excision gives an extremely bad functional result, and further osteophytic outgrowths are very apt to occur around the divided end of the bone, so that the operation is likely to result in an increase of the trouble.

In the knee, on the other hand, excision may be justifiable when the pain is so great as to prevent the patient getting about, and when this joint is the only one affected. The bones unite readily and a stable limb is obtained. Excision of one knee may, however, be followed comparatively rapidly by the appearance of the disease in the other knee, probably brought about to some extent by the increased strain thrown upon the movable articulation by the stiff limb. At the same time, the risk of this is not sufficient to warrant our refusing to relieve the patient of his existing trouble by excision. In the elbow, operation gives a very fair result; and in the shoulder, excision often gives marked relief, although it seldom gives a perfectly useful joint. The excision in these cases need not be the prolonged proceeding that is necessary in tuberculous cases. There is no need to remove all the synovial membrane, and therefore the operation should not be accompanied by any shock.

CHAPTER XVII.

LOOSE BODIES IN JOINTS.

By a loose body in a joint is understood an abnormally movable structure, which is apt to get between the articular ends of the bones and to interfere with their movements.

Loose bodies may be divided into those originating inside the joint and those introduced from without; the latter should strictly be called foreign bodies, examples being bullets, pieces of glass, etc. The loose bodies having an intra-articular origin may be divided into two classes, namely: (a) structures which normally form part of the articulation, but which have become detached; and (b) those derived from the growth or deposition of new materials which form no part of the normal joint. Of the former class a typical example is a detached fibrocartilage, but this will be considered more appropriately in connection with the particular joints in which the fibro-cartilages occur. Sometimes portions of cartilage may be detached from the underlying bone by injuries, and may form loose bodies. The common type of loose body in the joint belongs to the second group of which we have spoken, and is formed within the joint. Three conditions may be mentioned: (1) detached hypertrophied villous processes; (2) the so-called 'rice bodies'; and (3) the true loose cartilages which are not the result of injury, but are due to the development of cartilage in the synovial fringes.

We have already referred to the villous condition of the synovial membrane (see p. 107), and the rice-like bodies occurring in tendon sheaths and joints have also been discussed (see Vol. II. p. 83). We need therefore only deal here with the true loose cartilages.

Loose cartilages are usually few in number in any joint and are very often single. They are generally smooth, ovoid, and flattened, and consist of a layer of true hyaline cartilage which may be undergoing ossification in the interior. They originate in the synovial fringes, in which a few cartilage cells may be present and may undergo development. In the early stage these bodies are not free, but are attached to the synovial

membrane by a delicate pedicle which may be so long and narrow as to allow the cartilage to move in various directions. Some accident sets the body free in the joint by tearing across or twisting the pedicle. It would appear that loose bodies may actually increase in size after all organic connection with the synovial membrane has been severed. Loose bodies are not uncommon in connection with osteo-arthritis, but it is doubtful whether they are the result of the rheumatoid change or whether their presence in the joint sets up the rheumatoid condition.

The joint most frequently involved is the knee; the next in frequency is the elbow, but the bodies may occur in any joint. The inconvenience caused varies according as the cartilage is loose or attached. If the cartilage is loose, it is very apt to become caught between the articular surfaces, when sudden and intense agony is caused, and the joint is temporarily locked. On the other hand, when it remains attached to the synovial membrane, it may not get between the ends of the bones, and may only cause some slight obstruction to certain movements and occasional effusion into the joint.

TREATMENT.-The only treatment of value is early removal by operation, and it is well to remember that in all such operations a healthy joint is opened, and that therefore the strictest asepsis is necessary. The chief difficulty in the operation lies in finding the body, which slips about extremely easily. Unless the body can be located and fixed before operation, it is quite possible to open a joint and fail to find it, even after a very prolonged and thorough search. This particularly applies to the knee, in which the body may slip behind the femur and cannot be got out. It was formerly the practice not to operate unless it could be found and fixed just before the operation was undertaken, notwithstanding that the surgeon knew from actual examination that there was a loose body in the joint; at the present time, however, this rule does not hold good.

In the knee, the best position in which to fix the loose body, if this is possible, is on one side of the supra-patellar pouch, preferably the inner. The patient may be able to keep it in place with the finger, or strapping and a pad may be fixed over it, so as to prevent it from slipping whilst the anaesthetic is being administered. During disinfection of the skin, fixation may be secured by transfixing the loose body by means of a stout needle thrust into it through the skin. A curved incision is made, a flap of skin and subcutaneous tissue is thrown back, all bleeding is arrested, and the capsule is incised directly over the loose body which is held steady by the needle thrust through it. When the capsule has been opened, a sharp hook is inserted into the cartilage, which is then pulled out.

When, as sometimes happens, the loose body recedes deeply into the joint at the moment of incision, a very useful manœuvre is to flush out the joint with the saline solution under considerable pressure; the body

may be dislodged by the fluid and carried within reach. Should this fail, the opening in the capsule must be enlarged sufficiently to expose the interior of the joint and the loose body searched for; it will almost certainly come into view, especially if the knee be flexed and extended rapidly several times. After the loose body has been removed, the joint is flushed out with normal saline solution, the incision in the capsule accurately stitched up with fine catgut, and the flap sutured in place. A drainage tube is unnecessary; no splint need be used, and the patient may move the limb as soon as he wishes to do so after the wound has healed.

CHAPTER XVIII.

ANCHYLOSIS.

TRUE anchylosis implies absolute rigidity of the joint, and is usually due to actual osseous union between the bones; but, from the practical point of view, it is well to include under this term other less extensive interferences with movement. Anchylosis may therefore be described under four heads: (1) osseous union between the ends of the bones; (2) partial or complete obliteration of the synovial cavity by fibrous adhesions; (3) contraction and rigidity of the peri-articular tissues; (4) adhesion of muscles to the bones in the vicinity of the joint. In the treatment of the affection, we have also to consider whether the position of the limb is good or bad.

BONY UNION BETWEEN THE ARTICULAR SURFACES.

Before bony anchylosis can occur, the articular cartilage must have been completely destroyed.

TREATMENT.-The only circumstances under which the surgeon is called upon to interfere, in cases of true bony anchylosis, are: when there is much pain, when there is deformity of the limb from faulty position, and when the patient desires to obtain a movable joint in place of a stiff one. When the joint is in good position and free from pain, and when a movable joint is not required, it is unnecessary to employ any treatment.

Painful bony anchylosis is comparatively rare, but it may be met. with when anchylosis accompanies a still active osteitis of the articular ends; in some cases there may be an abscess in the end of the bone. Under these circumstances it will be necessary to cut down upon the thickened and painful bone, gouge a hole in it, and seek for an abscess as recommended for osteitis and abscess of bone (see Vol. II.). This procedure usually relieves the pain completely, even though pus is not found.

In bony anchylosis accompanied by deformity the condition cannot