SECTION IV.

OF DEGENERATION OF THE ARTICULAR CARTILAGES.

Fibrous degeneration of the articular cartilages. -As articular disease commences ordinarily in the bone or in the synovial membrane, the cartilages become implicated secondarily; and, when inflammation is arrested in the former structures, the cartilages do not undergo destruction. There are, however, changes incident to the cartilage itself, which commence and proceed independently of any morbid action either in the synovial membrane or in the bone. In old age, for example, atrophy of the articular cartilages always takes place it advances gradually, until the whole cartilage may be entirely removed, or, as Mr. Toynbee says, "Articular cartilage during the whole of life gradually becomes thinner, by being converted into bone."* Whether it be atrophy of the cartilage simply, however, or whether this be converted into bone, a concomitant change in the articular surface of the bone is observed; namely, calcareous degene

ration. This change, however, is a condition incident to age, and not a state of disease.

There is another, and in its results, a somewhat similar affection, to which I would especially refer—a diseased condition however, and not a natural change -fibrous degeneration. This affection of the articular cartilages occurs for the most part in elderly people who have been subject to rheumatic pains in the joints. In the first instance, the cartilage loses its glistening appearance; fissures then form in it vertical to the surface, and gradually and slowly they pass through it to the calcareous surface of the bone, widening as they advance, until the cartilage is entirely removed. This change commences in the cartilage, and other structures are not necessarily involved. It is, therefore, painless; for the cartilage is not provided with vessels or with nerves, and is consequently devoid of sensation.

This destruction of the cartilages is, during life, altogether unsuspected; the process being without pain, and mobility not being disturbed. Simultaneously with this destruction of the articular cartilage, there occurs a change in the articular surface of the bone itself (similar to that result of age to which allusion has been above made)-porcellanous transformation, or eburnation. This, as Dr. Redfern remarks,

30 DEGENERATION OF THE ARTICULAR CARTILAGES.

is the only repair which is observed when the whole thickness of the cartilage is thrown off, without the occurrence of disease in the neighbouring parts; or, in the words of Professor Pirrie-" Reproduction of cartilage never takes place, and the place of disintegrated cartilage may be occupied by an amorphous formation, technically called the porcellanous deposit. This substance fills up the cavity, and its smooth and polished surface compensates for the want of cartilage and of synovial membrane.'

Thus, it is shown, that disease being limited to the articular cartilages, the motion of the joint may remain unimpaired, and that, when mobility is destroyed, other textures besides the articular cartilages are affected.

NOTE. It was stated in an early page of this chapter, that these pathological observations would be limited to the results of discase, and that the diseases themselves would not be considered in detail. It could not have been otherwise, unless this work had been enlarged far beyond its present dimensions.

*The Principles and Practice of Surgery,' p. 414. 1852.

CHAPTER II.

THE DIAGNOSIS OF TRUE AND OF FALSE ANCHYLOSIS.

It is only within the last few months that we have had to deplore the death of one who especially elucidated this department of surgery-one who was an ornament to his profession and who was beloved by those around him-M. Bonnet. I regret to have to allude to him as of the past. M. Bonnet wrote, “We have not any certain signs by which we can recognise bony anchylosis." This sentence was written before anæsthetics were in general use in surgery. Now, it is easy to recognise bony anchylosis. But not only through the employment of anæsthetics may this be determined, for, except in very rare cases, an accurate diagnosis may be made even without their aid.

It may be impossible, however, so perfectly to grasp a bulky limb, with one hand above and the other below

the articulation, and thus to overcome the influence of its proper muscles, as that no doubt shall exist with regard to the condition of the articulation. Also, in the case of the temporo-maxillary articulation, the teeth of the upper and lower jaws may be so closely approximated, that it may not be possible to determine, except under the influence of chloroform, that one at least of these articulations is not ossified.

As a general rule, the sensation of solidity in bony anchylosis is unmistakable, on grasping the limb above and below the articulation. Bony consolidation in the moveable articulations is so rare, however, that an examination should always be instituted after the full effect of chloroform has been obtained, before an opinion favorable to synostosis is delivered.

False anchylosis is the rule; and it is so common, that adhesions should always be held to be fibrous until they are proved to be bony.

Immobility alone is not a sign of synostosis; it not unfrequently exists where the adhesions are fibrous. And even when chloroform has been administered, immobility may be as great as before.

Immobility will frequently exist until muscular action is entirely removed through anæsthetic influence: then, a certain, definite amount of motion may usually be obtained. Occasionally, however, the limb will