HEALTH & DISEASE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site fractures and dislocations Types of fracture. From left to right: fractured humerus with displacement; fracture of the ulna, in the forearm; incomplete fracture of the tibia. Although is bone is very hard and strong, even the largest and thickest bones in the body are sometimes broken or moved out of place at the joint. This can happen if a bone is knocked violently or if it is forcibly bent or twisted. The medical term for a break in a bone is a fracture, and several different types are recognized. In a simple fracture the skin over the injured bone is not damaged. In a compound fracture the skin over the break is torn, or lacerated, and parts of the broken bone may even show through. When the fragments move out of their correct positions, after a bone is broken, there is said to be displacement. Symptoms of a fracture Pain is the most obvious symptom of a fracture. It begins at the moment of injury and may be very severe. Because of the pain, and because the framework of the injured part is broken, it is often impossible to move the damaged part. The tissues all round the fracture swell up, and where there is displacement of the fragments of a broken bone the injured part may have an unnatural shape. Symptoms of a fracture A suspected fracture should always be examined by a doctor, who may order an X-ray to see how much damage has been done. Simple fractures without displacement generally heal quickly if they are kept still in plaster-of-paris. Compound fractures and fractures with displacement need surgical treatment before the plaster is put on. Healing In bone, the cells are arranged in small groups within the substance of the bone and also under the periosteum, a tightly fitting membrane which covers the surface of each bone. They are called osteoblasts, which means "bone-forming cells." Their task is to collect the calcium from the blood and to deposit it around themselves in the form of calcium phosphate and calcium carbonate, which are salts that are insoluble in water. It is the mixture of these two salts which provides bone with its remarkable hardness and rigidity. The various stages in healing of a fractured bone are shown in the illustrations below. Considerable bleeding occurs at the fracture. The blood lies between the bone ends and under the periosteum. In a few days a blood clot forms. Soon the clot is invaded by osteoblasts from the nearby bone and from the periosteum. The osteoblasts lay down new bone which fills the gap between the fragments and bulges out at the sides. This is the callus. Over a period of many months the callus is absorbed by the osteoblasts, and they make more new bone exactly like the original one. Dislocations From left to right, dislocation of the elbow, , and little finger. When a joint, instead of a bone, suffers a severe strain, the result may be a dislocation. In an injury of this kind no bones are broken, but one bone is pushed out of its proper place. Dislocated joints are very painful. They usually look deformed because the bones are in the wrong position. Illustrated here are three quite common dislocations. The drawings in the red circles show how the bones should normally look. The process of putting the bones back into their normal positions in a joint is called reduction of the dislocation. The patient is typically given an anesthetic which relaxes his or her muscles. The surgeon can then usually get the bones back into their proper positions quite readily. When a joint is dislocated there is bound to be some stretching of the parts round it. This can be that the joint is loosened and later may be dislocated again. Related category    • HEALTH AND DISEASE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP