Calcaneus Axial (Plantodorsal) is a radiography positioning projection of the Lower Extremity. Foot dorsiflexed, CR angled 40° cephalad through plantar surface. SID 40". The centering point is located base of the 3rd metatarsal, emerging just distal to the lateral malleolus; sole near perpendicular to the IR. The central ray is angled 40 degrees cephalad from the long axis of the foot (40 degrees from vertical with the foot perpendicular to the IR), entering at the base of the third metatarsal and exiting just distal to the lateral malleolus. Image-quality criteria include entire calcaneus visible, from tuberosity to talocalcaneal joint, no rotation: part of the sustentaculum tali in profile medially. A sample technique is 70 kVp with DR 1.8 or CR 3.2 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Calcaneal tuberosity in profile.
- Lateral process and sustentaculum tali.
- Talocalcaneal joint articulation.
- Talocalcaneal (subtalar) joint.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove footwear, socks, and any radiopaque foot jewelry.
- Position the patient supine or seated with the leg extended.
- Place the affected foot on the IR with the plantar surface facing the tube.
- Dorsiflex the foot to place the plantar surface perpendicular to the IR.
Position & centering point
Base of the 3rd metatarsal, emerging just distal to the lateral malleolus; sole near perpendicular to the IR.
Central ray
Angled 40 degrees cephalad from the long axis of the foot (40 degrees from vertical with the foot perpendicular to the IR), entering at the base of the third metatarsal and exiting just distal to the lateral malleolus.
Exposure / technique
- kVp
- 70
- mAs
- DR 1.8 / CR 3.2
- SID
- 40" (102 cm)
- Notes
- CR angled 40 degrees cephalad. Sample technique: DR 1.8 / CR 3.2 mAs at 70 kVp, 40 in SID, for an 8 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Entire calcaneus visible, from tuberosity to talocalcaneal joint.
- No rotation: part of the sustentaculum tali in profile medially.
- Talocalcaneal joint open; tuberosity not distorted; calcaneus adequately elongated.
- Bone trabeculae sharp, no motion artifact.
- Collimation: include the entire calcaneus from tuberosity to talocalcaneal joint.
Common errors
- 1 Not increasing the angle when the sole is not perpendicular to the IR distorts the calcaneus.
- 2 Foot not dorsiflexed to near perpendicular to the IR.
- 3 CR not directed to the base of the 3rd metatarsal.
- 4 Rotation: no part of the sustentaculum tali in profile medially.
Clinical indications
- Pathologies or fractures with medial or lateral displacement.