Radiographic assessment of pediatric foot alignment

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Introduction
 It is a difficult, complex and often confusing topic.
 The difficulties range from a lack of knowledge of the
congenital and neuromuscular disorders associated with
foot deformities, inexperience in analyzing paediatric foot
radiographs and lack of understanding of the descriptive
terms used to document the abnormalities.
 Malalignment of the bones of the foot may present a
complex diagnostic problem for radiologists.
 Radiography is a valuable tool for assessing the pediatric
patient.

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Introduction
 The function of the foot is to transmit load, adapt to
varying surface conditions and act as a lever for
progression with effects at the knee and the hip.
 Adaptation requires flexibility, and only during weight
bearing or simulated weight bearing will the
configuration of the bony skeleton allowed by the
constraints of the ligamentous structures become
apparent.

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Obtaining the adequate radiograph
 Most of the measurements are based on the
dorsoplantar (AP) and lateral radiographic views.
 Frequently obtained on weight bearing or
simulated weight bearing.
 In infants or non-ambulatory patients, weight
bearing can be simulated by dorsiflexion stress.

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Dorsoplantar view
 Patient standing, the tibia
perpendicular to the
cassette and the central
ray angled 15° posteriorly
to avoid overlap of the leg
onto the posterior aspect
of the foot.

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Lateral view
 Obtained with a standing
patient and the tibia
perpendicular to the film
cassette.

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Anatomical Considerations and Terminology
The anatomy of the foot is complex.
Broadly divided into three main parts:
Hindfoot:
• The most posterior portion of the foot, comprised of the
talus and calcaneus.
• This includes the ankle joint (tibiotalar) and subtalar joint
(which has three facets: anterior, middle and posterior)
• The hindfoot is joined to the midfoot via the mid tarsal
joint
Midfoot:
• This lies between the hindfoot and forefoot and contains
the navicular, cuboid and cuneiforms.
• It is joined to the forefoot via the tarsometatarsal joints.
Forefoot:
• This includes the metatarsals and phalanges

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Definitions and terminologies
8
Hindfoot Alignment
Terminology

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Hindfoot valgus
calcaneus is abducted and rotated
away from the talus
= Increased talocalcaneal angle
Hindfoot varus
near parallel alignment of the talus and
calcaneus,
= Decreased talocalcaneal angle

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Entire foot is in equinus
Superior elevation of the posterior
part of the foot with respect to the
calcaneus
=increased tibiocalcaneal angle
Calcaneus position and cavus
Increased dorsiflexion of anterior calcaneus
and plantarflexion of metatarsals, resulting in
cavovarus deformity
=Decresed tibiocalcaneal angle

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Definitions and terminologies
Forefoot Alignment Terminology

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Forefoot adduction
metatarsals as a
unit toward midline
pivoting at their bases
Forefoot abduction
metatarsals as a
Unit away from midline
pivoting at their bases

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Inversion (varus and supination)
AP- increased superimposition of the metatarsal bases
Lateral – ladderlike arrangement of metatarsals, with fifth metatarsal corresponding to
lowest rung of ladder

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Hindfoot Geometry
 Analysis of the osseous AXES and associated
ANGLES is also valuable for determining the
pathology present.

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Foot Axes
Dorsoplantar View
 Talar Axis (A)
the bisection of the long axis of the head and neck
of the talus.
 Calcaneal Axis (B)
The calcaneal axis is the bisection of the long axis
of the ossified portion of bone
 First and Second Metatarsal Axes (C&D)
A line connecting several midpoints along the
length of the metatarsal forms a metatarsal axis.

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Foot Axes
Lateral View
 Talar Axis (A)
measured the same way as in the dorsoplantar view.
 Calcaneal Axis (B)
is a line formed by connecting the two most plantar
points at the proximal and distal ends of the
calcaneus.
 First Metatarsal Axis (C)
An axis for the metatarsal is made from a line
connecting several midpoints along the length of the
metatarsal.
 Tibial axis(E)
Mid point of tibial shaft created between its cortex
E

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Foot Angles
Dorsoplantar Radiograph
Talocalcaneal Angle:
 Relationship between the talus and the calcaneus.
 This represents the attitude of the rearfoot and its
relationship to the leg
 The midcalcaneal line parallel to the lateral cortex of
the calcaneum which usually intersects the base of
the fourth metatarsal and the midtalar line drawn
parallel to the medial cortex of the talus which usually
passes through the base of the first metatarsal
Normal talocalcaneal angle (on both AP and lateral) is 25-55o
,
with average in the adult of 35o
.

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 An increase in the talocalcaneal angle indicates the calcaneus
and the remainder of the foot have moved out and away
(abducted and everted)
 Clinically seen as a congenital pes valgus (flatfoot or
calcaneovalgus) deformity
 A decreased talocalcaneal angle indicates the calcaneus, and
the remainder of the foot are directly underneath the talus and
leg.
 Clinical seen of as is talipes equinovarus deformity.

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Foot Angles
Talar–First Metatarsal Angle
 Measured using the bisection of the long
axes of the ossified portions of the talus and
first metatarsal.
 Relationship between the forefoot and the
rearfoot. Ideally, the talus and first
metatarsal should be collinear.
The normal value is -20° to 0°

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Foot Angles
Lateral Radiograph
The tibiocalcaneal angle
 Formed by the lines represent the plantar
prominence of the calcaneus and
anatomic axis of the tibia.
Normal value is 60-80o

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Foot Angles
Lateral Radiograph
The talocalcaneal angle
 Formed by the lines representing the
bisection of the long axes of the
ossified portions of the talus and
calcaneus
Normal talocalcaneal angle (on both AP and lateral) is 25-55o
,
with average in the adult of 35o
.

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 An increased talocalcaneal angle indicates that the talus
has plantarflexed relative to and alongside the calcaneus as
in calcaneovalgus or congenital pes valgus.
 A decreased angle indicates the talus is “riding” on top of
the calcaneus as is seen in talipes equinovarus deformity.

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Foot Angles
Talar–First Metatarsal Angle
 long axis of the talus should
normally pass through or be
parallel to the long axis of the
first metatarsal, resulting in a 0°
angle

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 When the first metatarsal axis is dorsiflexed
relative to the talar axis, indicates a flatfoot
deformity.
 first metatarsal axis is plantarflexed relative to
the talar axis in a cavus deformity.

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Foot Angles
Calcaneal Inclination Angle
 Intersection formed between the
bisection of the long axis of the
ossified portion of the calcaneus
and the weight-bearing surface
forms the calcaneal inclination
angle.
 Represents the attitude of the
calcaneus to the ground in stance.
The normal range for this angle is 35° to 40°

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 Increased angle indicates a cavus or high-arched
foot.
 A decreased calcaneal inclination angle indicates a
low-arched foot, as in or pes planovalgus
flatfoot deformity.

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Foot Angles
Talar Declination Angle
 Determined by the angle formed
between the lines representing
the bisection of the long axis of
the ossified portion of the talus
and the weight-bearing surface.
 Represents the position of the
talus relative to the ground in
stance.
The normal angle is 30°

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 Increase in the declination of the talus indicates
that the calcaneus is not in position underneath the
talus, allowing it to “drop” down.

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Normal foot radiography measurements

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Approach to the foot alignment
First, evaluate the relationship of the
tibia to the hindfoot,
then the relationship of the hindfoot to
the midfoot,
finally the relationship of the midfoot to
the forefoot
Ankle joint
Subtalar joint
Midtarsal joints

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 Consider the movement of 3 main joints of the foot and ankle:
 Ankle joint
 Subtalar joint
 Midtarsal joints
Ankle joint Subtalar joint Midtarsal joints
Plantarflexion deformity
Equinus
Dorsiflexion deformity
Calcaneus
Inversion deformity:
Hindfoot varus
Eversion deformity:
Hindfoot valgus
Plantarflexion deformity:
Pes cavus
Dorsiflexion deformity:
Pes planus
Adduction deformity:
Forefoot varus
Abduction deformity:
Forefoot valgus

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Ankle joint
 Plantarflexion deformity – Equinus
 Fixed plantarflexion of the
hindfoot
 The calcaneus is plantar flexed
(anterior end down) on the lateral
view, making an angle of >80o to
tibia
 anteriorly with the tibia
 Dorsiflexion deformity – Calcaneus
 An abnormal dorsiflexion of the
calcaneus (anterior end up)
 The calcaneus is in an increased
vertical position
Equinus
Calcaneus

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Subtalar Joint
 Inversion deformity: Hindfoot varus
 AP view: Mid-talar line falls lateral
to the first MT base because of
adduction of the anterior end of the
calcaneus and foot
 Lat view: The talus cannot
plantarflex because of the
adduction of the anterior calcaneus
under the talus, thus the axes of
the two bones become parallel to
each other.
 Lateral view shows the nearly
parallel talus and calcaneus, with a
decreased talocalcaneal angle.
 Summary: Decreased talocalcaneal
angle on both AP and lateral views
a. Normal
Hindfoot varusNormal

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Subtalar Joint
 Eversion deformity: Hindfoot valgus
 AP view: Due to abduction of the
anterior end of the calcaneus and
foot, the talar axis falls medial to
the first MT.
Normal Hindfoot valgus

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Subtalar Joint
 Hindfoot valgus (Lat view):
 Lat view: Due to abduction of the
anterior calcaneus, support is
withdrawn from the anterior talus,
causing the long axis of the talus
and that of the first MT to angulate
plantarward
 The talus is plantarflexed
 Lateral talocalcaneal angle:
 The normal range is 20-40o
 An increased angle indicates
hindfoot valgus
Normal
Hindfoot valgus

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Midtarsal Joints
 Normal Arch:
 Long axis of talus aligns with long
axis of first MT
 Normal calcaneal pitch: Calcaneal
inclination angle 18-20o
 Plantarflexion deformity:
 Pes cavus – a high longitudinal arch
of the foot
 Dorsiflexion deformity:
 Pes planus – a flattened longitudinal
arch of the foot
Normal long axis of the talus
Normal calcaneal pitch

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Midtarsal Joints
 Pes cavus (high arch): High
longitudinal arch of the foot with long
axis of talus abnormally dorsiflexed
with respect to first metatarsal on the
lateral view.
 Pes cavus with abnormally high
calcaneal pitch.
Long axis of talus dorsiflexed
High calcaneal pitch

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Midtarsal Joints
 Pes planus (flat arch): Low longitudinal
arch of the foot. Long axis of talus is
abnormally plantar flexed with respect
to first metatarsal on lateral view.
 Decreased calcaneal inclination angle
(calcaneal pitch):
 18-20o
is generally considered
normal, although measurements
ranging from 17-32o
have been
reported to be normal.
Long axis of talus plantarflexed
Decreased calcaneal pitch

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Midtarsal Joints
 Adduction deformity: Forefoot varus
 AP view:
 Axis of MTs angle toward
midline of the body
 Calcaneus axis points lateral to
4th MT head
 Axis of 1st MT and talus form
an obtuse angle with apex
pointing laterally
 Lat view:
 ladderlike configuration of the
metatarsals

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Midtarsal Joints
 Abduction deformity: Forefoot valgus
 AP view:
 Axis of MTs angle away from
midline of the body
 Calcaneus axis points medial to
4th MT head
 Axis of 1st MT and talus form
an obtuse angle with apex
pointing medially
 Lat view:
 metatarsal bones are nearly all
superimposed
Talus
Calcaneus

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Common congenital foot deformities
 Congenital vertical talus
 Metatarsus adductus
 Talipes equinovarus
 Pes planus

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Congenital vertical talus
 Unknown, more common in males
 Condition may occur as an isolated
primary deformity or in association with
CNS and MSK abnormalities
 Clinical
 Rigid deformity with the sole of the foot
convex resulting in rockerbottom
appearance
 Head of the talus is markedly prominent
on the medial and plantar aspect
 The forefoot is abducted and dorsiflexed
at the midtarsal joint

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Congenital vertical talus
 Radiographic findings:
 Ankle joint – equinus deformity
 Subtalar joint – hindfoot valgus
 Midtarsal joint – forefoot valgus
 There is primary dislocation of the
talonavicular joint; the navicular
articulates with the dorsal aspect of the
talus, locking it in a plantarflexed
vertical position
 Subluxations of adjacent joints,
resulting in rockerbottom deformity are
secondary/adaptive

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Findings:
Ankle joint – equinus deformity
calcaneus makes an angle > 80o
to
tibia
Subtalar joint – severe hindfoot valgus
AP: Midtalar line falls medial to 1st MT
Lat: Talar long-axis is plantarflexed
because of abduction of the anterior
calcaneus resulting in lack of support
from the anterior talus
Midtarsal joint – forefoot valgus AP:
Axis of MTs angles away from midline
of the body, midcalcaneal line points
medial to 4th MT head

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Metatarsus Adductus
 50% of cases bilateral
 Slight female predilection
 Clinical:
 Forefoot is adducted and inverted, the
heel is in mild to moderate valgus
 Those having normal hindfoot are
classified as metatarsus varus
 Range of dorsiflexion of the foot and
ankle is normal
 Deformity is present at birth, but
frequent unrecognized until 3rd-4th
month
 Immediate treatment recommended as
deformity will not spontaneously
correct
N MTA

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Metatarsus Adductus
 Ankle joint – normal
 Subtalar joint – normal or in
hindfoot valgus
 Midtarsal joint – forefoot varus

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Findings:
Ankle joint – normal
calcaneus is in normal position (60-80o
to tibia)
Subtalar joint – normal or in hindfoot
valgus
AP: Midtalar line falls medial to 1st MT
because of abduction of the anterior
calcaneus resulting in lack of support
from the anterior talus
Midtarsal joint – forefoot varus AP:
Axis of MTs angles toward midline of
the body, midcalcaneal line points
lateral to 4th MT head

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Pes Planus (flat foot)
 One of the most common foot
malformations, usually bilateral with
strong hereditary pattern
 No gender predilection
 Clinical:
 Limited plantarflexion with prominent
medial and plantar aspect of foot
 Foot dorsiflexes to a normal or greater
than normal angle.

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Pes Planus (flat foot)
 Ankle joint – normal
 Calcaneus lies horizontal, but not in
equinus
 Subtalar joint – hindfoot valgus
 Midtarsal joint –
 Pes planus deformity with long axis of
the talus angulated plantarward,
indicating sagging of the longitudinal
arch
 Forefoot valgus

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Findings
Ankle joint – normal
calcaneus is in normal position (60-
80o
to tibia)
Subtalar joint – hindfoot valgus AP:
Midtalar line falls medial to 1st MT
because of abduction of the
anterior calcaneus resulting in lack
of support from the anterior talus
Midtarsal joint – forefoot valgus AP:
Axis of MTs angles away from the
midline, midcalcaneal line points
medial to 4th MT head
Midtarsal joint – pes planus
Lat: midtalar axis plantar-flexed
compared to 1st MT, decreased
calcaneal pitch

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Pes planus in a 16-year-old boy, right foot. a, b
Anteroposterior weightbearing radiograph (a) demonstrates
increased talocalcaneal angle (black angle), loss of the
normal co-linear talus–1st metatarsal and calcaneus–4th
metatarsal axes, and talonavicular offset lateral
weightbearing radiograph (b)
demonstrates decreased calcaneal pitch angle (green
angle),
increased talocalcaneal angle (red angle) and negative
Meary angle (blue lines)

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Congenital talipes equinovarus
(Clubfoot)
 Incidence:
 1:1000 live births
 2:1 male to female ratio
 57% unilateral
 May be seen with spina bifida or arthrogryposis
 Clinical
 Variable severity
 Affected foot points downward, with the toes
turned inward and the bottom of the foot
twisted inward
 Achilles tendon is tight and muscles in the calf
are often smaller compared to a normal lower
extremity

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 Ankle joint – equinus
deformity
 Subtalar joint – hindfoot
varus
 Midtarsal joint –
 forefoot varus
 cavus deformity (may not be
apparent because of marked
rotation of the forefoot in
varus)
Congenital talipes equinovarus
(Clubfoot)

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Findings:
Ankle joint – equinus deformity
calcaneus makes an angle >80o
to tibia
Subtalar joint – hindfoot varus
AP: Midtalar line falls lateral to 1st MT
Lat: Talar long-axis is dorsiflexed because of
adduction of the anterior calcaneus under the
talus (talus and calcaneus appear parallel)
Midtarsal joint – forefoot varus
AP: Axis of MTs angles toward midline of the
body, midcalcaneal line points lateral to 4th
MT head
Midtarsal joint – pes cavus
Lat: midtalar axis dorsiflexed compared to 1st
MT, increased calcaneal pitch

Radiographic assessment of pediatric foot alignment

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Radiographic assessment of pediatric foot alignment