Axiolateral hip CR: into the groin, perpendicular to the femoral neck, with the IR at the outer hip

For the axiolateral hip, the horizontal central ray (CR) enters the groin of the affected side and runs perpendicular to the femoral neck. The image receptor (IR) stands at the outer hip, parallel to the neck. Bontrager’s and Merrill’s agree that the CR is perpendicular to the neck and the IR is parallel to it. The groin entry point is from Merrill’s. Bontrager’s text for this projection doesn’t give it.

When is it used?

It’s the lateral hip for trauma, surgery and post-surgery patients who can’t move or rotate the affected leg. Merrill’s notes it is often called the cross-table or surgical lateral. The ARRT® 2022 outline lists it as the cross-table (horizontal beam) lateral hip, and the 2027 outline adds the name Danelius-Miller.

Don’t substitute a frog-leg when a fracture is possible. Our femur, pelvis and hip chapter explains why abducting that hip can displace a fracture.

How do you set it up?

1. Place the patient supine. Raise the pelvis slightly on a support if the patient is thin or on a soft surface.
2. Flex the unaffected hip and knee until the thigh is near vertical and outside the collimated field.
3. Hold that leg on a proper support. Never rest it on the tube or collimator, as Bontrager’s warns of burns and electric shock.
4. Check that the pelvis isn’t rotated, with equal distance from each ASIS to the table.
5. Stand the IR at the outer hip, with its top in the crease above the iliac crest. Angle it parallel to the femoral neck.
6. Use a holder or sandbags for the IR. Keep the grid perpendicular to the CR, with its lines running horizontally, to avoid grid cutoff.
7. Direct the CR into the groin, perpendicular to the neck and to the IR, and suspend respiration.

Use a minimum SID of 102 cm (40 in). The full axiolateral hip page lists the criteria and errors.

What about rotating the affected leg?

Bontrager’s warns against internal rotation on an initial trauma exam. Both books allow 15 to 20 degrees only if it isn’t contraindicated. Merrill’s adds that a physician should manipulate a limb with an unhealed fracture.

What if the other hip can’t flex?

If the patient has bilateral hip fractures, bilateral arthroplasty or a stiff unaffected leg, Merrill’s says the Danelius-Miller can’t be used. The Clements-Nakayama modification keeps the leg neutral and angles the CR posteriorly. The books differ slightly on that angle: Merrill’s gives 15 degrees, and Bontrager’s gives 15 to 20 degrees.

What does a good image show?

You should see the femoral head, neck, trochanters and acetabulum, with no grid lines. The raised thigh shouldn’t overlap the hip. Only a small part of the lesser trochanter should show if the leg was inverted.

For the frontal view in the same exam, see AP pelvis centering. Our Procedures guide covers the rest of the region, and you can drill it with the head, spine and pelvis questions.