TUBERCULOSIS OF JOISTS Etiology and joints may be infected ether from the neighboring bone (osteoarthritis) or metastatically by the blood current. In both cases miliary tubercles will he formed on the inside of the synovia, which reacts by exudation into the joint cavity, and also by exuberant granulations, which become easeous and break down, forming purulent foci that gradually fill the joint and destroy it.
The cartilage is eroded and lifted off the bone, which in turn is affected and filled with pus. The ligaments are also destroyed by the suppuration. Finally the pus will break through the capsule, thickened from the reactive processes, and will appear on the surface (suppurat ing form).
Afore rarely the process will remain at the primary exudative stage (hydrops tuberculosus); these are the cases of quickly disappearing swellings of the knee- and hip-joints and what the call "rhu matisme tuberculcux" (Poncet).
In children we also rarely observe the dry form (caries sicca), which is rather frequent in old people and in which the joint is destroyed with out the formation of pus (see shoulder-joint).
The most frequent form in children is that in which the joint is filled with slowly growing granulations either with or without a primary exudate. The joint is in its characteristic medium position, the capsule is dilated and covered by the tense and glistening skin (tumor albus).
The fungoid masses distend the joint like a sponge (pseudo-fluc tuation). The process may either stop at this stage and heal with the formation of scars and fibroid thickening or it may break down and form a joint abscess.
The prognosis is more favorable in children than in adults, as only a small percentage succumb to general infection (meningitis, amyloid degeneration). The prognosis is worse as to the function of the joints; the dropsical form alone leaves the joint intact, in all other forms the joint is generally destroyed. Healing takes place with fibrous scars which also involve the capsule and the ligaments and which make the joint stiff even if the denuded ends of the bones have not grown together.
The general treatment is identical with that for tuberculosis of the bones.
The suppurating joint must be regarded as a cold abscess and be treated accordingly (iodoform emulsion, camphor naphthol, Wreden). Otherwise each individual joint and bone offers so many varieties for clinical observation and treatment that it will be necessary to speak of each separately.
The diagnosis of joint tuberculosis depends upon the symptoms Peculiar to each joint, but otherwise, with only few variations, is identical with that of bone tuberculosis.
(a) Tuberculosis of the Shoulder-joint shoulder-joint is relatively rarely affected in chil dren. It usually assumes the type of caries sicca, though all other varie ties may be observed. The capsule is distended by a primary exudate or by the growing masses of granulations. The deltoid muscle which runs over it appears swollen and increases the protrusion of the shoulder.
In cases in which the process heals by fibrous scars or in those of the dry type the picture is just the opposite. The muscle atrophies from disuse and the shoulder becomes smaller. The head of the humerus is very sensitive to pressure. Function is interfered with, the joint is held in the position enforced by its weight, namely, adduction and slight rotation inwards; any change from this position produces pair. Apparent motion can be produced in this joint by moving the shoulder blade on the thorax, with the shoulder-joint itself held stiff.
Suppuration, either from breaking down of granulations or from the perforation of bony foci into the joint, produces the picture of a joint abscess.
The head of the humerus is eroded by cuneiform bone foci, and the epiphyseal line, which is inside the joint cavity in the shoulder-joint, is destroyed; the pus perforates the capsule and either follows the biceps tendon into the upper arm or it appears in the axilla, or posteriorly below the scapula. The axillary glands are always affected.