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Abstract

a case-control study was conducted to compare static plantar pressures and distribution of body weight across the two lower limbs, as well as the prevalence of gastrocnemius soleus equinus, in children with and without calcaneal apophysitis (Sever's disease). the participants were 54 boys enrolled in a soccer academy, of which eight were lost to follow-up. Twenty-two boys with unilateral Sever's disease comprised the Sever's disease group and 24 healthy boys constituted a control group. Plantar pressure data were collected using pedobarography, and gastrocnemius soleus equinus was assessed. peak pressure and percentage of body weight supported were significantly higher in the symptomatic feet of the Sever's disease group than in the asymptomatic feet of the Sever's disease group and the control group. Every child in the Sever's disease group had bilateral gastrocnemius equinus, while nearly all children in the control group had no equinus. high plantar foot pressures are associated with Sever's disease, although it is unclear whether they are a predisposing factor or a result of the condition. Gastrocnemius equinus may be a predisposing factor for Sever's disease. Further research is needed to identify other factors involved in the disease and to better understand the factors that contribute to abnormal distribution of body weight in the lower limbs.
ORIGINAL ARTICLES
Plantar Pressures in Children With and Without
Sever’s Disease
Ricardo Becerro de Bengoa Vallejo, DPM, PhD*
Marta Elena Losa Iglesias, PhD
David Rodrı
´guez Sanz, BS
Juan Carlos Prados Frutos, MD, PhD§
Paloma Salvadores Fuentes, PhD
Jose
´Lo
´pez Chicharro, MD, PhD*
Background: A case-control study was conducted to compare static plantar pressures
and distribution of body weight across the two lower limbs, as well as the prevalence of
gastrocnemius soleus equinus, in children with and without calcaneal apophysitis
(Sever’s disease).
Methods: The participants were 54 boys enrolled in a soccer academy, of which eight
were lost to follow-up. Twenty-two boys with unilateral Sever’s disease comprised the
Sever’s disease group and 24 healthy boys constituted a control group. Plantar pressure
data were collected using pedobarography, and gastrocnemius soleus equinus was
assessed.
Results: Peak pressure and percentage of body weight supported were significantly
higher in the symptomatic feet of the Sever’s disease group than in the asymptomatic
feet of the Sever’s disease group and the control group. Every child in the Sever’s
disease group had bilateral gastrocnemius equinus, while nearly all children in the
control group had no equinus.
Conclusions: High plantar foot pressures are associated with Sever’s disease, although
it is unclear whether they are a predisposing factor or a result of the condition.
Gastrocnemius equinus may be a predisposing factor for Sever’s disease. Further
research is needed to identify other factors involved in the disease and to better
understand the factors that contribute to abnormal distribution of body weight in the
lower limbs. (J Am Podiatr Med Assoc 101(1): 17-24, 2011)
Apophysitis, or inflammation of an apophysis, is
caused by microavulsions at the bone-cartilage
junction
1
resulting from repetitive motion and
overuse during periods of rapid growth. Calcaneal
apophysitis was first described in 1912 by Sever
2
and later given the name ‘‘Sever’s disease.’’ The
calcaneal apophysis is a cartilaginous growth center
onto which the Achilles tendon inserts.
3, 4
Kvist and
Heinonen
5
and Kim et al
6
refined the definition of
Sever’s disease to indicate a traction epiphysitis. It
is most commonly associated with sports that
involve running and jumping.
7-9
In a retrospective
study of 20 children with Sever’s disease, McKenzie
et al
10
found that all of the children participated in
such sports, mainly in track and field events and
soccer.
Sever’s disease has been reported to be the most
common cause of heel pain in athletic children.
8, 11
Orava and Puranen
12
and Orava and Virtanen
13
found that it comprises 16.3% and 22.7% of exertion
injuries in children, respectively. The heel pain
limits physical activity and may interfere with
*Escuela Universitaria Enfermeria, Fisioterapia y Podologia,
Facultad de Medicina, Universidad Complutense de Madrid,
Madrid, Spain.
Facultad de Ciencias de la Salud, Universidad Rey Juan
Carlos, Madrid, Spain.
Soccer Club Atle
´tico de Madrid, Madrid, Spain.
§Facultad de Medicina, Universidad Complutense de Madrid,
Madrid, Spain.
Corresponding author: Ricardo Becerro de Bengoa
Vallejo, DPM, PhD, Escuela Universitaria Enfermeria, Fisio-
terapia y Podologia, Facultad de Medicina, Universidad
Complutense de Madrid, Avenida Complutense s/n, Madrid,
28040 Spain. (E-mail: ribebeva@enf.ucm.es)
Journal of the American Podiatric Medical Association Vol 101 No 1 January/February 2011 17
activities of daily living. The condition is self-
limiting because the calcaneal cartilage disappears,
at about age 14 years in girls and 16 years in boys, to
allow for complete calcaneal ossification.
5
The
etiology of Sever’s disease is controversial,
14
and
proposed contributing factors include participation
in high-impact sports, improper footwear, running
on hard surfaces, and excessive pressures on the
plantar heel.
15
The condition is associated with
radiographic changes such as variations in the
normal ossification pattern.
8
Cessation of the high-
impact activity and thus reducing mechanical
overload at the affected heel is a standard compo-
nent of treatment.
16-18
We sought to investigate the relationship between
mechanical heel overload and development of
Sever’s disease by measuring static plantar pres-
sures of young athletes with and without Sever’s
disease. We also sought to determine the distribu-
tion of body weight between the two limbs and to
investigate its association with Sever’s disease. The
association between gastrocnemius soleus equinus
and Sever’s disease was also evaluated because of
the relationship found between gastrocnemius
soleus equinus and Achilles tendon thickening.
19
The calcaneal apophysis is a cartilaginous growth
center onto which the Achilles tendon inserts.
3, 4, 20
Haglund
21
titled his article ‘‘Concerning Some Rare
but Important Surgical Injuries Brought on by
Violent Exercise,’’ but he provided no justification
of how violent the exercise was. Many au-
thors
2, 5, 10, 12, 18, 22-27
have noted anecdotally that
affected children were active and vigorous and that
symptoms often presented at the beginning of the
sporting season and while the child was undergoing
a growth spurt. However, none of these studies
measured or reported the children’s actual activity
levels or provided evidence of growth spurts.
The plantar fascia originates from the medial
tubercle on the plantar aspect of the calcaneus, near
the attachment of the Achilles tendon to the
calcaneus, a secondary bony growth center, or the
epiphysis.
7, 28-30
Proximal to the epiphysis is the
apophysis, where the Achilles tendon actually
inserts. The apophysis has its own slower-growing
growth plate, separate from the physeal plate.
3, 4
The calcaneal growth plate and the apophysis are
situated in an area subject to high stress from the
plantar fascia and Achilles tendon
31
and may be
affected by increased tension on the calcaneus.
The main theory in the literature on the patho-
genesis of Sever’s disease is that it is an overuse
syndrome from repetitive microtrauma from in-
creased traction on the apophysis. This increased
traction is believed to be initiated by running and
jumping, which causes avulsion fractures on a tiny
scale followed by inflammation.
8, 20, 32-36
Because of
the rapid proliferation of cells in growth plates, the
apophysis is thought to be more susceptible to
injury.
37
Liberson et al
31
examined calcaneal apoph-
yses histologically and with computed tomography
and found fibrous bands in the cartilage perpendic-
ular to os calcis. This finding indicated powerful
stresses in the remodeling process, leading Liberson
et al
31
to suggest a traction-stress argument, where
pain is thought to occur when remodeling exceeds
certain rates.
The theory that tight triceps surae cause exces-
sive tension through the Achilles tendon, increasing
the traction on the apophysis, has been a commonly
cited mechanical factor in much of the litera-
ture.
1, 7, 8, 17-19, 32, 37-44
Studies
8, 18, 19, 32
that looked
at patients with Sever’s disease generally involved
assessment by multiple raters of foot dorsiflexion
on the leg, thereby reducing uniformity of measure-
ment and reliability of results. This omission calls
into question the existence of excessive tightness in
the triceps surae at all. No studies have compared
whether symptomatic patients are tighter in the
triceps surae than their asymptomatic counter-
parts.
45
References to biomechanical influences in Sever’s
disease are scattered throughout the literature.
However, neither prospective systematic measure-
ment of the feet of those identified with Sever’s
disease nor comparison to an asymptomatic popu-
lation has been performed.
45
Krantz
32
observed
limited ankle dorsiflexion and postulated traumatic
inflammation to the apophysis. McKenzie et al
10
noted, retrospectively, that 95% of their Sever’s
disease patients had a biomechanical imbalance
that produced a whipping action in the Achilles
tendon, increasing the stress on the apophysis.
However, this theory has no supportive evidence.
Szames et al
19
found that of 79 children with Sever’s
disease, 65 (82.3%) tested positive for ankle equinus
owing to Achilles tendon tightness and concluded
that equinus may predispose a child to Sever’s
disease.
The exact mechanism by which equinus may
influence Sever’s disease is unknown.
46
In a
retrospective study, we also found a relationship
between equinus and Sever’s disease. This strong
relationship between the calcaneal apophysitis and
equinus could explain why treating heel lift and
limiting strenuous activity seem to relieve symp-
toms. A child with Sever’s disease usually reports
nonradiating pain in the posterior calcaneus with
18 January/February 2011 Vol 101 No 1 Journal of the American Podiatric Medical Association
weightbearing activities, which is relieved by rest.
The pain is usually accompanied by tight triceps
surae, resulting in a reduction of dorsiflexion to 108
or less.
2, 8, 11, 14, 17-19
One possible cause of the pain
is the tension on the Achilles tendon due to
shortening of the gastrocnemius soleus complex
and production of excessive traction force on the
apophysis.
47
Patients and Methods
Participants
Participants in this study were boys enrolled in a
soccer school who presented for a final health
screening of the season. The study protocol
conformed to the guidelines set forth in the
Declaration of Helsinki, and written parental con-
sent for the evaluation was obtained. All of the boys
spent the same amount of time participating in their
sport, including after-school and weekend training
and competition. The exclusion criterion was a
recent history of ankle injury, including sprain,
tendinitis, or any pathology other than Sever’s
disease. None of the participants had a neurologic
condition affecting the lower extremity.
The soccer school enrolled 215 children aged 8 to
15 years. Fifty-four boys were selected randomly
from individuals who presented to the study, of
which eight were lost to follow-up (two with and six
without Sever’s disease). Thus, 46 boys completed
the study. They were divided into two groups: 1)
those who had been diagnosed (by a podiatrist
[R.B.B.V.] affiliated with the study) with unilateral
Sever’s disease between September 2006 and
August 2007, and 2) those who were healthy, who
served as the control group. The asymptomatic foot
of each child in the Sever’s disease group was also
used as a control. No child had been diagnosed with
bilateral Sever’s disease or had bilateral heel pain.
For diagnostic purposes, Sever’s disease was
defined as pain on mediolateral compression of
the calcaneus in the area of the growth plate.
48
The
pain had to be of at least 2 months’ duration and
coincide with physical activity, as well as be severe
enough to sufficiently interfere with normal physi-
cal activity such as walking.
11
All of the children
were symptomatic when they presented to the
clinic.
The characteristics of the boys in the Sever’s
disease and control groups are given in Table 1. All
of the children were in the ‘‘healthy weight’’
category as defined by the Centers for Disease
Control and Prevention,
49
from the 5th percentile to
the 85th percentile, except for one 11-year-old boy
in the Sever’s disease group who was underweight
(4th percentile). Body mass index was not consid-
ered in the inclusion criteria for either group.
Study Protocol and Data Collection
Plantar pressure data have been shown to be
sensitive to the data-collection protocol.
50
Using a
pressure platform to collect data can be challenging,
particularly with children who often have trouble
staying still. We collected data as follows: the child
stood on the pressure platform and simulated gait
by walking in place to accommodate the feet to the
platform at the normal angle. After 15 sec, the child
was told to stop moving and to stand still in a
natural manner, with the entire foot on the mat and
the feet in the normal angle of gait, looking straight
ahead with the arms close to the body. The plantar
foot pressure measurements for both feet during a
30-sec period were taken simultaneously and
recorded by an independent observer. If the child
moved, the data were discarded, and the trial was
repeated until data were obtained with the child
remaining still. Aside from these cases, no ‘‘practice
trials’’ were conducted.
Gastrocnemius soleus equinus was assessed with
the knee extended and flexed. The amount of ankle
dorsiflexion was determined by using a goniometer
to measure the angle between the plantar aspect of
the heel (medially or laterally) and the tibia. Care
was taken to maintain the subtalar joint in a neutral
position and to measure ankle dorsiflexion and not
midfoot dorsiflexion (rocker bottom) or midfoot
equinus (pseudoequinus).
46
The Silfverskio
¨ld test
was performed to differentiate gastrocnemius equi-
nus from other types of equinus.
46, 51
The normal
amount of ankle dorsiflexion is approximately 108
with the knee extended and 208with the knee
flexed.
46, 52, 53
Gastrocnemius equinus is the inabil-
ity of the ankle to dorsiflex normally with the knee
extended but the ability of the ankle to dorsiflex
more than 108with the knee flexed. Gastrocnemius
soleus equinus is the inability of the ankle to
dorsiflex beyond a neutral position with the knee
extended (it remains ,08) or with the knee flexed (it
remains ,08).
54, 55
Ankle joint dorsiflexion range of motion was
performed by the same clinician with broad
experience in foot and ankle physical examinations.
The study by Evans and Scutter
56
assessed the
intrarater and interrater reliability of sagittal ankle
range of motion in children. The results show that
measures of ankle dorsiflexion in children are
Journal of the American Podiatric Medical Association Vol 101 No 1 January/February 2011 19
highly variable among examiners and, in general,
that gastrocnemius range of motion is more reliable
than is soleal range of motion. The most reliable
clinical examination of the pediatric ankle sagittal
plane range of motion has been found with knee
extension, an accepted proxy for gastrocnemius
length. Examination of ankle range of motion with
knee flexion (soleus length) has been demonstrated
to be highly unreliable.
Plantar pressures were measured by an indepen-
dent observer using a digital portable force plate
(EPS-Platform; Loran Engineering, Castel Maggiore,
Bologna, Italy). The platform dimensions were 70 3
50 cm, the thickness was 5 mm, the weight was 7 kg,
and the number of resistive sensors was 2,304.
Measurements were accurate to the nearest 0.001
kPa. The equipment met the CE Declaration of
Conformity and was calibrated a few days before
the study began. Vertical force was recorded at a
frequency of 60 Hz. The platform was linked via an
interface unit to a personal computer containing the
data-collection software program Foot Checker,
version 4.0 for Windows (Loran Engineering). The
software produced pressure maps with pressure
measured in kilopascals for each incident of data
collection.
The following static measurements were obtained
for all children in both groups: peak pressure (kPa)
under each foot, percentage of body weight sup-
ported by each limb, and plantar surface area (cm
2
)
of each foot in contact with the pedobarograph.
Statistical Analysis
The Kolmogorov-Smirnov test was used to test the
normality of the data. The results of these tests
indicated that the data were normally distributed
and that parametric statistical tests were most
appropriate. Independent Student ttests were
performed to determine whether there were statis-
tically significant differences in height, weight, and
age between the two groups. Paired Student ttests
were performed to determine differences between
the symptomatic and asymptomatic feet in the
Sever’s disease group and between the right and
left feet in the control group. Independent Student t
tests were performed to determine differences
between the symptomatic and asymptomatic feet
in the Sever’s disease group and the corresponding
feet in the control group. The association between
gastrocnemius soleus equinus and Sever’s disease
was measured by using the Pearson product
moment correlation with v
2
analysis. In all of the
analyses, P,.05 (with a 95% confidence interval)
was considered statistically significant. Data analy-
sis was conducted with SPSS software, version 14.0
(SPSS Science, Chicago, Illinois).
Results
No statistically significant differences were found
between the two groups for participant height (P,
.138), weight (P,.106), or age (P,.924), but one
was found for body mass index (P,.021). The
results for the variables measured are shown in
Table 2. In the Sever’s disease group, the sympto-
matic feet had significantly higher peak pressure
values than the asymptomatic feet (P,.001) and
supported a significantly higher percentage of body
weight (P,.001). The surface area of the foot in
contact with the pedobarograph can affect the peak
pressure measured, but no significant differences in
surface contact area were found between the
symptomatic and asymptomatic feet in the Sever’s
disease group (P..05). In the control group, no
significant differences were found between the left
and right feet in peak pressure, percentage of body
weight supported, or plantar surface area in contact
with the pedobarograph (P..05).
In the comparison between the two groups, a
statistically significant difference was found in peak
pressure between the symptomatic feet in the
Sever’s disease group and the corresponding feet
in the control group (P,.001). No difference was
found between the asymptomatic feet of the Sever’s
disease group and the corresponding feet in the
control group (P..05). A significantly higher
percentage of body weight was supported by the
Table 1. Characteristics of Children in the Sever’s Disease and Control Groups
Characteristic Sever’s Disease Group (n =22) Control Group (n =24)
Age, mean 6SD (range), y 10.45 60.80 (9–12) 10.50 60.78 (9–12)
Height, mean 6SD, cm 144.0 64.11 147.19 62.26
Weight, mean 6SD, kg 34.78 64.87 37.04 65.31
Body mass index, mean 6SD
a
16.70 61.44 17.12 61.86
a
Calculated as the weight in kilograms divided by the square of the height in meters.
20 January/February 2011 Vol 101 No 1 Journal of the American Podiatric Medical Association
symptomatic feet in the Sever’s disease group than
by the corresponding feet in the control group (P,
.001). A significantly lower percentage of body
weight was supported by the asymptomatic feet in
the Sever’s disease group than by the corresponding
feet in the control group (P,.001). No significant
difference was found in the plantar surface area of
the foot in contact with the pedobarograph between
the symptomatic feet in the Sever’s disease group
and the corresponding feet in the control group (P
..05), or between the asymptomatic feet in the
Sever’s disease group and the corresponding feet in
the control group (P..05).
A statistically significant difference was found
between the two groups in the prevalence of
gastrocnemius equinus, with all 22 children in the
Sever’s disease group having bilateral gastrocnemi-
us equinus and 21 of 24 children in the control group
having no equinus (P,.001).
Discussion
The main findings of this study were the statistically
significant differences in static peak pressure and
percentage of body weight supported between the
symptomatic and asymptomatic feet in the Sever’s
disease group. Using the asymptomatic feet as
controls eliminated many potential confounding
variables such as differences in age, weight, and
physical activity. Our results indicate that in a child
with Sever’s disease, the symptomatic foot supports
a greater percentage of body weight than the
asymptomatic foot, leading to higher pressure at
the heel of the symptomatic foot. The absence of
pain in the asymptomatic heel may be due to the
smaller load that it supports. The greater load
supported by the symptomatic heel could translate
into greater injury to the growth cartilage of the
heel. However, the asymptomatic feet in the Sever’s
disease group supported a lower percentage of body
weight than the corresponding feet in the control
group. These results indicate that Sever’s disease is
associated with abnormal distribution of body
weight between the two limbs. The control group
demonstrated a more balanced distribution of body
weight, with each foot supporting about half the
load. This may avoid overloading one heel, decreas-
ing the risk of heel inflammation associated with
Sever’s disease.
Overload in tissues may be associated with an
inability to adequately attenuate forces during gait.
Lower loading rates are widely regarded as less
damaging than higher rates. Jahss et al
57
postulated
that if force or repetition of force is not attenuated
to below a critical level, tissue destruction can
result, with healing responses leading to further
structural change and alteration of tissue mechan-
ics. This can increase forces on the heel during gait,
Table 2. Peak Pressure, Percentage of Body Weight Supported by Each Foot, and Plantar Surface Contact Area in the
Symptomatic and Asymptomatic Feet in the Sever’s Disease Group and the Corresponding Feet in the Control Group
Variable N Mean 6SD Minimum Maximum 95% CI PValue
PP (kPa)
Sever’s symptomatic foot 22 57.41 64.45 52.30 62.40 22.93 to 29.78
Control corresponding foot 24 31.05 66.73 19.40 43.60 22.98 to 29.73 ,.001
a
Sever’s asymptomatic foot 22 35.00 612.45 15.30 52.30 –2.27 to 9.30 ,.001
a
Control corresponding foot 24 31.48 66.28 22.40 43.60 –2.50 to 9.53 .227
b
PBW (%)
Sever’s symptomatic foot 22 62.24 69.22 46.50 79.40 7.90 to 17.90
Control corresponding foot 24 49.33 67.58 38.20 66.10 7.85 to 17.96 ,.001
a
Sever’s asymptomatic foot 22 37.75 69.22 20.60 53.50 –17.90 to 7.90 ,.001
a
Control corresponding foot 24 50.66 67.58 33.90 61.80 –17.96 to 7.85 ,.001
b
PS (cm
2
)
Sever’s symptomatic foot 22 24.68 66.25 18.00 49.00 –1.41 to 4.61
Control corresponding foot 24 23.08 63.64 15.00 30.00 –1.50 to 4.70 .291
a
Sever’s asymptomatic foot 22 24.36 66.14 10.00 35.00 –2.66 to 3.80 .829
a
Control corresponding foot 24 23.79 64.69 17.00 39.00 –2.71 to 3.85 .723
b
Abbreviations: CI, confidence interval; PP, peak pressure; PBW, percentage of body weight supported; PS, plantar surface area in
contact with the pedobarograph.
a
Versus Sever’s symptomatic foot.
b
Versus Sever’s asymptomatic foot.
Journal of the American Podiatric Medical Association Vol 101 No 1 January/February 2011 21
leading to repetitive microtrauma to the subcalca-
neal tissues.
58
Tax,
59
McCrea,
37
and Alexander
60
suggested that Sever’s disease is probably caused by
isolated or repeated trauma, and Madden and
Mellion,
7
Peck,
4
and Topham and White
61
noted
that anecdotal evidence supports major or minor
trauma as a probable etiology. This supports the
pathophysiological concept most often presented in
the literature of Sever’s disease as an overuse
syndrome caused by repetitive microtrauma from
increased traction on the apophysis.
8, 62-64
In a
review by Scharfbillig et al,
45
recommended treat-
ments for Sever’s disease included rest or cessation
of sports, as well as padding, which helps reduce
pressures in the heel. The authors stated that little
information had been reported on how these
treatment regimens work; further research is
needed to determine how the plantar pressures
could be relieved or affected by different forms of
treatment.
Although many authors have attempted to specify
the necessary degrees of ankle dorsiflexion, norma-
tive values have been limited.
53, 54
Biomechanically,
the maximum amount of dorsiflexion in the stance
phase of normal gait occurs just before heel lift with
the knee extended.
53
The minimum amount of ankle
range of motion necessary for normal gait is 108of
dorsiflexion and 208of plantarflexion.
53-55
The most
widely accepted values in the literature for static
measurements, and for the purpose of this study,
state that the minimum amount of dorsiflexion
necessary at the ankle for normal gait is 108of
motion.
46, 62-67
Equinus imparts a major deforming force to the
foot and is a causative factor in many foot and ankle
pathologic entities, including plantar fasciitis, pes
planus, hallux abducto valgus, Achilles tendinosis,
Charcot’s midfoot collapse, and diabetic ulcera-
tions.
55
DiGiovanni et al
54
found either gastrocne-
mius or gastrocnemius soleus equinus in patients
with a symptomatic foot and ankle. In asymptom-
atic patients, gastrocnemius and gastrocnemius
soleus equinus are not uncommon (33% and 17%,
respectively).
68
In this study, we found a 100% incidence of
bilateral gastrocnemius equinus in the Sever’s
disease group, which probably accounts for the
mechanical overload in the symptomatic heel.
Szames et al
19
evaluated 79 cases of calcaneal
apophysitis in 53 patients. They found that 82.3% of
the cases had ankle equinus due to muscular
retraction, but they did not distinguish between
gastrocnemius and soleus contracture in the equi-
nus conditions, unlike in our study. Gastrocnemius
equinus may be a predisposing factor, and increased
plantar foot pressures at the heel seem to be
associated with unilateral Sever’s disease, but
further research is needed to identify other factors
involved. A recent review of Sever’s disease by
Scharfbillig
45
found that no studies have compared
whether symptomatic patients are tighter in the
triceps surae than their asymptomatic counterparts.
However, one limitation of this study is that the
results do not allow determination of whether high
plantar pressures are a predisposing factor or a
result of Sever’s disease. Further research studies
are needed to monitor plantar foot pressures, before
or during heel pain and after heel pain has ceased,
before making a recommendation about the initia-
tion of preventive or therapeutic action. All 22
children diagnosed with Sever’s disease had symp-
toms in the left heel, and 20 of these children had
right-limb dominance, using the right foot to kick
the ball while playing soccer. Thus, it seems that the
increased amount of time during which the left foot
supports the body in ‘‘right-footed’’ athletes leads to
overload of the left heel. It is important to
investigate the relationship between limb domi-
nance and development of the disorder in a specific
foot, as other authors have done for other patho-
logic entities,
69-71
to confirm or refute this hypoth-
esis. An important limitation of this study is that
only static plantar pressures were measured. This
initial study focused on static pressures because the
children with Sever’s disease had pain during
standing.
Conclusions
Children with unilateral Sever’s disease demon-
strate higher static plantar pressures at the affected
foot than the unaffected foot and the corresponding
foot in healthy children. Thus, high plantar foot
pressures are associated with the Sever’s disease
symptoms that characterize this condition. Gastroc-
nemius equinus may be a predisposing factor for the
increased plantar pressures at the heel found in
patients with Sever’s disease and could serve as a
screening tool to indicate the need for pressure
measurements. Further research is needed to
identify other factors involved in the disease, as
well as to better understand the factors that
contribute to abnormal distribution of body weight
in the lower limbs.
Financial Disclosure: None reported.
Conflict of Interest: None reported.
22 January/February 2011 Vol 101 No 1 Journal of the American Podiatric Medical Association
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24 January/February 2011 Vol 101 No 1 Journal of the American Podiatric Medical Association
... Care was taken to maintain the subtalar joint in a neutral position and to measure ankle dorsiflexion and not midfoot dorsiflexion (rocker bottom) or midfoot equinus (pseudoequinus) [15,20]. The Silfverskiöld test was performed to differentiate gastrocnemius equinus from other types of equinus [15,21]. A normal amount of ankle dorsiflexion is approximately 108 with the knee extended and 208 with the knee flexed [12]. ...
... The exclusion criteria were determined with a questionnaire, and were as follows: obesity (more than 30 based on Quetelet's equation of BMI = weight/height 2 ); history of problems with the feet or lower extremities or any pathological condition in the past 12 months [22,23]; having a history of foot surgery; congenital or acquired deformity of the foot (flat feet, cavus foot, hallux valgus, hallux limitux, hammer toes, congenital, or traumatic deformity of the lower limb [22][23][24]), to have normal dorsiflexion in the ankle joint complex [21], and the presence of musculoskeletal and joint injuries, pelvic pain, ankle sprains, and lower back pain [25] identified during clinical examination; visual and/or hearing impairments; and any problems in the lower limbs or spine that might affect the normal gait. ...
... Technical specifications of the pressure platform are shown in the Table 2. This pressure platform is indicated for use in studies of footprints during the stance phase of the gait cycle [21,32,33]. We used the platform in self-calibrating mode. ...
Article
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Some studies suggest that gender is related to gait. Females show significantly higher ankle motion and vertical ground reaction forces. Males have significantly larger plantar contact surface areas in all regions of the foot than females in most, but not all, prior studies. However, there is no research on sex differences in a functional equinus condition. In this study, 119 individuals, including 59 females (29.7 ± 5.15 years, 58.74 ± 6.66 kg, 163.65 ± 5.58 cm) and 60 males (31.22 ± 6.06 years, 75.67 ± 9.81 kg, 177.10 ± 6.16 cm), with a functional equinus condition walked onto a pressure platform. In two separate testing sessions, five trials of each foot were conducted for the first, second, and third steps. We measured the contact surface areas for each of the three phases of the stance phase. We computed the intraclass correlation coefficient and standard error of the mean to assess the reliability. We found significantly greater contact surface areas in males than females in the first, second, and third steps in all phases of the stance phase: heel strike, mid-stance, and take-off. This is important information for the design of footwear and orthotics and gender knowledge. In a functional equinus condition, males have registered greater contact surface areas than females in all phases of the dynamic footprint of the stance phase.
... (accesses on 20 March 2017). The software produced pressure maps with pressure measured in kilopascals for each incident of data collection [23]. In a previous study, this platform has been shown to be reliable in clinic, with an ICC between 0.88 and 0.97 in all dynamic variables [24]. ...
... Only one previous study has analyzed the reliability and repeatability of different dynamic variables using the pressure platform used in our study [23]. In the study by Becerro de Bengoa Vallejo et al. [23], they obtained a reliability measured by the ICC of 0.706 to 0.972 for the dynamic variables analyzed: mean pressure, integral pressure time, contact time or duration, peak pressure or maximum and integral pressure force time or force. ...
... Only one previous study has analyzed the reliability and repeatability of different dynamic variables using the pressure platform used in our study [23]. In the study by Becerro de Bengoa Vallejo et al. [23], they obtained a reliability measured by the ICC of 0.706 to 0.972 for the dynamic variables analyzed: mean pressure, integral pressure time, contact time or duration, peak pressure or maximum and integral pressure force time or force. These results are like those obtained in our study for the variable %CLA, which was shown as a reliable and repeatable dynamic variable. ...
Article
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Background: The analysis of the center of pressure (COP) is a method used to assess the foot function, but its reliability and repeatability have not been evaluated. COP can be altered by diverse conditions, like an excessive foot pronation. Low-Dye taping is commonly used for the treatment of symptoms related to an excessive pronation. To date, no study has evaluated the effects of the Low-Dye taping on COP and the duration of its effects. Thus, the main purpose of this manuscript was to assess the reliability and repeatability of the percentage of center of pressure locus area (%CLA) in feet with an excessive pronation, and secondarily, to assess that the Low-Dye taping modifies the %CLA during the immediate 48 h. Methods: An observational study of the reliability and repeatability of the %CLA variable with the Low-Dye taping in feet with excessive pronation was carried out. We used the EPS-Platform to evaluate the results of the variable in 6 conditions in a first session to evaluate the reliability of the results. We compared the results of the first session with the results in a second session to evaluate the repeatability of the results. We also carried out an ANOVA test to evaluate the changes that the taping produced in the variable between without taping with the rest of the 6 conditions. Results: For the %CLA, we observed a reliability greater than 0.80, measured by the interclass ratio index, both in the first session before taping, and in the second session before taping, thus being a repeatability variable. In the following times, with taping, at 10 min with tape, at 20 min with tape, at 24 h with tape and at 48 h with tape; an interclass ratio coefficient (ICC) higher than 0.80 was again obtained, thus being a reliable variable in all measurements made. The Low-Dye taping did not change %CLA from the time the tape was put in until 48 h (p-value = 1.000). Conclusions: The %CLA variable, in feet with excessive pronation, proved to be a reliable variable in all the measurements obtained before putting on the tape and during the following 48 h with the tape, and a repeatable variable. The Low-Dye taping did not change the %CLA from the time the tape was put in until 48 h.
... 5 Previous research addressed the role of plantar loading in this condition and reported higher peak plantar pressures beneath the heel in pediatric patients with Sever's disease. 12 A study by Becerro de Bengoa Vallejo et al 12 reported peak plantar pressures of 339+/-27 kPa in Sever's disease patients during standing, compared to 83+/-2 kPa in healthy controls. During walking, reported peak plantar pressures reached 880+/-78 kPa in Sever's disease patients, and 88+/-11 kPa in healthy controls. ...
... During walking, reported peak plantar pressures reached 880+/-78 kPa in Sever's disease patients, and 88+/-11 kPa in healthy controls. 12 As ...
Article
Full-text available
Sever’s disease is an underreported prevalent pediatric condition that causes heel pain in children worldwide. It is often described as an overuse injury that can present with either unilateral or bilateral heel pain. Even though the exact mechanism of injury is unknown, it is often thought it involves repetitive stress and pressure on the calcaneal growth plate. Diagnosing Sever’s disease mainly relies on a thorough clinical investigation and physical examination, with a positive squeeze test usually sufficient to establish diagnosis. Nevertheless, radiographic imaging can help exclude other differential diagnoses. Therapeutic options of Sever’s disease are mostly conservative, and these include rest, physical therapy, kinesiotherapy, and orthoses. Educating parents and coaches on the symptomatology and presentation of Sever’s disease is pivotal for the establishment of efficient preventive interventions and earlier diagnoses. This study presents a case of a pediatric patient with Sever’s disease and offers medical insight into the diagnostic, clinical, pathologic, and therapeutic characteristics of this condition, in light of the current existing literature.
... Becerro de Bengoa Vallejo et al. and Szames et al. both described the relationship between Sever's disease and equinus [17,18]. Pediatric flatfoot is another common pediatric lower extremity condition associated with an underlying equinus deformity [19,20]. ...
... This scenario is also a problem in diabetic patients as they are prone to a tightness of the GSC due to glycosylation of the tendon requiring a maintenance program [62]. In the pediatric patient, bone has been shown to grow faster than muscle (GSC) during growth spurts leading to an equinus deformity [17,18]. A child experiencing a growth spurt may require maintenance therapy. ...
Chapter
Full-text available
Equinus deformity is a common condition that plays a significant role in the development of numerous lower extremity pathologies. In the pediatric patient, equinus deformity has historically been associated with neurological conditions. Equinus in the non-neurological patient is prevalent, especially in those patients with lower extremity biomechanically related pathologies. Defining equinus based on the literature is the initial requirement to understand, evaluate, and treat the deformity. Ankle joint dorsiflexion ≤ − 5° with the foot maximally supinated and the knee fully extended is a definition based on evidence-based medicine (Gatt, Foot 30:47–52, 2017). The anatomy of the gastrocsoleus complex, especially that of the gastrocnemius muscle crossing the knee, ankle, and subtalar joints, and its functions during the gait cycle can result in biomechanical abnormalities when abnormally tight. Compensation for an equinus deformity occurs distally with dampening of the peroneus longus tendon function leading to midtarsal hypermobility and plantarflexion of the naviculocuneiform joint. The distal and lateral movement of the center of pressure relative to the subtalar joint axis results in a net increased pronatory moment on the foot. This distal compensation for equinus deformity leads to numerous lower extremity pathologies. Management of any condition with an underlying equinus component must include treatment of the equinus deformity. This treatment may be either nonsurgical or surgical, but it must be part of the global deformity management.
... The lower limb flexor muscles muscle activation pattern has demonstrated a relationship with static and dynamic balance. Therefore, stretching of the flexor muscles may help to improve the muscle functionality [15][16][17][18][19][20][21]. ...
... Therefore, intermittent stretching use has been recommended for pathologies that present an increased heel pressure such as heel pain (Sever's disease [20,21], fasciitis [32]) as well as those with increased pressure in the forefoot (fasciitis [32], diabetic foot ulcers [33,38], metatarsalgia [39], Achilles tendinopathy [40]). Gajdosik et al. [34] found an increased ROM after ten static wall intermittent stretches held for 15 s in each repetition, five times per week for 6 weeks. ...
Article
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Background: Postural balance and fall efficacy (self-perceived confidence in performing daily physical activities) have been found to be risk factors associated with falls in older adults. Stretching is one intervention that has been investigated to improve balance and therefore reduce fall risk. Various forms of stretching have been evaluated with different outcomes, but there is a lack of knowledge about the effect of stretching (continuous and intermittent) on plantar pressures and balance. Therefore, the aim of the present study was to analyze the effects of stretching (continuous and intermittent) of the bilateral ankle plantar flexors on plantar pressures and static balance. Methods: A randomized clinical trial was carried out. Forty-eight healthy subjects (42 females and 6 males) were recruited in an outpatient clinic. Subjects were randomly assigned to an intermittent stretching group (five sets of 1 min; 15 s of rest) or a continuous stretching group (2 min of continuous stretching) of the plantar flexors. Plantar pressures and balance using stabilometry were measured before and after stretching. Results: There were significant differences between intermittent and continuous stretching in rearfoot maximum pressure, forefoot surface area, and center of pressure surface area with eyes open. Conclusions: Bilateral intermittent stretching of the ankle plantar flexors was found to be more effective than continuous stretching for the reduction of rearfoot maximum pressure and improved balance.
... Researchers have hypothesized both intrinsic and extrinsic potential factors. Possible intrinsic factors include a limited range of ankle dorsiflexion motion [10,11] and high static [12] and dynamic plantar pressures [13] at the heel. Potential extrinsic factors include activities with high foot impact, footwear, and sports activities on hard surfaces [8,14,15]. ...
... Our results are consistent with prior research, which also indicated that static and dynamic plantar pressures [12,13] were higher in children with Sever's disease than in healthy children. To our knowledge, no prior study has investigated the velocity of the COP during walking in relation to Sever's disease. ...
Article
Full-text available
Background: This study determined if the body mass index, dynamic plantar-pressures, plantar surface contact-area, velocity of the centre of pressure (COP), gastrocnemius equinus, and gastrocnemius soleus equines are related to calcaneal apophysitis (Sever's disease) in athletic children. Methods: This case-control study examined 106 boys enrolled in a soccer academy, including 53 with Sever's disease and 53 age-matched healthy controls. The dynamic average and maximum peak plantar-pressures, plantar surface contact-area, and velocity of the COP were evaluated with a digital pressure sensor platform. Goniometry was used to measure the ankle dorsiflexion range of motion and thereby identify gastrocnemius equinus and gastrocnemius soleus equinus. Results: Participants with Sever's condition had significantly higher BMI and peak plantar-pressures (maximum and average) at the heel (Cohen's d > 3 for pressures) than the controls. Those with Sever's disease also had significantly slower velocity of the COP (Cohen's d > 3). Boys with Sever's disease were also 8 times more likely to have bilateral gastrocnemius equinus than disease controls. Conclusions: High heel plantar pressure and low velocity of COP are related to Sever's condition in boys, although it is not clear whether these factors predispose individuals to the disease or are consequences of the disease. Gastrocnemius ankle equinus could be a predisposing factor for Sever's condition.
... Beside physical activity, studies conducted among adults have shown that some of the factors of plantar pressure during walking include prominent metatarsal heads in the forefoot model, Charcot deformity in the midfoot model and hammer toe deformity in the lesser toes 23 . In children, one previous study has shown that peak plantar pressures and percentage of body weight supported (contact area) are significantly higher in children affected by the disease 24 . However, no study to date has systematically established significant factors associated with several foot functions in children and adolescents and apparently healthy individuals. ...
Article
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The main purpose of the study was to establish foot characteristics during walking in children. In this cross-sectional study, we recruited 1 284 primary-school students aged 6-14 years (714 boys and 570 girls) randomly selected from five schools in the city of Brno, Czech Republic. Children walked across a pressure platform (EMED-xl; NovelGmbH, Munich, Germany) to collect the data for both left and right foot during three trials. After the procedure, the software generated several foot characteristic variables: (1) force-time integral, (2) pressure-time integral, (3) contact area, (4) contact time, (5) peak pressure and (6) average pressure for the total foot. Curves for the 5th, 10th, 25th, 50th, 75th, 90th and 95th percentiles were calculated using the Lambda, Mu and Sigma (LMS) Chartmaker software. Our results showed that boys had longer force-time integral, higher contact area and contact time values, and higher peak plantar pressure, while no significant differences in pressure-time integral and average plantar pressure between sexes were observed. Older boys and girls had higher values in all measured variables. Our results provide for the first-time sex- and age-specific foot characteristics during walking in 6-14-year-old children.
... Functional equinus is the greatest symptom producer of the human foot, and the most profound causal agent in foot pathomechanics. 1 Stretching of the ankle flexor muscles may help to improve the muscle functionality. [2][3][4][5][6][7][8] Continuous stretching compared with intermittent stretching improved the range of motion, 9 lowered muscle oxygenation levels, 10 created a significant ischemic response occurring during a continuous stretch 10 as a result of a prominent increase in intramuscular pressure, 11 and lowered torque loss magnitude and duration, and the prolonged (30 minutes) torque loss of 5% after intermittent stretching could not be explained by central factors. 9 However, the detrimental effect of passive continuous stretching on maximal force was largely explained by a reduction in central drive. ...
Article
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Objective: The purpose of this study was to analyze the immediate effects of an intermittent plantar flexion static-stretching protocol on balance and plantar pressures. Methods: The study included a sample size of 24 healthy participants (21 female and 3 male). Participants were 32.20 ± 8.08 years, 166.20 ± 8.43 cm, and 62.77 ± 9.52 kg. All participants performed an intermittent plantar flexion static-stretching protocol. Five sets (60 seconds intermittent stretch; 15 seconds for the rest time) of a passive plantar flexor stretching (70% to 90% of the point of discomfort) were performed. Static footprint analysis and a stabilometry analysis were performed before and after stretching. A P value < .05 with a CI of 95% was considered statistically significant for all tests. Results: Intermittent ankle plantar static stretching resulted in a significantly greater forefoot surface contact area and lower rear foot medium and maximum plantar pressures. In addition, static stretching caused a lower displacement of the center of pressure for both eyes open and eyes closed conditions. Conclusion: An intermittent plantar flexor static-stretching protocol improved balance and reduced rear foot plantar pressures (maximum and medium pressures).
Article
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Overuse injuries imply the occurrence of a repetitive or an increased load on a specific anatomical segment which is unable to recover from this redundant microtrauma, thus leading to an inflammatory process of tendons, physis, bursa, or bone. Even if the aetiology is controversial, the most accepted is the traumatic one. Limb malalignment has been cited as one of the major risk factors implicated in the development of overuse injuries. Many authors investigated correlations between anatomical deviations and overuse injuries, but results appear mainly inconclusive. Establishing a causal relationship between mechanical stimuli and symptoms will remain a challenge, but 3D motion analysis, musculoskeletal, and finite element modelling may help in clarifying which are the major risk factors for overuse injuries.
Article
Background: Heightened vertical load beneath the foot has been anecdotally implicated in the development of activity-related heel pain of the calcaneal apophysis in children but is supported by limited evidence. Research question: This study investigated whether vertical loading patterns during walking and running differed in children with and without calcaneal apophysitis. Methods: Vertical ground reaction force, peak plantar pressure (forefoot, midfoot, heel) and temporospatial gait parameters (cadence, step length, stride, stance and swing phase durations) were determined in children with (n = 14) and without (n = 14) calcaneal apophysitis. Measures were acquired during barefoot walking and running at matched and self-selected speed using an instrumented treadmill, sampling at 120 Hz. Statistical comparisons between groups were made using repeated measure ANOVAs. Results: There were no significant between group differences in vertical ground reaction force peaks or regional peak plantar pressures. However, when normalised to stature, cadence was significantly higher (≈ 5%) and step length shorter (≈ 5%) in children with calcaneal apophysitis than those without, but only during running (P <.05). Maximum pressure beneath the rearfoot during running was significantly correlated with self-reported pain in children with calcaneal apophysitis. Significance: Peak vertical force and plantar pressures did not differ significantly in children with and without calcaneal apophysitis during walking or running. However, children with calcaneal apophysitis adopted a higher cadence than children without heel pain during running. While the findings suggest that children with calcaneal apophysitis may alter their cadence to lower pressure beneath the heel and, hence pain, they also highlight the benefit of evaluating running rather than walking gait in children with calcaneal apophysitis.
Article
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Plantar heel pain development reflects an interaction among multiple extrinsic and intrinsic risk factors. Intrinsic risk factors include biomechanical factors such as limb length discrepancy, increased eversion at the subtalar joint, range of motion at the ankle joint, arch height, foot type and heel pad thickness. Extrinsic risk factors such as footwear have been identified as influencing the incidence of plantar heel pain. The type of design may also have an impact on risk factor identification and on the strength and validity of a study. With the current emphasis on injury prevention, a study designed to identify and quantify risk factors is needed to provide valuable data in diagnosing, assessing and planning treatment for athletes.
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Low back pain is one of the most common complaints of athletes, and the differential diagnosis is challenging because the cause can be biomechanical, neoplastic, infectious, developmental, or traumatic. The author reviews diagnostic steps from medical history and physical examination to the use of bone scans, myelography, and tomography. He also reviews injuries and diseases specific to the adolescent spine and urges physicians to use flexibility exercises to correct the athlete's problem while allowing sports participation to continue. Treatment goals should include pain relief and prevention of further lumbar segment injury.
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Athletic injuries among children often fall into the category of overuse, with mechanisms similar to overuse injuries in adults. However, the implications for young, growing athletes are much different because the growth plates are involved, resulting in such problems as traction apophysitis and Little League elbow. Early, appropriate intervention, which sometimes includes cessation of certain athletic activity, can prevent potential long-term complications in growing athletes.
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In the presence of fairly well defined kinematic patterns in human walking there was considerable variability at the kinetic level. Intra-subject variability of joint moment patterns over the stride period was high at the knee and hip, but low at the ankle and in a recently defined total limb pattern, called support moment. A similar profile of variability was evident for inter-subject trials at slow, natural and fast cadences, with the percentage variability at the knee and hip decreasing as cadence increases. These moment of force patterns were not random, but were highly correlated. Such a finding points to compensating mechanisms by the biarticulate muscles crossing these joints. Also shown was the fact that these compensating patterns were highly predictable from link segment theory.
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Since the discovery of roentgen rays less than forty years ago, the study of the pathologic physiology of bone has been markedly facilitated and, as was to be expected, a number of hitherto unknown pathologic conditions of bone have been revealed. Beginning with Osgood's report in 1903, an important group of syndromes, accompanied by certain definite symptoms and by similar epiphyseal changes observed roentgenographically, have been described and elevated to the dignity of specific diseases. Among these diseases are: avulsion of the tibial tubercle (Osgood, 1903; Schlatter, 1908), tarsal scophoiditis (Kohler, 1908), osteochondritis deformans of the hip (Legg, 1910; Perthes, 1910), infraction of metatarsal heads (Freiburg, 1914), kyphosis dorsalis juvenilis (Buchmann, 1925) and traumatic malacia of the carpal semilunar bone (Kienbóck, 1910). Furthermore, it has gradually become apparent that there are marked similarities in the general pattern of these diseases, for they all seem to follow trauma of one kind