A bone bruise is a traumatic injury that is less severe than a bone fracture. It occurs when your small blood vessels are damaged, and causes blood and fluid to leak into nearby tissues and blood vessels. A fracture refers to a cracked or broken bone. Fractures usually occur when your bone absorbs more impact than it can take, such as during a sports injury, car accident or fall. In general, it is unlikely for a bone bruise to turn into a fracture.