l fractures.

_Atrophy_ of bone may proceed to such an extent in old people, or in
those who for long periods have been bed-ridden, that slight violence
suffices to determine a fracture. This most frequently occurs in the
neck of the femur in old women, the mere catching of the foot in the
bedclothes while the patient is turning in bed being sometimes
sufficient to cause the bone to give way. Atrophy from the pressure of
an aneurysm or of a simple tumour may erode the whole thickness of a
bone, or may thin it out to such an extent that slight force is
sufficient to break it. In general paralysis, and in the advanced
stages of locomotor ataxia and other chronic diseases of the nervous
system, an atrophy of all the bones sometimes takes place, and may
proceed so far that multiple fractures are induced by comparatively
slight causes. They occur most frequently in the ribs or long bones of
the limbs, are not attended with pain, and usually unite
satisfactorily, although with an excessive amount of callus.
Attendants and nurses, especially in asylums, must be warned against
using force in handling such patients, as otherwise they may be
unfairly blamed for causing these fractures.

Among diseases which affect the skeleton as a whole and render the
bones abnormally fragile, the most important are rickets,
osteomalacia, and fibrous osteomyelitis. In these conditions multiple
pathological fractures may occur, and they are prone to heal with
considerable deformity. In osteomalacia, the bones are profoundly
altered, but they are more liable to bend than to break; in rickets
the liability is towards greenstick fractures.

Of the diseases affecting individual bones and predisposing them to
fracture may be mentioned suppurative osteomyelitis, hydatid cysts,
tuberculosis, syphilitic gummata, and various forms of new-growth,
particularly sarcoma and secondary cancer. It is not unusual for the
sudden breaking of the bone to be the first intimation of the presence
of a new-growth. In adolescents, fibrous osteomyelitis affecting a
single bone, and in adults, secondary cancer, are the commonest local
causes of pathological fracture.

_Intra-uterine fractures_ and fractures occurring _during birth_ are
usually associated with some form of violence, but in the majority of
cases the foetus is the subject of constitutional disease which
renders the bones unduly fragile.

TRAUMATIC FRACTURES

Traumatic fractures are usually the resul