General Considerations.— A fracture is a break in a hone.
Its Causes are of two kinds—Predisposing and Exciting.
Predisposing causes include the age and sex of the patient. In youth the animal matter abounds, so that bending is more likely to occur than breaking. In old age the mineral matter abounds, and, therefore, the bones are more brittle. In infancy, accordingly, the number of fractures is less than at any other period of life. The number increases about the ages of seventeen and twenty-five., The greatest num ber, however, occurs after forty. Men are more liable than women.
Constitutional diseases increase the liability, such as scurvy, syphilis, and especially rickets.
Local diseases, that is, diseases affecting the bone itself, such as inflammation, tumours, softening, ulceration, wasting, predispose by diminishing the resistance of the bone.
Exciting causes are those which actually produce the fracture, and are of two kinds— (1) Violence, (2) Muscular Contraction. (1) The violence may be applied to the limb directly or indirectly. Thus when a cart-wheel passes over a man's leg it breaks the bone by direct violence; a blow from a stick breaking an arm would also be a case of direct violence. But when a person jumps from a height, though lie lands quite rightly on his feet, he may break one of the bones of his leg by the shock communicated upwards. This would be indirect violence. Similarly, a man thrown from his horse fre quently breaks his collar-bone, though nothing has touched the clavicle itself. (2) Muscular contraction is not, of course, so common a cause of fracture. It is the severe muscular contrac tions that occur in fits that are most liable to do this. Violent coughing in old people may break some of the ribs ; and this would be a case of muscular contraction.
Kinds.—(1) Simple. Here the bone is merely broken at one point, straight across or in a slanting direction.
A simple fracture may occur either in the shaft of the bone or at the extremities. When it occurs at the extremities it may separate the ends—epiphyses—from the shaft, with which they have not yet been completely united. This
can happen only in persons whose development has not been completed. It is never found after fifteen, and seldom after eight, years of age. Separation of epiphyses is called diastasis.
(2) Compound. This implies not only that there is a bone broken, but also that a wound exists 'which leads down to the break from the outside. It is not sufficient that a wound exists in the neighbourhood of the fracture ; it is only where that wound opens externally and com municates with the place of fracture that the case is properly one of compound fracture. Now this wound may be made in two ways : (a) from without, as when the violence applied outside has both caused the wound and pro duced the fracture; and (b) from within. In flue latter case the jagged ends of the broken bone may, by movement, have been forced through the muscles and skin. Again, an abscess may have formed at the seat of fracture, and the matter may have burst out and so made an opening. Or the ends of the bone may not have been properly set, and may have pressed against the soft parts, causing an opening by ulceration. Compound fracture, where the wound is due to the bursting of the jagged ends through the tis sues, is likely to be less dangerous than that in which the wound has been produced from with out. For, in the latter case, the damage done to the soft parts is liable to be more ex tensive.
(3) Comminuted fractures are those in which the violence has been sufficient to break part of the bone into fragments. A comminuted frac ture may also be compound, that is to say, the bone may have been broken to pieces, and a wound may exist leading from the seat of frac ture to the outside.
(4) Green-stick fracture is the name applied to the incomplete break occurring frequently in the bones of children. If a fresh sapling be violently bent it will break only half-way through, one side being broken, the other only bruised. So in children the bones are soft and pliable, and one side, the convexity of the bend, may be broken, the other only bruised.