What is a contusion?
A bruise (contusion) is a mark on your skin caused by blood trapped under the surface. It happens when an injury crushes small blood vessels but does not break the skin. Those vessels break open and leak blood under the skin. Bruises are often painful and swollen. You can get skin, muscle and bone bruises. Bone bruises are the most serious. It can take months for a bruise to fade, but most last about two weeks. They start off a reddish color, and then turn bluish-purple and greenish-yellow before returning to normal. To reduce bruising, ice the injured area and elevate it above your heart. See your healthcare provider if you seem to bruise for no reason, or if the bruise appears to be infected.
What is a strain?
A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can cause a strain. Strains can happen suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing sports. Symptoms include pain, muscle spasms, swelling and trouble moving the muscle.
What is a sprain?
A sprain is a stretched or torn ligament. Ligaments are tissues that connect bones at a joint. Falling, twisting, or getting hit can all cause a sprain. Ankle and wrist sprains are common. Symptoms include pain, swelling, bruising and being unable to move your joint. You might feel a pop or tear when the injury happens.
What is a fracture?
If more pressure is put on a bone than it can stand, it will split or break. A break of any size is called a fracture. If the broken bone punctures the skin, it is called an open fracture (compound fracture). A stress fracture is a hairline crack in the bone that develops because of repeated or prolonged forces against the bone.
United States Department of Health and Human Services