Procedures · Lower Extremity

Foot Positioning Series

Explore the foot's anatomy, then use Practice mode to position the AP axial, oblique, and lateral projections yourself.

Foot

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The routine foot series

The projections this region is examined with. Set them up yourself in Practice positioning.

AP axial foot (dorsoplantar)

Dorsoplantar projection · CR 10° posteriorly

Demonstrates: The whole foot face-on — phalanges, metatarsals and tarsals. The bases of the first and second metatarsals separate, while the bases of the second through fifth stay overlapped.
Part position: Supine or seated with the knee flexed. The foot is plantar flexed just enough to keep the plantar surface resting flat and firmly on the image receptor, with the long axis of the foot aligned to the central ray and to the long axis of the receptor. The foot is not rotated.
Central ray: Angled 10° toward the calcaneus, centered to the base of the third metatarsal.
Why it is positioned this way: With the plantar surface flat the metatarsals slope down toward the toes, so a beam left at 90° to the receptor cuts across the tarsometatarsal joint spaces instead of passing through them. Angling 10° toward the calcaneus puts the beam square to those joints and opens them. A 15° wedge under the forefoot does the same job with the beam at 90° — the wedge and the angle are alternatives, not additions.

Also covered by this projection

AP axial weight-bearingThe same projection taken erect under body weight, angled 15° toward the calcaneus, centered midway between the feet. It is how a Lisfranc injury is looked for, because abnormal separation between the first and second metatarsal bases shows up under load and can be missed without it.

AP oblique foot — medial rotation 30°

AP oblique projection · foot rotated medially 30°

Demonstrates: The third through fifth metatarsals free of superimposition, the tuberosity of the fifth metatarsal in profile, and the joint spaces around the cuboid open.
Part position: Supine or seated as for the AP axial, then rotate the leg and foot medially as a unit until the plantar surface sits at 30° to the image receptor, which puts the general plane of the dorsum of the foot parallel to the receptor and at 90° to the central ray. The lateral border lifts; the medial border stays down.
Central ray: 90° to the image receptor, centered to the base of the third metatarsal.
Why it is positioned this way: Lifting the lateral border throws the lateral metatarsals clear of one another and turns the tuberosity of the fifth metatarsal — a common fracture site — into profile. Rotate to 30° and no further: past that, the lateral cuneiform is thrown over the cuneiforms beside it.

AP oblique foot — lateral rotation 30°

AP oblique projection · foot rotated laterally 30°

Demonstrates: The space between the first and second metatarsals and between the medial and intermediate cuneiforms — the interspaces the medial oblique closes.
Part position: Supine or seated as for the AP axial, then rotate the leg and foot laterally as a unit until the plantar surface sits at 30° to the image receptor. The medial border lifts; the lateral border stays down.
Central ray: 90° to the image receptor, centered to the base of the third metatarsal.
Why it is positioned this way: It is the mirror of the medial oblique and exists for the opposite half of the foot: the medial rays that a medial rotation superimposes. The foot’s own arch already supplies some of this obliquity, which is why the two texts agree on 30° here even though they differ on the medial oblique.

Lateral foot (mediolateral)

Mediolateral projection · beam enters medial, exits lateral

Demonstrates: The whole foot in profile with the tarsals superimposed, the tibiotalar joint open, the tarsal sinus open and the longitudinal arch visible. The distal tibia and fibula are included.
Part position: Lateral recumbent with the affected side down and that knee flexed about 45°, the opposite leg placed behind the injured limb to prevent over-rotation. Support the leg and knee so the plantar surface sits at 90° to the image receptor, and dorsiflex the foot as far as the patient tolerates — never forced.
Central ray: 90° to the image receptor, centered to the medial cuneiform, at the level of the base of the third metatarsal.
Why it is positioned this way: The beam enters the medial surface and exits the lateral, which is what makes this a mediolateral projection rather than a lateromedial one.

Also covered by this projection

Lateral weight-bearingTaken erect under load. Its criterion is that the longitudinal arch is demonstrated in its entirety — exactly what a non-weight-bearing lateral cannot show, and why arch conditions are assessed this way.

Procedures lessonFoot & ankle