Positioning foot and ankle

What CR angulation is required for the AP oblique projection of the foot?

CR is perpendicular, no angulation

Extending the ankle joint or pointing the foot and toes downward is called?

Plantar flexion

To properly visualize the joint spaces with the AP projection of the foot, the CR must be:

Perpendicular to the metatarsals

What is the purpose for the AP stress views of the ankle?

Demonstrate possible joint separations

How much rotation from an AP of the ankle will produce a mortise view

15-20 degrees

Where is the CR placed for a mediolateral projection of the calcaneus?

1 in. inferior to the medial malleolus

How much CR angulation to the long axis of the foot is required for the platodorsal axial projection of the calcaneus

40 degrees

If a patient is unable to assume the positions recommended for demonstration of the sesamoid bones of the foot, what projection may be used instead?

Lateral of the 1st digit in dorsiflexion

Which metatarsals are free of superimposition on a correctly obliqued foot>

Third, fourth, fifth

The CR is directed to the base of the _____________ metatarsal for AP and oblique feet projections.

Third

Which metatarsal is most commonly fractured?

Fifth

For an axial projection of the calcaneus, the plantar surface of the foot should be ______________ in relationship to the film.

Perpendicular

Which position of the foot will be best demonstrate the lateral cuneiform?

AP oblique with medial rotation

Which joint surfaces of the ankle joint are open with a true AP projection of the ankle? (Spaces between the tibia, fibula, and talus)

Medial and superior

A radiograph of a mortise view of the ankle reveals that the lateral malleolus is slightly superimposed over the talus and the lateral joint space is not open. What is the most likely error?

Insufficient medial rotation of foot

What tube angle is recommended for an AP projection of the feet?

10 degrees toward the calcaneus

Which medical professional is responsible for moving the ankle for stress projections?

Physician

The sesamoid bones of the foot lie posterior to the __________ metatarsal.

First

The recommended kVP ranges for radiography of the toes, foot, or ankle are:

55-65

True or False? Standing radiographs of the foot are done to evaluate the arches of the foot.

True

True or False? The medial malleolus lies more inferior to the lateral malleolus.

False

True or False? The technologist should always try to separate the uninjured toes away from the injured toe when taking a lateral projection.

True

True or False? The foot should be obliqued laterally when the fourth digit is the digit of interest.

True

True or False? The correctly positioned AP mortise ankle will frequently also demonstrate a fracture of the base of the 5th metatarsal if present.

True

Bonus: Explain the difference between an AP oblique and an AP mortise view of the ankle. Make sure to include the differences in obliquity (if there is any) and what structure would be more visible on each.

Pathology involving mortise and 5th tuberosity for mortise shot. Pathology involving distal tibia and fibula joint, distal fibula and lateral malleolus and base of 5th

Central ray angulation for AP foot

10 degrees posterior

Purpose of the 10 degree angle on AP foot

to place the CR perpendicular to the metatarsals

Where is the CR centered for AP foot

base of third metatarsal

Acceptable CR angle range for AP foot

10 to 15 degrees posterior

Key to open joint spaces on AP foot

CR perpendicular to metatarsals

Need collimation on AP foot to include what

the heel

Toe oblique rotation for digits 1 through 3

30 to 45 degrees medially

Toe oblique rotation for digits 4 and 5

30 to 45 degrees laterally

CR location for oblique toe

metatarsophalangeal joint of interest

Angle used for oblique toe

none

Common student mistake on oblique toe

forgetting to remove the 10 degree angle

Lateral toes centering

interphalangeal joint of great toe or PIP for digits 2 through 5

Tangential sesamoid view purpose

to demonstrate sesamoid bones of first MTP joint

Foot routine views

AP foot medial oblique foot lateral foot

Oblique foot rotation and direction

30 to 40 degrees medial

Structures best demonstrated on oblique foot

cuboid and lateral cuneiform with metatarsals 3 through 5 free of superimposition

Optional external oblique foot demonstrates

bases of first and second metatarsals

CR location for oblique foot

base of third metatarsal

Angle used for oblique foot

none

Lateral foot CR location

medial cuneiform at level of base of third metatarsal

Important positioning for lateral foot

dorsiflex foot to form 90 degree angle with tib fib

Key evaluation on lateral foot

fibula should be in posterior half of tibia

Weight bearing foot purpose

evaluate arches under load

Weight bearing AP foot CR angle

15 degrees posterior

Required marker on weight bearing views

weight bearing marker

Weight bearing lateral foot centering

medial cuneiform at level of base of third metatarsal

Heel routine views

axial heel and lateral heel

Axial heel CR angle and direction

40 degrees cephalic toward base of third metatarsal

Axial heel foot relationship to IR

plantar surface perpendicular to IR

Technique for axial heel

6 at 60

Lateral heel CR location

1 inch inferior to medial malleolus

Ankle routine views

AP mortise and lateral

CR location for AP ankle

midway between malleoli

Intermalleolar plane relation to IR on AP ankle

15 to 20 degrees off parallel

Best joint surfaces seen on AP ankle

medial and superior aspects of mortise joint

Mortise ankle rotation

15 to 20 degrees medial

Intermalleolar plane relation to IR on mortise view

parallel

Joint surfaces open on mortise view

medial superior and lateral

Common error if mortise joint not open

under rotation

Optional 45 degree medial oblique ankle demonstrates

distal tibiofibular joint

Effect of 45 degree medial oblique on mortise joint

closes medial and superior aspect

CR location for lateral ankle

medial malleolus

Evaluation for lateral ankle

fibula in posterior half of tibia

Coincidental fracture often seen on ankle exams

base of fifth metatarsal

Stress ankle projections purpose

evaluate ligament damage or ankle joint separation

Who performs stress ankle projections

physician or physical therapist

Typical kVp range for foot and ankle

50 to 60 plus or minus 5

Broden's view rotation and angle

45 degrees medial rotation with 30 degree posterior angle

Broden's view purpose

evaluate calcaneus fracture and subtalar joint

Digits joint type for great toe

interphalangeal joint

Digits joint type for toes 2 through 5

proximal interphalangeal joint

Marker placement rule for these exams

marker on lateral side of part

AP foot appearance at heel region

whited out from talus superimposed on calcaneus

AP foot collimation guidance

tips of toes through heel

Typical technique for AP foot or toes

3 point 2 at 55

Toe oblique field coverage

include all tarsals to the talus

Toe oblique adjacent toes rule

no more than one extra toe in view

Toe separation method

tape toes to reduce superimposition

Lateral toes joint centering rule

IP for great toe PIP for toes two to five

Best routine view to show sesamoids without tangential

lateral first digit

Tangential sesamoids positioning key

dorsiflex toes 15 to 20 from vertical

Weight bearing AP foot setup

plexiglass over IR on floor not standing on IR

Weight bearing AP foot angle choice

15 degrees posterior commonly used

Weight bearing labeling requirement

add weight bearing marker

Weight bearing lateral foot practice

one foot at a time

Weight bearing foot instruction

apply some weight to foot of interest

Weight bearing oblique foot method

30 to 40 degree lateral to medial tube angle

Lateral foot include ankle

include about one inch of ankle joint

Lateral foot flexion caution

do not plantar flex

Axial heel tube start position

start vertical then angle 40 toward head

Lateral heel anatomy to include

entire calcaneus talus and navicular

AP ankle toe position

neutral do not dorsiflex into joint space

Intermalleolar plane fact

lateral malleolus sits more distal than medial

Mortise quick setup tip

rotate until laser points toward fifth digit

AP appears like mortise fix

externally rotate 10 to 15 to get true AP