This is Barry Belosis, one of the musculoskeletal radiology fellows at Stanford University. 16-year-old female elite gymnast present with nonspecific right dorsal foot pain, concern for dorsal navicular stress fracture. The patient in this case presented with this lateral radiograph showing mild increased but nonspecific sclerosis of the navicular. The patient then underwent MRI without contrast here in our sagittal T2 facet imaging demonstrating edema or this increased signal of the navicular and on our T1 we may see this hypo-intense band. In the coronal imaging we can see again this edema signal in the navicular with small linear hypo-intense band consistent with stress fracture. This is on a different patient, on a 28-year-old gymnast with mid-foot pain showing that in most cases stress fracture or reaction may be difficult to visualize but should be the initial imaging modality of choice to exclude any other abnormality. The patient then underwent CT without contrast showing a normal navicular but a follow-up CT three months later shows a stress fracture in the central portion of the navicular. This also demonstrates that CT is less sensitive compared to MRI. As we can see on the MRI of this patient, we have our navicular with edema and some central hypo-intensity both seen on our T2 and our T1 compatible with stress fracture. On a different patient, here MRI foot without contrast, again we can see the edema signal in the navicular here with some linear hypo-intensity or dark band centrally consistent with the stress fracture. The coronal imaging shows us the most common location of the stress fracture which is at the dorsal aspect of the navicular as seen here. In our T2 FATSAT imaging we can see the bone marrow edema associated with this fracture. There is no recommended time frame for following up stress fracture on MRI as bone marrow edema signal resolution varies from patient to patient. On this patient however, he had a follow-up CT demonstrating sclerosis along the stress fracture margin with periosteal reaction at the dorsal margin of the navicular. And here we can see the stress fracture line. And although this sclerosis and periosteal reaction may demonstrate healing, we cannot totally exclude ongoing fracture given the persistence of the fracture line.

2nd Edition, CASE 12

2nd Edition

Foot and Ankle

gymnast

navicular stress fracture

MRI

dorsal foot pain

healing signs