Our son is a military cadet in basic training. He says he has a foot injury that may or may not be a navicular fracture. The X-ray was negative. His military career could be on the line here. Should he request an MRI or other more advanced imaging test?

Studies show that foot fracture is a condition that has put an end to many athletic careers. There are far fewer reports on the results of military recruits.

The best advice on record suggests cast immobilization without putting any weight on the foot for six weeks is the treatment of choice for navicular stress reactions or fractures. If the bone is reacting to stress but an actual fracture line doesn't show on X-ray, then more advanced studies are needed.

CT scans show more fractures than MRIs. When a bone fracture or stress to the bone starts to heal, fluid and blood around the damaged area starts to get absorbed. The new bone being layed down at the fracture site may prevent the MRI signal from showing a fracture line. CT scans are better able to show subtle fracture lines.

A recent study was done of athletes with navicular fractures. There were more re-fractures and fewer patients returning to sports who didn't have the cast treatment. It's probably a good idea to ask for more testing. Early diagnosis is always the key to the most effective treatment.