. In young subjects, destruction of the
tissues at the ossifying junction may result in considerable
shortening of the arm.

The _diagnosis_ is to be made from (1) arthritis deformans, in which
the movements are less restricted, and are attended with grating and
cracking; (2) paralysis involving the deltoid and scapular muscles--by
the absence of pain, and the flail-like character of the movements;
(3) disease in the sub-deltoid bursa--by the absence of rigidity and
other evidence of implication of the articular surfaces; and (4)
sarcoma of the upper end of the humerus--by the history of the case,
the use of the X-rays or an exploratory incision. Injuries in the
region of the upper epiphysis resulting in loss of movement, may, in
the absence of a reliable history, be mistaken for tuberculous
disease.

While the _prognosis_ is favourable on the whole, recovery is usually
attended with fibrous ankylosis and incapacity to raise the arm above
the level of the shoulder. The disease often progresses slowly, and
may last for years.

_Treatment._--The limb should be immobilised in the position of
abduction with the forearm and hand directed forwards; the most
efficient apparatus is a plaster spica embracing the thorax and the
upper limb down as far as the wrist. If the articular surfaces are
affected and the disease is likely to lead to ankylosis, the arm
should be abducted to a right angle. The severe pain of caries sicca
may be relieved by blistering or by the application of the cautery. To
inject iodoform, the needle is introduced either immediately outside
the coracoid process, or just below the junction of the acromion
process and spine of the scapula. When the disease does not yield to
conservative measures, or the X-rays show a gross lesion in the bone,
excision of the joint should be performed; a close fibrous ankylosis
usually results, and the arm is quite a useful one provided the
abducted position has been maintained throughout.

#Pyogenic Diseases.#--The shoulder-joint may be infected by extension
of suppurative osteomyelitis from the upper end of the humerus, or
from suppuration in the axilla, or through the blood stream by
ordinary pus organisms, pneumococci, typhoid bacilli, or gonococci.
Extension should be applied to the arm abducted at a right angle. When
it is necessary to open the joint, the incision should be placed
anteriorly in the line of the inter-tubercular groove; if a
counter-opening is require