X-RAY OF FOOT
X-ray Foot D/P View
Foot AP (DP)
Region:phalanges, metacarpal bone, tarsal bone
Pathology:fracture, dislocation and bony lesion of foot
SID: 100 cm (40 inches)
Central Ray: beam directed at the base of the third metatarsophalangeal joint with 10˚ angulation toward calcaneus
Respiration: unrelated
Position:
1. The patient is placed either in a supine
position or in a sitting position.
2. Place the plantar on the image receptor (IR) by flexing the knee.
3. Place the major axis of the foot on the vertical axis of the image receptor
(IR).
Collimation: Include the entire foot.
Evaluation:
1. Phalanges, metatarsal
bone, navicular
bone, cuneiform
bone and cuboid
bone must be included.
2. The first and second bases of metatarsal
bones should be distinguishable and the second to fifth base of
metatarsal bones should be shown in stack.
3. Sesamoid
bone must be shown on the first head of metatarsal.
kVp-55, mAs-3.2
Tip:
X-ray Foot Oblique View
Foot Medial Oblique
Region: phalanges, metacarpal bone, tarsal bone
Pathology: fracture, dislocation and bony lesion of foot
SID: 100 cm (40 inches)
Central Ray: perpendicular beam directed at the base of the third metatarsophalangeal joint
Respiration: unrelated
Position:
1. The patient is placed either in a supine
position or in a sitting position.
2. While flexing the knee, rotate the patient's body toward the contralateral
side of the filming leg.
3. Place the major axis of the foot on the vertical axis of the image receptor
(IR).
4. Medially rotate the leg to 30° to the IR.
Collimation: Include the entire foot.
Evaluation:
1. The entire foot including proximal talus
bone, posterior calcaneus,
and distal phalanx must
be shown.
2. Overlaying of the cuboid
bone and the calcaneus cavity should be avoided
3. The medial and intermediate cuneiform
bone should not overlap.
4. The image of the third, fourth, and fifth metatarsal
bones should not overlap.
kVp: 57, mAs-3.2
Tip:
1. Foot Medial Oblique Projection needs
higher angle of rotation than Foot Lateral Oblique Projection due to transverse
arch.
Anatomy Foot
The bones of the foot provide mechanical support
for the soft tissues; helping the foot withstand the weight of the body whilst
standing and in motion.
They can be divided into three groups:
Tarsals – a set of seven irregularly shaped bones. They
are situated proximally in the foot in the ankle area.
Metatarsals – connect the phalanges to the tarsals.
There are five in number – one for each digit.
Phalanges – the bones of the toes. Each toe has three phalanges
– proximal, intermediate, and distal (except the big toe, which only has two
phalanges).
The foot can also be divided up into three regions: (i)
Hindfoot – talus and calcaneus; (ii) Midfoot – navicular, cuboid, and
cuneiforms; and (iii) Forefoot – metatarsals and phalanges.
In this article, we shall look at the anatomy of the
bones of the foot – their bony landmarks, articulations, and clinical
correlations.
Fig 1.0 – Overview of the bones of the human foot.
Tarsals
The tarsal bones of the foot are organised into three rows:
proximal, intermediate, and distal.
Proximal Group (Hindfoot)
The proximal tarsal bones are the talus and
the calcaneus. These comprise the hindfoot, forming the bony framework around
the proximal ankle and heel.
Talus
The talus is the most superior of the tarsal
bones. It transmits the weight of the entire body to the foot. It has three
articulations:
Superiorly – ankle
joint – between the talus and the bones of the leg (the tibia and
fibula).
Inferiorly – subtalar joint – between the talus and
calcaneus.
Anteriorly – talonavicular joint – between the talus
and the navicular.
The main function of the talus is to transmit forces from
the tibia to the heel bone (known as the calcaneus). It is wider anteriorly
compared to posteriorly which provides additional stability to the ankle.
Whilst numerous ligaments attach to the talus, no muscles
originate from or insert onto it. This means there is a high risk of avascular
necrosis as the vascular supply is dependent on fascial structures.
Calcaneus
The calcaneus is the largest tarsal bone and lies underneath the
talus where it constitutes the heel. It has two articulations:
Superiorly – subtalar (talocalcaneal) joint – between
the calcaneus and the talus.
Anteriorly – calcaneocuboid joint – between the
calcaneus and the cuboid.
It protrudes posteriorly and takes the weight of the body as
the heel hits the ground when walking. The posterior aspect of the calcaneus is
marked by calcaneal tuberosity, to which the Achilles tendon attaches.
Fig 2 – The tarsal bones of the foot.
Intermediate Group (Midfoot)
The intermediate row of tarsal bones contains one bone,
the navicular (given its name because it is shaped like a boat).
Positioned medially, it articulates with the talus
posteriorly, all three cuneiform bones anteriorly, and the cuboid bone
laterally. On the plantar surface of the navicular, there is a tuberosity for
the attachment of part of the tibialis posterior tendon.
Distal Group (Midfoot)
In the distal row, there are four tarsal bones – the cuboid
and the three cuneiforms. These bones articulate with the metatarsals of the
foot
The cuboid is furthest lateral, lying anterior to
the calcaneus and behind the fourth and fifth metatarsals. As its name
suggests, it is cuboidal in shape. The inferior (plantar) surface of the cuboid
is marked by a groove for the tendon of fibularis longus.
The three cuneiforms (lateral, intermediate (or
middle) and medial) are wedge shaped bones. They articulate with the
navicular posteriorly, and the metatarsals anteriorly. The shape of the bones
helps form a transverse arch across the foot. They are also the
attachment point for several muscles:
Medial cuneiform – tibialis anterior, (part of)
tibialis posterior and fibularis longus
Lateral cuneiform – flexor hallucis brevis
Clinical Relevance: Fractures of the Talus and
Calcaneus
The talus and the calcaneus sit in the proximal part of the
foot and ankle, and are involved in transmitting forces from the body to the
ground. They are the most frequently fractured of all the tarsal bones.
Talus
Talar fractures most commonly occur in the neck of the talus
(50%) but can occur in the talar body or lateral process, with those in the
talar head being the least common.
Neck fractures – typically high energy injuries,
caused by excessive dorsiflexion of the foot. The neck of the talus is pushed
against the tibia. In this type of fracture, the blood supply to the talus may
be disturbed, leading to avascular necrosis of the bone.
Body fractures – usually occur from jumping from a height.
Metatarsals
The metatarsals are located in the forefoot, between
the tarsals and phalanges. They are numbered I-V (medial to lateral).
Each metatarsal has a similar structure. They are convex
dorsally and consist of a head, neck, shaft, and base (distal to proximal).
They have three or four articulations:
Proximally – tarsometatarsal joints – between the
metatarsal bases and the tarsal bones.
Laterally – intermetatarsal joint(s) – between the
metatarsal and the adjacent metatarsals.
Distally – metatarsophalangeal joint – between the
metatarsal head and the proximal phalanx.
Clinical Relevance: Fractures of the Metatarsal Bones
Metatarsal fractures can occur by three main mechanisms.
The most common method of fracture is a direct blow to
the foot – usually from a heavy object dropping onto the foot.
Another type of metatarsal injury is a stress
fracture, an incomplete fracture caused by repeated stress to the bone. It is
common in athletes and occurs most frequently at the necks of the second
and third metatarsals and the proximal fifth metatarsal.
The metatarsals can also be fractured by excessive
inversion of the foot. If the foot is violently inverted, the fibularis
brevis muscle can avulse (‘tear off’) the base of the fifth metatarsal.
Phalanges
The phalanges are the bones of the toes. The
second to fifth toes all have proximal, middle, and distal phalanges. The great
toe has only 2; proximal and distal phalanges.
They are similar in structure to the metatarsals, each
phalanx consists of a base, shaft, and head.
