Foot and ankle injuries are among the most common reasons patients visit emergency departments and urgent care centers. As a radiologic technologist, mastering the positioning techniques for the foot, ankle, and calcaneus is essential — not just for the ARRT exam, but for producing diagnostic-quality images that enable accurate clinical decisions. A poorly positioned foot or ankle radiograph can miss subtle fractures, misrepresent joint alignment, or require a repeat exposure that subjects the patient to unnecessary radiation.
This guide reviews common adult foot, ankle, and calcaneus projections, including positioning, centering, collimation, and image-evaluation points. Exact series composition, detector size, SID, and beam-angle conventions vary by department and patient; the current order and local procedure manual govern.
Projection names and series composition are not completely uniform. In particular, a neutral AP ankle and an AP oblique mortise are distinct views; a department may acquire both or use a protocol-specific series. This article does not assign a fixed number of ARRT competencies. Use the current ARRT documents, program requirements, and clinical procedure manual.
Before discussing positioning, it is important to understand the bony anatomy you will be imaging. The foot is divided into three anatomical regions:
The ankle mortise is formed by the distal tibial plafond and medial malleolus, the distal fibula/lateral malleolus, and the talar dome. The distal tibiofibular syndesmosis is assessed using the series as a whole: the neutral AP retains expected tibiofibular overlap, while the internally rotated mortise view demonstrates the joint around the talar dome with little tibiofibular overlap.
Foot: The base of the 3rd metatarsal is the routine DP and oblique centering landmark; the base/tuberosity of the 5th metatarsal is important to include. Ankle: Use the medial and lateral malleoli to locate the midpoint and assess rotation. Calcaneus: For the lateral projection, center about 2.5 cm (1 inch) distal to the medial malleolus; for the plantodorsal axial projection, center near the base of the 3rd metatarsal with the prescribed cephalic angle.
A common non-weight-bearing foot series uses dorsoplantar (DP), medial-oblique, and lateral projections. Many texts call the DP projection “AP” or “AP axial.” Rotation, beam angle, and weight-bearing views are protocol dependent.
Position: Seat or place the patient supine with the knee flexed, plantar surface flat on the IR, and long axis aligned with the detector. For the common AP axial/DP protocol, direct the CR to the base of the 3rd metatarsal at 10° toward the heel; this better matches the metatarsal arch. A perpendicular CR is a recognized departmental variant. Document and follow the local protocol rather than mixing the two methods.
Position: From the DP position, rotate the entire foot and ankle about 30° medially; 30–40° is a common protocol range adjusted for anatomy. Support the elevated medial side so the plantar surface forms the prescribed angle with the IR. Direct a perpendicular CR to the base of the 3rd metatarsal. Do not call this a 45° view unless the local protocol actually specifies 45°.
Both the DP/AP-axial and medial-oblique foot are commonly centered at the base of the 3rd metatarsal. Their beam directions differ: the DP/AP-axial commonly uses 10° toward the heel (perpendicular is a protocol variant), whereas the oblique commonly uses a perpendicular beam.
Projection terms identify beam direction. In a mediolateral projection the beam enters medially and exits laterally, so the lateral surface is nearest the IR; “medial side down” would instead describe a lateromedial projection. For trauma, do not rotate the injured limb merely to reproduce a routine position—use a horizontal-beam cross-table lateral or other approved modification when needed.
Position (routine mediolateral): Place the patient on the affected side with the lateral foot against the IR, knee flexed, and plantar surface perpendicular to the IR. Direct a perpendicular CR to the base of the 3rd metatarsal.
Weight-bearing foot radiographs may demonstrate alignment, deformity, arthritis, or instability not apparent without load and may be part of a suspected Lisfranc protocol. They are not simply non-weight-bearing views made upright: beam direction, stance (bilateral versus single-leg), and detector placement are department-specific. Obtain only the ordered views and only if the patient can stand safely; use supports and fall precautions, and never force weight-bearing after acute trauma.
Examples of measurements interpreted on weight-bearing views (reference ranges vary with method and population):
A common ankle series includes a neutral AP, an AP oblique mortise, and a lateral; some protocols use a different combination. The mortise is not a “true AP”: its intentional internal rotation and anatomy demonstrated differ from the neutral AP. No single projection should be described as sufficient or universally most sensitive for all ankle fractures.
Position: The patient sits or lies supine with the leg extended. The foot is dorsiflexed to approximately 90 degrees (plantar surface perpendicular to the table). The entire leg and foot are internally rotated 15-20 degrees until the intermalleolar line (imaginary line connecting the medial and lateral malleoli) is parallel to the IR. This rotation opens the ankle mortise.
The mortise uses only enough internal rotation—commonly 15–20°—to place the intermalleolar line parallel with the IR. It profiles the mortise with minimal tibiofibular overlap. A routine 45° ankle oblique is a different projection and demonstrates different relationships. Suspected instability is assessed from the complete examination and clinical context, not from a technologist applying a single universal clear-space cutoff.
Position: The patient sits or lies supine with the leg extended and the foot dorsiflexed as close to 90° as tolerated. Unlike the mortise view, no intentional rotation is applied. Direct a perpendicular CR midway between the malleoli.
Position: For a routine mediolateral, place the patient on the affected side with the knee flexed and lateral ankle against the IR. Dorsiflex as tolerated without forcing the injury. Align the ankle for a true lateral and direct a perpendicular CR to the medial malleolus. For trauma, maintain the limb as found and use an approved horizontal-beam lateral when necessary.
Weight-bearing ankle projections are protocol-specific and may be ordered to assess alignment, arthritis, or instability under load. Confirm the exact projection and whether bilateral stance is required. Do not obtain an unrequested contralateral comparison and do not make an acutely injured or unstable patient stand; provide support and fall precautions whenever upright imaging is performed.
The calcaneus is the largest tarsal bone and may be fractured after an axial load such as a fall from height. A common calcaneus series includes lateral and plantodorsal axial projections. “Plantodorsal” and “dorsoplantar” identify opposite beam directions and must not be used interchangeably.
Position: The patient sits on the table with the affected leg fully extended. Dorsiflex only as tolerated, ideally until the plantar surface is approximately perpendicular to the table. A strap or towel may help maintain position in a nontraumatic, pain-free foot but must not be used to force an injury. The CR enters the plantar surface and is directed toward the calcaneus.
“Harris” or “Harris–Beath” is used inconsistently for axial/hindfoot techniques, including specialized weight-bearing alignment or subtalar evaluation. Confirm the requested patient position, beam direction, angle, and clinical purpose instead of relying on the eponym alone.
Position: For the routine mediolateral, place the patient on the affected side with the knee flexed and lateral surface against the IR; dorsiflex only as tolerated. The key difference from a lateral ankle is centering: direct the perpendicular CR to the calcaneus, approximately 2.5 cm distal to the medial malleolus. Use a horizontal-beam modification when trauma prevents safe rotation.
Böhler's angle is formed on a lateral image by a line from the highest point of the anterior process to the highest point of the posterior facet and a second line from that facet to the highest point of the tuberosity. A commonly cited adult reference interval is roughly 20–40°, but published ranges and diagnostic cutoffs vary. Depression supports calcaneal collapse/fracture; it neither proves an intra-articular fracture nor determines treatment, and a normal value does not exclude fracture.
| Projection | CR Centering | CR Angle | IR Size | Key Evaluation Point |
|---|---|---|---|---|
| DP/AP-Axial Foot | Base of 3rd metatarsal | 10° toward heel; perpendicular is a labeled protocol variant | 10×12 | Entire foot, no unintended rotation |
| Medial-Oblique Foot | Base of 3rd metatarsal | Perpendicular; foot about 30° medial (30–40° protocol range) | 10×12 | Cuboid, sinus tarsi, 5th-metatarsal base |
| Mediolateral Foot | Base of 3rd metatarsal | Perpendicular | 10×12 | Metatarsal heads nearly superimposed |
| AP-Oblique Mortise Ankle | Midway between malleoli | Perpendicular; 15–20° internal rotation | 10×12 | Mortise demonstrated, minimal tibiofibular overlap |
| Neutral AP Ankle | Midway between malleoli | Perpendicular; no intentional rotation | 10×12 | Expected partial distal tibiofibular overlap |
| Mediolateral Ankle | Medial malleolus | Perpendicular | 10×12 | Talar domes nearly superimposed; fibula over posterior tibia |
| Axial Plantodorsal Calcaneus | Plantar surface near base of 3rd metatarsal | 40° cephalad to long axis of foot | 8×10 | Entire elongated calcaneus; sustentaculum medially |
| Lateral Calcaneus | 2.5 cm distal to medial malleolus | Perpendicular | 8×10 | Entire calcaneus and posterior subtalar region |
The Ottawa Ankle Rules (OAR) are clinician decision rules for acute ankle- and midfoot-zone trauma. They do not cover every foot structure or clinical scenario and do not authorize a radiographer to cancel or expand an order. ACR variants apply the rules to adults and children aged 5 years or older when no exclusionary condition prevents reliable evaluation; neurologic disorder or peripheral neuropathy are examples of exclusions.
An ankle X-ray series is indicated if there is:
A foot X-ray series is indicated if there is:
The OAR are designed for high sensitivity, but performance varies by population and implementation; “100%” should not be presented as guaranteed. Under ACR guidance, radiography is usually appropriate when the applicable rule is positive and usually not appropriate when it is negative and no injury outside the rule is suspected. If OAR cannot be applied, or pain/tenderness concerns anatomy outside the malleolar or midfoot zones, clinical judgment and the relevant ACR variant govern.
Radiography is first-line for many acute foot and ankle presentations. For suspected Lisfranc injury, tendon injury, or occult fracture/dislocation with normal or equivocal foot radiographs, ACR rates CT foot without contrast and MRI foot without contrast as usually appropriate next studies. Persistent ankle pain or suspected syndesmotic/ligamentous injury after negative radiographs also follows a separate ACR pathway. The ordering clinician and radiologist select the modality; CT is not automatic for every low Böhler angle.
In a routine dorsoplantar (DP) foot projection, the beam enters the dorsum and exits the plantar surface. A common textbook protocol angles the CR 10° toward the heel at the base of the 3rd metatarsal; some departments use a perpendicular ray. Plantodorsal (PD) describes the reverse beam direction and is a distinct protocol, not a synonym for DP.
The mortise is an AP oblique ankle projection with about 15–20° internal rotation, adjusted until the intermalleolar line is parallel to the detector. It demonstrates the mortise around the talar dome with minimal tibiofibular overlap and is distinct from the neutral AP ankle, which retains overlap.
For the routine plantodorsal axial projection, extend the leg, dorsiflex the foot as tolerated, and direct the CR about 40° cephalad to the long axis of the foot, entering near the plantar base of the 3rd metatarsal. A dorsoplantar axial method is a separate prone/caudal-beam protocol.
They may be requested for alignment, deformity, arthritis, or instability and can assist assessment of suspected Lisfranc injury. Obtain them only when ordered and safe; never force an acutely injured patient to bear weight.
For acute ankle-zone injury, the OAR support ankle radiographs for posterior-edge/tip tenderness of either malleolus or inability to bear weight both immediately and for 4 steps at evaluation. For midfoot-zone injury, foot radiographs are supported by navicular or base-of-5th-metatarsal tenderness or the same weight-bearing criterion. Applicability limits and clinical judgment matter.
Try these educational multiple choice questions based on this article. They are not official ARRT questions. Click an option to check your answer — correct answers turn green, wrong ones turn red.