Foot Medial Oblique is a radiography positioning projection of the Lower Extremity. Foot rotated medially 30-40 degrees, CR perpendicular. SID 40". The centering point is located base of the 3rd metatarsal, with the foot rotated medially 30 to 40 degrees.. The central ray is perpendicular to the ir with the foot rotated medially 30 to 40 degrees.. Image-quality criteria include medial border of foot on the ir, entire foot visible., first through fifth metatarsals demonstrated without excessive overlap.. Standard exposure ranges from 60 to 70 kVp, 3 to 6 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- All five metatarsals in slight oblique.
- First and second metatarsals without overlap.
- Tarsometatarsal joints clearly demonstrated.
- Talar head separated from the navicular bone.
- Cuboid and the sinus tarsi.
- Bases of the third, fourth and fifth metatarsals.
Patient preparation
- 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 flat on the IR.
- Rotate the foot medially (inward) 30 to 45 degrees.
Position & centering point
Base of the 3rd metatarsal, with the foot rotated medially 30 to 40 degrees.
Central ray
Perpendicular to the IR with the foot rotated medially 30 to 40 degrees.
Exposure / technique
- kVp
- 60–70
- mAs
- 3–6
- SID
- 40" (102 cm)
- Notes
- Rotate the foot medially 30 to 40 degrees so the medial border approaches the IR.
Image-quality criteria
- Medial border of foot on the IR, entire foot visible.
- First through fifth metatarsals demonstrated without excessive overlap.
- Tarsometatarsal articulations clearly shown.
- Lateral tarsals open: cuboid, sinus tarsi and the bases of the 3rd to 5th metatarsals.
- Bone trabeculae sharp, no motion artifact.
- Collimation: 1 inch on all sides of foot, 1 inch above medial malleolus.
Common errors / ARRT traps
- 1 Insufficient medial rotation fails to open the tarsal joints.
- 2 Rotating the foot too far superimposes the cuboid on the calcaneus.
- 3 Centering off the first metatarsal area clips anatomy.
- 4 Lifting the medial border off the IR closes the medial joints.
Clinical indications
- Evaluation of the cuboid, sinus tarsi and lateral tarsal alignment.
- Suspected midfoot fracture or dislocation.
- Assessment of pes planus (flat foot) deformity.
Aligned to the current ARRT Radiography Content Specifications.