Anchylosis (Gr. a bending), that condition of a joint in which its natural mobility is greatly impaired or entirely lost. The derivation of the word would imply that the joint is bent, but it is used to designate the abnormal condition in any position. Anchylosis may be true or false. In the former the material which has been produced by the diseased process, and which prevents the proper degree of motion, is bone; in the latter it is fibrous tissue, or the muscles which surround the joint are shortened to such an extent as to curtail movement. In either case the material may be between those surfaces of the bones which help to form the joint (intra-articular), or may lie chiefly or entirely outside (extra-articular). Anchylosis is usually the result of an inflammation in or near the joints affected, though it may occur in cases where the joint has been retained in a fixed position for a considerable length of time, the disease or injury being in a distant part. If a bone be broken, it must be kept fixed in order that it may unite; and to effect this it is usually necessary to render the joint above and that below the fractured part immovable until union has taken place.
During this period, if proper precaution be not exercised, the joint may become stiffened, and in this case it is almost always by false anchylosis. This result is more apt to occur if the fracture be very near to, or especially if it implicate, the articulation. When a joint is inflamed, the immobility necessary to cure this condition, and still more the not infrequent partial or complete destruction of those struetures which form it, are frequent causes of anchylosis. This result, though never desirable, is at times unavoidable, and the most favorable termination that can be expected. - The treatment is of three kinds, preventive, precautionary, and remedial. Anchylosis may be prevented by moving the joint at proper times, the parts which surround it being in this way kept from contracting. As regards precautionary treatment, where anchylosis is inevitable, the surgeon should always endeavor to place the part in such a position as that it shall be most useful to the patient; e. g., a nearly straight position for the knee, a bent position for the elbow.
To remedy the resulting deformity or inconvenience, the contracted parts may be stretched gradually by proper apparatus, or they may be stretched and ruptured suddenly; and some which refuse thus to yield may in appropriate cases be divided by a nar-row-bladed knife passed subcutaneously. The above treatment can be practised only where the anchylosis is of the false kind; if it be true, a portion of the bone at or near the joint may be removed, and the parts be allowed to stiffen in a more convenient position, or an attempt may be made to form a new joint by keeping up motion. Where the limb is useless and inconvenient, it may be advisable to remove it.