Anatomy Msk · Year 1 · from Anatomy Msk
Case 2: Occult Hip Fracture on MRI
Clinical Image
Source: Wikimedia Commons - Hip MRI - CC BY-SA 4.0
Case Presentation
A 75-year-old woman with osteoporosis presents with left hip pain after a fall in her home 2 days ago. She reports difficulty bearing weight since the fall and has had persistent groin pain. She has no obvious deformity, and initial emergency department radiographs were read as "no acute fracture." She was discharged with a diagnosis of hip contusion. She now presents to her primary care physician with ongoing pain. Physical examination reveals tenderness with palpation over the left groin and pain with internal rotation of the hip. She is unable to perform a straight leg raise on the left. Given high clinical suspicion despite negative X-rays, MRI of the left hip is obtained. MRI demonstrates a non-displaced subcapital femoral neck fracture with linear hypointensity on T1 and corresponding hyperintensity on T2/STIR images representing the fracture line and surrounding bone marrow edema. There is no evidence of avascular necrosis. She is taken to the operating room for percutaneous screw fixation of the non-displaced fracture to prevent displacement.
Key Learning Points
- Up to 10% of hip fractures are not visible on initial radiographs (occult fractures)
- MRI is the gold standard for detecting occult hip fractures with near 100% sensitivity and specificity
- MRI shows fracture as a hypointense line on T1 with surrounding bone marrow edema (bright on T2/STIR)
- CT has lower sensitivity than MRI for non-displaced fractures but may be used if MRI is unavailable
- Clinical suspicion should override negative X-rays; delayed diagnosis leads to fracture displacement and worse outcomes