Foot Case 3 Diagnosis
Stress fracture of 2nd metatarsal
Plain film radiography is the initial ED test. Plain films are highly specific but sensitivity is largely dependent upon the time since injury. It can take 4-6 weeks for any changes to be visible on x-ray.
Typical radiographic findings include new periosteal bone, radiolucent lines (especially in the navicular, so-called "thin black line"), and endosteal thickening.
Due to plain film limitations and an often normal physical examination, the physician must maintain a high index of suspicion.
The most sensitive test is a bone scan (although not very specific), which becomes abnormal after 24 hours. Diagnosis can also be made by CT or MRI. Any of these can be outpatient studies since the diagnosis is not emergent.