RADPOS - Trigger 8

Tangential (Lewis & Holly Methods)

(1) Projections for Sesamoid

Tangential (Lewis & Holly Methods)

Patient Position

• Place the patient in the prone position for the Lewis method and in a sitting position for the Holly method.

• Elevate the ankle of the affected side on sandbags for stability, if needed. A folded towel may be placed under the knee for comfort.

Part Position

• Rest the great toe on the table in a position of dorsiflexion and adjust it to place the ball of the foot perpendicular to the horizontal plane.

Central Ray

• Perpendicular and tangential to the first MTP joint.

Structures Shown

• The resulting image shows a tangential projection of the metatarsal head in profile and the sesamoids.

Prone

What is the patient position for the Lewis method in the sesamoid tangential projection?

Sitting

What is the patient position for the Holly method in the sesamoid tangential projection?

• Dorsiflexion

• Ball of foot perpendicular to horizontal plane

In the sesamoid tangential projection, how is the great toe positioned?

Perpendicular and tangential to first MTP joint

How is the CR directed in Sesamoid Tangential Projections?

• Metatarsal head in profile

• Sesamoids

What structures are demonstrated in Sesamoid Tangential Projections?

• AP or AP Axial Projection

• AP Oblique Projection: Medial Rotation

• Lateral Projection: Mediolateral

• Lateral Projection: Lateromedial – Longitudinal Arch (Weight-Bearing Method)

• AP Axial Projection: Lateromedial – Longitudinal Arch (Weight-Bearing Composite Method)

(5) Projections for Foot

AP or AP Axial of Foot

When a 10-degree posterior angle is used, the central ray is perpendicular to the metatarsals, reducing foreshortening.

Patient Position

• Place the patient in the supine or seated position.

• Flex the knee of the affected side enough to rest the sole of the foot firmly on the radiographic table.

Part Position

• Position the IR under the patient’s foot, center it to the base of the third metatarsal, and adjust it so that its long axis is parallel with the long axis of the foot.

• Hold the leg in the vertical position by having the patient flex the opposite knee and lean it against the knee of the affected side.

• Ensure that no rotation of the foot occurs.

Central ray

• Directed one of two ways:

  • (1) 10 degrees toward the heel entering the base of the third metatarsal or

  • (2) perpendicular to the IR and entering the base of the third metatarsal.

Structures Shown

• The resulting image shows an AP (dorsoplantar) projection of the tarsals anterior to the talus, metatarsals, and phalanges. This projection is used for localizing foreign bodies, determining the locations of fragments in fractures of the metatarsals and anterior tarsals, and performing general surveys of the bones of the foot

Supine or seated

What is the patient position in AP/AP Axial Foot?

• Flex affected side

• Sole flat on table

How is the knee positioned in AP/AP Axial Foot?

Base of 3rd metatarsal

Where is the IR centered in AP/AP Axial Foot?

Long axis parallel with foot

How is the IR aligned in AP/AP Axial Foot?

Opposite knee flexed, leaned against

How is the leg stabilized in AP/AP Axial Foot?

Rotation

What foot positioning must be avoided in AP/AP Axial Foot?

10° toward heel to base of 3rd MT

What is the first CR option in AP/AP Axial Foot?

Perpendicular to base of 3rd MT

What is the second CR option in AP/AP Axial Foot?

Tarsals anterior to talus, metatarsals, phalanges

What structures are shown in AP/AP Axial Foot?

AP Oblique: Medial Rotation of Foot

Patient Position

• Place the patient in the supine or seated position.

• Flex the knee of the affected side enough to rest the sole of the foot firmly on the radiographic table.

Part Position

• Place the IR under the patient’s foot, parallel with its long axis, and center it to the midline of the foot at the level of the base of the third metatarsal.

• Rotate the patient’s leg medially until the plantar surface of the foot forms an angle of 30 degrees to the plane of the IR.

Central ray

• 1 inch (2.5 cm) on all sides and 1 inch (2.5 cm) beyond the calcaneus and distal tip of the toes

Structures Shown

• The resulting image shows the interspaces between the following: the cuboid and the calcaneus, the cuboid and the fourth and fifth metatarsals, the cuboid and the lateral cuneiform, and the talus and the navicular bone. The cuboid is shown in profile. The sinus tarsi is also well shown.

Supine or seated

What is the patient position in AP Oblique Foot (Medial Rotation)?

• Flex affected side

• Sole flat on table

How is the knee positioned in AP Oblique Foot (Medial Rotation)?

Midline of foot at base of 3rd metatarsal

Where is the IR centered in AP Oblique Foot (Medial Rotation)?

Parallel with long axis of foot

How is the IR aligned in AP Oblique Foot (Medial Rotation)?

Medially 30°

How is the leg rotated in AP Oblique Foot (Medial Rotation)?

• 1 inch on all sides

• 1 inch beyond calcaneus and toes

What is the CR coverage in AP Oblique Foot (Medial Rotation)?

• Cuboid & calcaneus

• Cuboid & 4th/5th metatarsals

• Cuboid & lateral cuneiform

• Talus & navicular

What interspaces are shown in AP Oblique Foot (Medial Rotation)?

Cuboid

What bone is shown in profile in AP Oblique Foot (Medial Rotation)?

Sinus tarsi

What space is well demonstrated in AP Oblique Foot (Medial Rotation)?

Lateral: Mediolateral of Foot

The lateral (mediolateral) projection is routinely used in most radiology departments because it is the most comfortable position for the patient to assume. The lateral (lateromedial) on the other hand, is performed to project a TRUE lateral projection of the foot.

Patient Position

• Have the patient lie on the radiographic table and turn toward the affected side until the leg and the foot are lateral.

• Place the opposite leg behind the affected leg.

Part Position

• Elevate the patient’s knee enough to place the patella perpendicular to the horizontal plane.

• Medial surface of the foot should be parallel with the plane of the IR.

• Adjust the foot to place the plantar surface of the forefoot perpendicular to the IR.

• Dorsiflex the foot to form a 90-degree angle with the lower leg.

Central ray

• Perpendicular to the base of the third Metatarsal

Structures Shown

• The resulting image shows the entire foot in profile, the ankle joint, and the distal ends of the tibia and fibula

• Lie on affected side

• Foot lateral

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

Behind affected leg

Where is the opposite leg placed in Lateral Foot (Mediolateral)?

Elevated; patella perpendicular to horizontal plane

How is the knee positioned in Lateral Foot (Mediolateral)?

Medial surface

Which foot surface should be parallel to IR in Lateral Foot (Mediolateral)?

Forefoot perpendicular to IR

How is the plantar surface positioned in Lateral Foot (Mediolateral)?

90° with lower leg

How is the foot dorsiflexed in Lateral Foot (Mediolateral)?

Perpendicular to base of 3rd metatarsal

What is the CR in Lateral Foot (Mediolateral)?

• Entire foot in profile

• ankle joint

• distal tibia & fibula

What structures are shown in Lateral Foot (Mediolateral)?

Lateral Projection: Lateromedial – Longitudinal Arch (Weight-Bearing Method)

Patient Position

• Place the patient in the upright position, preferably on a low riser that has an IR groove. If such a riser is unavailable, use blocks to elevate the feet to the level of the x-ray tube.

Part Position

• Have the patient stand in a natural position, one foot on each side IR, with the weight of the body equally distributed on the feet.

• Adjust the IR so that it is centered to the base of the third metatarsal, and place the medial surface of the foot against the IR.

Central ray

• Perpendicular to a point just above the base of the third metatarsal

Structures Shown

• The projection is used to show the structural status of the longitudinal arch. The right and left sides are examined for comparison

Upright on low riser/blocks

What is the patient position in Lateral Foot (Lateromedial, Longitudinal Arch)?

Equally on both feet

How is the weight distributed in Lateral Foot (Lateromedial, Longitudinal Arch)?

Base of 3rd metatarsal

Where is the IR centered in Lateral Foot (Lateromedial, Longitudinal Arch)?

Medial surface

Which surface of the foot is against the IR in Lateral Foot (Lateromedial, Longitudinal Arch)?

Perpendicular just above base of 3rd metatarsal

What is the CR in Lateral Foot (Lateromedial, Longitudinal Arch)?

Longitudinal arch

What structure is shown in Lateral Foot (Lateromedial, Longitudinal Arch)?

For comparison

Why are both sides examined in Lateral Foot (Lateromedial, Longitudinal Arch)?

AP Axial Projection: Lateromedial – Longitudinal Arch (Weight-Bearing Composite Method)

Patient Position

• Place the patient in the standing-upright position. The patient should stand at a comfortable height on a low stool or on the floor.

Part Position

• With the patient standing upright, adjust the IR under the foot and center its midline to the long axis of the foot.

• To prevent superimposition of the leg shadow on that of the ankle joint, have the patient place the opposite foot one step backward for the exposure of the forefoot and one step forward for the exposure of the hindfoot or calcaneus.

Central ray

• To use the masking effect of the leg, direct the central ray along the plane of alignment of the foot in both exposures.

• With the tube in front of the patient and adjusted for a posterior angulation of 15 degrees, center the central ray to the base of the third metatarsal for the first exposure.

• Caution the patient to carefully maintain the position of the affected foot and to place the opposite foot one step forward in preparation for the second exposure.

• Move the tube behind the patient, adjust it for an anterior angulation of 25 degrees, and direct the central ray to the posterior surface of the ankle. The central ray emerges on the plantar surface at the level of the lateral malleolus. An increase in technical factors is recommended for this exposure

Structures Shown

• The resulting image shows a weightbearing AP axial projection of all bones of the foot. The full outline of the foot is projected free of the leg

Standing upright

What is the patient position in AP Axial Foot (Composite Method)?

Midline to long axis of foot

Where is the IR centered in AP Axial Foot (Composite Method)?

Opposite foot one step backward (forefoot) / one step forward (hindfoot)

How is leg shadow prevented in AP Axial Foot (Composite Method)?

15° posterior, base of 3rd metatarsal

What is the CR angulation and centering for the first exposure in AP Axial Foot (Composite Method)?

25° anterior, posterior ankle, exits plantar surface at lateral malleolus

What is the CR angulation and centering for the second exposure in AP Axial Foot (Composite Method)?

Weight-bearing AP axial of all foot bones

What structure is shown in AP Axial Foot (Composite Method)?

Free of the leg

How is the foot outline projected in AP Axial Foot (Composite Method)?

• AP Projection (Kite Method)

• Lateral Projection (Kite Method)

• Axial Projection (Kandel Method)

(3) Projections for CONGENITAL CLUBFOOT DEFORMITY

AP (Kite Method)

The AP projection shows the degree of adduction of the forefoot and the degree of inversion of the calcaneus.

Patient Position

• Place the infant in the supine position, with the hips and knees flexed to permit the foot to rest flat on the IR.

• Elevate the body on firm pillows to knee height to simplify gonad shielding and leg adjustment.

Part Position

• Rest the feet flat on the IR with the ankles extended slightly to prevent superimposition of the leg shadow.

• Hold the infant’s knees together or in such a way that the legs are exactly vertical (i.e., so that they do not lean medially or laterally).

• Using a lead glove, hold the infant’s toes. When the adduction deformity is too great to permit correct placement of the legs and feet for bilateral images without overlap of the feet, each foot must be examined separately

Central ray

• Perpendicular to the tarsals, midway between the tarsal areas for a bilateral projection

• An approximately 15-degree posterior angle is generally required for the central ray to be perpendicular to the tarsals.

• Kite stressed the importance of directing the central ray vertically for the purpose of projecting the true relationship of the bones and ossification centers.

• Degree of forefoot adduction

• calcaneus inversion

What does the AP Projection (Kite Method) show?

Supine, hips and knees flexed

What is the patient position in AP Projection (Kite Method)?

Simplifies gonad shielding and leg adjustment

Why elevate the body on firm pillows in AP Projection (Kite Method)?

Feet flat, ankles slightly extended

How should the feet be placed on the IR in AP Projection (Kite Method)?

Held together, legs exactly vertical

How are the knees positioned in AP Projection (Kite Method)?

With a lead glove

How are the toes held in AP Projection (Kite Method)?

Examine each foot separately

What if the adduction deformity is too great in AP Projection (Kite Method)?

Perpendicular to tarsals, midway between tarsal areas

What is the CR direction in AP Projection (Kite Method)?

15° posterior

What CR angulation is generally required in AP Projection (Kite Method)?

To project true relationship of bones and ossification centers

Why did Kite stress directing the CR vertically?

Lateral (Kite Method)

The Kite method lateral radiograph shows the anterior talar subluxation and the degree of plantar flexion (equinus).

Patient Position

• Place the infant on his or her side in as near the lateral position as possible.

• Flex the uppermost limb, draw it forward, and hold it in place.

Part Position

• After adjusting the IR under the foot, place a support that has the same thickness as the IR under the infant’s knee to prevent angulation of the foot and to ensure a lateral foot position.

• Hold the infant’s toes in position with tape or a protected hand

Central ray

• Perpendicular to the midtarsal area

• Anterior talar subluxation

• Degree of plantar flexion (equinus)

What does the Lateral Projection (Kite Method) show?

Infant on side, near lateral position

What is the patient position in Lateral Projection (Kite Method)?

Flexed and drawn forward

How is the uppermost limb positioned in Lateral Projection (Kite Method)?

Support equal in thickness to IR

What support is placed under the knee in Lateral Projection (Kite Method)?

To prevent angulation and ensure lateral foot position

Why is support used under the knee in Lateral Projection (Kite Method)?

With tape or protected hand

How are the toes held in Lateral Projection (Kite Method)?

Perpendicular to midtarsal area

What is the CR direction in Lateral Projection (Kite Method)?

Axial (Kandel Method)

For this method, the infant is held in a vertical or a bending-forward position. The plantar surface of the foot should rest on the IR, although a moderate elevation of the heel is acceptable when the equinus deformity is well marked. The central ray is directed 40 degrees anteriorly through the lower leg, as for the usual dorsoplantar projection of the calcaneus.

Infant held vertical or bending-forward

What is the patient position in Axial Projection (Kandel Method)?

On the IR

How should the plantar surface of the foot rest in Axial Projection (Kandel Method)?

Moderate elevation of heel

What is acceptable if the equinus deformity is well marked in Axial Projection (Kandel Method)?

40° anteriorly through lower leg

What is the CR direction in Axial Projection (Kandel Method)?

Usual dorsoplantar calcaneus projection

CR direction in Axial Projection (Kandel Method) is similar to what projection?

• AP

• Lateral

• Medial oblique

What are the basic routine procedures for the foot?

Jones fracture

Transverse fracture at the base of the 5th metatarsal, about 1.5–3 cm (≈ ¾ inch) distal to the tuberosity. Common in athletes — results from inversion of the foot (ankle rolls inward).