gorous traction and
twisting of the soft parts, matted together as they are by
scar-tissue, causes reactive changes in the vessels and tissues which
render them more liable to yield on subsequent attempts at reduction.
In old people, and where there is an absence of suffering from
pressure on nerves or vessels, it may be wiser to leave the
dislocation unreduced, and strive rather by massage and movement to
obtain a useful variety of false joint. If the conditions are
otherwise, it may be better to improve the function of the limb by an
_open operation_. Tight ligaments and other structures are divided,
and the socket is cleared out. If reduction is still impossible, a
partial excision may be performed and a flap of fascia lata introduced
to prevent ankylosis (arthroplasty). In the case of the hip, the
dislocation may be left alone and the femur divided below the
trochanter, especially if there is pronounced flexion.

#Habitual or recurrent dislocation# is almost exclusively met with in
the shoulder, and will be described with the injuries of that joint.

#Pathological Dislocations.#--Joints may become dislocated in the
course of certain diseases. These pathological dislocations fall into
different groups: (1) those due to gradual stretching of the capsular
and other ligaments weakened by inflammatory and suppurative
processes, such as sometimes follow on typhoid, scarlet fever, or
diphtheria, and in pyaemia; (2) those due to destructive changes in the
ligaments and bones--typically seen in tuberculous arthritis, in
arthritis deformans, in Charcot's disease, and in nerve lesions,
_e.g._ dislocation of the hip in spastic conditions, such as Little's
disease; (3) those associated with deformed attitudes of the limb; (4)
those due to changes in the articular surfaces, _e.g._ the phalanges
in arthritis deformans. These will be considered with the conditions
which give rise to them.

#Congenital Dislocations.#--Congenital dislocations are believed to be
the result of abnormal or arrested development _in utero_, and are to
be distinguished from dislocations occurring during birth, which are
essentially traumatic in origin. They will be described along with the
Deformities of the Extremities.

CHAPTER III

INJURIES IN THE REGION OF THE SHOULDER AND UPPER ARM

Surgical Anatomy--FRACTURES OF CLAVICLE: _Varieties_--DISLOCATION OF
CLAVICLE: _Varieties_--DISLOCATION OF SHOULDER:
_Varieties_--Sprains and contu