A High Degree Of Inflammation In Bone

A High Degree Of Inflammation In Bone leads to the effusion either of a fibrinous product, which more or less rapidly softens; or of a purulent exudation, which varies in fluidity, according to the quantity of serum it contains, and is yellow and frequently tinged by an admixture of the coloring matter of the blood, and of blood itself; or, lastly, of a greenish or brownish discolored sanies. There are some striking instances of this kind of inflammation, which run their course very rapidly: they occur not only after injury of a bone, especially after concussion, but also in consequence of cold; and they are associated with endocarditis and several other exudative inflammatory processes. The periosteum in these cases is loose and movable to some extent over the bone, the exudation being poured out beneath it: in well-marked cases, it becomes loose all round the bone, and distended into a fluctuating sac, which contains a large quantity of the exudation. The tissue of the periosteum is loosened and infiltrated: the bone is of the same color as the exudation, and has accordingly a dun, a dirty yellowish or a greenish or reddish appearance, which results from all its spaces being occupied by the exudation. The exudation is deposited in greatest quantity in the cancellous structure; but when the compact tissue is minutely examined, the Haversian canals are found to contain it too. The surface of the bone, especially when the exudation is sanious, appears rough, that is to say, its outermost layer is eroded, and the loss of substance is produced by the solution of its tissue during the process of exudation itself, and by contact with a product which exerts an absolute dissolving power. The walls of the Haversian canals exhibit similar loss of substance, and are rough and eroded, or completely perforated. The cells of the cancellous structure show it still more clearly, and the membrane which covers its cells and network is opaque, dull, and discolored like the exudation, and is easily torn. It is this form of ostitis which, if it do not prove fatal by its coexistence with other exudative processes, very commonly puts life in the greatest danger, or actually destroys it by leading to absorption of the purulent and sanious matter into the circulation (the coats of the veins probably being dissolved in the exudation around them), and by metastasis. When the case is favorable, necrosis of the diseased bone, or portion of bone, is inevitable.

But inflammations of bone, which are accompanied by the production of pus and sanies, are more frequently chronic. The suppurative inflammation mostly occurs as a consequence of complicated injuries of bone and of necrosis: the chronic inflammation with an ichorous product, arises from internal causes, sometimes commencing spontaneously, sometimes being excited by injury to the bone, and sometimes, under the influence of the internal causes just alluded to, being an early or a late degeneration of the suppurative inflammation. It produces loss of the substance of the bone by ulceration, and constitutes Caries (Vereiterung - Beinfrass).

Suppurative Inflammation

In suppurative inflammation, especially in cases of considerable injury of bone, exposure, for instance, for a lengthened period, there very commonly takes place, in the benumbed tissue, a visible exfoliation of a layer of bone of various thickness. When the necrosed portion is very thin, exfoliation is rightly assumed to be going on imperceptibly by the separation of small and scarcely discernible particles. But there are several cases in which symptoms have been ascribed to necrosis and insensible exfoliation, merely as it appears, for the sake of the theory, and in which no such process occurred. The circumstances were in reality more favorable; for as, when suppuration in its most benignant form takes place anywhere, the first secretion of pus is attended by some breach of substance - by some solution - of the tissue in which it occurs, so is it in these cases. The softening which many observers have adduced as a constant phenomenon in the suppuration of a layer of bone, must be regarded as such a process of solution: a portion of bone disappears, and the exudation beneath it, like that beneath exfoliated bone, becomes organized into granulations, which spring from the tissues lining the Haversian canals. This view is supported generally by the process of sanious destruction, which is allied to the suppurative, and is only distinguished from it by the relatively greater amount and the progressive increase of the solution; while it is upheld more particularly by the state in which a bone is found when this peculiar loss of its substance is the consequence of an acute inflammation attended by the production of pus or sanies, or when it results from caries: and lastly, it is further borne out by the condition of a sequestrum: but this is a subject to which I shall revert when speaking of necrosis.

A spot of suppuration in bone is always skirted by an inflammatory process, which leads to an exudation of bone. If the affected part be the outer layer, an osseous exudation is found not only encircling the suppurating spot, but also on the inner table of the bone, and vice versd. When suppuration takes place in spongy bones, this process occasions so much condensation, that in a few cases an abscess becomes enclosed within a capsule of compact bone. This capsule is lined by a cellular membrane which is richly supplied with vessels, and it resembles an abscess in the soft parts enclosed within callous walls. Abscesses of this kind have been pretty frequently observed in the extremities of the tibia (Brodie, Mayo); and on a few occasions they have been met with in the compact substance of the shaft of that bone and of the femur (Arnott). Having hitherto treated of those terminations of inflammation in which bone is increased in volume and density (sclerosis, which is equivalent to induration in the soft parts), and in which suppuration ensues; I am induced by the importance of the subjects to bestow separate sections upon the consideration of caries - chronic inflammation with production of sanies - and necrosis.