Although no well-marked line of distinction can be drawn between the exostosis and the osteophyte, yet the latter presents such striking peculiarities, that, in the majority of cases, it may at once be recognized, and is but rarely liable to be confounded with the former.

Unlike exostosis, the osteophyte mostly occupies extensive tracts on a bone, investing or springing from it in a great variety of forms. Moreover, it is generally the product of an inflammatory process in the superficial part of the bone and in the periosteum, and hence is very commonly found adjoining and surrounding not only portions which are inflamed, carious, or necrosed, but also spots of bone affected with various other diseases, which in some stage of their existence have occasioned a reaction in the tissue of the bone. This explains why the osteophyte is found chiefly upon and near vascular portions of bones; as on and near their articular ends, on their rough lines, etc.; and why in the skull it mostly occurs near the sutural cartilages. Regarded in this view, the osteophyte acquires a further and special interest; for as certain processes in bone, arising from a constitutional affection, appear to produce a definite and peculiar osteophyte, the nature of a disease can be determined by the characters which the osteophyte presents. I shall have an opportunity hereafter of introducing what I have observed on this subject; it may, perhaps, be deemed a contribution to our knowledge of diseases of bone, in its present incomplete state.

In the first place, Lobstein has conceived that a distinction should be drawn between exostosis and what he denominates osteophyte. I shall not, however, follow his subdivision, but shall attempt to give a more practical representation of the disease.

A. The Velvety Villous Osteophyte

The Velvety Villous Osteophyte sometimes appears as a single and very thin layer, resembling a coating of hoar-frost; sometimes it measures one or two lines or more in thickness. It seems to be composed of delicate fibrils and lamellae, which are fixed at acute angles on the surface of the bone, and give it the appearance of velvet, or of felt with a very fine nap. As it increases in density it gradually acquires a smooth exterior, which is pierced with very numerous fine pores; while its deeper structure is more distinctly laminated. Although, at first, in contact with the bone, it is usually almost entirely unattached to it, and can easily be raised in large pieces from its surface. The osseous surface under it is sometimes as smooth as in the natural state; but sometimes we find, upon close examination, that it has lost its smoothness, and is distinctly rough, the pores for its vessels being somewhat enlarged, and its outermost layer here and there expanded into filaments. At a later period, the osteophyte is found attached to the bone by some intervening minute round pillars and plates: after having gradually become compact, it unites with the bone. A layer of cellular (diploetic) substance forms for some time a line of demarcation between it and the bone, but when this disappears, the osteophyte and the compact surface of the bone compose one uniform whole. It corresponds to the "osteophyte diffuse et fibrillo-reticulaire " of Lobstein. Sometimes, as an exception, it is produced in more considerable quantity, and forms an intimate connection with the bone, uniting with the filamento-cellular structure into which the outer layer of the bone expands.

Should the periosteum have taken part in the process by which the osteophyte is produced, that portion of the exudation which attaches to it, becomes organized into a vascular cellular tissue, while that which belongs to the bone, and which ossifies, forms a compact osseous layer: the surface of the latter presents a great number of pores, and of exceedingly tortuous and convoluted half canals, which have been occupied by the newly-formed cellular tissue, and its vascular twigs. We notice this chiefly when such an osteophyte is situated on the inner table of the skull.

The color of this osteophyte in the recent state depends on the intensity of the process which produced it, on the period of its existence, and on the progress of its ossification: and it varies accordingly from bluish or rosy-red to yellowish and dirty white, or it may be a dazzling white, and glisten like silk or asbestos. At its commencement it is a soft, gelatinous exudation; afterwards it becomes tough and elastic, like cartilage; and finally it ossifies.

This kind of osteophyte is seen chiefly on compact bones. It accompanies almost all inflammatory processes, abscesses, and necrosis in bone, especially in young persons with abundant fluids (succulent): it frequently extends from the diseased spot over considerable portions of the surface of the bone, while it accumulates in greatest quantity in the immediate neighborhood of the disease, and occasionally on the rough lines, etc. It is very frequent in the skull, especially on its inner table; and on that part particularly there is a bony growth, which has some connection with pregnancy, and which we call the puerperal osteophyte. It possesses great interest, and will receive a fuller consideration when we come to treat of the diseases of the cranial bones.

B. Allied To This Osteophyte

Allied To This Osteophyte is another which I will call the splintered and laminated osteophyte. It presents itself in the form of rather large excrescences and lamellae, which measure several lines in length, are conical in shape, and mostly terminate in a sharp point: they are composed of a compact wall, pierced with fine pores, which encloses a coarsely cellular, osseous tissue, or even a single (medullary) cavity. It is chiefly, and indeed commonly, abundant in the neighborhood of the cancellous parts of a bone affected with caries, especially caries of the articular ends of bones in young subjects, which is generally considered to be of scrofulous nature.

C. Warty And Stalactitic Osteophyte

This is a bony growth either of excrescences resembling warts and attached sometimes by a broad base, sometimes by a pedicle, or of larger, irregular, rugged masses resembling stalactites. It seems to be found only in the neighborhood of the joints; it accumulates particularly around enlarged articular concavities, forms a tuberculated addition to the margin of articular heads, which have been flattened out like a mushroom, and thence extends in abundance also to adjoining rough parts of the bone. They generally consist of a chalky, white, very brittle substance; they occur most commonly on the hip bones, and appear to be connected with gouty metamorphosis of that joint.

D. The Osteophyte In The Form Of Thorny Or Styloid

The Osteophyte In The Form Of Thorny Or Styloid, single or branched plates, or of rounded, gnarled, and pediculated processes, occurs chiefly on spongy bones, on the vertebrae, and the bones of the pelvis, selecting in both these instances the neighborhood of the synchondroses. It occurs also on the articular ends of bones, and very frequently follows, as it grows, the direction of the fibres of the periosteum, ligaments, tendinous insertions of the muscles, intermuscular septa, interosseous membranes, etc. When growths of this kind spring from two adjoining bones, they frequently meet somewhat in a symmetrical manner, and unite together: in this manner they enclose the synchondrosal cartilage in a more or less complete bony capsule, and give rise to a peculiar kind of anchylosis, which is often observed on the bodies of the vertebrae. Not unfrequently they supply the place of callus which has been arrested in its development, and imperfectly unite the ends of broken bones. Similar formations are sometimes seen around the cloacal openings in the capsule of a sequestrum. They arise from a chronic inflammation of the bones, in which the periosteum and ligamentous apparatus become involved: they are often found on the vertebrae of old persons, and while the bone to which they are attached, as well as some others, or even the whole skeleton, is atrophied, the osteophyte itself is of dense structure, and hard.

E. There Is Another Osteophyte

There Is Another Osteophyte, which looks as if a quantity of bony matter had been poured over a bone, and had coagulated as it flowed. It forms masses which sometimes give the impression, that the bony sub-stance had been dropped upon a bone, and had then solidified; in which case the surface of the mass, whether even or uneven, is smooth: at other times it appears as if the bony matter had been poured in a stream over larger surfaces of a bone, and had then coagulated. This osteophyte is compact. I have seen it on the inner table of the skull, when the cranial bones were indurated; and have met with it still more frequently covering a considerable extent of the anterior surface of the vertebral column in old persons, and producing anchylosis of the vertebrae.

In accordance with the foregoing descriptions, I exclude from amongst the osteophytes all those bony growths which form a more or less complete external capsule, or an internal radiated thorn-like skeleton, for the various adventitious structures that occur in bone, whether enchon-droma, osteosarcoma, or cancer; as Well as those which are found at the base of similar adventitious structures in the softer organs.

Osteophytes have in some few cases been observed covering large portions, and even almost the whole of a skeleton. Sometimes they are accompanied by hypertrophy, sometimes by atrophy of the bones. We are quite ignorant of any general diseased condition of the system to which this can be attributed.

The periosteum may not share in the diseased process going on in the exterior of the bone, and then it remains nearly unaltered; but if it do take part, it becomes Vascular, reddened, infiltrated, and thickened (hypertrophied), and furnishes sheath-like prolongations, which invest the more bulky of the bony excrescences.

The changes which the osteophyte undergoes in the course of time have been already partly noticed. The fibrils and lamellae which compose the velvety osteophyte approach each other and increase in size, and, at the same time, assume a position parallel to the lamellae of the bone beneath them; the whole osteophyte becomes more dense, and unites either immediately or by an intervening layer of diploe, with the bone. Hence the bone becomes a layer of compact tissue thicker - Lobstein's "supracorticale osteoscleroses" In other cases, as the velvety, or the splintered and laminated, osteophyte becomes condensed, its fibrils and lamellae retain their relative position to the bone, and the osteophyte becomes a compact osseous mass, which, though attached to the bone, can be distinguished from it by the different direction of its lamellae and the course of its medullary canals. Sometimes the osteophyte appears to be diminished by absorption, but it can hardly disappear altogether.