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.
On this page:
Patient position
patient is supine
legs are in a neutral position, often with the knee caps facing anteriorly
Technical factors
AP projection
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centering point
the midpoint of the anterior superior iliac spine and the pubic symphysis
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collimation
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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
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orientation
landscape
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detector size
will vary with patient size and age
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exposure 1
63-70 kVp
2-5 mAs
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SID
100 cm
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grid
if patient thickness is above 10 cm use of a grid is advisable 1
Image technical evaluation
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
Practical points
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