As the disease proceeds, and the bodies of one or more vertebrze are removed, those which remain approximate more or less above and below : the spinous processes project, and a bending of the body forward is produced. The character of this curve is influenced by the extent of the destruction that has been accomplished within ; it is sharper and more angular when the body of one vertebra only has been removed; it is more sweeping and gradual when three or four have suffered. Never, we believe, is the angle so sharp as to permit the denuded surfaces of the vertebr2e above and below to come into actual contact, the sound condition of the bony parietes of the spinal sheath effectually preventing this ; and hence, when recovery takes place, it is not by the adhesion of these surfaces, but by the forma tion of a quantity of new bone which fills up the vacant space, producing a perfect example of true anchylosis.
The developement of such a curative pro cess as this is scarcely to be expected in a scrofulous system, yet is it satisfactory to know that even under such circumstances the case is not utterly hopeless. We have seen repeated instances of angular curvature without the occurrence of abscess, in patients apparently deeply tainted with scrofula, one of which is so very remarkable as to deserve particular notice, because it illustrates a mode of union that frequectly occurs in scrofulous cases, and because the preparation is in existence to de monstrate the fact. In July, 1830, a wretched young girl was brought into the Meath hospital with a very acute angular curvature of the dorsal vertebrze. Almost every joint in her body was diseased, and the knees so extensively that the eroded condyles of the thigh-bones were exposed, from the surface of one of which the mud of the street was wiped away after her admission. It need scarcely be added that her sufferings were not of long duration, and an opportunity vvas speedily afforded for examining the pathological condition of the back. It appeared that three of the vertebrce had been engaged, the spongy portion of one of which had been completely removed. There was nothing like a reproduction of osseous material, although the caries had long ceased, and the spine was sufficiently strong for every ordinary purpose of support ; but the space that had been left by the absorption of the bone was filled up by a ligamento-cartilaginous substance, which, attached like a new and adventitious ligament to the vertebree above and below, held them with a sufficient tight ness to prevent the smallest motion, and gave to the entire column a tolerable degree of firm ness. We have also seen examples of true
bony anchylosis in patients apparently scrofu lous, but it seems to occur generally in males rather than in females, and more particularly in patients about or approaching to the age of puberty, a period at which it is generally sup posed some important change takes place in the constitution of scrofulous subjects. Where there is no such taint, or where, as Sir B. Brodie expresses it, the bones retain their na tural texture and hardness, it may be easily conceived that a cure is effected in less time and with less difficulty.
There is another specimen of caries or ulce ration of bone without the formation of matter, occasionally observed in the neck of the thigh bone of very old persons, the symptoms of which have particular relation to the hip-joint ; we shall therefore postpone our remarks on it until we come to discuss the pathology of joints.
Necrosis.—There are few subjects more in teresting either to the pathological inquirer or to the practical surgeon than the death of a portion of the osseous system, and the circum stances connected with this event. Neither is there any one with respect to which the ideas of medical men generally are less definitively settled. Thus also some confusion has crept into our nomenclature, and necrosis and ex foliation have been often indifferently used, as if they applied to one and the same diseased action ; or, perhaps, to speak more correctly, the term necrosis has been made to extend to every case in which a bone or a portion of a bone is deprived of vitality, no matter how the dead material is to be removed or replaced. According to the etymology of the term such is in fact its true meaning; nevertheless, we are hardy enough to dissent from this applica tion of the word, and to confine its use to one form of the death of a bone, •exfoliation more properly belonging to another. And we do so the more readily because not only do these two affections present different pathological pheno mena, but there are such practical discrepancies between them that it is essential to every sur geon to have a distinct and separate notion of each.
El:foliation, then, expresses the death of a portion of bone which is either never replaced, or replaced by a process which is set up after the soft parts, where the slough is thrown off, and the consequent ulcer subsequently heals by granulation and cicatrization.