Foot - Medial Oblique

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Radiographic Positioning


Adult
Other related pages of interest

Name of projection Foot - Oblique (Medial Rotation)
Area Covered Entire foot from distal phalanges to the calcaneus, and the talus
Pathology Shown Fractures, dislocation, foreign body, joint space abnormalities
Radiographic Anatomy Foot Radiographic Anatomy
IR Size & Orientation 24 x 30cm
Portrait, divided in two can usually fit 2 views, use lead masking for unused area
Film / Screen combination Detail
(CR and DR as recommended by manufacturer)
Bucky / Grid No
Filter Yes - when using film a thin filter covering phalanges and distal metatarsals
Exposure 57 kVp
3.2 mAs
FFD / SID 100cm
Central Ray Directed at base of the 3rd metatarsal
Perpendicular to the IR
Collimation Outer skin margins of the foot on four sides
Markers Distal and Lateral
marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
Respiration Not applicable
Positioning
  • Patient supineon the X-ray table or barouche
  • Flex the knee of the affected leg
  • Place IR under foot parallel to its long axis
  • Internally (medially) rotate the leg until the plantar surface is at a 45° angle to the IR (refer to Special Notes below)
  • Use a sponge for stabilising the foot in this position
Critique

Positioning
  • The correct obliquity is evidenced by
  1. the 1st and 2nd metatarsals should only be superimposed at the bases
  2. 3rd through 5th metatarsals should not be superimposed
  3. base of the 5th metatarsal (tuberosity) should be well shown
  4. the tarsal sinus is well shown
  5. joint spaces around the cuboid are open
  6. the cuboid is seen in profile
Area Covered
  • The entire foot should be demonstrated to show all phalanges, metatarsals, calcaneum and proximal talus
Collimation
  • Centre: The base of the third metatarsal
  • Shutter A: Open to include the outer skin margins of the lateral and medial sides of the foot
  • Shutter B: Open to include the soft tissue of the toes and the proximal calcaneus
Exposure
  • Bony trabecular patterns and cortical outlines are sharply defined
  • Soft tissues are visualised
  • Correct use of a filter will give uniform density of phalanges and metatarsals
Special Notes Effect of over rotation
  • the base of the 5th metatarsal is superimposed over the tubercle of the 4th metatarsal
  • the joint space between the 4th and 5th metatarsals is closed
Effect of under rotation
  • the base of the 4th metatarsal is superimposed over the base of the 5th metatarsal
  • the joint space between the 4th and 5th metatarsals is closed
Angle of obliquity
  • This angle will vary according to the arch of the foot.
    • 45° for a normal arch
    • 30° for a low arch
    • 60° for a high arch