What is the recommended initial imaging study for a patient's hip following a fall?

Initial Imaging Recommendation for Hip Following a Fall

Radiography is the recommended initial imaging modality for evaluating a patient's hip following a fall, consisting of an anteroposterior (AP) view of the pelvis with approximately 15 degrees of internal rotation and a cross-table lateral view of the affected hip. 1, 2

Rationale for Initial Radiographic Imaging

• Radiographs are rapidly obtained, well-tolerated by patients, and detect approximately 90% of proximal femoral fractures 1, 2
• Standard orthogonal views provide complementary information:
  • AP view of the pelvis allows visualization of both hips for comparison
  • Cross-table lateral view provides an orthogonal perspective critical for complete evaluation 2
• When a fracture is clearly demonstrated on radiographs, frequently no additional imaging is needed for treatment planning 1

Complete Radiographic Assessment

• The complete initial radiographic assessment should include:
  1. AP view of the pelvis
  2. AP view of the symptomatic hip (sometimes included)
  3. Cross-table lateral view of the affected hip 2

Clinical Pitfalls to Avoid

• Do not omit the cross-table lateral view even when the AP view shows a fracture, as the lateral view can change treatment decisions in some cases 1, 2
• Do not exclude the pelvis from initial imaging, as associated pelvic fractures are common in patients with suspected proximal femur fractures 1, 2
• Be aware that patients with hip fractures may present with vague symptoms (pain in buttocks, knees, thighs, groin, or back) rather than typical hip pain 3
• Displaced fractures typically present with external rotation, abduction, and shortening of the affected leg 4

When Radiographs Are Negative but Clinical Suspicion Remains

If initial radiographs are negative but clinical suspicion for fracture remains high:

1. MRI without contrast is the recommended next imaging study with 99-100% sensitivity for detecting occult hip fractures 1, 2, 5
2. CT scan is an alternative when MRI is contraindicated or unavailable, though it is less sensitive than MRI 1, 2

High-Risk Scenarios Requiring Advanced Imaging

Advanced imaging should be strongly considered when radiographs are negative in:

• Patients aged 80 years or older (44% occult fracture rate) 5
• Cases with equivocal radiographic reports (58% occult fracture rate) 5
• Patients with a clear history of trauma (41% occult fracture rate) 5
• Patients unable to bear weight on the affected extremity 3

Clinical Importance

Prompt and accurate diagnosis is critical because:

• Delays in diagnosis and treatment are associated with increased complications, longer hospital stays, and higher mortality rates 1
• Early detection of occult fractures allows for appropriate treatment planning and can prevent rapid decline in quality of life 3
• Even seemingly isolated greater trochanter fractures may have intertrochanteric extension when evaluated with advanced imaging 1

Remember that approximately 32% of elderly patients with hip/pelvic pain after low-energy trauma who have negative initial radiographs will later be diagnosed with a fracture on advanced imaging 6, highlighting the importance of maintaining a high index of suspicion.