Callosities, corns, and calluses

Abstract

Inappropriate shoes, abnormal foot mechanics, and high levels of activity produce pressure and friction that lead to corns and calluses. Most lesions can be managed conservatively by proper footwear, orthoses, and, if necessary, regular paring. The lesions usually disappear when the causative mechanical forces are removed. Surgery is rarely indicated and should be specifically aimed at correcting the abnormal mechanical stresses.

Full text

EDUCATION
&
DEBATE
Fortnightly
Review
Callosities,
corns,
and
calluses
Dishan
Singh,
George
Bentley,
Saul
G
Trevino
Callosities
can
be
painful,
and
the
symptoms
may
be
so
intense
as
to
seriously
affect
a
person's
gait,
choice
of
footwear,
and
activities.
While
many
patients
seek
symptomatic
relief
from
a
chiropodist
or
pharmacist,
doctors
should
be
familiar
with
the
diagnosis
and
man-
agement
of
these
common
disorders.
Nomenclature
Many
medical
textbooks
fail
to
clearly
differentiate
between
the
various
types
of
keratotic
lesions.
Further-
more,
the
terminology
used
by
British
surgeons,
Ameri-
can
surgeons,
rheumatologists,
dermatologists,
and
podiatrists
is
different
and
sometimes
confusing.'9
The
definitions
below
reflect
the
most
widely
accepted
use
of
the
terms
(fig
1).
CALLOSrrY
A
callosity
occurs
when
the
process
of
keratinisation,
which
maintains
the
stratum
corneum
of
the
skin
as
a
horny
protective
cover,
becomes
overactive
due
to
shearing
or
compressive
forces.
This
is
a
normal
protec-
tive
response-as
seen
in
the
hands
of
manual
labourers
and
the
feet
of
those
who
walk
barefoot-and
a
callosity
becomes
pathological
only
when
it
is
so
large
as
to
cause
symptoms.
Institute
of
Orthopaedics,
Royal
National
Orthopaedic
Hospital,
Stanmore,
Middlesex
HA7
4LP
Dishan
Singh,
senior
lecturer
George
Bentley,
professor
Baylor
College
of
Medicine,
Houston,
Texas,
USA
Saul
G
Trevino,
associate
professor
Correspondence
to:
Mr
Singh.
BMJ
1996;312:1403-6
CORN
A
corn
represents
a
circumscribed,
sharply
demar-
cated
area
of
traumatic
hyperkeratosis.
It
has
a
visible
translucent
central
core
which
presses
deeply
into
the
dermis,
causing
pain
and
sometimes
inflammation.
The
term
heloma
(Greek
helus,
a
stone
wedge)
is
often
used
by
podiatrists
to
denote
a
corn
(Latin
cornu,
horn).
The
hard
corn
(heloma
durum)
represents
the
classic
corn
a
dry
horny
mass
most
commonly
found
on
the
dorsolateral
aspect
of
the
fifth
toe
or
the
dorsum
of
the
interphalangeal
joints
of
the
lesser
toes
(fig
2).
It
is
often
termed
the
digital
corn.
The
soft
corn
(heloma
molle)
is
an
extremely
painful
lesion
that
occurs
only
interdigitally
and
is
probably
best
termed
an
interdigital
corn.
It
is
essentially
a
corn
that
has
absorbed
a
considerable
amount
of moisture
from
sweat,
leading
to
characteristic
maceration
(fig
3)
and
sometimes
secondary
fungal
or
bacterial
infection.
It
is
most
common
in
the
fourth
interdigital
space.
Sometimes
two
opposing
lesions
can
be
found
and
are
termed
"kissing
lesions."
Digital
(hard)
corn
Corn
Interdigital
(soft)
corn
Plantar
corn
Callos
Localised
callus
Diffuse
callus
Fig
1-Classification
of
callosities
in
the
foot
CALLUS
A
callus
is
a
broad
based,
diffuse
area
of
hyperkerato-
sis
of
relatively
even
thickness,
most
commonly
found
under
the
metatarsal
heads.
A
callus
is
less
circum-
scribed
than
a
corn,
is
usually
larger,
does
not
have
a
central
core,
and
may
or
may
not
be
painful.
The
terms
tyloma
or
clavus
are
sometimes
used
to
denote
a
callus.
While
there
is
some
agreement
about
labelling
large
diffuse
areas
of
traumatic
plantar
hyperkeratosis
simply
as
diffuse
plantar
callus,
there
is
much
confusion
in
the
naming
of
more
discrete
localised
areas
of
traumatic
hyperkeratosis
that
occur
on
the
sole
of
the
foot
(fig
4).
Fig
2-Hard
(digital)
coms
on
dorsolateral
aspect
of
fifth
toe
and
dorsum
of
third
toe
BMJ
VOLUME
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1996
-
Summary
points
*
Corns
and
calluses
arise
from
hyperkeratosis,
a
normal
physiological
response
to
chronic
excessive
pressure
or
friction
on
the
skin
*
They
may
be
caused
by
excessive
irritation
from
poorly
fitting
shoes
or
by
abnormal
pressure
if
there
is
a
deformity
of
the
foot
*
Treatment
should
therefore
not
only
provide
symptomatic
relief
(such
as
by
regular
paring
or
using
keratolytic
agents)
but
should
also
alleviate
the
underlying
mechanical
cause
*
Most
lesions
can
be
managed
conservatively
by
use
of
sensible
footwear
(properly
fitting
shoes
with
low
heels,
soft
upper,
and
roomy
toebox)
and
orthoses
to
redistribute
mechanical
forces
*
Surgery
is
rarely
indicated
and
should
be
specifi-
cally
aimed
at
correcting
the
abnormal
mechanical
stresses
1403

Fig
3-Soft
(interdigital)
corn
between
fourth
and
fifth
toes
In
a
classic
paper
in
1954,
Giannestras
pointed
out
that
many
of
these
localised
lesions
had
previously
been
thought
to
be
plantar
warts
(see
below)
and
coined
the
term
plantar
keratosis.'0
Mann
and
DuVries
introduced
the
term
intractable
plantar
keratosis
to
denote
a
symp-
tomatic
plantar
callosity
that
does
not
resolve."
This
term
is
popular
in
North
America
and
is
often
abbrevi-
ated
to
IPK.
These
same
localised
areas
are
sometimes
referred
to
as
plantar
callus,5
tyloma,5
callosity,2
plantar
corn,3
8
plantar
heloma,4
and
keratoma.9
We
prefer
to
use
the
term
plantar
corn
to
denote
the
small,
well
localised
and
painful
lesions
(found
beneath
either
the
tibial
sesamoid
or
a
sharp
projection
of
the
fibular
con-
dyle
of
a
metatarsal
head)
that
contain
a
central
keratin
plug.
These
lesions
are
usually
called
focal
intractable
plantar
keratosis
in
American
literature.'2
We
use
the
term
localised
callus
to
denote
larger
lesions
usually
measuring
over
1
cm
across,
not
containing
a
keratin
plug,
and
caused
by
misalignment
of
a
metatarsal
head.
American
authors
prefer
the
term
diffuse
intractable
plantar
keratosis.'2
Fig
5-Diagrams
showing
bony
prominences
that
lead
to
(a)
digital
and
interdigital
corns,
(b)
plantar
corns,
and
(c)
localised
plantar
callus.
Areas
shaded
black
represent
the
bony
resec-
tion
that
may
be
necessary
Fig
4-Localised
callosity
under
second
metatarsal
head.
Superficial
layers
should
be
pared
with
a
scalpel
to
distinguish
between
a
plantar
corn
(translucent
central
core),
wart
(end
arteries),
and
localised
plantar
callus
(homogene-
ous
appearance)
Pathogenesis
Bones
of
the
foot
have
many
projections,
especially
over
the
condyles
of
the
heads
and
bases
of
the
metatar-
sals
and
phalanges.
Pressure
is
applied
to
the
skin
over-
lying
those
bony
projections
either
by
a
tight
shoe
or
during
walking
(fig
5).
The
body
attempts
to
protect
the
irritated
skin
by
accumulation
of
the
horny
layer
of
the
epithelium
(callosity),
but
this
accumulation
itself
causes
a
prominence
that
increases
the
pressure
in
a
tight
shoe.
Thus,
a
vicious
cycle
is
generated
that
may
ultimately
lead
to
the
keratin
plug
pressing
into
the
der-
mis
and
causing
pain.
Abnormal
mechanical
stresses
may
be
extrinsic
(from
without)
or
intrinsic
(from
within).
Intrinsic
and
extrinsic
factors
are
often
combined,
as
in
the
claw
toe-the
intrinsic
factor
is
the
toe
deformity,
and
the
extrinsic
factor
is
the
toebox
of
the
shoe.
BMJ
VOLUME
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1996
(b)
(c)
(a)
Factors
that
may
lead
to
development
of
callosities
Extrinsic
factors
*
Poor
footwear
Tight
shoe
Irregularities
in
shoe
Open
shoes
*
Activity
level
Athletes
Intrinsic
factors
*
Bony
prominences
Prominent
condylar
projection
Malunion
of
a
fracture
*
Faulty
foot
mechanics
Cavovarus
foot
Toe
deformity
(claw,
hammer,
mallet)
Short
first
metatarsal
Hallux
rigidus
Transfer
lesion
from
osteotomy
or
removal
of
adjacent
metatarsal
head
1404

Table
1-Treatments
for
different
callosities
Symptomatic
Callosity
treatment
Shoes
Orthoses
Surgery
Hard
digital
corn
on
Remove
central
core
Soft
upper
Silicone
sleeve
Correct
toe
deformity
deformed
toe
Regular
trimming
Extra
depth
Low
heeled
Stretching
Hard
digital
corn
on
Remove
central
core
Soft
upper
Silicone
sleeve
Trim
condyles
or
excision
fifth
toe
Regular
trimming
Wide
arthroplasty
Stretching
Interdigital
soft
corn
Lamb's
wool
or
deflective
Soft
upper
Toe
spacer
Trim
condyles
padding
Wide
Stretching
Plantar
corn
Removal
central
core
Wide
Metatarsal
pad
Condylar
arthroplasty
Regular
trimming
Low
heeled
Insole
with
metatarsal
relief
Localised
plantar
callus
Regular
trimming
Extra
depth
Metatarsal
pad
Poor
results
Wide
Insole
with
metatarsal
relief
Low
heeled
Diffuse
plantar
callus
Regular
trimming
Cushioning
Cushioning
insole
Not
indicated
Diagnosis
Patients
should
be
asked
about
their
footwear
and
previous
treatments
(such
as
osteotomies,
orthoses,
etc).
Patients'
gait
should
be
observed,
and
the
alignment
of
their
feet
should
be
examined
for
faulty
mechanics
(cavovarus
foot,
etc).
The
location
and
char-
acteristics
of
the
keratotic
lesions
should
be
noted,
and
they
should
be
palpated
to
assess
which
bony
prominence
is
involved.
Radiographs
of
weightbearing
feet
are
useful
for
identifying
bony
prominences.
Pressure
studies
(pedobarographs)
may
help
to
define
the
exact
location
of
increased
plantar
pressure
and
to
differentiate
between
transfer
lesions
and
lesions
caused
by
direct
pressure.
Verrucas
and
plantar
corns
are
best
distinguished
by
careful
paring
of
the
thickened
stratum
corneum
with
a
sharp
scalpel
blade.
As
the
cornified
layer
of
skin
over
a
verruca
is
removed,
the
end
arteries
appear
there
may
be
punctate
bleeding,
or
black
dots
may
be
visible
if
the
end
arteries
are
thrombosed.
Treatrnent
It
should
always
be
remembered
that
callosities
are
signs
of
increased
mechanical
stress
rather
than
an
actual
disease.
The
principles
of
treatment
should
therefore
be
to
(a)
provide
symptomatic
relief,
(b)
determine
the
mechanical
aetiology,
(c)
formulate
a
conservative
management
plan
by
advising
on
footwear
and
prescribing
orthoses,
and
(d)
consider
surgery
if
conservative
measures
fail
(table
1).
SYMPTOMATIC
RELIEF
Callosities
may
be
acutely painful
because
of
pressure
of
the
central
keratin
plug
on
underlying
nerves
in
the
papillary
layer.
Paring
the
lesion
with
a
sharp
number
22
scalpel
and
removing
the
central
keratin
plug-with
a
local
anaesthetic
if
necessary
provides
almost
complete
pain
relief.
Recurrence
can
be
prevented
by
weekly
gentle
trimming
with
a
pumice
stone
or
emery
board
after
soaking
the
lesion
in
warm
water
for
20
minutes.
Some
patients
prefer
to
use
a
motorised
sand-
paper
disc
if
there
are
several
lesions
or
a
large
lesion,
while
others
benefit
from
regular
paring
by
a
podiatrist
or
chiropodist.
An
emollient
cream
can
be
useful
for
softening
the
skin.
Patients
who
present
with
a
plantar
callus
(localised
or
diffuse)
that
is
not
painful
or
tender
and
whose
only
complaint
is
of
the
cosmetic
appearance
of
the
callus
need
only
to
be
advised
to
use
a
pumice
stone
regularly
after
soaking
the
foot
in
warm
water.
Silicone
sleeves
(fig
6)
provide
good
pain
relief
by
cushioning
and
by
slow
release
of
mineral
oil
to
soften
the
keratotic
lesion.
Careful
application
of
dilute
solutions
of
keratolytic
agents
(such
as
10-15%
salicylic
acid)
or
pads
containing
keratolytic
agents
are
sometimes
beneficial,
but
overzealous
applications
of
concentrated
solutions
(such
as
40%
salicylic
acid)
may
cause
chemical
burns.
For
a
painful
soft
interdigital
corn,
padding
the
web
space
with
lamb's
wool
or
deflec-
tive
padding
will
often
provide
relief
and
will
usually
induce
healing
of
the
maceration.
We
do
not recommend
the
subcutaneous
injection
of
bovine
collagen4
or
fluid
silicone5
advocated
by
some
podiatrists
as
it
fails
to
address
the
primary
problem
and
may
induce
an
immune
reaction.
The
intralesional
use
of
triamcinolone'
or
chymotrypsin'
may
even
increase
the
mechanical
pressure
by
thinning
the
skin.
It
seems
unnecessary
to
prescribe
high
doses of
oral
vitamin
A
as
Fig
6-Silicone
sleeve
for
symptomatic
relief
from
hard
digital
corn
BMJ
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Distinguishing
features
of
warts
and
plantar
corns
Wart
Plantar
corn
*
Relatively
rapid
onset
*
Develops
over
months
or
years
*
May
or
may
not
be
under
bony
*
Localised
under
bony
prominences
prominences
*
Skin
lines
pass
through
lesion
*
Skin
lines
pass
around
lesion
*
Maximum
pain
with
direct
pressure
*
Maximum
pain
with
squeezing
*
No
end
arteries
visible
on
paring
side
to
side
*
Slower
recurrences
at
least
a
week
*
End
arteries
visible
on
paring
after
shaving
*
Rapid
recurrence
after
shaving
and
padding
1405

Fig
7-Metatarsal
pad
to
provide
relief
from
painful
callosities
under
metatarsal
heads
an
antikeratotic
drug3
as
it
may
lead
to
a
raised
intracra-
nial
pressure.3
Similarly,
local
excision
of
the
corn
with-
out
simultaneous
removal
of
the
protuberant
bone
has
a
high
risk
of
recurrence
as
well
as
a
risk
of
sinus
forma-
tion
and
osteomyelitis.
FOOTWEAR
Tight
shoes
are
the
main
cause
of
most
callosities-
corns
are
merely
the
symptoms
of
"shoe
disease"
and
do
not
occur
in
people
who
walk
barefoot.
Patients
must
be
advised
to
wear
low
heeled
shoes
with
a
soft
upper
and
a
roomy
toebox
is
imperative.
Extra
depth
is
needed
to
accommodate
corns
on
deformed
toes
(such
as
hammer
or
claw
toes),
and
extra
width
is
needed
for
corns
on
the
lateral
aspect
of
the
fifth
toe
and
interdigital
soft
corns.
Shoes
may
also
be
stretched
by
a
cobbler
to
relieve
mechanical
pressure
on
a
lesion.
Irregularities
in
a
shoe
such
as
a
poorly
positioned
seam
or
stitching
may
be
responsible
for
mechanical
irritation
on
a
fifth
toe.
Sometimes
a
shoe
modification
by
an
orthotist
may
be
necessary-such
as
a
medial
wedge
for
a
cavovarus
foot.
Conversely,
shoes
that
are
too
loose
(such
as
unlaced
trainers
and
open
backed
sandals)
may
induce
shearing
forces
on
the
edges
of
the
weight
bearing
area
of
the
sole
of
the
foot
to
produce
the
so
called
"marginal
callus"
or
"heel
fissures."
ORTHOSES
As
a
hyperkeratotic
lesion
will
always
recur
unless
the
mechanical
stress
is
removed,
orthoses
are
useful
in
redistributing
forces
to
allow
the
lesion to
heal.
Dough-
nut
shaped
corn
pads,
heloma
shields,
and
silicone
toe
splints
are
available
to
relieve
pressure
from
the
tender
central
core
in
corns.
An
interdigital
wedge
made
of
plastazote
or
a
silicone
orthodigital
splint
will
promote
healing
of
an
interdigital
soft
corn.
In
the
case
of
a
localised
plantar
callus
a
metatarsal
pad
placed
proximal
to
a
prominent
metatarsal
head
will
reduce
the
pressure
of
the
metatarsal
head
on
the
underlying
skin
(fig
7).
Placement
of
the
adhesive
meta-
tarsal
pad
in
the
shoe
can
be
helped
by
applying
lipstick
to
the
callus
as
a
guide.
It
is
best
to
start
with
a
thin
pad
and
to
build
it
up
gradually.
A
ready
made
full
length
shoe
inlay
of
padded
leather
or
plastazote
may
sometimes
provide
better
relief
and
can
be
moved
from
shoe
to
shoe.
A
customised
shoe
inlay
of
vacuum
moulded
plastazote
with
added
metatarsal
relief
is
best
at
relieving
pressure
but
can
only
be
worn
in
extra
depth
shoes
and
cannot
be
worn
in
most
dress
shoes.
SURGICAL
PROCEDURES
Surgery
to
remove
bony
prominences
or
change
the
mechanics
of
the
foot
is
indicated
only
if
all
conservative
measures
have
failed.
Surgical
correction
of
a
claw
toe,
hammer
toe,
or
mallet
toe
will
heal
a
corn
on
the
deformed
toe.6
Hard
corns
on
the
fifth
toe
and
soft
interdigital
corns
can
be
treated
by
resection
of
the
prominent
condyles6
or
excision
arthroplasty
of
the
proximal
interphalangeal
joint
of
the
fifth
toe
(fig
5).
Syndactylisation
of
the
web
space
between
the
fourth
and
fifth
toes
is
rarely
indicated.
Localised
painful
plantar
keratoses
on
the
ball
of
the
foot
(a
common
cause
of
metatarsalgia)
require
careful
study
of
radiographs
and
pedobarographs
to
allow
identi-
fication
of
bony
prominences
and
transfer
lesions.
Many
patients
have
been
harmed
by
failure
to
diagnose
a
trans-
fer
lesion
so
that
operation
on
one
metatarsal
then
leads
to
problems
with
the
next
metatarsal
head
and
so
forth.
A
modified
DuVries
metatarsal
condylectomy7
is
preferable
to
excision
of
the
metatarsal
head
for
a
plantar
corn.
Patients
with
multiple
callosities
under
the
metatarsal
heads
are
best
managed
conservatively
as
surgery
"to
level
the
tread"
is
contraindicated:
metatarsal
shortening
and
excision
of
the
metatarsal
head
or
the
floating
osteotomies
have
unpredictable
results
and
may
lead
to
the
development
of
transfer
lesions.2
Summary
Inappropriate
shoes,
abnormal
foot
mechanics,
and
high
levels
of
activity
produce
pressure
and
friction
that
lead
to
corns
and
calluses.
Most
lesions
can
be
managed
conservatively
by
proper
footwear,
orthoses,
and,
if
neces-
sary,
regular
paring.
The
lesions
usually
disappear
when
the
causative
mechanical
forces
are
removed.
Surgery
is
rarely
indicated
and
should
be
specifically
aimed
at
correcting
the
abnormal
mechanical
stresses.
We
thank
Mr
John
Michael,
podiatrist
at
the
Royal
National
Orthopaedic
Hospital,
for
providing
some
of
the
photographs,
and
Mrs
Colleen
Power
for
the
drawings.
1
Baker
H.
Common
skin
disorders.
In:
Klenerman
L,
ed.
The
foot
and
its
dis-
orders.
3rd
ed.
Oxford:
Blackwell
Scientific
Publications,
1991:
113-22.
2
Klenerman
L,
Nissen
KI.
Common
causes
of
pain.
In:
KIenerman
L,
ed.
Thefoot
and
its
disorders.
3rd
ed.
Oxford:
Blackwell
Scientific
Publications,
1991:
93-111.
3
Arnold
HL,
Odom
RB,
James
WD.
Andrews'diseases
of
the
skin:
clinical
der-
matology.
Philadelphia,
PA:WB
Saunders,
1990:
44-6.
4
Whiting
MF.
Skin
and
subcutaneous
tissues.
In:
Lorimer
DL,
ed.
Neale's
common
foot
disorders:
diagnosis
and
management:
a
general
clinical
guide.
4th
ed.
Edinburgh:
Churchill
Livingstone,
1993:
93-121.
5
Yale
JF.
Yale's
podiatric
medicine.
3rd
ed.
Baltimore,
MD:
Williams
and
Wilkins.
1987.
6
Coughlin
MJ,
Mann
RA.
Lesser
toe
deformities.
In:
Mann
RA,
Coughlin
MJ,
eds.
Surgery
of
the
foot
and
ankle.
6th
ed.
St
Louis,
MO:
CV
Mosby,
1993:
341-411.
7
Mann
RA,
Coughlin
MJ.
Keratotic
disorders
of
the
plantar
skin.
In:
Mann
RA,
Coughlin
MJ,
eds.
Surgery
of
the
foot
and
ankle.
6th
ed.
St
Louis,
MO:
CV
Mosby,
1993:
413-65.
8
Richardson
GE.
Lesser
toe
abnormalities.
In:
Crenshaw
AH,
ed.
Campbell's
operative
orthopaedics.
St
Louis,
MO:
CV
Mosby,
1992:
2729-56.
9
Regnauld
B.
The
foot:
pathology,
aetiology,
semiology,
clinical
investigation
and
therapy.
Berlin:
Springer-Verlag,
1986.
10
Giannestras
NJ.
Shortening
of
the
metatarsal
shaft
for
the
correction
of
plantar
keratosis.
Clin
Orthop
1954,4:225-31.
11
Mann
RA,
DuVries
HL.
Intractable
plantar
keratosis.
Orthop
Clin
North
Am
1973;4:67-73.
12
Mann
RA.
Intractable
plantar
keratoses.
Instructional
course
lectures
of
the
AAOS.
St
Louis,
MO:
CV
Mosby,
1984:
287-301.
Correction
Recent
advances
in
medical
genetics
A
typesetters'
error
occurred
in
this
article
by
John
R
W
Yates
(20
April,
pp
1021-5).
The
first
point
of
the
summary
box
should
read
"over
60
disease
genes
were
isolated
in
1995"
[not
1955].
1406
BMJ
VOLUME
312
1
JUNE
1996