Anchylosis, or ankylosis (from ankulos, bent, crooked), stiffness of a joint, the result of injury or disease. The rigidity may be complete or only partial, and may be due to disease of the tendinous or muscular structures outside the joint, or to disease of the joint itself. When the structures outside the joint are affected, the term "false" anchylosis has been used in contradistinction to "true" anchylosis, in which the disease is within the joint. Anchylosis is also used as an anatomical term, bones being said to anchylose (or ankylose) when, from being originally distinct, they coalesce, or become so joined that no motion can take place between them. The term ankylosis agrees best with the etymology.