ted bones, discoloration may only show
on the surface after some days, and at a distance from the break.

Alterations in the relative position of _bony landmarks_ are valuable
diagnostic guides. Alteration in the _length_ of the limb, usually in
the direction of shortening, is also an important sign. Before drawing
deductions, care must be taken to place both limbs in the same
position and to determine accurately the fixed points for measurement,
and also to ascertain if the limbs were previously normal.

_Shock_ is seldom a prominent symptom in uncomplicated fractures,
although in old and enfeebled patients it may be serious and even
fatal. During the first two or three days after a fracture there is
almost invariably some degree of traumatic _fever_, indicated by a
rise of temperature to 99 deg. or 100 deg. F.

#Complications.#--_Injuries to large arteries_ are not common in
simple fractures. The popliteal artery, however, is liable to be
compressed or torn across in fractures of the lower end of the femur;
extravasation of blood from the ruptured artery and gangrene of the
limb may result. If large _veins_ are injured, thrombosis may occur,
and be followed by pulmonary embolism.

_Injuries to nerve-trunks_ are comparatively common, especially in
fractures of the arm, where the radial (musculo-spiral) nerve is
liable to suffer.

The nerve may be implicated at the time of the injury, being
compressed, bruised, lacerated, or completely torn across by broken
fragments, or it may be involved later by the pressure of callus. The
symptoms depend upon the degree of damage sustained by the nerve, and
vary from partial and temporary interference with sensation and motion
to complete and permanent abrogation of function.

In rare instances _fat embolism_ is said to occur, and fat globules
are alleged to have been found in the urine. In persons addicted to
excess of alcohol, _delirium tremens_ is a not infrequent
accompaniment of a fracture which confines the patient to bed.

#Prognosis in Simple Fractures.#--_Danger to life_ in simple fractures
depends chiefly on the occurrence of complications. In old people, a
fracture of the neck of the femur usually necessitates long and
continuous lying on the back, and bronchitis, hypostatic pneumonia,
and bed-sores are prone to occur and endanger life. Fractures
complicated with injury to internal organs, and fractures in which
gangrene of the limb threatens, are, of course, of g