margin of one of the ligamenta alaria of the knee-joint manifestly injected, and fringed with a number of various-sized villous projections. These consisted of a fibro-homogeneous, granulous substance, imbedding numerous glomeruli. A layer of similar matter was spread over the whole of the synovial surface, which was not injected with blood. The cartilage was ulcerated in some part of its extent, its surface rendered

From a case of secondary depot in knee-joint, the same as described in the text, in the next page. (c) A cartilage-cell, immensely hypertrophied, lying in fibrous stuff.

(b) A villous process springing from the synovial membrane.

(a) A strip of fibrous tissue containing three enlarged cartilage-cells-one is also figured separately.

irregular by superficial erosions, and its texture altered to a lax fibroid stuff. The cartilage-cells in these parts were most remarkably changed, containing sometimes 20-25 celloid masses in their interior, instead of the two or three which they might contain in their normal state. The inter-cell substance was entirely deprived of its natural consistence; it broke down under slight pressure. The following description of the condition of a joint which had been long in a state of suppuration is so

faithful and life-like that we cannot forbear transcribing it. Rokitansky says: "The quantity of purulent fluid effused into the cavity of the joint is generally considerable, and the capsule is, consequently, much enlarged; the synovial membrane is lined with a firm, shreddy layer of lymph, which is dissolving into pus, and a soft, purulent precipitate, which can be easily removed, adheres to the cartilages." The term precipitate, which is here employed, is worth noticing, as Rokitansky states most strongly, in a previous paragraph, "that no exudation is deposited on that portion of the synovial membrane which covers the cartilage;" if any is found there, it is to be regarded as a "secondary precipitate" from the general exudation. This circumstance strongly confirms our view of the disposition of the synovial membrane. The layer of fibrin, lining the synovial membrane, "is opaque and lustreless, its surface is rough, and serum is infiltrated, and blood in small spots extravasated through its tissue, as well as through that of the fibrous capsule of the joint, and neighboring cellular structures. As the disease advances, the infiltration and thickening of the neighboring structures increase, they become filled with a gelatinous, lardaceous, white product, in the midst of which fibrous tissues, capsules, ligaments, or aponeuroses, can no longer be recognized. Here and there, in the mass, there are cavities of different dimensions, the lining of which is vascular, spongy, and granulating, and the contents purulent. The muscles near the joint are pale and flabby, infiltered and attenuated. At length the infiltration reaches the subcutaneous cellular and adipose tissues, and the integuments become fixed to the disorganized structures. beneath. The diseased joint then presents the following external appearance it is swollen, and always more or less bent; it feels everywhere soft and flabby, or in some spots flabby, in others firm, elastic, doughy, and at the same time tuberculated; the integuments over it are tense and pallid, leuco-phlegmatic, or they are traversed by varicose veins.

At length ulceration commences, and advances in various directions. "Externally, the capsule ulcerates in one or more spots, and then the soft parts adjoining it. In some instances large openings form in the capsule, and connect the joint with ulcerated cavities in the soft parts; in others, mere sinuses are formed; but in either case they open externally through the skin, and occasion and maintain a discharge of the contents of the joint. Internally, the inter-articular cartilages and the ligaments ulcerate, the cartilage covering the bones, when brought into contact with the matter, is destroyed in the way that has been mentioned, and the ulcerative inflammation attacks even the bones, if they have not been involved already. The cavity of the joint appears like a cloaca, surrounded with a gelatino-lardaceous mass; the integuments covering it are of a dark red hue, and are especially discolored at the orifices of the sinuses. The joint contains pus or sanies of an offensive odor and variously discolored; the repeated hemorrhages which take place when there is acute caries of the bones, very frequently giving it a red or brown tinge; the ligaments ulcerate, and the cartilages separate partly, or entirely, from the bones; the osseous surfaces are laid bare, their compact wall is destroyed, and the spongy tissue is exposed,

infiltrated with pus, and ulcerating, and surrounded on all sides by osteophytes of various shapes; remains of the fibrous structures of the joint, pieces of loosened cartilage, and of necrosed bone, are mixed with the matter discharged from the joint. The soft parts, and the entire bones. belonging to the diseased joint, are wasted, most of the fat is absorbed, the muscles are remarkably blanched and thin, and the bones, being generally in a state of eccentric atrophy, are soft and fragile. More or less quickly after the disease has reached this stage, spontaneous dislocations, as they are called, ensue." The exudative product of inflammation, in some instances, is, according to Rokitansky, converted into tubercle. This occurs when there is a great amount of general tubercular disease. The articular extremities of bones are sometimes affected by tuberculosis simultaneously with the synovial membrane, sometimes before it.

Inflammation may attack the cellular tissue around joints, causing effusion of coagulating fluid and consequent swelling, with subsequent formation of pus. One or more spots only may be affected, so that small, local deposits of pus are produced; or the whole may be involved, and the joint become enveloped in a large abscess. In its later stages, the disease extends to the synovial membrane and the cartilages, or recovery may take place, the joint remaining sound.

Pulpy degeneration of the synovial membrane is a very curious and peculiar disease, with the exact nature of which we are yet scarcely acquainted. It was first described by Sir B. Brodie, as a morbid alteration of structure peculiar to the articular lining membranes, nothing analogous having been observed in the serous sacs. He says: "The disease seems to commence in the reflected portions of the synovial membrane, converting them into a light brown, pulpy substance, varying from a quarter to a half, or even a whole inch in thickness, intersected with white membranous lines and red spots, formed by small vessels injected with their own blood. It then attacks the synovial membrane of the cartilages,' beginning at their edge and extending gradually over them, ulceration in those cartilages going on correspondently, till the carious or ulcerating surfaces of the bone are exposed. The cavity of the joint sometimes contains pale-yellow fluid in the floating flakes of lymph, or pus, which is discharged externally by ulceration; but sometimes neither. Or abscesses may exist in the altered synovial membrane itself, without communication in the joint." We have given, in the Pathological Report for 1848-49, a detailed account of the disposition and structure of the synovial membrane thus peculiarly altered, from which we extract the following summary: The new growth formed prominent fringes of a soft, grayish structure, which overlapped and encroached considerably on the surface of the articular cartilage. The marginal zone of the cartilage, for a varying extent, was converted into a kind of fibrous tissue, and blended with the altered synovial membrane. More internally the cartilage was grooved on the surface, probably so as to correspond with the overlying fringe. The fibrous tissue. into which the cartilage was transformed was of an imperfect kind, not divided into distinct fibres, and not containing any of the natural cells, but strewed over with numerous oil drops and yellowish molecules. The

change in the cartilage was effected by extraordinary enlargement of its cells, which were crowded with an endogenous growth of young cells containing each a small oil drop and much clear fluid. At the margin of the cartilage, which was obliquely truncated, the change was most

(A) Vertical section of cartilage in process of absorption towards the left, and overlapped by the vascular ized pulpy synovial fringe. The edge of the cartilage where it is obliquely truncated is continuous with the fibrous tissue on the left hand.

(B) Healthy cartilage-cells from the right-hand side, more magnified.

(c) Greatly enlarged cartilage-cell, containing young cells.

(D) Loculus, from thickened synovial membrane, filled and surrounded with nuclei.

advanced; in the interior the structure was quite natural. The pulpy synovial tissue consisted principally of well-formed nuclei and granular matter, with which were mingled a few fusiform and circular cells. These elements were contained in an enveloping membrane, very thin, of whitish aspect, and nearly homogeneous texture. There existed scarce any trace of stromal fibres, but a good many large vesicles, or loculi, formed of almost homogeneous walls, and filled with material similar to that which surrounded them. Delicate-walled blood vessels ramified through the mass, but not in great numbers. It seems very probable that the altered synovial tissue promotes and is concerned in the absorption of the cartilage. The disease almost always occurs before the middle period of life. "In general, it can be traced to no evident cause; but occasionally, it is the consequence of repeated attacks

of inflammation." It rarely occurs elsewhere than in the knee, but has been seen in the ankle, and in a joint of the fingers. Sir B. Brodie classes it with malignant disease, but from this it is differenced by wellmarked characters.

Fig. 344.

Another very curious alteration, which is sometimes observed in the synovial membrane, consists in its free internal surface being covered by a growth of large villous processes, quite perceptible to the naked eye, which hang into the cavity of the joint, and present a shaggy appearance. They are not developed on the surface of the cartilages. They have sometimes the form of simple threads, or flattened shreds, or their free extremities are split into filaments, like a tassel, or they have a club shape, or resemble melon-seeds, hanging singly or in clusters from each stalk. In structure, they consist of a fibroid material, containing, we believe, in many instances, more or less fat, and approaching herein to that peculiar form of fatty tumor which is called Lipoma arborescens. The healthy texture of the articulation is not materially interfered with, at least in many cases. They seem to be the result of a slow exudation of plasmatic matter, which may pass into a low form of organization.

Fimbriated

knee-joint;

the surface of the patella is the only part unoccupied.

chronic, is said to

Inflammation of the ligaments, both acute and occur; but Wickham states that, according to his experience, "the ligaments are the last of all the different parts diseased, and that it is very common to find the ligaments perfect, even when every other texture is either altered or destroyed." From Mr. Key's account, it seems that inflamed ligaments become thickened and more pulpy than natural. The areolar tissue which penetrates among their fibres becomes highly vascular, and is probably concerned in producing the softening and ulceration of their substance, which sometimes takes place.

Relaxation of the ligaments may be the result of long-continued chronic inflammation, or of simple disuse of the limb. In the latter case, it has been known to proceed to such an extent as to allow the head of the femur to slip out of the acetabulum. Frequent and heavy strains may produce a similar effect; Mr. Wickham mentions a case in which the leg was so much bent outward at the knee as to be at nearly right angles with the thigh.

Loose cartilages (so called) are not unfrequent in the cavities of joints. They are usually from the size of a millet-seed to that of a pea, but have been met with as large as a walnut. In shape, they are more or less oval and flattened. Their surface is smooth, as if invested by a serous covering, which they sometimes evidently possess, when they are attached to the synovial membrane by a pedicle of varying length. Formations of this kind commence in the subserous tissue, and as they enlarge gradually, make their way inward towards the cavity of the joint, in which at last they become free by the dissolution of the pedicle. Others are formed by a condensation of fibrinous coagula; "they are distinguished," Rokitansky says, "by their uniform smoothness through