While most people think of normal fractures as the only injury affecting bones, there are actually two other common bone injuries: stress reactions and stress fractures. A stress reaction is basically the beginning stage of a stress fracture. It occurs when a bone is unable to rebuild itself as fast as it is being broken down. When the reaction is left untreated, it can develop into an actual break in the bone. This condition typically occurs as a result of repetitive impact to the affected bone. For that reason, stress reactions and fractures are very common among certain groups of athletes, including long-distance runners and gymnasts. The main symptom of these bone injuries is a specific area of pain over the portion of the bone affected by the injury. Stress fractures can occur in any bone but are more common in the bones of the lower leg (e.g., the tibia and fibula) due to the weight-bearing nature of these structures. Unlike stress reactions, stress fractures can, in some cases, be seen with an X-ray. However, conclusive diagnosis may necessitate another form of medical imaging, such as a bone scan, CT scan, or MRI. Most often, rest is the recommended form of treatment for stress reactions and fractures as the bone needs time to adequately rebuild before it can sustain any additional stress or impact.