Ankle Competency Evaluation

This builds off of the foot by adding on questions specific to only the ankle.

Trimalleolar fracture looks like what

What are all of the potential positions?

Anteroposterior (AP) Projection​

AP Mortise – 15-20 Degree Rotation*​

AP Medial Oblique – 45 Degree*​

AP Lateral Oblique – 45 Degree (optional)​

Lateral​

What does the ankle need to include

Proximal metatarsals through distal one third of tibia and fibula.

Picture how to position for an AP ankle

Foot position:

IR:

CR:

Plantar is nearly vertical to IR

Lengthwise

midpoint between the malleoli + 1-2inch above lateral malleolus

AP ankle structures best demonstrated

Medial mortise joint open.

Lateral mortise closed.

Some superimposition of distal fibula with tibia and talus.

AP Medial Oblique ankle positioning/factors:

Foot position:

angle:

IR:

CR:

dorsiflex foot (toes up) so plantar surface is vertical to IR

internally rotate 45 degrees

lengthwise

Center midway between the malleoli.

AP Medial Oblique ankle structures best demonstrated:

Distal tibiofibular joint space open.
Lateral malleolus and talus articulation with little or no superimposition.
Medial malleolus partially superimposed

AP External Oblique ankle positioning/factors:

Foot position:

angle:

IR:

CR:

dorsiflex foot so plantar surface is vertical to IR

45 degree external rotation

lengthwise

Center midway between the malleoli

AP External Oblique ankle structures best demonstrated:

Posterior aspect of the medial malleolus

Distal tibia

AP External Oblique ankle purpose:

Rule out trimalleolar fracture.

what is a trimalleolar fracture

• Lateral malleolus

• Medial malleolus

• Distal posterior aspect of the tibia, called the posterior malleolus.

Mortise ankle positioning/factors:

Foot position:

angle:

IR:

CR:

flexed somewhat

15-20 degrees internally rotated or until intermalleolar line appears parallel to IR

lengthwise

1-2inch above lateral malleolus

Mortise ankle structures best demonstrated

Ankle mortise joint space open between medial and lateral malleoli.

Minimal superimposition at the distal tibiofibular joint.

The mortise joint refers to the space formed by

• Medial malleolus

• Lateral malleolus

• Talus between them.

latera ankle position:

IR:

CR:

flex foot

lengthwise

1 inch inferior to the medial malleolus

lateral ankle structures best demonstrated

Open tibiotalar joint

Trochlea of the talus

Distal tibia and fibula superimposed.

Lateral malleolus superimposed over posterior tibia and talus.

Tibiotalar Joint: joint classification / movements allowed

Diarthroidal hinge joint.

dorsiflexion and plantar flexion.

Distal Tibiofibular Joint: joint classification / movements allowed

Syndesmoses, amphiarthroidal joint.

Slight movement only.