If tibial stress fracture is suspected but plain radiographs are negative, which imaging modality is most sensitive?

• A. MRI
• B. Ultrasound
• C. Bone scan
• D. CT

Answer: (A)

When tibial stress injury is suspected but X-rays are negative, MRI is the most sensitive option because it can detect bone marrow edema and early microstress reactions before any visible fracture line forms. This marrow signal change on MRI appears early in the injury cycle, making it possible to confirm a stress injury even when radiographs look normal. MRI also provides detail on surrounding soft tissues and helps rule out other causes of leg pain. In comparison, bone scans, while sensitive, are less specific and take time to become positive; CT is excellent for defining a cortical fracture once visible on plain films but is less sensitive in the early, non-displaced stages; ultrasound isn’t reliable for detecting tibial stress fractures.