AP Proximal Femur is a radiography positioning projection of the Lower Extremity. Supine, leg internally rotated 15-20 degrees (Bontrager) or 10-15 (Merrill's) unless a fracture or dislocation is suspected. Hip joint included. The centering point is located midpoint of the IR (Bontrager); midfemur and center of the IR (Merrill's). Include the hip joint on the IR. The central ray is perpendicular to the femur and IR; top of the IR at the ASIS (Merrill's) to include the hip joint. Image-quality criteria include proximal two-thirds of femur including hip joint visible, femoral neck shown in profile without foreshortening. A sample technique is 87.5 kVp with DR 7.1 or CR 14 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Femoral head and neck in profile.
- Greater and lesser trochanters.
- Proximal two-thirds of the femoral shaft.
- Hip joint.
Patient preparation
- WARNING: do not rotate the leg if a fracture or dislocation is suspected. With trauma, do not move the injured limb if the leg is externally rotated: take an AP of both hips first (Bontrager).
- Verify patient identity using two identifiers.
- Remove radiopaque items from the pelvic and femur region.
- Position patient supine with both legs extended.
- Unless a fracture or dislocation is suspected, rotate the leg in 15-20 degrees (Bontrager) or 10-15 (Merrill's).
- Confirm pregnancy status when applicable.
- Collimate closely. Bontrager still says to shield outside the region of interest; Merrill's reports that NCRP Statement No. 13 recommends ending routine gonadal shielding in abdominal and pelvic radiography, and AAPM also limits routine shielding. Follow your department's policy.
Position & centering point
Midpoint of the IR (Bontrager); midfemur and center of the IR (Merrill's). Include the hip joint on the IR.
Central ray
Perpendicular to the femur and IR; top of the IR at the ASIS (Merrill's) to include the hip joint.
Exposure / technique
- kVp
- 87.5
- mAs
- DR 7.1 / CR 14
- SID
- 40" (102 cm)
- Notes
- Grid required. 14"x17" lengthwise IR. Bontrager recommends a unilateral hip routine or pelvis for a proximal site, and prints digital 80 +/- 5 kV; the sample is Merrill's chart. Sample technique: DR 7.1 / CR 14 mAs at 87.5 kVp, 40 in SID, for a 19 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Proximal two-thirds of femur including hip joint visible.
- Femoral neck shown in profile without foreshortening.
- Lesser trochanter not seen or seen only slightly.
- Soft tissues and trabecular pattern clearly demonstrated.
Common errors
- 1 External rotation of the leg foreshortens the femoral neck.
- 2 Failure to include the hip joint on the receptor.
- 3 Insufficient internal rotation foreshortens the femoral neck and shows more of the lesser trochanter.
- 4 CR not directed to the midpoint of the IR.
Clinical indications
- Suspected proximal femur or hip fracture.