What should you look for on a CT scan of the hip in a patient with hip pain?

Key Findings to Look for on CT Scan of the Hip in a Patient with Hip Pain

When evaluating a CT scan of the hip in a patient with hip pain, you should primarily look for occult fractures, which are detected in 24.1% of cases with negative radiographs and lead to management changes in 20% of cases. 1

Traumatic Hip Pain Assessment

Fracture Evaluation

• Look for radiographically occult fractures that weren't visible on initial X-rays 2
• Examine for:
  • Femoral neck fractures (particularly non-displaced)
  • Intertrochanteric fractures
  • Acetabular fractures
  • Pubic rami fractures
  • Stress fractures

Fracture Classification

• Assess intracapsular femoral neck fractures for:
  • Displacement status (displaced vs. non-displaced) 2
  • Stability of intertrochanteric fractures (stable vs. unstable)

Non-Traumatic Hip Pain Assessment

Joint-Related Findings

• Evaluate for:
  • Osteoarthritis changes (joint space narrowing, subchondral sclerosis, osteophytes)
  • Loose bodies within the joint
  • Femoroacetabular impingement (FAI) morphology:
    • Cam deformity (femoral head-neck junction abnormality)
    • Pincer deformity (acetabular overcoverage)
  • Subchondral cysts

Soft Tissue Assessment (Limited on Non-Contrast CT)

• Look for:
  • Calcifications in tendons or bursae
  • Joint effusion
  • Synovial thickening
  • Periarticular fluid collections

Special Considerations for Total Hip Arthroplasty

If the patient has a hip prosthesis, evaluate for:

• Component loosening (sensitivity 84.85%, specificity 95.4-96.9%) 2
• Periprosthetic osteolysis
• Liner wear (thinning of liner contour, gap between components) 2
• Periprosthetic fractures
• Heterotopic ossification

Important Pitfalls to Avoid

• Limited sensitivity compared to MRI: CT has lower sensitivity (79-94%) compared to MRI (99-100%) for detecting occult fractures 1
• False negatives: Patients with persistent clinical concern for hip fracture after a negative CT will still need an MRI 2
• Metal artifacts: Can limit evaluation in patients with hip prostheses, though metal artifact reduction algorithms help mitigate this issue 2
• Limited soft tissue evaluation: Non-contrast CT has limited ability to evaluate labral tears, cartilage damage, and tendinopathies compared to MRI 1

Anatomic Approach to Evaluation

1. Osseous structures: Femoral head, femoral neck, acetabulum, pubic rami
2. Joint space: Width, subchondral bone, osteophytes
3. Surrounding soft tissues: Calcifications, effusions
4. Prosthetic components (if present): Position, fixation, wear

Remember that while CT is excellent for bone detail and detecting occult fractures, MRI remains superior for comprehensive evaluation of hip pain, particularly for soft tissue pathology 1.