Tuberculous spondylitis (caries): a, osteogenesis and osteosclerosis; c, cavity formed by degeneration of tuberculous focus. (Krause.)
Tuberculosis of bone always assumes the phase of miliary lesions, followed by the formation of a granuloma, which may gradually encroach upon surrounding tissues or may assume a more fulminating type and spread rapidly. Apparently because of the circulatory conditions these lesions generally occur near the epiphyseal lines of the long bones, apparently seeking the ends of the bones, as pulmonary lesions seek the terminations of the lungs. These lesions may be solitary or multiple. Beginning always minutely, they spread so as to produce foci perhaps two inches in diameter. As the result of the formation of granulation tissue, the surrounding bone melts away and disappears, the result being a great weakening of its structure and expansion of its dimensions in order to make room for the growing mass within. The tendency of this granulation tissue thus imprisoned is always to escape in the direction of least resistance. This carries it sometimes into the joint, sometimes out through epiphyseal junctions, and sometimes through channels in the bone made by its own pressure, with external escape and appearance of the dusky distinctive tissue, felt beneath and then upon the skin. Where bone is so weakened in one direction it is usually strengthened by compensatory deposition of calcium salts at other points, and the result frequently is a striking combination of osteoporosis in the immediate presence of the disease, with osteosclerosis, sometimes to a remarkable degree, even to eburnation, of an adjoining portion. When this mass undergoes caseous degeneration the progress of the disease is much slower and the pain less. When it undergoes suppuration there are more evidences of inflammation, with more pain and systemic disturbance, as well as local swelling, tenderness, etc. The surrounding musculature is rarely involved, although the periosteum is nearly always so. In fact, it is stated that in an inflamed and suppurating bone lesion, if the muscles are extensively invaded, it may be regarded as of syphilitic rather than of tuberculous origin. The pyophylactic membrane already alluded to is seen in almost every instance of tuberculous disease. The spina ventosa of some writers refers to the expansion of the shaft and medullary cavity of a long bone whose interior is occupied by a mass of tuberculous gumma, which is perforated at one point, and through which opening it escapes as does lava from a crater, to involve the structures on the outer side. The appearance of this granulation tissue in joints as fungous tissue has already been mentioned. In a general way it preserves its fungoid characteristics until attacked by pyogenic or saprogenic organisms, when it quickly breaks down, forming an ulcer if upon the surface, or a cold abscess if not externally open. Tuberculous disease of the bone is most common in the young, and in them the majority of tuberculous joints are those whose bony structures have been first involved. In other words, the majority of cases of tuberculous pyarthrosis are due to primary bone disease. As the result of the tuberculous infection the bones become distorted, which is best illustrated in Pott’s disease of the spine; while, as the result of the constant irritation, joint ends become displaced by chronic muscle spasm, and joint contours entirely altered by expansion of the affected bone and thickening and infiltration of the overlying soft parts.
I have often, for the sake of illustration to medical students, drawn a certain analogy (following Savory) of the gross resemblances between lungs and bones in their behavior when involved in tuberculous disease. In either case the structure is in a measure spongy and contains cavities and networks of tissue; in each case the structures are invested by a resisting membrane—in the one instance pleura, in the other periosteum. Again, each is closely related to a serous cavity—the lungs to the pleural cavity, the bones to the serous cavities of the joints. Tuberculous disease manifests a predilection for the extremities of both organs. Perforation into the adjoining serous cavity is frequent, and previous to perforation collections of serous fluid are frequently noted—in one instance pleurisy, in the other hydrarthrosis. Moreover, these fluids may frequently become contaminated, and then become purulent, constituting empyema or pyarthrosis as the condition may be. One sees, too, in each place the same striking combinations of weakening of tissue and strengthening in order to atone for the undermining of the disease. These are not all of the similarities that might be adduced, but are perhaps sufficient for the purpose of showing that tuberculous disease is essentially one and the same thing, no matter what tissue is invaded.
In the tendon sheaths and bursæ we frequently find manifestations of tuberculosis. When seen early these are always in the direction either of miliary affection, or, most commonly, of tuberculous gumma, while when seen late the disease has usually advanced to the point of suppuration, and we now have cold abscess of the affected part.
In many joints and tendon sheaths, particularly the latter, we find certain detached, usually colorless, firmly resistant masses, of smooth and polished surface, lying in a collection of fluid, in size from a minute particle up to that of a melon-seed. These have been known at various times as rice grains, melon-seed bodies, corpora oryzoidea, etc., and for a long time their explanation was a mystery. It is now well established that in the majority of instances these are the result of fungous granulations which have become detached in small pieces, which then, in the absence of infection, have shrunken and become rounded and polished by attrition. The bursal enlargement and distention with fluid in which they are usually found is commonly spoken of as hygroma of that particular bursa. Tuberculosis of these bursæ, however, does not always result so harmlessly as the formation of these bodies, but, on the contrary, tuberculous infiltration may extend beyond the serous limits to the surrounding soft parts, with a tendency finally to external escape, just as in the case of bone lesions. These constitute affections of the soft parts which are more or less destructive, and are difficult, often impossible, to deal with, because of the mutilation which a thorough extirpation of the disease would necessitate.
In the testicles and ovaries, particularly in the former, tuberculous disease is frequently met with. In the testicles it begins usually in the epididymis, forming a somewhat dense nodule and a distinct tumor, easily observed from the outside, although its minute character may be still concealed. The tendency here is almost invariably to progressive infiltration and breaking down, either into a caseous mass or, more commonly, into puruloid material, while sometimes acute infection supervenes.
It is not always easy to distinguish between syphilis and tuberculosis of the testicle, though the latter is usually characterized by the same tendency to effusion into the adjoining serous cavity, i. e., that of the tunica vaginalis, as is manifested in disease of the lungs or bones. When the disease is extensive the overlying skin is involved, and frequently the surgeon is called to deal with cases of perforation and escape of fungoid tissue on the outside.
In the kidneys, in the ureters, as also in the bladder, tuberculous lesions are noted, the miliary form being particularly frequent in the former. Tuberculous disease of the kidney leads sooner or later to caseation and a condition of pyonephrosis or its equivalent, which calls practically always for extirpation of the affected organ. Tubercle bacilli are sometimes recognized in the urine, but only when the lesion has an opportunity of discharging into one of the urinary passages.
In the peritoneum tubercle appears usually in the miliary form, leading sometimes to such extensive involvement of and interference with visceral functions as to produce anasarca or more general disturbance prior to death. Acute miliary disease here is as rapid and as essentially fatal as the same affection of the dura or pia, while the more chronic forms are followed by degenerations that may involve the intestines either in agglutinated masses or in ulcerations and possible perforations. The indication in all tuberculous lesions of serous membranes is for exposure by operation, disinfection of the surface, and evacuation of retained fluids. Recovery from tuberculous peritonitis, even of acute type, after abdominal section, is now definitely established as a possibility. The same would probably be true of tuberculous meningitis were we permitted to expose the membranes and attack them or drain them in the same way.