Of the predisposing causes, heredity is frequently observed. Women are much more liable to the disease than men. Age is of importance, most cases commencing between the ages of 40 and 50 years, but the disease may occur earlier and even children may be affected by it. In women puberty and the cli macteric are particularly liable to the affection.
Many authors have tried to isolate the microbes of rheumatoid arthritis, and in many instances they have suc ceeded in cultivating bacteria from ma terial taken from the affected joints. Unfortunately, however, they do not agree in the description of the micro organisms, and have not been able to reproduce the disease in animals.
Bannatyne and Wohlmann cultivated from the synovia taken from diseased joints a- dumb-bell-shaped bacillus, re sembling in many cases a diplococcus, as the ends of it were deeply stained by carbol-fuchsin and other coloring mat ters, whereas the connective portion was not at all stained; the bacillus was aerobic, grew on blood-serum, agar-agar, and in beef-bouillon. Blaxall found the same bacillus in the blood of the pa tients, but in small amount.
Schuller in 1893 described a bacillus cultivated from the synovia of the af fected joints, but his description of it, its manner of development, etc., make it obvious that it is not identical with that observed by Bannatyne.
Small diplococci which stained by Gram's method isolated from the exu date in the joints of a case dying after presenting clinical picture of extreme arthritis deformans. The organism grew in all media, but did not develop quickly. Similar micro-organisms were obtained from the liver; the injection of cultures of this diplococcus into the knee-joints of rabbits gave rise to a process similar to rheumatoid arthritis. Von Dengrun and Schneider (Milne med. Woeh., Oct. 25, '95).
Rheumatoid arthritis in the majority of instances appears to be a primary malady with characteristic features from the onset. Infrequently the pa tient suffering from this form of arthri tis has previously been affected with acute rheumatism. From a clinical and pathological standpoint there is still much room for the accumulation of facts bearing upon rheumatoid arthritis, and for the present we should take an ex pectant attitude in this matter. A. E.
I;arrod (Lancet, March 16, 1901).
From all these experiences it seems demonstrated that micro-organisms are constantly found in the synovia of the diseased joints, but until further experi ence their significance and mode of ac tion remain uncertain.
Pathology.—In the affected joints there is generally some increase of the synovia, especially in the earlier stages of the disease. The synovial membrane is thickened; in the acute stage is in jected and soft, in the chronic stage hard and dense. The ligaments are af fected in the same way and in chronic cases often present patches of cartilage; sometimes the patches inserted in the ligaments have a bony basis, while the surface consists of cartilage. The syno vial membrane is injected and granular and readily breaks down on pressure, the villi being thickened and more prominent than usual. Small erosions may be found on the cartilage, which presents a velvety appearance. The cartilage ordinarily shows erosions and disappearance of the central tissue, with formation of new cartilage in the pe riphery. The erosions may be such as to expose the heads, while the prolifera tion may give rise to the formation of marginal overgrowths. The bones also become much changed, being at first red and injected, soft, and easily broken down. Later on it becomes hard, white, and eburnated. When the bone is ex posed, it shows grooves and striae cor responding to the eminences of the op posing articulating surface. Osteophytes are a very common occurrence, bone be ing formed as well from the cartilage and from the ligaments as from the bone itself. In the cavity of the joints free bodies are often found, formed sometimes by coagulated fibrin or con sisting of cartilage or cartilage and bone. These, in most cases, arise from the fringes of the cartilage or have been formed in the ligaments, as mentioned above. In rare cases osteophytes are de tached by traumatisms and thus form free bodies. By the retraction of the new-formed connective tissue and the changes in all the component parts of the articulations, ankylosis is often caused; but true bony ankylosis is a very rare occurrence.