What CT (Computed Tomography) scan protocol is needed for a femoral neck fracture to plan for surgery?

CT Protocol for Femoral Neck Fracture Surgical Planning

For femoral neck fractures requiring surgical planning, a non-contrast CT scan of the hip without IV contrast is recommended to better characterize fracture morphology and guide appropriate surgical decision-making. 1

Initial Imaging Approach

• Initial evaluation should include standard radiographs (AP view of the pelvis with cross-table lateral view of the symptomatic hip) as the first-line imaging modality 1
• Approximately 90% of proximal femoral fractures will be identified on initial radiographs 1
• If radiographs are positive for femoral neck fracture and surgery is planned, additional imaging may be needed for treatment planning 1

CT Protocol for Surgical Planning

• Non-contrast CT of the hip is the appropriate protocol for surgical planning of known femoral neck fractures 1
• CT without IV contrast helps characterize fracture morphology for treatment planning purposes 1
• The CT should include:
  • Thin-slice (2mm) axial images through the femoral neck 2
  • Multiplanar reconstructions in coronal and sagittal planes 1
  • 3D reconstructions to aid in surgical decision-making 1

Clinical Impact of CT on Surgical Planning

• CT improves interobserver agreement regarding surgical decision-making (arthroplasty versus closed reduction percutaneous pinning) 1
• CT altered surgical decision-making in 21% of cases of non-displaced femoral neck fractures 1
• CT allows measurement of important angles that predict fracture stability:
  • Impaction angle in the coronal plane 1
  • Posterior tilt angle in the axial plane 1
• Femoral neck impaction angle >135 degrees on CT is associated with 11.73 times higher odds of secondary displacement if treated nonsurgically 1

Limitations of CT for Femoral Neck Fractures

• CT has lower sensitivity (69%) compared to MRI (99%) for detecting occult fractures 1
• CT may miss non-displaced or incomplete femoral neck fractures 3, 4
• In cases of femoral shaft fractures with suspected ipsilateral femoral neck fractures, CT has sensitivity of only 56%-64% 5
• The presence of lipohaemarthrosis on CT strongly suggests an intra-articular fracture 6

When to Consider MRI Instead of CT

• When radiographs are negative but clinical suspicion for fracture remains high 1
• For detection of occult femoral neck fractures not visible on radiographs 1
• In high-energy trauma with femoral shaft fractures where ipsilateral femoral neck fractures may be missed on CT 3, 4
• MRI has nearly 100% sensitivity for proximal femoral fracture detection 1

Practical Considerations

• CT is advantageous over MRI in terms of speed and use in patients with confusion 1
• There is no evidence supporting the use of contrast-enhanced CT for femoral neck fracture evaluation 1
• Several studies report improved interobserver reliability of fracture classification by CT compared to radiographs 1
• If a patient is undergoing CT of the abdomen/pelvis for other trauma, bone algorithm reconstruction of the pelvis and hips can be performed without additional scanning 1