In considering a caries of the bones, we should remember, that the bones have their vessels and circulating fluids, and the same general texture which the soft parts have; so that solidity, and a stronger cohesion of parts, are their only evident distinguishing characters.

Caries of spongy bones is cured with greater difficulty than of compact ones. Caries of the bones of the carpus and tarsus is, from their vicinity, easily com-municated to the neighbouring ones. The disease, when it occurs in the deeper seated bones near the trunk, is seldom to be relieved or cured. It partakes also of the danger of its cause; since, as cancer and scrofula are incurable, little expectation can be entertained of caries from either source. In young persons also it is more easily cured than in old.

Heister observes, that the cure of a caries depends on removing easily and speedily all the corrupted parts of the bone, and that in the gentlest cases this is done by rectified spirit of wine being applied by means of lint dipped in it; or alcohol caryophillatum, made by mixing alcohol. 3 iij- ol. caryoph. 3 i. This applied upon lint to carious bones quickens the exfoliation. Vinegar used in the same manner has been thought to answer the purpose equally well. In more violent cases, a solution of mercury in aqua fortis is required, and in the most malignant the actual cautery will be necessary: but these hinder suppuration, and retard the operation intended. See Exfoliatio.

An exfoliation of the carious laminae of the bone sometimes takes place in two or three weeks, and in other instances the laminae are not removed in a year.

It is necessary to examine strictly all circumstances, and to discover, if possible, what cause, either general or topical, may have induced the disease, that endeavours may be used to remove it, if it still subsist: the lues venerea, scrofula, scurvy, gangrene, abscess, wounds, contusions, and many other diseases may be the cause.

When the bone is perceived to separate, if the pus which flows from under it is mild and in a due quantity, it will be the best application, and nothing is to be done but to remove the pieces of bone as often as they are perceived to be loose. If the quantity of pus is too small, ung. resinae flavae, or a similar digestive, is useful. If the opening in the integuments is so small that the matter detained is either absorbed into the circulation or forms sinous ulcers, the aperture must be enlarged by means of sponge tents, and kept open by dossils of lint. Indeed, if the exfoliation is likely to be tedious, in some cases it may be hastened by the use of a caustic or actual cautery, though in general the suppuration, which contributes to throw off the diseased part, is thereby retarded; or the rasp may be used: if instead of the actual cautery a potential one is preferred, the common caustic is the best.

When caries is accompanied by an acrid discharge, which consumes the surrounding parts, this fluid may be absorbed by dry powders, and pledgets dipped in tincture of aloes and myrrh; or, in more violent cases, in a solution of nitrat of silver. The disease is then reduced to a necrosis. The dried piece should afterwards be moved frequently, and the fungous flesh, which would prevent exfoliation, prevented from rising. Sometimes, however, the strongest caustics will not desiccate the bone. The fluid discharge dilutes and lessens their action, and the actual cautery becomes necessary.

In the worm eaten caries it is necessary to destroy-all the affected part of the bone as soon as conveniently can be done, by rasping, chiseling, or trepanning, according as each instrument can be applied; after which, the method above described is to be pursued. When the ulcer is deep, honey, dissolved in vinegar and water, may be injected into it every day.

In the carneous caries, the fungous and corrupted parts are best destroyed by a caustic; though Gouch, in his Cases and Remarks, vol. ii. p. 359, gives an instance of the inefficacy of caustics in this case, and of the necessity of using the actual cautery, which he in general prefers.

The phagedenic caries may be reduced by one or two applications of the potential cautery to the most simple kind of caries; but sometimes great difficulties attend it.

In the scrofulous caries, the teguments which cover the abscess formed on the bone must be destroyed with a caustic; the eschar cut through the middle to evacuate the matter; and to save the eschar as long as possible, mild applications only should be laid on the sore; then, to assist the discharge of the matter, it should be washed with water; but if fetid, with vinegar and water.

In general a mild treatment is to be preferred. In the slighter cases we must endeavour to excite and continue a degree of inflammation in the adjoining sound part of the diseased bone, so that it may be the means of separating the mortified part. This is done by making a number of small perforations all over the surface of the carious bone, to such a depth as to give the patient a very little pain, and no further: this operation may be renewed in different parts every third day, or thereabout; thus suppuration will take place, and a consequent separation of the carious part. But when the disease is extensive, and goes deeper than the second lamella of the bone, instead of little perforations made by the pin which fixes the trepan, it will be advisable to use the small head of a trepan. This instrument, applied at proper distances over the surface of the caries, and carried just so deep as to produce a little uneasiness, will occasion the necessary inflammation and suppuration. As soon as any of the parts loosen at the edges, their final separation may be always hastened by daily insinuating below them the end of a common spatula, so as to press their edges a very little upwards. After the use of those instruments, apply to the ulcer the same dressings as in cases of a simple ulcer; and to moderate the fetor of the caries, they may be covered with lint, moistened with a strong decoction of the cort. Peruv. and fol. juglandis. After the separation, the dressings are the same as in cases of simple ulcers in fleshy parts. If the caries penetrates very deep into the substance of a bone, so that a considerable portion is affected, or, as frequently happens, the disease extends even round the bone, the shortest method is to take out at once all the diseased parts, either with the head of a trepan frequently applied, or by means of a small spring saw. This may be performed on the skull, hands, feet, legs, or arms. See the article Tibia for the process.

In the scirrho-cancerous caries, as in cancers of the glands, extirpation is the only remedy; but here also the disorder is apt to return in another part.

The spreading cancerous caries seldom heals: it may be dressed with lint, or a cautery may be applied; but it generally breaks out again after a seeming cure.

In the syphilitic caries, we must at first check the original disease. To the bones of the head, however, we cannot apply caustics, except to the mastoid process of the temporal bone. The other affected bones must be removed by the trepan. The other bones of the face, as the antrum maxillare from abscess there, or the os unguis from fistula lachrymalis, when carious, readily exfoliate. If the causes are removed the parts heal without any particular management.

Paris of the sternum are from different causes carious; and these may be safely removed, since the pleura thickens and becomes cartilaginous. It maybe also defended by a piece of leather or pasteboard. when it is thought dangerous to remove it, the bone may be perforated in a depending part to prevent the confinement of matter.

Some assert that sea water is more efficacious in caries of the bones than in glandular swellings.

A caries of the whole bone or bones, forming a limb, is sometimes productive of the necessity of amputation: particularly when the internal surface of such bones is affected as well as the external, through the whole extent, or near it. In such instances, if the whole bone is not removed by amputation, the patient will perish. It too often happens that in young subjects, with the best health, the whole habit will be so injured by the carious bone, and a hectic fever of the putrid kind, with all its horrid train of symptoms, will quickly destroy the patient.

See Almeloveen's edition of Celsus de Morbis Os-sium, p. 539. Petit's Diseases of the Bones. Heister's Surgery. Le Dran's Observations. Wiseman's Surgery. Monro's Account of the Caries, in the 5th vol. of the Ed. Med. Essays. Bell's Treatise on Ulcers, edit. 3.; and his System of Surgery. Pott's Works. London Med. Transactions, vol. iii. p. 25. Boyer on Diseases of the Bones.