Procedures · Head, Spine and Pelvis

Pelvis and Hip Positioning Series

Explore the pelvis and hip, then use Practice mode to position each routine projection yourself.

Pelvis and hip · Neutral (internal rotation)

Right

StudyBucky

Loading model…

Hover a bone, name it, then click to check · drag to rotate

The routine pelvis and hip series

The projections this region is examined with. Set them up yourself in Practice positioning.

AP pelvis

Anteroposterior projection · both limbs rotated internally 15–20°

Demonstrates: The whole pelvic girdle with the sacrum and coccyx, both femoral heads and necks and both greater trochanters. Correct positioning hides the lesser trochanters altogether, or shows only their tips, and leaves the two greater trochanters equal in size and shape. There is no rotation when the iliac wings, the ischial spines and the two obturator foramina look symmetric — a narrowed obturator foramen on one side means the pelvis is rotated toward that side.
Part position: Supine, with the midsagittal plane aligned to the midline of the table. Check that the pelvis is not rotated by confirming each ASIS sits the same distance from the tabletop. Separate the legs, then rotate the whole of both lower limbs internally 15–20° and hold them there.
Central ray: 90° to the image receptor, centered midway between the level of the ASIS and the symphysis pubis — about 2 inches (5 cm) below the level of the ASIS.
Why it is positioned this way: Both limbs turn inward because the femoral neck is anteverted: it sits angled forward out of the coronal plane, so with the legs at rest it is thrown at an angle to the receptor and projects short. Turning the limbs in swings the neck parallel to the receptor and shows it at true length. The lesser trochanter is the tell — it points backward and medially, so it disappears behind the shaft at exactly the rotation that puts the neck in profile, and a lesser trochanter in full view means the limbs were left turned out.

Also covered by this projection

Taken as part of a hip routineCentred 2 inches (5 cm) lower, at the level of the femoral heads and necks, so that more of the proximal femora is included.

AP unilateral hip

Anteroposterior projection · affected limb rotated internally 15–20°

Demonstrates: The proximal third of the femur with the acetabulum and the neighbouring parts of the pubis, ischium and ilium. The greater trochanter and the femoral head and neck appear in full profile without foreshortening, and the lesser trochanter does not project past the medial border of the femur.
Part position: Supine, with the femoral neck located and aligned to the midline of the table. Check that the pelvis is not rotated by confirming each ASIS sits the same distance from the tabletop. Rotate the affected leg internally 15–20°.
Central ray: 90° to the femoral neck, centered 1–2 inches (2.5–5 cm) medial to the ASIS and 3–4 inches (8–10 cm) distal to it — a point on the same horizontal plane as the symphysis pubis and the greater trochanters.
Why it is positioned this way: This one is centred to a structure that cannot be felt, so it is located by measuring from the ASIS rather than by palpating for it. The rotation does the same job as on the AP pelvis, and the same two findings prove it: neck in true length, lesser trochanter hidden.

Unilateral frog-leg — mediolateral (modified Cleaves method)

Mediolateral projection · femur abducted 45° from vertical · non-trauma only

Demonstrates: A lateral of the acetabulum, the femoral head and neck, the trochanteric area and the proximal third of the femur. At the routine abduction the femoral neck lies in profile with the greater trochanter superimposed on it; at the smaller abduction used to study the neck itself, the trochanter comes clear of it instead.
Part position: Supine, with the affected hip aligned to the midline of the table. Flex the knee and hip on the affected side and rest the sole of that foot against the inside of the opposite leg, near the knee. Then abduct the femur 45° from vertical. Do not attempt this position where a hip fracture or dislocation is possible, or on a patient who has had hip replacement surgery — abducting the limb is exactly the movement those cannot tolerate.
Central ray: 90° to the image receptor, centered to the midpoint of the femoral neck.
Why it is positioned this way: This projection turns the leg rather than the tube: the central ray stays at 90° to the receptor, and abducting the femur is what rolls the neck into a lateral. How far it is abducted decides what the image is good for. At 45° the head and acetabulum are well shown, which is why that is the routine. Abducting only 20–30° shows the femoral neck itself with the least distortion, at the cost of significantly foreshortening the rest of the proximal femur — so the smaller angle is chosen when the neck is the clinical question, not as a general improvement.

Also covered by this projection

Lauenstein–Hickey modificationThe patient is rotated further, onto the affected side, until the femur lies against the tabletop. It can show the head and acetabulum well, but it foreshortens the neck region.

Axiolateral inferosuperior hip (Danelius–Miller method)

Axiolateral inferosuperior projection · horizontal beam from the medial side

Demonstrates: The whole femoral head and neck, the trochanter and the acetabulum in lateral profile. Only the most distal part of the femoral neck should be covered by the greater trochanter, and little or none of the lesser trochanter shows. The raised opposite thigh must not lie over the hip being imaged.
Part position: Supine, with the pelvis raised 1–2 inches (2.5–5 cm) on supports where possible. Flex and elevate the UNAFFECTED leg until that thigh is near vertical and clear of the beam, and support it there — never resting it on the collimator or the tube. Check that the pelvis is not rotated by confirming each ASIS sits the same distance from the tabletop. Stand the receptor in the crease above the iliac crest, parallel to the femoral neck. Rotate the affected leg internally 15–20° unless a fracture is possible, in which case leave it exactly as it lies.
Central ray: 90° to the femoral neck and to the image receptor, centered to the femoral neck.
Why it is positioned this way: This is the lateral for a patient whose affected leg cannot be moved, which is what rules out the frog-leg after an injury: the frog-leg needs abduction, and abduction is what displaces a femoral-neck fracture. Here the injured limb is left where it lies and the tube moves instead. Everything the technique asks for follows from a horizontal beam crossing the body: the opposite leg goes up because it would otherwise sit in the beam over the hip, and the grid has to stay square to the central ray or it will cut off the image.

Also covered by this projection

Modified axiolateral (Clements–Nakayama method)The fallback when BOTH lower limbs are immobile, so the unaffected leg cannot be raised and this projection cannot be obtained at all. Both legs stay extended; the receptor is tilted 15° and the central ray angled 15° posteriorly, still at 90° to the femoral neck, the angle standing in for the internal rotation the limb cannot be given.

Procedures lessonPelvis, hip & SI joints