Hip (frog leg lateral view)

The frog leg lateral view is a special radiographic of the pelvis to evaluate the hip. Bilateral examination allows for better visualisation of the hip joints and femoral neck, and therefore is an important view in the assessment of: 

  • the patient is supine
  • the affected limb flexed at the knee approximately 30° to 40°, and the hip abducted 45° (this can be bilateral)
  • if unilateral the heel of the affected limb should rest against the medial aspect of the contralateral knee
  • if it is a bilateral examination, both knees are to be resting on sponges, giving the appearances of "frog legs"
  • lateral projection
  • centring point
    • midway between the anterior superior iliac spine and the pubic symphysis
  • collimation
    • superior to the iliac crest
    • inferior to the proximal third of the femur
    • lateral to the skin margins
  • orientation  
    • landscape
  • detector size
    • 24 x 30 cm
  • exposure
    • highly variable due to the view being a specialised paediatric projection
  • SID
    • 100 cm
  • grid
    • highly variable due to the view being a specialised paediatric projection
  • the entirety of the bony pelvis is imaged from superior of the iliac crest to the proximal shaft of the femur
  • the obturator foramina appear equal
  • the iliac wings have an equal concavity
  • greater trochanters of the proximal femur are in profile

Lead shielding may be used in some departments, for paediatric patients. Nevertheless, as x-ray dose reduction technology advances; the consequence of missing valuable information obscured by lead shielding and requiring a repeat should be considered, especially for first presentation 4.

In some institutions, paediatric patients with hip pain may be assessed with a single frog leg view to reduce radiation exposure. This is evidence to support this approach, but individual practice will vary by department 5.

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    Article information

    rID: 24499
    Section: Radiography
    Synonyms or Alternate Spellings:
    • Frog-leg lateral view

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    Cases and figures

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    Case 1: normal frog leg lateral
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    Case 2
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    Case 3: left SUFE
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