One of the most common types of fractures in the foot is a stress fracture. A stress fracture is a small crack in a bone or possibly severe bruising in a bone. Stress fractures are usually caused by repetitive motions or overuse, and especially common in those who participate in running activities. A sudden change in activities or sudden increase in intensity of activity can also trigger a stress fracture, as can changing the workout surface (indoor vs. outdoor). Certain diseases such as osteoporosis can weaken the bones, leading to stress fractures that can occur during simple everyday activities. Signs of a possible stress fracture or other type of foot/ankle fracture can include pain, swelling, redness, or bruising. Your doctor may use diagnostic tools such as x-ray, bone scan, or MRI to diagnose a stress fracture/other fracture, and determine what treatment is needed for the specific situation.