Procedures · Extremities2 min read5-question check
Hip and femur
Rotate the leg 15 to 20° internally for an AP hip unless fracture is suspected; then use Danelius-Miller.
Patient and part
For the AP hip, the patient is supine with the pelvis level and the affected leg rotated 15 to 20 degrees internally. The femoral neck angles forward, so internal rotation places it parallel to the IR. For the unilateral frog-leg, the modified Cleaves method, flex the hip and knee, place the sole against the opposite leg, and abduct the thigh about 45 degrees from vertical. For the axiolateral inferosuperior, the Danelius-Miller method, raise and support the unaffected leg out of the way, and place the IR in the crease above the iliac crest, parallel to the femoral neck. For the femur, take an AP with slight internal rotation and a lateral. In trauma, use a horizontal beam for the lateral and do not move the leg.
Central ray
Use 40 inches, about 100 cm. For the AP hip and frog-leg, the CR is perpendicular to the IR and centered to the femoral neck, about 1 to 2 inches medial to the ASIS at the level of the greater trochanter. For the Danelius-Miller, the CR is horizontal and perpendicular to both the femoral neck and the IR, and a grid must be aligned with the CR to avoid grid cutoff. For the femur, center to the midfemur and always include the joint nearest the injury. An adult femur often needs a second image to show both joints.
What a good image shows
On a good AP hip, the femoral neck appears in its full length without foreshortening, the greater trochanter is in profile laterally, and the lesser trochanter is barely visible or not visible. On the frog-leg, the lesser trochanter projects in profile medially. On the Danelius-Miller, the femoral head, neck and trochanters show in a lateral view free of the opposite thigh.
Fixing it
A prominent lesser trochanter on an AP hip means the leg is externally rotated, which foreshortens the neck. If no fracture is suspected, rotate the leg 15 to 20 degrees internally. A patient with a hip fracture often lies with the leg shortened and externally rotated; leave it there. The frog-leg is never used for a suspected fracture or dislocation, because abducting the leg can displace fragments. Use the Danelius-Miller instead.
Clinical Example
An elderly woman falls and arrives with her right leg shortened and externally rotated. You take the AP pelvis and AP hip without rotating the leg, then a Danelius-Miller with her left leg raised.
Common Mistakes
- Internally rotating the leg of a patient with a suspected hip fracture.
- Ordering a frog-leg as the trauma lateral.
- Leaving the unaffected thigh down, so its soft tissue covers the hip on the axiolateral.
Why It Matters
Moving a fractured hip can displace fragments and damage blood supply to the femoral head. The registry tests the internal rotation rule, the trauma lateral and the reading of the lesser trochanter.
Key Relationships
- AP hip: 15 to 20 degrees internal rotation, neck in full length
- Lesser trochanter prominent: leg externally rotated
- Suspected fracture: no rotation, no frog-leg
- Femur: include the joint nearest the injury