THE PATHOLOGICAL ANATOMY OF THE

OSSEOUS SYSTEM.

CHAPTER XLII.

PRELIMINARY REMARKS.

THE peculiar rigidity of the bones, and the large amount of earthy matter entering into their composition, as well as a certain difficulty of making such close and frequent examinations of them as of other tissues, rendered their pathology a terra incognita, until John Hunter demonstrated the close analogy which exists between morbid changes in the hard and soft textures of the body. While we detect with comparative ease variations in the consistency, vascularity, and structure of the latter, the determination of these points in bone is scarcely ever attempted, unless we have to deal with very manifest lesions, owing to the greater physical difficulty which presents itself; hence our knowledge of the early stages of disease, and of the accompanying changes, is less satisfactory than it might be. Fine sections for microscopic examination necessarily alter the relation of, or destroy, the soft parts that enter into the constitution of bone, and therefore deprive us of one important element in the diagnosis of morbid change. Still, much remains to be done in regard to investigating and describing alterations perceptible to the naked eye, and establishing the links connecting certain bone diseases with certain lesions of the system at large, with which we are already well acquainted. The labor necessary to gain this point is probably greater than will be performed in the dead-house of an ordinary hospital; and we must not expect a full solution of such recondite questions of morbid anatomy until we have established endowed professorships, which may enable the incumbents to devote their energies and time solely to scientific purposes.

We have passed over the consideration of monstrosities in other parts of the frame, or of their diseases during the foetal period. In our remarks on the deformities occurring in after-life, we shall have occasion to allude to some congenital malformations which are persistent; it would, therefore, be inconsistent to review in detail the intra-uterine anomalies affecting the bone. After birth, the functions of the bones. may be said to remain almost dormant for some months; but a process of hardening and consolidation is preparing them for the greater tax

that is to be made upon them when the infant learns to shift for itself. It is at this period that our attention is occasionally called to the state of the bones, from their development not taking place in a ratio with the general evolution of the frame. Instances are recorded of a precocious ossification of parts that normally are only membranous or cartilaginous in infant life; but they are unusual. Thus, the fontanelles may close prematurely, or the epiphyses and shafts of the long bones be united by bone. Derangements are much more frequent in the opposite direction; an arrest of osseous growth being caused by a general defect of nutrition more immediately acting upon the process of ossification, or inducing morbid states which indirectly affect the bones.

PERIOSTEUM.

The intimate anatomical and physiological relation of the periosteum to the subjacent bone renders it advisable first to consider the affections to which it is liable. In many instances, the pathologist would probably find it impossible to determine whether disease has commenced in one structure or the other; the more so, as periosteal morbid action may be followed by similar products as we see arising from primary disease of the bone. Incipient inflammation of the membrane is characterized by a red blush, a humid succulent appearance, and more or less of a serous effusion, causing a slight separation from the bone. The periosteum may, as Lobstein' observes, be seen to present this condition in the vicinity of chronic ulcers or of old cicatrices. As the inflammation advances, the connection between the membrane and the bone becomes more lax, and the effusion exhibits a purulent character; or the separation may have been so sudden and extensive, especially in adynamic individuals, that, as Dr. Copland shows, before suppuration has time to supervene, gangrene of the periosteum and necrosis of the bone result. An inflammatory process in the periosteum is also essential to the reproduction of bone after fractures, or other lesions of continuity calling for repair. The membrane is peculiarly obnoxious to syphilis and rheumatism-diseases which are prone to fasten upon the fibrous investment of the bones, and induce various secondary disturbances of a more or less serious character. Both chiefly affect the more superficial parts; the periosteum of the skull, the sternum, and the tibia, being the points most commonly attacked. Syphilitic inflammation, or at least that which occurs in the course of syphilis, whether as a result of the virus or of the mercurial treatment, is apt to occur in numerous detached spots, at which tumefaction, induration, the formation of new osseous matter, and necrosis, present themselves. Mr. Stanley remarks, that the hardness of a syphilitic node does not in itself indicate its composi tion, as he has found supposed osseous nodes to prove mere indurated periosteum. He also states that the pericranium differs from the fibrous investment of other bones in never becoming ossified. Rheumatic perios

1 Anatomie Pathologique, vol. ii. p. 83.
On Diseases of the Bones, p. 346.

titis, like the former, presents chiefly the chronic type; it is more liable to occur in the vicinity of the joints, placed here to induce a peculiar form of bony deposit, to which we shall again refer. Another form of periostitis is that frequently met with in cachectic and scrofulous subjects; it is of a sluggish character, causing greater thickening of the membrane and closer adhesion to the bone, followed by suppuration in the tissue, and underneath or upon it. The small amount of pain and constitutional irritation resulting from a lesion, which, under other circumstances, or in other constitutions, would give rise to violent symptoms, is remarkable; while, in a therapeutic point of view, the curability of even very extensive lesions of this type affords a better ground for a favorable prognosis than we should expect à priori. This applies also to the cases in which scrofulous periostitis is followed by exfoliations of the subjacent bone; in these cases, there appears to be generally a coincident formation of new bone, sufficient to prevent not only a loss of strength, but even a deformity. In a practical point of view, we should look upon these local manifestations of the scrofulous cachexia rather as a tendency to concentrate diseased action at a distance from vital organs; they ought not, therefore, to be hastily interfered with, but should be regarded rather as a safety-valve to the system, which may be allowed, and even encouraged to act, until the system itself is sufficiently invigorated to elaborate all morbid action. The rapid evolution of scrofulous affections of internal organs, after the cure of the disease just spoken of, as well as the arrest of the former by a local and superficial eruption of the disease, is of too frequent occurrence to permit a doubt of the influence exerted upon the system by scrofulous periostitis. One of the forms of scrofulous periostitis not unfrequently met with, is that giving rise to the severer forms of panaritium or whitlow; the periosteum of the phalanges being the seat of inflammatory action. The longer the duration of periosteal inflammation in any part of the body, the more likely it is that the subjacent bone will become more or less affected by the process-a circumstance easily explicable by the physiological relation existing between the two. It is probable that a large number of the osteophytic, and other osseous growths which form upon the bones under various circumstances, are more immediately the result of periostitis. The large share which this membrane takes in the regeneration of fractured bones, and in the repair of loss of substance from other causes, as shown by surgical observation and physiological experiments, tends to confirm this view. An examination of the preparations of bones sawn through, contained in pathological museums, further establishes the point. Thus we see in St. George's Museum (prep. A. c. 10, H.), a femur considerably enlarged from inflammation; it is in fact a case of eccentric hypertrophy; but the section exhibits the shaft of the bone, though more compact and denser than normally of the ordinary dimensions, traceable through the deposit which has been derived from the periosteum. This deposit, in its turn, exhibits a cancellous texture adjoining the original surface of the femur, bounded by a compact lamella in contact with the periosteum. Here we could scarcely assume the new osseous matter to have been directly formed by the old bone, because in that case we should expect to see either a more entire fusion between

the old and the new formations, or the latter presenting a more complete identity with the former.

Females are liable to a peculiar form of periostitis, especially after parturition; Mr. Stanley, who has drawn attention to this point, states that it is remarkable on account of the severity of its effects, and on account of its liability to cause an error of diagnosis; it effects the pelvis, and mostly its posterior part; and when it occurs near the hipjoint, its symptoms so much resemble those of disease of the joint, that the two are apt to be confounded. A correct diagnosis is material, as the affection is very amenable to treatment.

Mr. Stanley describes a malignant disease of the periosteum, which he has met with on the bones of the hip, and which he attributes to longcontinued and repeated attacks of inflammation, altering its structure, and giving rise to the growth of a fungous excrescence upon the membrane. This is sometimes soft and flocculent on its surface, with a firm, grayish, gelatinous base; at others it consists throughout of a firm gelatinous substance; it is both sensitive and vascular, and appears to possess a considerable tendency to involve the adjacent bone and soft parts; after removal by operation, the disease is apt to recur in the adjoining tissues; it does not, however, appear, from the cases recorded by Mr. Stanley, that secondary formations of a similar character occur in other parts of the body; and he himself mentions one case in which, twenty years after the removal of a leg affected with this disease, the individual continued in perfect health.

BONE.

Authors commonly commence the consideration of the pathology of bone by an investigation of hypertrophy and atrophy-two conditions which are associated with, or are consecutive upon, various primary lesions; they are rather an element, or a symptom of diseased action, than the disease itself. The terms may be objected to, when we find them indiscriminately applied to morbid conditions essentially distinct; thus, hypertrophy is used to designate the increase of osseous matter, resulting from the physiological demands made upon the shaft of a long bone, after it has become curved by rickets, as well as to the numerous forms of bony growths, of a compact or cancellated structure, which we meet with upon the surface of the skeleton. Again, authors use atrophy as a generic term, under which they class diseases so remote in their character from one another, as absorption from pressure of a tumor, and mollities ossium. Under such circumstances, language is rendered rather a source of confusion than a means of intelligence; and it be comes a question whether it would not be advisable to eliminate from special pathology terms which indicate a single element in morbid changes, or rather the result of morbid processes, than the nature of the process. With this disclaimer, we shall first describe inflammatory conditions of bone, and incidentally devote a few remarks to hypertrophy and atrophy, but confine their application solely to an increase or a diminution in the normal size and constituents of the bones.

Occasions are sometimes presented of viewing the various stages of

inflammation in bone; and it is manifest that the osseous textures are subject to an increase in their vascular contents as are other organic tissues. The greater vascularity affects chiefly the lining membrane of the medullary and cancellous portions; the ordinary symptoms of inflammatory action may be noted in their incipient stages in surgical practice, but are scarcely seen in the dead-house, except in conjunction with more advanced disease in adjoining portions of the same bone. The first appreciable inflammatory changes in bone, to use Mr. Goodsir's words, "occur within the Haversian canals; these passages dilate, or become opened up, as may be seen on the surface of an inflamed bone, or better, in a section. The result of this enlargement of the canal is the conversion of the contiguous canals into one cavity, and the consequent removal or absorption of all the osseous texture of the part.' Some softening is observed to follow inflammation in its early stages, and this will be accompanied by tumefaction, at first of a more succulent, subsequently of a more indurated character. Acute inflammation rarely takes place, except associated with mechanical injury; the dense structure, and the necessarily slower process of effecting a change here than in the soft tissues, are the reason why disease of the bone commonly presents itself in the chronic form. The results of progressive inflammation are congestion, exudation, suppuration, caries, necrosis, with the coincident, and in many instances, as it were, accidental, increase of bone in adjoining parts. An enlargement of the affected portion is almost invariably met with, and may arise either from the changes which take place in its interior, or by a deposit on its surface, or from both. The specific character of the disease in which the inflammation arises determines whether the compact or spongy parts, the shafts or the epiphyses, of bones are effected, while the part of the skeleton attacked is likewise in a measure dependent upon certain uniform tendencies exhibited by various diseases. The spongy and medullary portions have the greater proclivity to take on inflammatory action, and of the hard bones, those that lie nearest the surface are the most liable to become inflamed. Unless resolution of the first or congestive stage takes place, an exudation of a rose-colored lymph, of a gelatinous appearance, is effected, which as we may observe in the same preparation, passes through a variety of shades, light-red, yellow, greenish, or white, filling up the cancelli, or expanding the Haversian canals. This exudation, in its turn, is absorbed, or becomes organized and converted into new bone, or, yielding to the continued morbid action, a destructive process ensues. In the case of its absorption, or of an arrest of the process, the parts may return to their normal condition, or the bone retains a permanently disorganized condition, which may present either an increased condensation and induration, or an abnormal rarefaction of the

Fig. 357.