Pediatric femur (AP view)

The anteroposterior femur view for pediatrics is part of a standard series examining the femur in its entirety, including the hip and knee joints.

Indications

This view demonstrates the pediatric femur in its natural anatomical position allowing for assessment of suspected dislocations, fractures, localizing foreign bodies and osteomyelitis within the long bone. Depending on departments, this view can be crucial for orthopedic surgeons to determine the length of the femur for prosthetic purposes.

Patient position

• patient is supine with the affected leg extended

• lower limbs are internally rotated 15-25° from the hip (do not attempt this if a fracture is suspected)

• to acquire the entire femur in one image, it may be necessary to place the detector in a diagonal position parallel to the femur

Technical factors

• anteroposterior projection

• centering point

  • mid femur region

• collimation

  • laterally to the skin margins

  • superior to ASIS

  • inferior to proximal third of tibia/fibula

• orientation  

  • portrait

• detector size

  • 30 cm x 43 cm

• exposure ¹

  • 63-70 kVp

  • 1.6-2.5 mAs

• SID

  • 100 cm

• grid

  • no

Image technical evaluation

• entirety of the femur should be seen on the image with the long axis of the femur running parallel to the long axis of the image

• greater trochanter should be seen in profile signifying adequate internal rotation of the limb 

Practical points

Preparing the room beforehand (setting up the detector, exposure and preparing lead gowns) is important as pediatric patients may not remain still when their affected leg is moved onto the detector. 

Immobilization techniques

It is important for the radiograph to be free from motion artifact and rotation to avoid repeated x-rays.

• it may be necessary for the parent or radiographer to hold the patient or use sandbags to keep the leg in position

• ideally the parent should be in the child's direct line of sight

• techniques will vary based on the department

• distraction techniques can be utilized to avoid scattered radiation to parents and staff ³