What is the best imaging modality to evaluate for a suspected hip fracture?

Best Imaging for Hip Fracture Evaluation

Radiography is the initial imaging modality of choice for suspected hip fractures, specifically an anteroposterior (AP) view of the pelvis and a cross-table lateral view of the symptomatic hip. 1, 2

Initial Imaging Algorithm

1. First-line imaging:

   • AP view of the pelvis (with approximately 15 degrees of internal rotation)
   • Cross-table lateral view of the symptomatic hip
   • Some institutions add a separate AP view of the symptomatic hip 2

2. If radiographs are negative but clinical suspicion remains high:

   • MRI without contrast of the pelvis and affected hip 1, 2
   • MRI has nearly 100% sensitivity for detecting occult hip fractures 2

Rationale for Initial Radiographic Approach

• Radiographs detect approximately 90% of proximal femoral fractures 1, 2

• The AP pelvis view allows:

  • Visualization of both hips for comparison
  • Detection of associated pelvic fractures (which occur in 30% of cases) 3
  • Assessment of potential abnormalities compared to the contralateral side 1

• The cross-table lateral view:

  • Provides an orthogonal perspective necessary for complete evaluation
  • Detects fractures not visible on AP view
  • Can change treatment decisions even when the AP view is clearly positive 1, 2

When to Use Advanced Imaging

• MRI without contrast is the recommended next step when:

  • Radiographs are negative but clinical suspicion remains high
  • MRI has demonstrated 99-100% sensitivity for detecting occult hip fractures 1, 4
  • MRI can also detect associated soft tissue injuries in 39% of patients 4

• CT scan:

  • Less sensitive than MRI for occult fractures
  • Reserved for problem-solving or better depicting fracture morphology for treatment planning 1
  • Not recommended as initial imaging for suspected hip fractures

Common Pitfalls to Avoid

• Incomplete radiographic assessment: Obtaining only an AP view without the cross-table lateral view may miss fractures and lead to misdiagnosis 1, 2
• Premature advanced imaging: MRI should be reserved for cases where radiographs are negative but clinical suspicion remains high 2
• Missing associated injuries: Failing to include the pelvis in the initial radiographic assessment may miss associated pelvic fractures 1, 2
• Delayed diagnosis: Delays in obtaining appropriate imaging can lead to delayed treatment and worse outcomes 1

Clinical Implications

• Early accurate diagnosis reduces delay to treatment with associated improved outcomes 5
• MRI-diagnosed hip fracture patients do not suffer more complications than regular hip fracture patients 3
• MRI prevents unnecessary hospitalization and delays in definitive treatment by shortening time to diagnosis 4
• MRI interpretation is most accurate when performed by senior radiologists 4