RADPOS - Trigger 10

• AP

• Lateral – Mediolateral

• AP Oblique (Mortise Joint) – Medial rotation

(3) Ankle Projections

AP of Ankle

Patient Position

• Place the patient in the supine position with the affected limb fully extended.

Part Position

• Adjust the ankle joint in the anatomic position to obtain a true AP projection. Flex the ankle and foot enough to place the long axis of the foot in the vertical position.

• Ball and Egbert' stated that the appearance of the ankle mortise is not appreciably altered by moderate plantar flexion or dorsiflexion as long as the leg is rotated neither laterally nor medially.

Central ray

• Perpendicular through the ankle joint at a point midway between the malleoli.

Structures Shown

• The resulting image shows a true AP projection of the ankle joint, the distal ends of the tibia and fibula, and the proximal portion of the talus

NOTE: The inferior tibiofibular articulation and the talofibular articulation will not be "open" nor shown in profile in the true AP projection. This is a positive sign for the radiologist because it indicates that the patient has no ruptured ligament or other type of separations. For this reason, it is important that the position of the ankle be anatomically "true" for the AP projection demonstrated

AP of Ankle

What projection shows a true AP of the ankle joint?

Supine, affected limb fully extended

What is the patient position in AP Ankle?

Flex enough so the long axis of the foot is vertical

How should the ankle and foot be flexed in AP Ankle?

Moderate plantar flexion or dorsiflexion

According to Ball and Egbert, what does not alter the mortise appearance if no rotation occurs?

Perpendicular, midway between malleoli

Where is the CR directed in AP Ankle?

• Ankle joint

• distal tibia/fibula

• proximal talus

What structures are shown in AP Ankle?

Indicates no ruptured ligament or separation

In AP Ankle, why is it significant that the inferior tibiofibular and talofibular articulations are not open?

Lateral – Mediolateral of Ankle

Patient Position

• Have the supine patient turn toward the affected side until the ankle is lateral

Part Position

• Place the long axis of the IR parallel with the long axis of the patient's leg and center it to the ankle joint.

• Ensure that the lateral surface of the foot is in contact with the IR.

• Dorsiflex the foot and adjust it in the lateral position. Dorsiflexion is required to prevent lateral rotation of the ankle.

Central ray

• Perpendicular to the ankle joint, entering the medial malleolus

Structures Shown

• The resulting image shows a true lateral projection of the lower third of the tibia and fibula, the ankle joint, and the tarsals

It is often recommended that the lateral projection of the ankle joint be made with the medial side of the ankle in contact with the IR. Exact positioning of the ankle is more easily and more consistently obtained when the limb is rested on its comparatively flat medial surface.

Lateral – Mediolateral of Ankle

What projection shows a true lateral ankle?

Supine, turned toward affected side

What is the patient position in Lateral Ankle (Mediolateral)?

Long axis parallel with leg, centered to ankle joint

How is the IR aligned in Lateral Ankle (Mediolateral)?

Lateral surface

What surface of the foot should contact the IR in Lateral Ankle (Mediolateral)?

Dorsiflexed, adjusted lateral

How is the foot positioned in Lateral Ankle (Mediolateral)?

Prevents lateral rotation of ankle

Why is dorsiflexion required in Lateral Ankle (Mediolateral)?

Perpendicular, entering medial malleolus

Where is the CR directed in Lateral Ankle (Mediolateral)?

• Lower third tibia/fibula

• ankle joint

• tarsals

What structures are shown in Lateral Ankle (Mediolateral)?

Medial side

What side of the ankle is often recommended to be in contact with IR for better positioning?

AP Oblique (Mortise Joint) – Medial rotation of Ankle

Patient Position

• Place the patient in the supine position.

Part Position

• Center the patient's ankle joint to the IR.

• Grasp the distal femur area with one hand and the foot with the other. Assist the patient by internally rotating the entire leg and foot together 15 to 20 degrees until the intermalleolar plane is parallel with the IR

• The plantar surface of the foot should be placed at a right angle to the leg

Central ray

• Perpendicular, entering the ankle joint midway between the malleoli

Structures Shown

• The entire ankle mortise joint should be demonstrated in profile. The three sides of the mortise joint should be visualized

AP Oblique (Mortise Joint) – Medial rotation

What projection demonstrates the ankle mortise joint in profile?

Supine

What is the patient position in AP Oblique Mortise Ankle?

ankle joint

What is centered to the IR in AP Oblique Mortise Ankle?

15–20° internally

How much should the leg and foot be rotated in AP Oblique Mortise Ankle?

To place the intermalleolar plane parallel with the IR

What is the purpose of the 15–20° medial rotation in AP Oblique Mortise Ankle?

At a right angle to the leg

How should the plantar surface of the foot be positioned in AP Oblique Mortise Ankle?

Perpendicular, midway between malleoli

Where is the CR directed in AP Oblique Mortise Ankle?

Entire ankle mortise joint in profile

What structures are shown in AP Oblique Mortise Ankle?

3

How many sides of the mortise joint should be visualized in AP Oblique Mortise Ankle?

• AP

• Lateral – Mediolateral

• AP Oblique

(3) Leg Projections

AP Leg

For this projection, as well as the lateral and oblique projections described in the following sections, the long axis of the IR is placed parallel with the long axis of the leg and centered to the midshaft. Unless the leg is unusually long, the IR will extend beyond the knee and ankle joints enough to prevent their being projected off the IR by the divergency of the x-ray beam. The IR must extend from 1 to 1 1/2 (2.5 to 3.8 cm) inches beyond the joints. When the leg is too long for this allowance and the site of the lesion is not known, two images should be made. Diagonal use of a 35 X 43 cm IR is also an option if the leg is too long to fit lengthwise and if such use is permitted by the facility

Patient Position

• Place the patient in the supine position.

Part Position

• Adjust the patient's body so that the pelvis is not rotated.

• Adjust the leg so that the femoral condyles are parallel with the IR and the foot is vertical.

• Flex the ankle until the foot is in the vertical position.

• If necessary, place a sandbag against the plantar surface of the foot to immobilize it in the correct position

Central ray

• Perpendicular to the center of the leg

Structures Shown

• The resulting image shows the tibia, fibula, and adjacent joints

AP Leg

What projection demonstrates the tibia, fibula, and adjacent joints?

Supine

What is the patient position in AP Leg?

Not rotated

How should the pelvis be positioned in AP Leg?

Parallel with IR

How are the femoral condyles positioned in AP Leg?

Vertical

How should the foot be positioned in AP Leg?

Flexed to place foot vertical

How is the ankle adjusted in AP Leg?

Sandbag against plantar surface

What can be used to immobilize the foot in AP Leg?

Perpendicular to center of leg

Where is the central ray directed in AP Leg?

• Tibia

• fibula

• adjacent joints

What structures are shown in AP Leg?

1–1 ½ inches (2.5–3.8 cm)

How much should the IR extend beyond the joints in AP Leg?

Take two images or use diagonal placement of 35×43 cm IR

What should be done if the leg is too long to fit on the IR?

Lateral – Mediolateral Leg

Patient Position

• Place the patient in the supine position.

Part Position

• Turn the patient toward the affected side with the leg on the IR.

• Adjust the rotation of the body to place the patella perpendicular to the IR and ensure that a line drawn through the femoral condyle is also perpendicular.

• Place sandbag supports where needed for the patient's comfort and to stabilize the body position.

Alternate method

• When the patient cannot be turned from the supine position, the lateral projection may be taken cross-table using a horizontal central ray.

• Lift the leg enough for an assistant to slide a rigid support under the patient's leg.

• The IR may be placed between the legs and the central ray directed from the lateral side.

Central ray

• Perpendicular to the midpoint of the leg

Structures Shown

• The resulting image shows the tibia, fibula, and adjacent joints

Lateral – Mediolateral Leg

What projection demonstrates the tibia, fibula, and adjacent joints in lateral profile?

Supine

What is the patient position in Lateral Leg?

Toward the affected side with leg on IR

How should the patient be turned in Lateral Leg?

Perpendicular to IR

How is the patella positioned in Lateral Leg?

Perpendicular

How should a line through the femoral condyles be positioned in Lateral Leg?

Sandbag supports

What is used for comfort and stabilization in Lateral Leg?

Cross-table with horizontal CR

What is the alternate method for Lateral Leg if patient cannot be turned?

Between the legs

Where is the IR placed in cross-table lateral Leg?

Lateral side

From which side is the CR directed in cross-table lateral Leg?

Perpendicular to midpoint of leg

Where is the CR directed in standard Lateral Leg?

• Tibia

• fibula

• adjacent joints

What structures are shown in Lateral Leg?

AP Oblique Leg

Patient Position

• Place the patient in the supine position on the radiographic table.

Part Position

• Perform oblique projection of the leg by alternately rotating the limb 45 degrees medially or laterally. For the medial rotation, ensure that the leg is turned inward and not just the foot.

• For the medial oblique projection, elevate the affected hip enough to rest the medial side of the foot and ankle against a 45-degree foam wedge, and place a support under the greater trochanter

Central ray

• Perpendicular to the midpoint of the IR

Structures Shown

• The resulting image shows a 45-degree oblique projection of the bones and soft tissues of the leg and one or both of the adjacent joints

AP Oblique Leg

What projection shows the tibia, fibula, and adjacent joints in oblique view?

Supine

What is the patient position in AP Oblique Leg?

45 degrees (medially or laterally)

How much is the limb rotated for AP Oblique Leg?

The whole leg (turned inward, not just the foot)

In medial rotation, what must be rotated — the foot only or the whole leg?

45-degree foam wedge under medial side of foot & ankle, support under greater trochanter

For medial oblique projection, what positioning aids are used?

Perpendicular to midpoint of IR

Where is the central ray directed for AP Oblique Leg?

45-degree oblique projection of tibia, fibula, soft tissues, and one or both adjacent joints

What structures are shown in AP Oblique Leg?