Pelvis (hip surveillance)

Last revised by Andrew Murphy on 23 Mar 2023

Hip surveillance radiographs are part of a concerted effort to monitor and enable early detection of hip displacement in patients with cerebral palsy or neuromuscular disorders. The radiographs consist of a modified AP pelvis in which the patient's legs are in a neutral position, with the patellae facing anteriorly. The screening process is a multi-faceted effort, involving the medical imaging team, physiotherapists and orthopedics.

  • patient is supine

  • legs are in a neutral position, often with the knee caps facing anteriorly 

  • AP projection

  • centering point

    • the midpoint of the anterior superior iliac spine and the pubic symphysis 

  • collimation

    • some departments only image the hip region rather than the entire pelvis after the first presentation; in this case, collimation should only be superior to the ASIS

      • laterally to the skin margins

      • superior to above the iliac crests

      • inferior to the proximal third of the femur

  • orientation  

    • landscape 

  • detector size

    • will vary with patient size and age

  • exposure 1

    • 63-70 kVp

    • 2-5 mAs

  • SID

    • 100 cm

  • grid

    • if patient thickness is above 10 cm use of a grid is advisable 1

  • the pelvis should be horizontal

  • there should be neutral abduction/adduction of the limbs (there is a tolerance of 6 degrees)

  • clear visualization of the triradiate cartilages

  • no rotation evident via the obturator foramina appearing equal and iliac wings having an equal concavity

  • it is of uttermost importance these radiographs are performed to the criteria mentioned above, the radiographer must ensure the patella of the patient is facing upwards with a neutral abduction/adduction of the legs for accurate assessment of migration percentage via Hilgenriener’s line

  • positioning these patients can be challenging and require radiographers with experience in immobilization techniques to ensure reproducibility of examinations

  • patients with significant lordosis will have a tilted pelvis in the natural supine position, this can overcome by placing a sponge beneath the legs.

  • overall, ensure the radiographer documents how the examination was performed for future reference

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