606 
RING-BONE. 
or outer side of the joint. Post-mortem examination shows the articular 
surface to be healthy, hut the ligamentous apparatus is thickened, and 
moie or less well-developed exostoses exist at its points of insertion, 
particularly at the points of insertion of the lateral ligaments, though 
they also occur at the spot where the posterior ligaments of the coronet- 
joint become attached to the suffraginis. Sometimes the insertion of the 
synovial capsule is also the seat of exostosis (fig. 229). As the articular 
cartilage is free from disease, this condition has by some been named 
false ring-bone. 
(d) Lhachitic ring-bone. In young animals suffering from rhachitis, 
thickenings sometimes persist on the lower extremity of the suffraginis 
and at the upper extremity of the coronet bones, and, as they cause swell¬ 
ing around the joint, have been described as ring-bones. In such cases, 
however, there is no pathological change either in the joint proper or in 
its ligaments. 
(4) The term “traumatic ring-bone” includes all enlargements about 
the coronary joint produced by periostitis due to other (usually traumatic) 
causes, whether following treads on the coronet or acute inflammatory 
disease of neighbouring parts, gangrene, &c. This classification meets 
practical requirements, for, in clinical diagnosis, it is quite possible to 
distinguish the different forms, and to modify the prognosis according to 
circumstances. 
Causes. The cause of the coronet-joint being so frequently the seat 
of disease lies in its anatomical formation. To act as an incomplete 
