A medical device may fail at any time and for almost any reason. For example, a crutch may break as a patient goes down a flight of stairs, or the brakes on a wheelchair may fail while a patient goes down a hill. Other serious failures may involve devices that go inside a patient’s body. A defect in artificial joints, pacemakers, stents, or surgical pins may all cause a loss of function in a body part, an infection, or may even necessitate an additional surgery to correct.