Femoral Neck AP Oblique (Modified Cleaves) is a radiography positioning projection of the Pelvis. Supine, hips and knees flexed about 90 degrees, femora abducted 40-45 degrees, soles together. SID 40". The centering point is located 1 inch above pubic symphysis at midline, between both femoral necks. The central ray is perpendicular to IR, 1 inch above pubic symphysis. Image-quality criteria include femoral heads, necks, acetabula and trochanteric areas shown on one image, femoral heads and necks and greater and lesser trochanters symmetric if both thighs are abducted equally. A sample technique is 85 kVp with DR 14 or CR 28 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Bilateral femoral heads.
- Bilateral femoral necks (Bontrager: foreshortened, with the greater trochanters over them; Merrill's: clear of the trochanters).
- Bilateral acetabula.
- Bilateral greater and lesser trochanters.
- Pubic bones.
- Ischial spines.
Patient preparation
- CONTRAINDICATED in destructive hip disease or potential hip fracture or dislocation (Bontrager), any suspected fracture or other pathologic disease (Merrill's), and after hip replacement (Bontrager): use the Danelius-Miller axiolateral instead.
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from hip and pelvic region.
- Place patient supine on table.
- Flex hips and knees about 90 degrees, then abduct the femora 40-45 degrees from vertical.
- Place feet together; support knees if needed.
Position & centering point
1 inch above pubic symphysis at midline, between both femoral necks.
Central ray
Perpendicular to IR, 1 inch above pubic symphysis.
Exposure / technique
- kVp
- 85
- mAs
- DR 14 / CR 28
- SID
- 40" (102 cm)
- Notes
- Grid required. Bontrager: at 40-45 degrees the femoral necks are foreshortened under the greater trochanters; 20-30 degrees foreshortens the necks least but shortens the proximal femora. Merrill's: about 45 degrees places the necks parallel to the IR and clear of the greater trochanter, and excess abduction lets the trochanter obstruct the neck. Follow your program's source. Sample technique: DR 14 / CR 28 mAs at 85 kVp, 40 in SID, for a 19 cm part (Merrill's sample chart). Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Femoral heads, necks, acetabula and trochanteric areas shown on one image.
- Femoral heads and necks and greater and lesser trochanters symmetric if both thighs are abducted equally.
- Lesser trochanters equal in size, projected beyond the medial femoral margins.
- Bone trabeculae sharp, no motion blur.
- No pelvic rotation; ischial spines symmetric.
- Collimation: 14 x 17 inch crosswise.
Common errors
- 1 Abducting the femora by unequal amounts makes the hips asymmetric.
- 2 Pelvis rotated: pelvic bones, obturator foramina and ischial spines look asymmetric.
Clinical indications
- Bilateral comparison of femoral neck and trochanteric anatomy.
- Demonstration of a nontrauma hip.
- Developmental dysplasia of the hip (DDH).
- Follow-up with a fixation device in place (Merrill's shows this). Not after hip replacement: Bontrager bars frog-leg positions there.