A stress fracture of the forearm is a hairline crack or break in either of the forearm bones and is rare although may occur in sports where repetitive strain or overloading of the forearm muscles happens such as baseball, swimming or racket sports.
A stress fracture is not likely to show up on an X-ray until the injury has already begun to heal. It is possible passing ultrasound over the site of the fracture or even using a tuning fork could stimulate vibrations in the fracture triggering pain which could help confirm the diagnosis. If a stress fracture is suspected then complete rest is required for a few weeks to allow the bone to heal.