IA (Ankle) 10-08-2025

What are the three routine ankle views

AP, AP mortise, lateral

Where should the ankle be centered on every image

Directly over the ankle joint in the center of the field of view

What distal foot anatomy must be included on all ankle views

Proximal half of the metatarsals and the base of the fifth metatarsal tuberosity

How much of the lower leg must be included proximally

Distal one third of the lower leg

What soft tissues must be included

All surrounding soft tissue margins

How are ankle images hung for display

As if the patient is standing facing you with the tibia toward 12 o'clock and metatarsals toward 6 o'clock

On a left AP/mortise where should the fibula appear on the display clock

Toward 3 o'clock

On a right AP/mortise where should the fibula appear on the display clock

Toward 9 o'clock

On lateral ankles which direction should the toes point for a left ankle

Toward 3 o'clock

On lateral ankles which direction should the toes point for a right ankle

Toward 9 o'clock

What characterizes a correctly positioned AP ankle

Medial and superior mortise open with lateral mortise closed and slight tibia/talus overlap on the fibula

How is the intermalleolar line oriented on a true AP relative to the detector

Angled 15-20° to the detector

What does internal (medial) rotation error do on an intended AP

Opens the lateral mortise and reduces tibia over fibula superimposition

What does external (lateral) rotation error do on an intended AP

Closes mortise spaces and increases tibia over fibula superimposition

Where is the CR for ankle views

Midway between the medial and lateral malleoli (mid-malleoli)

Which lower-leg bone bears most weight

Tibia

What is the support/stabilizer bone of the ankle

Fibula

What is the tibial plafond

The distal articular surface of the tibia forming the mortise roof

What is the fibular notch of the tibia

The lateral tibial depression where the fibula articulates

What is the talar dome

The smooth superior contour of the talus seen as a single clean line on a true lateral

Which mortise portions must be open on a good AP

Medial and superior portions

Which joint should remain closed on a correct mortise view

The distal tibiofibular joint

How much patient rotation is used for the mortise view

10-15° internal rotation of the entire leg

How is the intermalleolar line oriented on a correct mortise relative to the detector

Parallel to the detector

How is the intermalleolar line oriented relative to the beam on a correct mortise

Perpendicular to the beam

What indicates under-rotation on a mortise image

Lateral mortise remains closed like an AP

What indicates over-rotation on a mortise image

Medial mortise closes and distal tib-fib may start to open

At approximately what rotation does the distal tib-fib joint open

Around 45° internal rotation

Which tarsals are best seen on the lateral ankle

Calcaneus and talus in profile

What defines a true lateral ankle regarding tib-fib relationship

Fibula superimposed within the posterior half of the tibia

What error is present if the fibula projects too posterior on a lateral

Over-rotation (toes/knee too close to table)

What error is present if the fibula projects too anterior or mid-tibia on a lateral

Under-rotation (toes/knee too far from table)

Why is dorsiflexion desired on ankle imaging

To open the tibiotalar joint and reduce calcaneal overlap

What does a lateral view uniquely demonstrate in terms of orientation

Anterior versus posterior relationships

What does an AP/oblique view uniquely demonstrate in terms of orientation

Medial versus lateral relationships

What is the routine ankle technique mentioned

Approximately 4 mAs at 60 kVp (room-dependent)

What image quality cues confirm adequate exposure

Visible cortical margins, trabecular detail, and soft-tissue outlines

Why review the exposure indicator on digital systems

Post-processing can mask over/under-exposure so EI confirms detector dose

If an image appears too light and EI is low

What adjustment is indicated, Increase exposure (typically mAs)

If an image appears too dark and EI is high

What adjustment is indicated, Decrease exposure (typically mAs)

Which factor does the instructor prefer to adjust first

mAs rather than kVp

What common artifacts should be removed before imaging

Shoes, socks, ankle bracelets, and clothing elastic or metal

What is the recommended SID for ankle radiographs

40 inches

What anatomical marker must appear on every image

Right or left marker

What is the distal tibial projection name

Medial malleolus

What is the distal fibular projection name

Lateral malleolus

Which joint name is used on AP/mortise images

Mortise joint

Which joint name is commonly used on lateral images

Tibiotalar joint

What structure forms the ankle joint with tibia and fibula

Talus

What structures form the subtalar (talocalcaneal) joint

Talus and calcaneus

Which space is visible on a good lateral between talus and calcaneus

Sinus tarsi

What is the ankle joint classification and motion type

Sellar (saddle) joint with ginglymus (hinge) motion

What is the best view to evaluate the tibiotalar joint space

Lateral ankle (with dorsiflexion)

What is the minimum distal anatomy that must be included to accept an image

Base of the fifth metatarsal

How much lower leg should be included proximally on ankle views

About one third of the distal tibia/fibula

What centering error leads to excess lower leg and clipped metatarsals

CR positioned too proximal

What is assessed first when evaluating any image

Centering to the joint and collimation coverage

What indicates correct mortise positioning succinctly

Mortise joint evenly open medially, superiorly, and laterally

If all mortise spaces are closed and fibula is heavily overlapped

What is the likely error, External (lateral) rotation on intended AP

If lateral mortise is open on an intended AP

What is the likely error, Medial (internal) rotation

What dorsiflexion cue suggests adequacy on lateral

Open tibiotalar space without calcaneal overlap

What pediatric feature can mimic fracture lines

Epiphyseal growth plates

When should foot-only rotation be avoided for mortise

Always—rotate the entire leg 10-15° not just the foot

What positioning aid can reduce motion

Sponges or sandbags

Why align the long axis of the lower leg with the detector

To prevent slanted images and ensure even coverage

If the distal tib-fib joint is open on a mortise

What does that indicate, Over-rotation beyond the mortise range

If the medial mortise appears widened while lateral is closed

What does that indicate, Under-rotation toward AP

If the talar domes are not superimposed on lateral

What does that indicate, Rotation error or inadequate dorsiflexion

What should be checked before exposure besides positioning

Patient comfort, motion control, CR centering, collimation, and markers

What view best shows anterior vs posterior displacement of fractures

Lateral ankle

Why avoid plantarflexion on the lateral

It causes calcaneus to obscure the tibiotalar joint space

What is the purpose of the three-view ankle series

To evaluate fractures, dislocations, alignment, and joint spaces from multiple perspectives

Which joint should always be evaluated for alignment on all ankle images

The tibiotalar joint

What does consistent visualization of cortical margins and trabecular detail indicate

Proper exposure and image quality

What marker orientation rule helps confirm correct hanging for a right mortise

Fibula should be toward 9 o'clock with heels toward 6 o'clock

What minimum inclusion rule may allow acceptance even if half MTs are not fully included

Inclusion of the base of the fifth metatarsal

What is the quick test for lateral rotation adequacy using tib-fib

Fibula confined to the posterior half of the distal tibia

Which error places the fibula down the center of the tibia on lateral

Under-rotation

Which error makes the fibula protrude beyond the posterior cortex

Over-rotation

What typical patient instruction reduces motion blur

Hold still and support with sponges or sandbags

What additional anatomy labeling should learners recognize on mortise/AP

Tibial plafond, fibular notch, medial malleolus, lateral malleolus, talus, calcaneus, navicular, cuboid, cuneiforms

What is the subtalar joint alternative name

Talocalcaneal joint

What is the other name for the calcaneus

Os calcis

What is a fast way to judge centering on mortise/AP

Visualize an X through the image and ensure the joint is at its intersection

What indicates correct collimation front-to-back on lateral

Adequate anterior and posterior soft tissue margins without clipping

Which way do you adjust exposure if EI is below target

Increase mAs to raise detector exposure

Which way do you adjust exposure if EI is above target

Decrease mAs to lower detector exposure

Why can't we rely only on appearance for exposure

Digital post-processing can normalize brightness despite incorrect detector dose

What does the fibula's position indicate when it is seen in the anterior half of the tibia on a lateral

Under-rotation (toes/patella too far from the table)

What does the fibula's position indicate when it is seen beyond the posterior tibial margin on a lateral

Over-rotation (toes/patella too close to the table)

What joint should remain closed on a correct mortise view

Distal tibiofibular joint

What does dorsiflexion help demonstrate on the lateral ankle

Opens the tibiotalar joint

How can you confirm correct hanging of an ankle image

Fibula toward 3 o'clock for left or 9 o'clock for right, heel toward 6 o'clock, tibia at 12 o'clock

What angle does the intermalleolar line form with the IR on a true AP

15-20 degrees

How much obliquity is used for the mortise view

15-20 degrees medial rotation of the entire leg

What is the CR for a lateral ankle

Perpendicular to the medial malleolus

What anatomy should be identifiable on ankle radiographs in addition to foot structures

Medial, lateral, posterior malleoli; anterior tubercle; fibular notch of tibia; distal tib-fib joint; tibial plafond; tibia; fibula

What tarsals are in profile on a lateral ankle

Talus and calcaneus

What tarsals articulate on the calcaneocuboid joint

Calcaneus and cuboid

What is another name for the calcaneus

Os calcis