Foot - LateralThis is a featured page

Radiographic Positioning


Adult
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Name of projection Foot - Lateral (mediolateral or lateromedial)
Area Covered Entire foot - distal phalanges to the calcaneus and proximal ankle joint
Pathology shown Fractures, degree of anterior or posterior displacement of fractures, foreign bodies, effusions
Radiographic Anatomy Foot Radiographic Anatomy
IR Size & Orientation 24 x 30cm
Landscape
Film / Screen Combination Detail
(CR and DR as recommended by manufacturer)
Bucky / Grid No
Filter No
Exposure 60 kVp
4 mAs
FFD / SID 100cm
Central Ray Centered to the base of the metatarsals
Perpendicular to IR
Collimation Outer skin margins of foot to include proximal ankle
Markers Superior to dorsal surface
Marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
Respiration Not applicable
Positioning
  • Patient is supineon the X-ray table or barouche
  • Turn patienttoward affected side until leg and foot are lateral
  • The lower leg should be parallel to the table in most cases, however if not, then the foot and IR can be elevated on sponges to achieve this desired position
  • Keep the other leg behind to prevent over rotation
  • Ask the patient to dorsiflex their foot, if possible, so that the plantar surface is at 90° to the lower leg. (This will best show the anterior pretalar fat pad)
  • Plantar surface of foot is perpendicular to IR
  • Place the IR under the foot so that the midline is parallel with the long axis of the foot
  • Centre to the base of the metatarsals
Critique

 Positioning
The correct lateral position is evidenced by
  • Metatarsals should be nearly superimposed
  • Fibula overlapping the posterior portion of distal tibia
  • Tibiotalar joint demonstrated
  • The domes of the talus are superimposed
Area Covered
Entire foot should be demonstrated to show
  • distal phalanges to the calcaneus
  • proximal ankle joint
  • 2.5cm of distal tibia/fibula
  • soft tissue of the foot
Collimation
  • Centre: The base the metatarsals
  • Shutter A: Open to include 2.5cm of the tibia and soft tissue of the sole of the foot
  • Shutter B: Open to include the soft tissues of the toes and the heel
Exposure
  • Enough density to demonstrate the superimposed tarsals and metatarsals
  • soft tissues are shown
  • bony trabecular patterns and cortical outlines are well defined
  • correct contrast and density to show the fat pads of the foot and ankle (posterior pericapsular and anterior pretalar fat pads)
Special Notes The effect of incorrect lower leg angle
i.e. Lower leg not being parallel to table
  • Talar domes will not be superimposed, one will show more superior to the other. If the proximal tibia is higher than the distal tibia then the lateral talar dome will appear higher (more proximal) than the medial talar dome. If the distal tibia is higher than the proximal tibia then the medial talar dome will appear higher (more proximal) than the lateral talar dome.
  • Tibia talar joint will not show open

The effect of poor foot positioning
i.e. Lateral foot surface not being parallel to IR
  • Talar domes will not be superimposed, one will show more anterior to the other. If the leg and foot are externally rotated too far (that is, the heel is raised too far) then the medial talar dome is more anterior than the lateral talar dome. If the toes are raised too much (that is, the heel lateral heel is pressed against the IR) then the lateral talar dome is more anterior than the medial talar dome.
  • Tibia talar joint will not show open





AndyC
AndyC 		Latest page update: made by AndyC , Jun 18 2011, 4:26 PM EDT (about this update About This Update AndyC Edited by AndyC

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Keyword tags: foot foot positioning lateral foot
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