X-ray examination of the ankle Flashcards
What are the clinical indications for an X-ray of the ankle joint?
- Fractures or dislocations of the ankle joint (involving distal tibia and fibula, talus, etc.)
- Bony lesions or diseases involving the ankle joint, distal tibia and fibula, proximal talus, and proximal fifth metatarsal
- Foreign radiopaque materials
What is the supplementary projection for the ankle joint?
Anteroposterior Oblique - 45° medial rotation
What are the basic projections for the ankle joint?
Anteroposterior mortise projection
Lateral projection
What steps should be taken for patient preparation before an ankle X-ray?
- Check the area to be examined.
- Explain the procedure to the patient carefully and ensure they understand fully.
- Instruct the patient to remove their shoes, socks, and any bandages if necessary, and pull up trousers if needed.
- Remove tights where applicable.
What equipment is required for the anteroposterior mortise projection of the ankle?
24 x 30 cm image receptor lengthwise, split into two equal parts (shield the unexposed part with a lead sheet when exposing the other half)
Sheet of lead rubber
Foam pad
Sandbag
Lead protective waist apron or gonad shield
How should the patient be positioned for the anteroposterior mortise projection of the ankle?
The patient is either supine or seated on the X-ray couch with both legs extended.
A foam pad may be placed under the knee for comfort.
Center and align the ankle joint to the central ray and to the long axis of the portion of the image receptor being exposed.
The foot should be positioned perpendicular to the X-ray table, with the toes pointing straight up.
The foot should be internally rotated approximately 20 degrees to open the mortise joint. This is achieved by turning the toes slightly inward.
The mid-tibia should be immobilized using a sandbag.
What is the centering point and direction of the central ray for the anteroposterior mortise projection of the ankle?
Centering point:
midway between the malleoli
Direction of central ray:
Vertical beam at 90° to the image receptor
What indicates proper obliquity for the mortise joint in the AP ankle joint image?
Demonstration of open lateral and medial mortise joints with malleoli demonstrated in profile.
Only minimal superimposition should exist at the distal tibiofibular joint.
Collimation to the area of interest.
What anatomy should be demonstrated in the evaluation criteria for the AP ankle joint image?
- Distal one-third of tibia and fibula, tibial plafond involving the epiphysis if present, lateral and medial malleoli, talus, and proximal half of the metatarsals.
- Entire ankle mortise should be open and well visualized (3 to 4 mm space over the entire talar surface is normal; an extra 2 mm widening is abnormal).
What are the exposure criteria for the AP ankle joint image?
No motion as demonstrated by sharp bony outlines and trabecular markings.
Optimal exposure should demonstrate soft tissue structures and sufficient density (brightness) for talus and distal tibia and fibula.
