CT Hip Indications in an 84-Year-Old with Post-Fall Hip Pain
CT hip without IV contrast is indicated when plain radiographs are negative or indeterminate but clinical suspicion for hip fracture remains high, as rapid diagnosis is critical to reduce fracture-related morbidity and mortality in elderly patients. 1
Imaging Algorithm for Traumatic Hip Pain
Initial Imaging
- Plain radiographs (AP pelvis and lateral hip) are the first-line imaging modality for all elderly patients with acute traumatic hip pain after a fall 1
- Radiographs detect most displaced fractures and dislocations but have limited sensitivity for nondisplaced fractures 1
When to Proceed to CT Hip
CT hip without IV contrast is indicated when:
- Plain radiographs are negative or indeterminate AND persistent clinical concern for hip fracture exists 1
- The patient has pain on axial loading of the limb (though this alone cannot exclude fracture) 2
- The patient is unable to weight-bear despite negative radiographs 3, 2
- Pain worsens or persists over 1-2 days after initial negative radiographs 1
Key advantages of CT in this setting:
- CT detects occult hip fractures in 24.1% of patients with negative radiographs and changes management in 20% of cases 1
- CT has 94% sensitivity and 100% specificity for detecting radiographically occult hip fractures 1
- CT is faster and more accessible than MRI, supporting its use as the next imaging examination when rapid diagnosis is needed 1
- Modern CT technology does not miss clinically significant fractures requiring surgery 4, 5
Technical Specifications
Use CT hip WITHOUT IV contrast only 1
- There is no evidence supporting CT with IV contrast or CT without and with IV contrast for acute traumatic hip pain evaluation 1
Critical Caveat: When CT is Insufficient
If CT is negative or equivocal but clinical suspicion remains high, MRI is still necessary 1
- MRI remains the reference standard with superior sensitivity (79% for CT vs. higher for MRI) 1
- In one series, 39% of patients with negative radiographs ultimately had surgical hip fractures detected on MRI 1
- MRI is more accurate than CT for detecting occult fractures, particularly subtle femoral neck fractures 6
Clinical Context: Why This Matters
Rapid diagnosis reduces morbidity and mortality by:
- Decreasing length of immobility 1
- Reducing risk of osteonecrosis 1
- Enabling surgery within 24-48 hours, which significantly reduces short-term and mid-term mortality 7
- Preventing complications from delayed treatment 1
Common Pitfalls to Avoid
- Do not rely on clinical signs alone to exclude fracture - pain on axial loading and restricted mobility increase fracture likelihood but cannot definitively rule it out 2
- Do not increase the number of radiographic projections instead of proceeding to CT - this does not decrease the need for cross-sectional imaging 1
- Do not use bone scan - there is insufficient evidence for bone scan in acute traumatic hip pain evaluation 1
- Do not delay imaging - average time from presentation to advanced imaging should be minimized (ideally <2 days) 4
Differential Diagnoses to Consider
When CT is performed, it may reveal:
- Proximal femoral fractures (33% of cases) - most require surgical intervention 3
- Pelvic fractures (25% of cases) - commonly pubic rami and sacral fractures, typically managed non-operatively 3
- Isolated greater trochanter fractures - may be managed non-operatively if no femoral neck extension 1, 3
- Soft tissue injuries alone (38% of cases) - gluteal muscles, iliopsoas complex, trochanteric bursa 3