Stiffness of a joint may be either true or false. In the first condition, the mobility of the joint is destroyed by a bony union of the articulating bones. In false anchylosis, the stiffness is due to the formation of fibrous bodies between the bones of the joint, to the contraction of ligaments, muscles, or tendons, or their adhesion together or to adjacent tissues, and various other causes.

The Treatment of Anchylosis - Stiff Joint

Bony anchylosis is incurable. In some cases, however, the difficulty may be greatly relieved by a surgical operation by means of which a new joint may be formed. This has been effected in the hip joint by removal of the end of the femur, or of a portion of the bone near the end, and, in case of the elbow and the knee joints by the removal of the ends of the articulating bones. By keeping up passive motion after the operation, the ends of the bones are prevented from uniting, and thus an artificial joint is produced by a process which sometimes occurs in fractures when bones fail to unite. False anchylosis, may in mild cases be relieved by fomentations, manipulation, and passive movements, of the stiffened joints. Sometimes considerable force is required to overcome the rigidity of the joints. Various forms of apparatus have been constructed for the purpose of applying the necessary force.