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R E S E A R C H Open Access
The effect of shoe toe box shape and volume on
forefoot interdigital and plantar pressures in
healthy females
Helen Branthwaite
1*†
, Nachiappan Chockalingam
1†
and Andrew Greenhalgh
1,2†
Abstract
Background: Ill-fitting footwear can be detrimental to foot health with the forefoot being an area for most
discomfort. Studies on footwear have primarily examined sports or orthopaedic prescription shoes and little is
known about the effects that everyday flat shoes have on the forefoot. The aim of this study was to investigate the
effect of toe box shape in a popular slip-on pump on dorsal and plantar pressures with particular interest around
the forefoot in a healthy female population.
Method: A convenience sample of 27 female participants with no known foot pathologies was recruited. After
assessment of foot size, plantar foot pressure and interdigital pressures were recorded for each of the 3 different
toe box styles; round, square and pointed. Participants walked at a self-selected speed over a 10 m walkway whilst
wearing each of the 3 styles of shoe and also whilst barefoot. Processed and analysed data extracted included peak
pressure, time to peak pressure, contact time and pressure time integral. ANOVA and Freidman analysis was used to
test for statistical significance.
Results: Shoes with a round toe showed least pressure around the medial aspect of the toes whilst the pointed
shoe had least pressure on the lateral toes. Contact times for the plantar regions were not altered in any shoe
condition yet contact around the medial aspect of the toes was highest in the pointed shoe.
Conclusion: This study highlights that the shape of the toe box in footwear can significantly influence the amount
of pressure applied to the forefoot. Furthermore, the contours of the shoe also have an impact on the contact time
and pressure time integral around the forefoot and also the peak plantar pressure in the toe region. The changes
observed could be significant in the development of pathology in certain footwear toe box shapes. Consideration
should be given to footwear design around the toe box to improve fit and reduce pressure. Further work is
required to investigate the effect of toe box shape and volume on a pathological population with pressure related
lesions.
Keywords: Foot pressure, Shoe shape, Digital pressure, Footwear, Toe box
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 im-
proves comfort [5,6]. Sole stiffness and thickness alter
stability and balance [7-9] and motion control has a var-
ied impact on rearfoot kinematics [6,10]. However, run-
ning 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].
* Correspondence: h.r.branthwaite@staffs.ac.uk
†
Equal contributors
1
Centre for Sport, Health and Exercise Research, Faculty of Health Sciences,
Staffordshire University, Leek Road, Stoke on Trent ST4 2DF, UK
Full list of author information is available at the end of the article
JOURNAL OF FOOT
AND ANKLE RESEARCH
© 2013 Branthwaite et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Branthwaite et al. Journal of Foot and Ankle Research 2013, 6:28
http://www.jfootankleres.com/content/6/1/28
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 [12]. Hammer toe de-
formity where the interphalangeal joint is often promin-
ent, 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 meta-
tarsal 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].
Most soft tissue lesions can be managed conservatively
by the use of shoes with a good fit and appropriate pad-
ding to redistribute pressure. Off loading 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 pro-
gression of pre-ulcerative conditions toward lesions. Pre-
vious studies indicate that for the site to be off loaded
effectively, peak pressures needs to be below 99 N/cm
2
[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 particu-
lar the width fitting of shoes worn by two thirds of eld-
erly females has been shown to be too narrow at the toe
box [25,26]. This altered fit and disparity between fore-
foot shape and shoe volume are thought to significantly
contribute to the development of toe deformities and
the persistence of symptoms that require clinical inter-
vention [27]. Changes in footwear from narrow fitting
shoes to a broader walker style have shown to reduce the
incidence of foot pain [28]. Education on the ill-effects of
tight fitting footwear is poor and research indicates that
footwear in the younger population is influenced by fash-
ion and colour [29,30]. Footwear choice in young females
is determined by the activity that is planned with high
heels being chosen for socialising, boots for warmth and
flat ballet pumps for school [11].
This study aimed to investigate differences in toe box
volume and shape with a particular focus on peak pres-
sure, time to peak pressure, total contact time and pres-
sure time integral around the dorsal aspect of the
forefoot and defined plantar foot regions in a healthy
young female population with no known foot pathology.
Methods
Participants
27 asymptomatic healthy females were recruited from a
convenience sample with an average age of 22.5 (+/−
4.5) years, body mass of 63.3 (+/−8.9) kg, height of 1.64
(+/−0. 6.5) m, shoe size UK 5.5 (+/−0.8). All recruited
subjects gave full consent to participate in the study.
Ethical approval was sought and granted from Stafford-
shire University ethics committee. All subjects included
in the study were asymptomatic at the time of testing
and were excluded if any musculoskeletal foot patholo-
gies were present, particularly in the forefoot for ex-
ample: hallux valgus, lesser toe deformities and fifth
metatarsophalangeal joint deformities.
Foot sizing measurements for foot length were taken
using a Brannock device® to match the foot tested with
the appropriate footwear size. A subjective assessment
for footwear fitting and comfort was conducted for each
subject prior to testing in that shoe. Three types of foot-
wear were used within this study. The key difference in
the 3 footwear styles tested was the shape and dimen-
sions of the toe box: square, round and pointed toe
(Figure 1). Colour and design were controlled by includ-
ing black ballet pumps with an accessory feature on the
toe box. Subjects were blinded to the brand of the foot-
wear by removing all labelling. Sole thickness and mater-
ial were assessed and closely matched, however
differences in sole material were present. The volume of
each shoe’s toe box was measured by calculating the
average quantity of fine sand that filled the shoe to a
level where the toe box upper finished (Figure 1).
Data collection
Plantar foot pressure was measured for each shoe condi-
tion as well as a barefoot condition using a 1 m pressure
plate (Footscan®, RsScan Olen, Belgium). The plate was
built into the walkway and placed 4 m along a total
length of 10 m. This enabled the subjects to attain a
normalised walking speed prior to data capture and prevent
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stepping onto the plate [31]. The plate was calibrated to
each individual participant’s body weight prior to data col-
lection. Each condition was tested in a randomised order
determined prior to data collection with subjects choosing
a folded card identifying the order of the test condition.
There were two successful walking trials collected for bare-
foot, square shoe, round shoe and pointed shoes.
Interdigital and dorsal pressure was collected se-
parately using Walkinsense® (Tomorrow Options Micro-
electronics, Portugal). See Figures 2 and 3. This new
system allows for individual sensors to be located any-
where on the foot and has been previously validated
[32]. Eight piezoresistive force 100Hz sensors were indi-
vidually secured with adhesive tape (Micropore™) to the
following landmarks (Figure 3):
(i) medial border of the 1st metatarsophalangeal joint,
(ii) medial border of the 1st interphalangeal joint,
(iii)interdigital (1/2, 2/3, 3/4, 4/5)
(iv) proximal interphalangeal joint,
(v) 5th proximal interphalangeal joint
(vi) lateral border of the 5th metatarsal head
Footwear was tested in the same randomised order as
the plantar pressure and data were collected from self se-
lected walking speed over a 10 m walkway. Barefoot data
was not captured for interdigital and dorsal pressures as
recordeddataisonlycapturedwhilstpressureisexerted
on the sensor. Data was captured for a whole gait cycle
and the overall pressure was analysed from footstep 3 and
6, these were identified to represent normal walking [33].
Data processing and analysis
Plantar pressure data from the pressure platform and
dorsal and interdigital pressure data from sensor place-
ment pressure measurement system were averaged and
processed to obtain the following measures: peak pres-
sure, time to peak pressure, contact time and pressure
time integral. These measures were assessed for each of
the 8 individual sensors and for the 10 anatomical areas
of the plantar pressure recording (heel lateral, heel
medial, midfoot, metatarsal 1,2,3,4 and 5, 1st digit and
toes 2–5) [34].
Processed data was then statistically analysed using
SPSS ver.19 (IBM, USA). Each data set was assessed
for normalcy and those test conditions meeting all
parametric assumptions were statistically analysed using
a one way repeated measures analysis of variance
(ANOVA). Test conditions that failed to meet all as-
sumptions for parametric testing were analysed using
the non parametric alternative Freidman Test with
significant results being further analysed with a post
hoc Wilcoxon Signed Rank Test with a Bonferroni ad-
justed alpha value.
Size Toe box Round
A
Square
B
Point
C
4Volume36 47 44
Width 7.4 7.6 7.5
Depth 3.8 4.5 6.5
5Volume45 55 60
Width 7.6 8.0 7.7
Depth 4.1 5.0 7.0
6Volume50 60 60
Width 7.9 8.2 8.0
Depth 4.2 4.9 7.0
7Volume54 73 68
Width 8.3 8.5 8.2
Depth 4.9 5.4 7.0
A
B
C
Figure 1 Three toe box shapes, (A) round, (B) square and (C) pointed. All shoes were a slip on flat pump. The volume of each shoe was
measured using the indicated shoe width and upper for definition of toe box, highlighted by white arrows. The table indicates the volume (cm
3
),
width and depth (cm) of the toe box for each shoe size tested.
Branthwaite et al. Journal of Foot and Ankle Research 2013, 6:28 Page 3 of 9
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Results
The volume for each shoe tested varied between style
and size (Figure 1). The round shoe shape had the least
volume in the toe box across all sizes and the square
toed shoe had the highest volume except in size 5.
Peak pressure
Statistical tests showed a significant difference between
shoe conditions for peak pressure at sensor 1, 2, 3, 4, 7
and 8 with the round shoe condition producing the least
amount of pressure for sensor 1, 2, 3, 4 and 8. The pointed
shoe applied the least pressure over sensor 6 and 7 which
were applied on the fifth digit, with the square shoe pro-
ducing the most pressure over this digit. Mean plantar
peak pressure was significantly different across all masked
areas of the foot with the exception of the second metatar-
sal where no difference was observed. Pointed shoes
demonstrated the highest peak plantar pressure at the
medial heel yet this shoe condition was the lowest pres-
sure value for the toe regions (Tables 1 and 2).
Time to peak pressure
Results from sensors 2, 4, 5 and 8 demonstrated significant
differences, with the round shoe condition demonstrating
an earlier time to peak pressure in all 8 sensors. Plantar
foot regions demonstrated exhibited similar time to peak
pressure in all of the masked regions however there was a
significant difference between the barefoot condition and
all shoe conditions (Tables 1 and 2).
Contact time
Sensors 2, 3, 4 and 5 and the toe regions showed signifi-
cant differences in contact time, whilst all other sensors
and plantar foot regions showed no differences between
shoe shape and barefoot conditions. The square shaped
shoe and pointed shoe was where the significance fell with
a pointed shoe being in contact with the foot for longer
periods of time on the dorsal aspect of the foot and the
square shoe being in contact with the toes two - five in the
plantar aspect of the foot.
Pressure time integral
Sensors 2, 3, 4 and 8 showed variable significant differ-
ences between the pointed shoe having a higher pressure
time integral at 2, 3 and 4 and the round shoe being sig-
nificantly lower at sensor 8. The midfoot region, first toe
Figure 2 Walkinsense equipment. Sensors are 1 cm
2
and <1 mm
thick.
1
8
7
6
5
4
3
2
Figure 3 Sensor placement 1–8 starting at the medial aspect of
the 1st metatarsophalangeal joint and finishing on the lateral
aspect of the foot at the 5th metatarsophalangeal joint.
Branthwaite et al. Journal of Foot and Ankle Research 2013, 6:28 Page 4 of 9
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and toes −2-5 were areas that also showed a significant
difference between conditions, with variance lying be-
tween the pointed shoe at the midfoot (having a significant
lower pressure time integral than the other conditions)
and the square shoe conditions. The barefoot condition
had a higher pressure time integral around the plantar re-
gion of the toes 2–5.
Discussion
The results of this study clearly indicate that the shape of
a shoe’s toe box has a significant impact on dorsal and
plantar pressures of the foot. Round toe shoes were shown
to produce less peak pressure around the medial aspect of
the foot, and the pressure time integral is also lower in this
region. Conversely, the pointed style of shoe distributed
Table 1 Interdigital and dorsal pressure results –mean (SD)
Round Square Point pvalue
Mean peak pressure (N/cm
2
)
Sensor 1 40.2(0.31) ‡57.85(0.34) 51.97(0.43) 0.017*
Sensor 2 16.67(0.24)§ 47.07(0.57) 48.05(0.47) 0.001*
Sensor 3 22.55(0.34) ‡§ 32.36(0.42) 39.22(0.48) 0.005**
Sensor 4 25.49(0.36) ‡§ 43.15(0.44) 45.11(0.44) 0.000*
Sensor 5 30.4(0.42) 38.24(0.41) 32.36(0.4) 0.134**
Sensor 6 57.85(0.45) 65.7(0.54) 50.01(0.37) 0.273*
Sensor 7 73.54(0.47)§ 89.23(0.51) 60.8(0.43) 0.001*
Sensor 8 34.32(0.29) ‡§ 57.85(0.3)†§ 83.35(0.44)†‡ 0.000*
Mean time to peak pressure (ms)
Sensor 1 190(0.19) 290(0.19) 260(0.19) 0.194*
Sensor 2 80(0.15)§ 160(0.19) 300(0.25) 0.011*
Sensor 3 150(0.21) 180(0.21) 230(0.23) 0.6**
Sensor 4 110(0.14)§ 190(0.17) 270(0.21) 0.008*
Sensor 5 160(0.17)‡§ 250(0.21) 240(0.2) 0.004**
Sensor 6 300(0.17) 340(0.19) 360(0.52) 0.038*
Sensor 7 280(0.13) 330(0.14) 290(0.15) 0.037*
Sensor 8 190(0.12)‡§ 300(0.13) 340(0.14) 0.000*
Mean total contact time (ms)
Sensor 1 610(0.36) 690(0.27) 640(0.19) 0.544*
Sensor 2 210(0.3) 210(0.23)§ 450(0.36) 0.003*
Sensor 3 220(0.26)‡§ 300(0.31)†§ 490(0.74)†‡ 0.003**
Sensor 4 300(0.36) 260(0.21)§ 450(0.33) 0.009*
Sensor 5 350(0.35) 430(0.38) 560(0.31)†0.029**
Sensor 6 590(0.33) 550(0.32) 590(0.67) 0.664*
Sensor 7 520(0.24) 520(0.19) 510(0.23) 0.893*
Sensor 8 420(0.24) 510(0.2) 540(0.19) 0.34*
Pressure–time integral (N/cm
2
/ms)
Sensor 1 15.54(17.01) 19.53(17.22) 17.06(19.54) 0.133*
Sensor 2 1.17(2.7) 6.32(10.64) 10.62(14.62)†‡ 0.001*
Sensor 3 3.24(6.97)‡§ 5.25(10.4) 8.64(14.33) 0.001**
Sensor 4 3.59(7.45) 7.01(10.27) 9.38(12.79)†0.001*
Sensor 5 7.07(13.83) 8.35(11.92) 9.23(15.76) 0.31**
Sensor 6 16.41(17.77) 18.5(23.1) 10.9(11.88) 0.56*
Sensor 7 17.97(18.87) 23.09(21.98) 15.7(18.13) 0.145*
Sensor 8 7.63(8.59)‡14.41(11.62)§ 18.45(16.19) 0.000*
* ANOVA.
** Friedman test.
†significantly different to round.
‡significantly different to square.
§ significantly different to point.
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Table 2 Plantar pressure results –mean (SD)
Barefoot Round Square Point pvalue
Mean peak pressure (N/cm
2
)
Heel –medial 19.29(7.42)§ 23.81(9.56)§ 22.47(11.09)§ 38.36(8.24) 0.000*
Heel –lateral 16.71(5.14)‡§ 17.45(7.08)‡§ 24.9(7.45)†§ 32.21(7.92)†‡ 0.000*
Midfoot 8.35(5.36)†§ 6.75(2.49) 8.29(4.01) 3.28(1.87) 0.000*
Metatarsal head 1 19.06(8.54)†‡§ 17.98(6.53) 15.05(5.93) 10.01(6.49) 0.000*
Metatarsal head 2 18.11(10.97) 18.89(10.23) 20.06(7.79) 21.79(8.23) 0.195*
Metatarsal head 3 17.16(9.3)†§ 18.85(11.7) 19.47(6.31) 24.06(10.61) 0.005*
Metatarsal head 4 17.79(7.57)†§ 23.99(12.99)‡§ 11.6(4)†§ 14.32(5.84)†‡ 0.000*
Metatarsal head 5 7.53(6.14)‡§ 16.67(12.74)‡§ 9.28(4.97) 5.41(2.99) 0.000*
Toe 1 24.4(18.8) 24.66(15.35) 12.27(6.28)§ 10.77(6.04) 0.000**
Toes 2-5 11.53(15.45)‡§ 15.78(15.09) 5.92(7.37)†§ 2.63(2.48) 0.000**
Mean time to peak pressure (ms)
Heel –medial 136.29(31.59) 139.4(97.94) 133.5(75.69) 115.63(64.6)†§ 0.000*
Heel –lateral 126.71(41.41)‡§ 129.67(62.78)‡§ 144.91(85.3)†§ 140.23(68.54)†‡ 0.000*
Midfoot 234.9(63.92)†‡ 290.98(97.43) 320.67(83.24) 234.51(66.64) 0.000*
Metatarsal head 1 490.82(139.71)†‡ 524.37(113.83) 512.25(67.26) 486.85(51.09) 0.000*
Metatarsal head 2 516.9(109.73) 515.53(109.21) 517.72(61.9) 517.59(45.53) 0.08*
Metatarsal head 3 497.34(108.83)†510.81(104.8) 479.37(66.1) 506.85(52.53) 0.002*
Metatarsal head 4 452.06(11.45)†‡ 462.91(104.35) 448.29(75.16) 471.97(67.76)†‡ 0.001*
Metatarsal head 5 350.09(174.91)‡§ 368.74(114.85)‡404.17(85.18) 402.79(92.98) 0.000*
Toe 1 595.71(116.74)†613.24(125.25) 525.59(144.43) 539.71(70.58) 0.006**
Toes 2-5 552.94(98.03)§ 490.09(179.56) 480.1(143.19)§ 510.43(93.12) 0.026**
Mean total contact time (ms)
Heel –medial 371.8(64.32) 410.31(106.4) 394.5(74.82) 387.83(68.15) 0.36*
Heel –lateral 365.9(62.3) 383.87(90.66) 395.04(77.02) 387.89(61.1) 0.109*
Midfoot 404.1(65.24) 421.81(82.7) 424.4(67.3) 388.54(79.95) 0.08*
Metatarsal head 1 491.3(112.34) 485.9(79.21) 479.26(84.9) 486.84(51.09) 0.42*
Metatarsal head 2 504.25(136.3) 514.5(108.83) 489.79(112.26) 518(69.69) 0.52*
Metatarsal head 3 533.74(106.8) 508.4(137.4) 525.09(62.56) 537.86(68.17) 0.24*
Metatarsal head 4 522.72(139.9) 547.2(106.3) 518.58(53.55) 540.45(56.58) 0.188*
Metatarsal head 5 502.61(96.28) 492.71(140.8) 484.95(82.6) 478.84(63.91) 0.79*
Toe 1 299.4(83.75)†§ 248.72(71.94) 279(115.1) 392.48(116.45) 0.000**
Toes 2-5 419.94(208.46)†§ 310.47(182.6) 453.87(214)§ 281.64(99.52) 0.003**
Pressure–time integral (N/cm
2
/ms)
Heel –medial 4.24(1.84) 5.35(2.31) 4.8(2.37) 8.38(2.91) 0.309*
Heel –lateral 3.58(1.26) 3.68(1.37) 5.42(1.71) 7.26(2.24) 0.642*
Midfoot 2.01(1.42)†§ 1.73(0.77) 2.19(1.07) 0.78(0.51) 0.000*
Metatarsal head 1 3.99(1.58) 3.71(1.58) 3.24(1.54) 2.17(1.55) 0.043*
Metatarsal head 2 4.27(2.79) 3.99(2.35) 4.31(2.02) 5.1(2.07) 0.999*
Metatarsal head 3 4.04(2.11) 4.37(3.25) 4.97(1.95) 5.91(3.22) 0.06*
Branthwaite et al. Journal of Foot and Ankle Research 2013, 6:28 Page 6 of 9
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the least amount of pressure in the lateral toe area. These
observations can be related directly to the dimension and
shaping of each the round and pointed shoe styles which
correlate to the natural anatomical contours of the foot.
However, the volume of the shoe was not correlated to
forefoot pressure, with the round shoe having the least
volume in the toe box across all shoe sizes tested and this
condition demonstrated the lowest pressure values. This
lack of correlation might be due to the stylised point of
the shoe. This pointed shoe has an extended length to the
normal foot contour, which increases the measured vol-
ume but does not alter the toe pressure due to lack of dir-
ect contact. The shape of the toe box therefore should be
considered as a cause of increased forefoot pressure and
not just the width of the shoe as previously mentioned as
a problematic design of ill-fitting footwear [12,25,26].
The dorsal digital area showed higher peak pressure
on the medial side of the foot whilst wearing a square
and pointed shoe shape, with the design of the shoes
encroaching on the natural shape of the first digit. Simi-
larly this correlation of shoe shape and foot shape was
also seen in the square toed shoe which exerted the
highest amount of peak pressure over the fifth digit. The
gradient of the lateral border of the toe box was similar
both in the square shaped and the pointed shoe. There
was greater variability regarding regional significance of
peak plantar pressure in the masked areas of the plantar
pressure with each shoe condition showing significance
at different regions of the foot. The sole material of each
shoe was not controlled within the study design and will
have altered plantar pressure distribution and results.
Although care was taken to choose three designs that
only differed by toe box shape it was difficult to replicate
the same sole characteristics. However, the round shoe
shape did consistently result in higher peak plantar pres-
sure within the forefoot region accompanied by lower
dorsal peak pressures around the medial forefoot. This
could be due to a lower recorded volume of the toe box
and possible cramping of the normal toe profile altering
toe function and plantar pressure during toe off.
It is also worth highlighting that the pointed shoe con-
dition produced a significantly higher peak plantar pres-
sure at the medial heel region than then other shoes.
The pointed shoe that was tested had a more flexible
heel counter compared to the other two shoe conditions,
this feature had not be controlled for, which could pos-
sibly explain the increased medial heel pressure due to
lack of structure.
The time to reach peak plantar pressure differed only
at the masked toe region with all shoe conditions redu-
cing the time to peak pressure compared to the barefoot
condition. The contact time for this region was also
lower for all shoe conditions excluding the shoes with a
square toe which resembled the barefoot condition. This
could be due to the stiffness of the sole of the shoe ra-
ther than the shape of the toe box which resulted in the
toe area having reduced contact. The dorsal aspect of
the foot around the fifth metatarsal and the first digit
were most different when wearing the pointed shoe with
increased time to peak pressure and contact in these re-
gions. This shoe shape intensifies pressure over the
border of the forefoot due to its angular shape.
There were significant differences between footwear
conditions when analysing the pressure time integral
data, which has been identified as significant when con-
sidering chronic tissue strain in the formation of callus
and other hyperkeratotic skin lesions [20,24]. The lateral
border of the foot around the fifth metatarsal and digit
exhibited the greatest differences when wearing the
pointed shoe with a lower pressure time integral. The
square shoe condition had the highest pressure time in-
tegral around this area. The fit of the foot in this style of
shoe due to its dimension and the lack of control for
heel to ball of foot measure could have induced this
higher result with the alignment of the toes differing be-
tween participants.
Clinical presentation of hyperkeratotic skin lesions
around the 5th digit could therefore be due to the shape
of the shoe toe box rather than the perception of
whether the shoe is a good fit or not. For example, a well
supported lace up shoe with a pointed or square toe box
may cause lateral irritation to the foot even though it is
deemed a good fit elsewhere.
The results of this study did not exceed the reported
peak pressure values of over 99Ncm
2
, which have been
acknowledged to be the threshold for tissue damage
Table 2 Plantar pressure results –mean (SD) (Continued)
Metatarsal head 4 5.18(2.66) 6.59(4.23) 2.97(1.15) 3.78(1.91) 0.396*
Metatarsal head 5 2.18(2.04) 2.32(3.39) 2.54(1.52) 1.31(0.85) 0.462*
Toe 1 3.08(2.39)‡§ 2.67(1.64) 1.24(0.82) 1.76(1.11) 0.001**
Toes 2-5 1.37(1.38) 1.48(1.57) 4.09(1.18)†§ 0.37(0.33) 0.002**
* ANOVA.
** Friedman test.
†significantly different to round.
‡significantly different to square.
§ significantly different to point.
Branthwaite et al. Journal of Foot and Ankle Research 2013, 6:28 Page 7 of 9
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[22,23]. The recorded forefoot pressures studied were
purposefully from a sample with no known pathological
foot problems to gather pre-pathology data. The inclu-
sion of toe deformities and forefoot pain may present
with differing results. There is, however, a lack of infor-
mation to define what quantity of pressure is required to
develop chronic responses to mechanical strain with the
common formation of hyperkeratotic callus, and further
studies into this area are recommended.
The fifth toe and interdigital fourth and fifth area are
common locations to develop focal chronic callus le-
sions. The results from this study suggest that the shape
of the toe box may play a part in the development of
such lesions with the lateral border of the forefoot
resulting in higher peak pressure and pressure time inte-
grals in the square shoe. An increase in pressure may be
attributed to the graduation of the toe box shape if does
not follow the anatomy of the foot. Changes to footwear
style may help to reduce the incidence of these common
problems and improve comfort for many females. Cases
have been reported where the fifth digit has been ampu-
tated to accommodate the foot in a desired shoe [35].
Further research into the impact of footwear styling at
the toe box on pathological feet is recommended.
Considering the results from this study, development
of shoe design needs to advance to encompass an ac-
cepted toe box for fashion as well as foot health. This
may involve the medial border of the shoe around the
1st metarsalphalangeal joint and the first toe being
designed in a round shape and the lateral border around
the 5th interphalangeal joint having a pointed graduated
shape. These style features could minimise peak pres-
sure, contact times and consequently pressure time inte-
gral in the forefoot. This style and shape of shoe is
infrequently seen in the market place with the majority
of footwear styles adopting a narrowed toe box with
equal shaping to the medial and lateral side of the shoe.
By limiting consumer choices on footwear shape people
are forced to choose footwear that has been shown to
alter pressure to the forefoot. Providing footwear choices
that do not impact on forefoot pressure could prevent
pathologies that are associated with ill fitting shoes.
There are limited studies to investigate the impact that
footwear shape and style have on foot pathologies how-
ever, there are strong links between foot pain and ill fit-
ting footwear especially in the elderly population [36].
Footwear choices are led by fashion and image rather
than health [11,29,30]. Changes in footwear design for
younger adults, to accommodate natural foot position
and shape, may be a useful way to help prevent painful
foot pathologies and deformities occurring prior to old
age.
The style of footwear investigated in this study was de-
termined by fashion and the most popular choice amongst
young females [11]. Although, the fit of the foot in the
shoe around the toe box may alter with increased heel
height, fastening of the shoe, shoe upper material and also
last shape, the conclusions outlined in this manuscript do
not address these factors. Further structured investigation
into quantifying the pressure under the upper is required.
Furthermore, there should be a detailed examination of all
shoe styles with varied toe box shapes. The pointed shoe
employed within this investigation was longer in the toe
box region than the square and round shoe and therefore
had an increased volume. The styled extension of this toe
box may have masked the actual fit of the foot inside the
shoe. This might require further scientific study of the re-
lationship between design and function. In addition to
this, studying a population with foot pathology will help in
understanding the contribution footwear style makes to
development of foot disorders.
Conclusion
The shape of the toe box can alter the pressure applied
to the forefoot around the digits and plantar aspect of
the foot in healthy young women with no known foot
pathology. Hence, footwear advice with reference to the
shape of the toe box is essential in the management of
pressure related lesions and when preventative measures
are being considered.
Competing interests
All authors involved in this manuscript can declare that they had no
competing interests.
Authors’contributions
HB led this study and was involved in the study design, data collection and
extraction including statistical analysis and prepared this manuscript. AG
wrote the code to extract and process all the raw data. NC was involved in
the design of the study and the preparation of the manuscript. All authors
reviewed and agreed on the final manuscript before submission.
Author details
1
Centre for Sport, Health and Exercise Research, Faculty of Health Sciences,
Staffordshire University, Leek Road, Stoke on Trent ST4 2DF, UK.
2
London
Sport Institute, School of Health and Social Science, Middlesex University,
Hendon NW4 4BT London, UK.
Received: 24 April 2013 Accepted: 24 July 2013
Published: 25 July 2013
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doi:10.1186/1757-1146-6-28
Cite this article as: Branthwaite et al.:The effect of shoe toe box shape
and volume on forefoot interdigital and plantar pressures in healthy
females. Journal of Foot and Ankle Research 2013 6:28.
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