If a table be constructed, based upon a large Dumber of cases in all stages of the disease, showing the frequency with which the sev.: eral joints suffer, it is obvious that those joints which tend to be earliest attacked will show the highest figures, and the order of fre quency of implication will correspond roughly to the order of invasion.
Such a table was constructed for the five hundred cases which have already been frequently referred to, and this table is here repro duced. It will be seen that the peripheral joints tend to suffer most, • and the hip-joints least; but the knees which are so liable to all kinds of arthritis, stand second upon the list, immediately after the hands.
In 252, or rather more than half the cases, the hand-joints were first affected; in 64 cases the knees, and in only 26 the feet, were first attacked.
The number of cases in the above table in which there was slight or severe affection of the temporo-maxillary and spinal joints will at once attract attention ; and their liability is a characteristic feature of arthritis deformans, which sometimes lends valuable aid in the diagnosis of a doubtful case, for with the exception of gonorrhoeal rheumatism there is no disease liable to be confused with arthritis deformans in which these joints are apt to be involved.
Clinical Character of the Articular Lesions.—Enlargement of the affected joints is the most important sign of arthritis deformans, and it is of three different kinds.
1. In the most chronic cases the enlargement is almost entirely due to osteophytic outgrowths upon, and lipping of the articular ends of, the bones. The shape of the enlarged bones is easily made out by the touch, and the osteophytes form distinct bony excrescences which are sometimes so sharp that they even threaten to pierce the skin. Lipping is particularly well made out at the lower end of the femur, and around the patella. This type of enlargement, which is very well seen in the hands of many old women, in whom the disease is almost of the nature of a senile change, is characterized by the abrupt increase of size at the level of the affected joint.
2. Fusiform enlargement to which the thickening of the synovial membrane and of the structures around the joint contribute largely.
In this condition, which is seen in its most typical form in younger subjects, the transition from the normal to the swollen parts is much more gradual, as the name by which I have described it implies, and the osteophytic outgrowths are much less conspicuous.
This form of enlargement is perhaps best seen in the middle joints of the fingers and in the wrist. In the case of the latter the natural narrowing of the limb at the wrist may be entirely or almost entirely abolished.
3. The third form of enlargement is due to the accumulation of fluid in the cavity of the joint or in the neighboring burs. The enlarged bursm are best seen upon the dorsal aspect of the wrist-joint, where they occasionally attain to a considerable size.
Enlargements of the second and third of the above classes are somewhat. amenable to treatment, and the improvement in the appear ance of a joint, when the bursal swellings disappear, and when the natural contour of the part is to some extent restored, is sometimes very striking. Osteophytic enlargement, on the other hand, is of course not amenable to treatment.
In the case of the terminal joints of the fingers, the enlargement of the ends of the bones is apt to produce a permanent and irreduci ble lateral deflexion of the terminal phalanges, usually toward the radial side, which is rendered more conspicuous by the ulnar deflex ion of the fingers as a whole, with which it is often associated but which is a deformity of an entirely different type.
In the larger joints such as the knee or elbow, great swelling is often present, especially if there is fluid effusion, but even the swell ing of the soft parts alone may be so considerable as to lead to the suspicion that fluid is present when it is not, until an examination is made.
In the earlier stages of the disease there is usually well-marked crackling in the joint on movement, such as is present in other forms of chronic arthritis, but when the bones have become bare of cartilage the grating of the bony surfaces upon each other, to which the grooves seen upon their surfaces post mortem bear eloquent testimony, may often be clearly felt.