4. Concretions of the joints do not always assume the same aspect. They
vary greatly as to number, size, figure, structure, &c. In general,
these bodies exist singly; sometimes, however, two of them are found
in the same joint, and then they may be extracted either at the same
time, or in succession, as was once done by Desault. Some English
surgeons have also met with two concretions, and Morgagni has found
even twenty-five, in the same joint.
5. They vary also in size. The largest ever met with by Desault, was
fourteen lines in its longest, and ten in its shortest diameter. Six
lines diameter in every direction, was the measure of the smallest one
that occurred in his practice.
6. Their figure is sometimes lenticular and smooth on both sides,
sometimes unequal, rough in one part, even in another, concave on
one side, convex on the opposite, sometimes marked around the
circumference and sometimes not with reddish points, and having
occasionally a stem of a cellular texture and of some length, as may
be seen in a paper by Theden. They usually consist of a single mass,
but are in some cases divided into several lobules united by a kind of
ligaments, as in the fourth case related in the Journal of Surgery.
Though most frequently detached and floating in the interior of the
joint, they have yet been found adhering by means of small portions of
cellular substance, loose and capable of being stretched, or tight,
hard, and even of a ligamentous nature.
7. If, from the external figure, we pass to the structure of these
bodies, we will find them existing in three different states. Sometimes
purely cartilaginous, sometimes completely bony, they at other times
partake of both these states, in which case a bony nucleus is covered
with a cartilaginous crust. Out of five cases, recorded by Desault,
three are of the first, and two of the third kind. Many authors have
met with the second kind, particularly Morgagni, who has even found in
the same joint, some bodies of a bony and others of a cartilaginous
nature. Hence it appears, that this variety of structure is to be
attributed to the longer or shorter standing of the disease, that every
concretion must pass successively through these three states, and that
there is a great analogy between the formation of such bodies and
natural ossification.
8. If we examine a body of the third kind cut in two through the
middle, we will find it red and vascular in the centre, like an
epiphysis, even when it is floating in the joint perfectly loose and
free from adhesion.
9. Bell, in his treatise on surgery, speaks of a kind of tumour, at
first soft, membranous, and adhering to the internal surface of the
capsule, but which, according to him, may become afterwards hard and
solid, and be detached so as to float loose in the joint. But are
not these tumours different in their nature from those destined to
be converted into bone? Do they, in fact, ever undergo the changes
mentioned by Bell? Desault having never met with any of them, was
unable to offer an opinion on the subject. In the mean time, an
observation made by Monro, may serve to throw some light on the
question: he once saw, in one of these productions, a cellular nucleus
surrounded by a covering of bone.
10. Though usually simple and free from complication, this affection
may, according to some authors, give rise occasionally to a dropsy in
the joint. Pare is the first who has made mention of this: he found
one of these bodies in a patient’s knee, into which he had made an
incision for the purpose of drawing off a collection of water. Simson,
on extracting a similar body, gave vent to four ounces of water. But,
as on the one hand, a dropsy of a joint oftentimes exists without
these foreign bodies; so, on the other, these bodies are almost always
found disconnected from dropsy. Nor is there any affinity between the
acknowledged causes of an accumulation of synovia, and the presence of
these bodies; so that when the two diseases do exist together, it is
altogether probable, that they are independent of each other.
§ III.