with simple suppuration of bone, MIESCHER concludes, that “the organic matter in caries is destroyed by necrosis, and that caries might very properly be named necrosis in particles, as the very able and experienced RUST had called it in his Lectures. It appears that dead and separated bony particles are not to be found in every carious ulcer; for when that destructive process exists, ulceration proceeds no further, but it is only oecupied in secreting sanious pus and producing granulations of a bad character, the previously dead particles having separated, and been thrown out with the pus, and no more make their appearance. It is further to be observed, that it is of no consequence what dead parts are separated and what destroyed by caries, but that in the destruction of the organic tissue much is to be attributed to the more active absorption as fitted for separating the dead parts." (212-13.)

"When a carious bone has been macerated, the diseased part," remarks SYME, “is found excavated and rough, the cancellated structure being remarkably spicular, white and brittle, so as to resemble a spongy bone which has been exposed to the action of fire. The surface thus affected, is often of considerable extent, though frequently very small, even in cases of old standing; but the disease seldom reaches to a considerable depth. The field of the disease seems to be determined by the primary inflammation, and after being thus established, has little or no tendency to become larger. Around the carious part there is always an effusion of new osseous matter, in the form of warts or tubercles, extending to a considerable distance, and greatly increasing the thickness of the bone. This new mass, which is no doubt produced in consequence of the irritation of the disease, like that formed to re-unite fractures, and supply the place of exfoliations, is characterized by compactness and smoothness when minutely examined, though on superficial inspection it appears rough and porous. The pores are apertures for the transmission of blood vessels, but their form is circular, and their edges rounded off, so that sharp edges cannot anywhere be perceived. The newly effused bone may thus be readily distinguished from the diseased part, to the irritation of which it owes its origin." (p. 170-71.)]

863. All injuries, producing inflammation of bone which ends in ulceration may be considered as causes of caries (1). They are either external or internal; to the former belong external hurts, kicks, blows, wounds, tearing of the periosteum, fractured bones, continued pressure, suppuration in the neighbourhood of the bone; exposure of the latter, especially if the air be freely admitted or the treatment have been improper. The internal causes are especially, scrofula, syphilis, scurvy, rickets, gout, rheumatism, suppression of customary discharges, metastasis after previous active or chronic eruptions of the skin (2). Ordinarily from the external causes rather the superficial, and from the internal rather the parenchyma or internal substance of the bone is affected. Caries most commonly occurs in the soft spongy bones.

As regards the distinction of bony ulcers from suppurating wounds of bone, and the exposure of the bone, what has been already said (par. 746) of the distinction of ulcers, especially from abscesses, here applies.

DELPECH (a) believes that the diseased changes which syphilis produces in bones does not deserve the name of caries, as therein the bones suffer little from change in their structure, but rather become necrotic. Although this is commonly the case, as already mentioned, (par. 823,) yet is it, however an opinion, which cannot in general be assented to.

[(1) "In caries," says MAYO, "absorption is preceded by a change in the bone, which (with very few and doubtful exceptions) has a well-marked inflammatory character. The same condition exists during the progress of the absorption. There is further present an imperfect restorative action, which is shown in the more or less partial growth of unwholesome granulations from the ulcerated surface. Of these changes, the inflamed condition of the bone is the primary and most important; the absorption is secondary and accidental.” (p. 36.)

(2) MIESCHER points out the seat of the various kinds of caries from internal causes as follows:-" Scrofulous caries, for the most part, attacks the spongy texture, as the bodies of the vertebra, the carpal and tarsal bones, and the joint-ends of the long bones; beginning in the previously formed internal tubercles of which, it excites in them in(a) Chirurgie Clinique de Montpellier. Paris et Montpellier, 1823, p. 454.

flammation and swelling, and afterwards attacks the soft parts, which at the commencement of the disease, were almost, or entirely free from it. The scrofulous differs especially from rheumatic caries, which is also situated in the joint ends, but arises from inflammation of the soft parts, the ligaments and synovial membrane, and thence sometimes seizes on the articular surface itself. The arthritic no less prefers the region of the joints, but attacks the external surface of the bone, having been mostly preceded by the formation of exostoses. In general, arthritic concretions are observed in its immediate neighbourhood. The syphilitic caries seems to be, next to the scrofulous, most frequent, but contrariwise, almost only resides in the compact substance of the bone; and then the scorbutic. These are especially distinguished, in that for the most part, the former is accompanied with the formation of exostoses, and that these exostoses are the seat of ulceration; whilst in the latter, but very rarely do exostoses appear." (p. 216.)]

864. The prognosis depends on the constitution, age, and circumstances of the patient, on the causes which have produced the caries, and on its seat. The prognosis is most unsatisfactory in very great general and especially in scrofulous ailment, and if the caries exist in the neighbourhood of a joint. If the hectic fever have exhausted the powers of the patient, the removal of the limb is often the only remedy. But in many cases, especially in young persons who have reached the age of puberty, nature effects the cure by her own powers, and in the following manner :-the air being kept from the diseased bone by the contraction of the fungous edges of the aperture of the ulcer, it either dies completely and is thrown off with suppuration as a granular powder, or in flakes, or in its whole thickness (Exfoliatio sensibilis); or it is removed by absorption, (Exfoliatio insensibilis,) whilst at the same time granulations arise from the bone, the suppuration improves and diminishes, and the external ulcer gradually closes.

865. As regards the treatment of caries, its causes must be first counteracted; the suitable mode of cure must be directed against scrofula, syphilis, rickets, gout, and so on, and close attention must be paid to the state of the patient's powers, which are to be supported by proper remedies, and especially by good nourishing diet, and by the enjoyment of good air. 866. The local treatment of the ulcers requires great cleanliness in dressing; the carious part must be defended from the approach of the air, and the free escape of the ichor must be provided for. To this end, if the situation of the ulcer in the soft parts do not permit the ready escape of the ichor, enlargement of the ulcerated opening is frequently needed. In other respects the local treatment agrees entirely with that generally applied to ulcers. The openings of the sores are to be covered superficially with lint, all stuffing and introduction of tents are to be avoided, moist warm applications of chamomile or other aromatic vegetables are to be used, rubbing in of volatile salves or spirituous fluids on the neighqouring parts, and the use of general or local aromatic baths. In inflammatory affections, leeches should be applied around; gray mercurial ointment rubbed in, and softening applications made. By this treatment it is expected that the vitality of the diseased bone may be changed, and that it should exfoliate imperceptibly or perceptibly; and in the latter case, provision must be made for the removal of the separated portion of bone. This mode of treatment is preferable to the use of injections of warm water, of slightly astringent decoctions, or aromatic vegetables, as chamomiles, oak, chestnut, or Peruvian bark, or green walnut shells; of dilute phosphoric acid, of a weak solution of sublimate, of lime water, kreosote, and so on; or if the secretion of the ichor be copious and stinking, some

slight aromatic remedy must be strewed in powder on the ulcers. But if the treatment mentioned be inefficient, the ulcers not being kept up by a general diseased cause, and the position of the carious bone permitting, the cure may be attempted by the removal of the carious part and the simple treatment of an exposed sound bone, by cutting into the caries of a rib, of the breast and collar bones, the skull and face bones, the bones of the meta-carpus and -tarsus, of the articular surfaces, if the caries be not very extensive. If the latter be the case with the bones of the limbs, and especially in the joints, and destruction is to be feared from hectic fever, amputation or exarticulation of the limb is the only remedy.

The numerous remedies proposed for caries, as assafatida, phosphoric acid, rubia tinctorum, semina phellandrii aquatici, muriate of barytes and so on, are not sustained by experience. RUST (a) recommends pills of equal parts of assafatida, phosphoric acid, and rad. calam, arom., from six to ten portions, three times a day, as especially effective, particularly if scrofula be the cause of the disease. The use of acrid remedies, as tinct. euphorbii, aloes, myrrhæ, the acrid ætherial oils, and the like for the purpose of bringing about a more complete death of the diseased bone, for which purpose also the actual cautery has been employed, are to be entirely discarded, as their effect is not restricted merely to the diseased bone, but may also extend to the underlying healthy bone: only in caries fungosa, has the actual cautery often appeared to me advantageous. FRICKE (b) considers the complete exposure of the diseased bone as the best mode of producing its quick exfoliation.

["The absorption may be prevented," says MAYO, “by subduing the inflammation; or may, having begun, be arrested, and the crop of unwholesome granulations converted into a healthy restorative growth, if the case is of such a nature as to allow of the suppression of the inflammatory or specific action." (p. 36.)

"The treatment must, in the inflammatory stage of caries, be antiphlogistic," says LAWRENCE;"take blood from the part locally, and adopt other antiphlogistic measures, and after this, counter-irritation, by the application of tartar emetic ointment, moxa, and so on, in the neighbourhood of the diseased bone. When we come to the ulcerative stage of the affection, we must employ the counter-irritant plan. So far as local means go, perhaps, we have no more effective methods of producing it, than by counterirritation, issues, and moxæ. Further, as a local means of treatment, we are recommended, when the carious affection occupies a small portion of bone within our reach, to denude the bone, and remove the diseased part by means of HEY's saw, or a stout pair of scissors, or pliers, or by any other mechanical means, to cut away that which is the seat of disease." (p. 359.)

"The treatment of caries,” says SYME, "is to be conducted on the same principle as that of cancer, and consists in the use of means which have the effect either of destroying the life of the morbid part, or of removing it at once from the system. There is this difference, however, that there being no malignant tendency to take on the same diseased action in the neighbouring parts, it is not necessary to remove any of them, except in order to gain access to the seat of the evil. Notwithstanding this favourable circumstance, it is found extremely difficult to eradicate the disease by depriving the part affected of its vitality. * * * The effect of all these applications, to wit, the concentrated mineral acids, nitrates of silver and mercury, red oxide of mercury, and the actual cautery, (with the view of killing the morbid part,) however carefully employed, is very superficial, and it is extremely difficult, if not impossible, to ensure their operation on the whole surface of the diseased part. They therefore always require to be frequently repeated, and generally prove quite inadequate to destroy the disease, unless it is very limited and accessible; and it is even not improbable that some of them, as the actual cautery, may occasionally make the matter worse, and extend the disease to the neighbouring bone, by exciting inflammation in it. For these reasons, excision ought to be preferred to caustics for removing the carious bone; and if the part affected be within reach, which can always be ascertained previous to commencing the operation, it may, by this method, be surely and thoroughly eradicated at once. If the disease is superficial, and of small extent, it is easily scooped out with a gouge, the toughness and compactness of the sound bone distinguishing it from the morbid portion.

(a) Handbuch der Chirurgie, vol. ii. p. 398.
(b) Fünfter Bericht über die Verwaltung des

allgemeinen Krankenhauses zu Hamburg, 182, p. 237.

If extensive and deep-seated, it is best removed by taking away the whole of the articulating extremities. When the situation of the caries prevents it from being cut out, amputation ought, if possible, to be performed; if this be impracticable, the disease will, sooner or later, prove inevitably fatal." (p. 172.)]

867. If from examination with the probe it appear, that the diseased bone is partially or completely loose, it must be seized with the forceps, and drawn out, for which purpose the ulcer in the soft parts oftentimes must be enlarged. Commonly after the removal of the bone, the part upon which it was situated is covered with granulations, which must be very carefully destroyed with stimulating remedies. In cases where a large piece of bone has been completely destroyed, but will not separate, its removal must be effected by taking hold with the forceps, and moving it backwards and forwards; or if this be insufficient, it must be assisted even with the trepan, or with the scraper, if the position of the diseased part permit.

B.-OF NECROSIS.

868. Its low degree of vitality, is the cause of bone easily dying, and necrosis, which is analogous to the gangrene of soft parts, occurs as a consequence of inflammation, suppuration, or of a considerable tearing of the periosteum. According as the necrosis occurs from inflammation and suppuration, or from destruction of the connexion of the nourishing vessels of the bone, it may be distinguished into consecutive and primary.

869. Necrosis takes place at every age, in every condition of life and in both sexes, although usually in childhood and at the period of manhood; it is most frequent in the compact part of tubular bones, in the shin-bone, thigh, lower jaw, collar-bone, upper-arm-bone, splint-bone, spoke-bone, and cubit; rarely in their spongy extremities. It also frequently attacks the flat bones. Necrosis is situated sometimes in the external, sometimes in the internal layer of the bone, or attacks it throughout its whole bulk. All ailments which destroy the nourishment of the bone by the periosteum, or by the medullary membrane are to be considered as causes of necrosis. They may be either external, as mechanical violence, tearing of the periosteum, exposure of the bone, particularly if it be long subjected to the influence of the air, or be treated with acrid irritating remedies, contusions, and so on; or internal, in which may be included all the dyscrasic diseases already mentioned (par. 863) from whence inflammation and death of bone arise. The external causes rather produce necrosis of the external layers of the bone, as the internal causes do internal necrosis. Oftentimes both causes operate together.

["If the periosteum, which, by its own vessels is in most intimate connexion with the vessels of the bone, be destroyed to any considerable extent, the external layer of the bone (not its whole thickness) dies," says MÜLLER (a), "because the vessels of the outer layer are rendered useless by the destruction of the periosteum. If the medullary tissue alone be destroyed by inflammation, or artificially in an animal's bone which has been sawn through, the inner layer (not the whole thickness) of the bone dies, because the vessels of the inner layer of the bone are in the closest connexion with the medullary vessels. Now the process which ensues, in internal necrosis, in the still living external part of the bone, and in external necrosis in the still living internal part of the bone, is remarkable: it becomes inflamed to the extent of exudative effusion, as in an inflamed fractured bone, and subsequently the effused matter, as in that case, becomes organized and ossified. If the bone be injured externally and there be an outer necrosis, the exudation takes place within the cavity of a tubular bone, and the medullary cavity is thereby diminished. This callus on the interior of the cavity of a tubular bone

(a) Physiologie des Menschen, vol. i.

strengthens its walls, of which the outer layer is dead. If, on the other hand, the medulla of a sawn-through tubular bone be destroyed, in consequence of which the inner layer dies, the exudation takes place on the outer surface, from the external still living layer of the bone. Most writers have not distinguished the swelling of an inflamed bone, called by SCARPA its expansion from the deposition of bone following the exudative condition, in the former case into the medullary cavity, and in the latter on the external surface between the periosteum and the bone. The exudation is a process continuing only for a certain time, but the swelling continues during the whole period of the inflammation, and first appears distinct when the bone softens and becomes very vascular opposite the necrosed piece. This expansion of the inflamed and softened bone, in the mammalia, plays the principal part in the regeneration of the necrosed piece of bone. At the part where the healthy external layer touches the internal necrotic, or where the sound internal layer touches the dead external, the still living inflamed bony layer is quite soft, red, and granulating, and in internal necrosis increases externally, whence, however, no new tube is formed around the internal necrotic layer, (sequester,) but a strengthening of the outer layer, or beneath the external separated necrotic layer, a strengthening of the internal layer ensues, both externally as well as towards the medullary cavity. This swelling proceeds whilst the surface of the inflamed and softened bone begins to suppurate, either internally opposite the internal necrosis, or externally opposite the external necrosis. If the whole thickness of a bone be dead, no bone is regenerated; the periosteum has nothing to do with it; on the contrary, regeneration ordinarily takes place when merely the outer or inner layer is destroyed; here, however, no new bone is formed, but the dead portion of the tube in internal necrosis is only the inner layer of the tubular bone, and the new tube around the dead is only the strengthened and swollen outer layer of the tubular bone." (p. 403, 404.)

Of necrosis produced by irritation, two very remarkable instances may be here mentioned. BROMFIELD'S (a) case, in which the pea of an issue slipping frequently out of its bed, was confined by "a compress with a shilling in it bound very tightly; this, by its pressure, soon destroyed the periosteum, and not long after made its way through the surface of the bone into its spongy parts. Though a deep bed was thus obtained for the pea, yet violent pain and great swelling of the knee ensued; by throwing out the pea and dressing the bone properly a large piece of the spongy substance came away and the sore healed." (p. 10.) In the case referred to by LAWRENCE, "the patient had received a slight injury over the tibia, the sore put on the appearance of sloughing phagedana or gangrene, and the concentrated nitric acid was applied to it. It appears that the acid affected the periosteum of the bone, at the part to which it was applied, and inflammation and necrosis of the tibia were the consequence." (p. 361.)]

870. The inflammation preceding necrosis has either an acute or chronic course, and is accompanied with more or less severe symptoms. If the inflammation be seated within the bone, there is first produced violent deepseated pain, not increased by motion nor pressure, and frequently accompanied with severe fever, and exhausting perspiration; a hard swelling appears, which gradually spreads, and over which the skin is neither tense nor red. After a longer or shorter time, according to the severity of the inflammation, abscesses form in different parts, which burst and discharge pus, without the swelling being diminished. These openings often correspond to the position of the diseased bone, often they form, especially if the bone be covered with much soft parts, fistulous passages, of which the external openings are surrounded with a wall of flesh, a line thick; some of them close and others again break out.

["When the ossific inflammation is not cured," says JOHN HUNTER, “suppuration takes place, first, on the surface of bones or on the periosteum; secondly, in the substance; thirdly, (p. 508,) in the medullary parts. *** The first species.---When inflammation attacks the surface of a bone, the first effects are adhesive; and when suppuration takes place, the periosteum is separated as far as the suppuration extends, making underneath a cavity for the matter. As the adhesive states take place some way round the abscess, there is in many cases a circle of adventitious bone formed in the periosteum round the abscess. *** Often, from the separation of the periosteum, part of the bone dies, and must exfoliate. The second species is of greater consequence, as more of the bone

(a) Chirurgical Observations and Cases, vol. ii. London, 1773.