The treatment is that of tuberculous lesions in general; if conservative measures fail, the choice lies between the injection of iodoform, and removal of the infected tissues with the sharp spoon.  In the ribs it is more satisfactory to remove the diseased portion of bone along with the wall of the associated abscess or sinus.  If all the tubercle has been removed and there is no pyogenic infection, the wound is stitched up with the object of obtaining primary union; otherwise it is treated by the open method.

#Tuberculous Osteomyelitis.#—­Tuberculous lesions in the marrow occur as isolated or as multiple foci of granulation tissue, which replace the marrow and erode the trabeculae of bone in the vicinity (Fig. 124).  The individual focus varies in size from a pea to a walnut.  The changes that ensue resemble in character those in other tissues, and the extent of the destruction varies according to the way in which the tubercle bacillus and the marrow interact upon one another.  The granulation tissue may undergo caseation and liquefaction, or may become encapsulated by fibrous tissue—­“encysted tubercle.”

[Illustration:  FIG. 124.—­Tuberculous Osteomyelitis of Os Magnum, excised from a boy aet. 8.  Note well-defined caseous focus, with several minute foci in surrounding marrow.]

Sometimes the tuberculous granulation tissue spreads in the marrow, assuming the characters of a diffuse infiltration—­diffuse tuberculous osteomyelitis.  The trabecular framework of the bone undergoes erosion and absorption—­rarefying ostitis—­and either disappears altogether or only irregular fragments or sequestra of microscopic dimensions remain in the area affected.  Less frequently the trabecular framework is added to by the formation of new bone, resulting in a remarkable degree of sclerosis, and if, following upon this, there is caseation of the tubercle and death of the affected portion of bone, there results a sequestrum often of considerable size and characteristic shape, which, because of the sclerosis and surrounding endarteritis, is exceedingly slow in separating.  When the sequestrum involves an articular surface it is often wedge-shaped; in other situations it is rounded or truncated and lies in the long axis of the medullary canal (Fig. 125).  Finally, the sequestrum lies loose in a cavity lined by tuberculous granulation tissue, and is readily identified in a radiogram.  This type of sclerosis preceding death of the bone is highly characteristic of tuberculosis.

[Illustration:  FIG. 125.—­Tuberculous Disease of Child’s Tibia, showing sequestrum in medullary cavity, and increase in girth from excess of new bone.]

Clinical Features.—­As a rule, it is only in superficially placed bones, such as the tibia, ulna, clavicle, mandible, or phalanges, that tuberculous disease in the marrow gives rise to signs sufficiently definite to allow of its clinical recognition.  In the vertebrae, or in the bones of deeply seated joints, such as the hip or shoulder, the existence of tuberculous lesions in the marrow can only be inferred from indirect signs—­such, for example, as rigidity and curvature in the case of the spine, or from the symptoms of grave and persistent joint-disease in the case of the hip or shoulder.