Dislocation refers to joint dislocation, which means that the joint head falls off from the joint fossa. The joint consists of one end of the skeleton of the limbs and the bone structure in the shape of a garlic nest, surrounded by tendons, muscles and joint capsules. The joint is a stable structure, but the joint head will fall off from the joint fossa due to direct or indirect violence after trauma, among which dislocation of shoulder joint, elbow joint and hip joint is more common.