Ordering X-rays of Both Hips
Order an anteroposterior (AP) view of the pelvis combined with cross-table lateral views of each affected hip as the standard initial imaging approach for bilateral hip evaluation. 1, 2, 3
Standard Radiographic Protocol
Essential Views for Both Hips
AP pelvis view is mandatory as it allows simultaneous visualization of both hips and provides crucial comparison between sides, serving as an internal control for detecting asymmetries and abnormalities. 2, 3
The AP pelvis should be obtained with 15 degrees of internal hip rotation to properly align the femoral neck parallel to the imaging plane and minimize the visibility of the lesser trochanter. 1, 2
Add cross-table lateral views of each symptomatic hip to complete the orthogonal imaging required for accurate diagnosis—these lateral views are essential and cannot be substituted with frog-leg laterals due to risk of fracture displacement in trauma cases. 1, 3
Critical Technical Specifications
Position both legs straight and parallel with toes pointing upward initially, then rotate internally 15-20 degrees using a positioning device secured with straps to prevent movement during acquisition. 1
Center the femoral neck in the scan field with the lesser trochanter barely visible when proper internal rotation is achieved. 1
Ensure the pelvis is not rotated during imaging, as even minor positional changes can artifactually alter measurements and lead to misdiagnosis. 4
Clinical Context Matters
For Acute Traumatic Hip Pain
The AP pelvis + cross-table lateral combination is the initial imaging of choice because it rapidly detects fractures and dislocations while allowing portable acquisition in the trauma bay without moving the patient. 1
This approach identifies concomitant pelvic fractures (sacrum, pubic rami) that occur frequently alongside hip fractures and would be missed with hip-only views. 3
Approximately 10% of proximal femoral fractures are not visible on initial radiographs, so maintain high clinical suspicion and proceed to MRI without contrast if radiographs are negative but clinical concern persists. 2, 3
For Chronic Hip Pain or Osteoarthritis Assessment
Start with AP pelvis radiograph as the first-line test before considering advanced imaging. 1
The hip-centered AP view may provide slightly better measurements than the standard pelvis view for joint space width assessment, though the difference is not statistically significant. 5
Common Pitfalls to Avoid
Never order isolated hip views without including the pelvis—this misses associated pelvic pathology and eliminates the ability to compare with the contralateral side. 2, 3
Do not accept frog-leg lateral views in trauma settings as they risk displacing occult fractures; always use cross-table laterals. 1
Recognize that patient positioning significantly affects measurements—hip flexion, abduction, or adduction of even 15-30 degrees can artifactually widen or narrow joint space width by 0.15-0.38mm, potentially leading to misinterpretation of disease progression. 4
Failing to obtain orthogonal views leads to missed diagnoses and altered treatment decisions, particularly for fracture classification. 3, 6
When to Add Supplementary Views
Consider adding a traction-internal rotation view in confirmed proximal femur fractures to improve fracture classification accuracy, particularly for distinguishing stable versus unstable intertrochanteric patterns—this changes surgical planning in 50% of reclassified cases. 6
Additional views beyond standard AP and lateral have not supplanted the basic protocol for routine evaluation, though they may aid in specific fracture classification scenarios. 1