Thank you for your question regarding hairline fractures. Hairline fractures are also known as stress fractures. They are caused by repeated stress on weight bearing parts of our bodies, so this usually ends up occurring in the feet and legs. This is in contrast to other types of fractures which are usually sustained from one single traumatic force. Runners are known to be particularly prone to stress fractures because they cause low impact stress to their feet and legs on a repeated basis. Symptoms of a stress fracture can include pain and tenderness of the area, possibly with swelling, and are generally nonspecific. Stress fractures appear as a small crack or sliver in the bone when they show up on imaging. Usually, it is difficult to pick up stress fractures with an x-ray
. Often, x-rays can be negative for a stress fracture for 2-3 weeks after an injury
and it may even take months before a stress fracture will show up on Xray. There was a time that bone scans used to be popular for picking up stress fractures, but this has now largely been replaced with the use of MRIs. MRIs are much better equipped at picking up a stress fracture. Talk with your doctor
if you have further questions about diagnosing the source of your pain.