The prognosis of fractures varies according to the kind of bone injured, what part of it is broken, the direction of the breach of continuity, and what other mischief complicates the case. Fractures of bones which have many strong muscles inserted into them are more difficult of cure than those of other bones, which have not so many powers or levers attached to them capable of displacing the fragments.

A fracture of the middle part of a long bone is less dangerous than a similar injury near one of its joints, which may be followed by synovial inflammation and ultimate anchylosis of the joint.

Inflammation of a joint, brought on by fractures, is attended with more severe symptoms in proportion as the contusion has been more violent. In a fracture near an articulation it is to be observed also that common splints have little command over the short fragments, so that it is often difficult with them to prevent displacement, and with respect to transverse fractures of the neck of a long bone, though the possibility of the reunion of such cases by means of bony matter is no longer a disputed point. The cure is more commonly effected only by means of a fibrous ligamentous substance.

When a bone is fractured in several places the case is more serious, while the difficulty of cure is far greater.

Again, oblique fractures are more troublesome and difficult of cure than transverse ones, because an oblique surface does not resist the retraction of the lower portion of the broken bone; and consequently the ends of the fracture are kept duly applied to each other with difficulty.

Fractures complicated with violent contusions of the soft parts, or with a wound, rendering them compound, are much more dangerous than others free from such accidents. The bad symptoms which render compound fractures so dangerous are of many kinds, such as hemorrhage, violent and extensive inflammation, fever, etc, while the wound of a large artery may add considerably to the danger of a fracture.