What is the best imaging modality to diagnose a calcaneal or cuboid stress fracture?

• A. X-ray
• B. CT
• C. MRI
• D. Bone scan

Answer: (C)

The key idea is that a stress fracture often starts with subtle bone marrow edema that isn’t visible on plain X-rays. MRI is the imaging modality that most reliably detects this early edema and any accompanying fracture line, giving both sensitivity and specificity for a calcaneal or cuboid stress fracture. On MRI you can see edema with fluid-sensitive sequences (fat-saturated T2 or STIR) and the fracture lines or talocalcaneal impaction if present, along with any surrounding soft-tissue or joint involvement. This enables early diagnosis before a cortical break is apparent on X-ray.

X-ray exams frequently come back normal in the early stages, limiting their usefulness for initial detection. CT excels at detailing the exact fracture anatomy once a fracture is evident, but it is less sensitive for early stress reactions. Bone scans are sensitive to stress injuries but are less specific and involve radiation. Thus MRI provides the best combination of early detection, diagnostic accuracy, and comprehensive assessment for these hindfoot stress fractures.