A contusion, also called a bruise, is a result of bleeding into a person's soft tissue, muscle, or bone. It is an injury that can happen when a body part hits or is hit by a blunt (not sharp) object. A bruise occurs when the blood vessels in the person's skin or muscles are damaged. A bruise in the skin is seen as a change in skin color. A muscle bruise happens when muscle cells are damaged and causes bleeding in the muscle. A bone bruise is when a bone is damaged or hurt without it being broken. A bruise may be caused by a fall, bump, or direct blow, such as being kicked or hit. Bruises are common in contact sports, such as football and hockey. Shin contusions may occur more commonly in soccer and several of the martial arts as they are in the prime position to be kicked and don't necessarily have a lot of protection. Medical problems such as hemophilia and von Willebrand disease may also cause or increase the risk of having bruises. Also, if a person takes non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin he may bruise more easily.