In exceptional cases, tuberculous joint disease follows an acute course resembling that of the pyogenic arthritis of infants.  This has been observed in children, especially in the knee, the lesion being in the synovial membrane, and attended with an accumulation of pus in the joint.  If promptly treated by incision and drainage, recovery is rapid, and free movement of the joint, may be preserved.

The onset and early stages of tuberculous disease, however, are more often insidious, and are attended with so few symptoms that the disease may have obtained a considerable hold before it attracts notice.  It is not uncommon for patients or their friends to attribute the condition to injury, as it often first attracts attention after some slight trauma or excessive use of the limb.  The symptoms usually subside under rest, only to relapse again with use of the limb.

The initial local symptoms may be due to the presence of a focus in the neighbouring bone, perhaps causing neuralgic pains in the joint, or weakness, tiredness, stiffness, and inability to use the limb, these symptoms improving with rest and being aggravated by exertion.

It is rarely possible by external examination to recognise deep-seated osseous foci in the vicinity of joints; but if they are near the surface in a superficial bone—­such as the head of the tibia—­there may be local thickening of the periosteum, oedema, pain, and tenderness on pressure and on percussion.

X-ray Appearances of Tuberculous Joints.—­Gross lesions such as caseous foci in the marrow of the adjacent bone show as clear areas with an ill-defined margin; a sclerosed focus gives a denser shadow than the surrounding bone, and a sequestrum presents a dark shadow of irregular contour, and a clear interval between it and the surrounding bone.

Caries of the articular surface imparts a woolly appearance or irregular contour in place of the well-defined outline of the articular end of the bone.  In bony ankylosis the shadow of the two bones is a continuous one, the joint interval having been filled up.  The minor changes are best appreciated on comparison with the normal joint of the other limb.

Wasting of muscles is a constant accompaniment of tuberculous joint disease.  It is to be attributed partly to want of use, but chiefly to reflex interference with the trophic innervation of the muscles.  It is specially well seen in the extensor and adductor muscles of the thigh in disease of the knee, and in the deltoid in disease of the shoulder.  The muscles become soft and flaccid, they exhibit tremors on attempted movement, and their excitability to the faradic current is diminished.  The muscular tissue may be largely replaced by fat.

Impairment of the normal movements is one of the most valuable diagnostic signs, particularly in deeply seated joints such as the shoulder, hip, and spine.  It is due to a protective contraction of the muscles around the joint, designed to prevent movement.  This muscular fixation disappears under anaesthesia.