RING-BONE. 
605 
IY.—RING-BONE. 
The term “ring-bone” has been used since olden times to indicate 
many chronic diseases about the coronary joint attended with swelling. 
At first such swellings were regarded as resulting from a single cause, 
but careful anatomical examination shows that they may be due to 
very different disease processes. The following forms of ring-bone have 
been differentiated :— 
(1) Articular ring-bone. This consists in an arthritis chronica. Some¬ 
times it consists of an arthritis chronica deformans in which the articular 
cartilage forms the point of origin of the disease, sometimes it follows 
synovitis. The articular cartilage of the os suffraginis or os coronae is 
Fig. 228.—Articular ring-bone. Fig. 229.—Periarticular ring-bone. 
found to be more or less altered, according to the age of the disease, 
whilst exostoses occur on the borders of the joint (fig. 229). We, there¬ 
fore, have to deal with an arthritis sicca vel deformans. In the later 
stages the suffraginis and coronet bones become covered with extensive 
ossific deposits, whilst the articular cartilage is totally destroyed; 
obliteration of the joint (synostosis) may even occur, as shown by 
numerous reported cases. 
(2) Periarticular ring-bone. In consequence of chronic periarthritis 
produced by displacement, or by continued strains on the limiting 
apparatus of the joint, thickening occurs, particularly at the points of 
insertion of the lateral ligaments, and produces swellings on the inner 
