying
mechanical cause yet continuation of ill fitting
footwear will ensure these painful conditions persist
[21]
.
[12]
Most soft tissue lesions can be managed
conservatively by the use of shoes with a good fit
and appropriate padding to redistribute pressure.
Offloading pressure does in fact represent an
indispensable precondition both for encouraging the
tissue-repair mechanism, where active lesions are
present, and for stopping the potential progression
of pre-ulcerative conditions toward lesions. Previous
studies indicate that for the site to be off loaded
effectively, peak pressures needs to be below 99
N/cm2 [22,23] . However, Pressure–time Integral is
thought to have a greater role in lesion pathogenesis
as the length of time that pressure is applied can be
significant in the formation of pathology [20,24] .
The forefoot has been highlighted as the most
frequent area of pain in subjects who have foot
pain related to footwear. Furthermore, subjects who
had pain in the forefoot associated that pain with
the footwear worn and had a significantly larger
circumference of the foot than the subjects without
any pain [12] . Other studies report similar findings
around forefoot shape and fit, in particular the width
fitting of shoes worn by two thirds of elderly females
has been shown to be too narrow at the toe box
[25,26]
. This altered fit and disparity between forefoot
shape and shoe volume are thought to significantly
contribute to the development of toe deformities and