Having offered these preliminary remarks, we proceed with an attempt at an arrangement of the pathology of the osseous system, fully aware, indeed, that every classification of dis ease must be more or less artificial, and, there fore, open to objection. Perhaps it may be advantageously considered under the three fol lowing heads. 1. Cases in which there is a real or supposed derangement or imperfection in the processes carried. on within the bone itself in order to its maintenance in the normal or healthy condition. 2. Cases in which there is inflammation of the bone, whether produced by injury, appearing idio pathically, or connected with some specific taint. The pathological conditions of the pe riosteum are so intimately connected with this part of the subject, that some reference to its diseases must of necessity be made. 3. Cases in which there is alteration of the original struc ture or development of a new one ; as thus:— consideration of this subject has been too frequently mixed up with that of the disease entitled mollities ossium (osteo malaxie), or with that of the interstitial absorp tion of bone which occurs in aged persons. Rachitis seems not to be so much a softening of bone that had previously been solid and perfect, as an interruption in the first instance of the process of ossification. It is a disease of early life, generally commencing, or at least first observed about the period when the infant should make its earliest attempts to walk, and rarely appearing after the age of two years. It would appear that the disease should be considered as connected with inadequate nu trition throughout the body generally, rather than as being confined to the osseous system ; its effects are only most obviously marked on that system ; and it is quite certain that all the bones of the skeleton are more or less af fected, although particular local causes com monly produce much greater deformity in one than in another.
The early symptoms of rickets are invariably those of imperfect or deranged nutrition, pale ness of skin, flaccidity of fibre, &c. Along with these symptoms or shortly succeeding to them the deformities appear which cause the disease to be ranked. amongst the affections of the osseous system. In mild cases these ex tend no farther than to an increase in the cur vature of some of the long bones and an aug mented expansion of their extremities. Whether from its supporting the whole weight of the body or from the action of the strong muscles behind it, the tibia generally suffers in a remarkable degree : the legs are not only bent forwards, the curve being sharp and sudden about the lower third of the bone, but they are twisted in such a manner as to bring the internal ankle below its proper level, deformities which, not withstanding a perfect recovery, are never com pletely removed afterwards. Rickets, consi dered alone, is not very dangerous to life : most instances it proceeds no farther than has been already described—the visceral derange ments are either subdued or subside sponta neously, the healthy functions are re-estab lished, and amongst them that of ossification, and the patient soon becomes enabled to per form the ordinary motions, while the deformity in some slight degree disappears. But if the disease is severe or protracted, or complicated with a scrofulous taint, it generally leaves tokens behind it which embitter the patient's future existence, or hurry him to a premature grave. Sometimes the head becomes flattened, or pushed so as to project backwards, or is otherwise strangely deformed. More frequently still the chest suffers in shape, either in the ribs, the spine, or in both, and the compressed and contracted thorax, or laterally curved spine, with all their accompaniments and consequences of deranged respiration, will be the result. But of all the parts which suffer from this disease, perhaps the pelvis is that which is most fre quently engaged. Placed between the spine
and the thighs, it is the fulcrum and centre on %t hich numerous motions-are performed ; it is surrounded by powerful muscles and subjected to irregular and unequal pressure ; and it also sustains the weight of the principal part of the body. Hence arise the strangest and some times the most complicated distortions, and woe to the female who at the age of woman hood becomes pregnant under such circum stances. The remote consequences of rickets may, therefore, be far more formidable than the immediate.
The actual condition of a bone with reference to its structure is the next point to which we must direct our attention. Is there an absolute deficiency in the quantity of ossific matter secreted, the place of which is supplied (espe cially about the epiphyses of the bones) by a soft substance which increases their bulk ? or is the earthy material removed by absorption previous to the deposition of this softer sub stance ? The question is not easily answered, for patients seldom die of rickets alone; and when they perish, it is generally in consequence of some complication of scrofula producing hydrocephalus, tabes mesenterica, glandular abscesses, or, it may be, caries ; and it is evi dent that the examination of a case so mixed cannot afford a satisfactory demonstration of the disease itself. It cannot, therefore, be a matter of surprise if some difference of opinion has existed. The following is the description of a ricketty bone as given by Boyer, It is lighter, of a red or brown colour, pierced by a great number of dilated bloodvessels, porous and spongy, soft and compressible, moistened with a sort of sanies that may be pressed out as from a sponge, or rather from leather that has been soaked to maceration. The walls of the medullary cylinder of the long bones of the extremities are greatly thinned, whilst the bones of the skull are increased in thickness and become spongy, and, as it were, reticulated. Both the one and the other, but especially the long bones, have acquired a remarkable sup pleness, but when bent beyond a certain point they break : and the fracture takes place more easily if the inflexion is made rapidly. The medullary cavity of the long bones contains, instead of marrow, a reddish serosity, totally devoid of that fat and oily character which appertains to marrow in its natural state. The result of Mr. Stanley'st experience is that the consistence of a ricketty bone is but slightly different from that of common cartilage, an opinion more consonant with our notions of the disease than Boyer's exaggerated descrip tion is calculated to convey. We ourselves have never met with that extreme degree of softness which has been occasionally described, or which would permit of the bone being di vided by a knife. MeckelT states that the bones of ricketty patients are soft, spongy, flexible, and curved, both in situations where they are subjected to muscular actions, and where they have some weight to support. In the meantime they receive more blood: The periosteum has undergone analogous changes. The chemical composition is not the same throughout. Thus, on the one hand, there is notalways the same rela tion between the respective proportions of phos phoric acid and lime—sometimes too much, sometimes too little of the acid : on the other, the proportion between the animal and earthy substance varies considerably. Sometimes the quantity of animal matter is greatly increased, so that the relation is 74 :26, or even 75,8:24,2, or so far as 79,54 : 20,6. Often it is the same as that met with in the healthy condition, or it is even less, as 25,5 : 74,5,* although the bones are spongy. These differences depend probably on the intensity, and, more particularly, on the period of the disease ; but they prove, at least, that the essence of rickets does not consist in an original deficiency of earthy material.