—In synovitis, as in pleurisy, there may be a minimum of serous outpour, such exudate as escapes into the joint being exceedingly rich in fibrin and coagulating easily. This material is variously disposed of, and may form adhesions which will limit motion, or masses of condensed fibrin which may be broken up into shreds or rounded off into seed-like or rice-grain bodies. When tenderness subsides sufficiently to permit it these may sometimes be felt within the joint. At other times they lead later to an hydrarthrosis, which may prove more or less disabling and require subsequent operation. Another form of synovitis sicca is met with in acute and perhaps chronic rheumatism, where masses of fibrin become loosened and can be felt as foreign bodies, or fringes, beneath the joint covering.
Acute Synovitis.
—The ordinary acute synovitis is characterized by more or less effusion, and corresponds to pleurisy with effusion. It is the result usually of external injury, or it is combined with what has already been described as sprain. The fluid outpour is watery, is rarely blood-stained, save in cases of lacerations, usually distends the joint capsule, often to a painful degree, but represents nothing more than the consequences of hyperemia. If this fluid collection can be protected from contamination by germs it will disappear under suitable treatment, with a return to almost normal original conditions. Let it once become contaminated, however, and the type of disease is quickly changed, for there will then be an acute inflammation with its attendant phenomena and consequences.
Treatment.
—Cases of simple character are of short duration, i. e., one to two weeks. If seen early they should be treated by gentle compression and the application of ice-cold, wet compresses. Heat applied at this time may give temporary comfort, but will encourage effusion. Even if a joint thus affected be not seen until the swelling is extreme, wet compresses will still afford the simplest and the most comforting method of treatment, although they need not now be kept cold; in fact, gentle heat may now promote absorption. If the compresses be moistened in salt solution, to which a little alcohol has been added, the stimulating effect will probably be still greater. Such a joint needs to be placed at rest, save perhaps in the case of an ankle-joint or wrist-joint, which may be snugly strapped after injury. In some of these latter cases the patient can resume use of the joint almost at once.
Purulent Synovitis.
—This rarely begins as a purulent condition, but may be the result of the non-inflammatory and non-purulent form. In such a case the character of the fluid outpour soon merges into the seropurulent, and later become almost nothing but pus. If the interior of a joint could be inspected, under these conditions, the intensity and extent of the vascularity and cellular changes going on within the synovial membrane and beneath it would present a different picture from that of the non-purulent form. The appearance of a joint interior, under these circumstances, is similar to that of a well-marked purulent conjunctivitis. Articular surfaces are quickly eroded or perforated, while cartilages thus once affected are often loosened from their attachments through necrosis and remain as foreign bodies in the fluid collection. Even strong ligamentous tissues will melt down and become so weakened as to permit a looseness of motion foreign to the natural joint. In fact, as between purulent synovitis and acute suppurative arthritis it is but a matter of extent of destruction, not of character of lesion. In this way pathological dislocations are produced, sometimes even within a few days, being the combined result of destruction of ligaments and the pull of muscles which are thrown into reflex spasm by the presence of intra-articular disease. Not only do we see caries of the exposed bone ends, but epiphyseal separations are not uncommon in the young, while every structure around and outside of the joint participates, even to the extent of abscess formation. Abscesses may form without the joint and work into it, or the purulent collection within may escape at points of least resistance and burrow, forming perhaps numerous foci at some distance from the joint first affected. If such a case is to be saved it will require numerous openings and counteropenings, with free drainage, while even then there can be no expectation of restoring joint function. There is, then, in these cases at least a sacrifice of joint, sometimes of limb, and in neglected cases of life itself.
Symptoms.
—Of the large joints only the shoulder and hip, especially the latter, are placed so deeply as not to permit of easy examination and diagnosis. Pain, swelling, and loss of function, with or without history of injury, will predominate in well-marked cases, while very early in most, and promptly in all, there will occur reflex spasm of those muscles which have to do with motion of the affected parts, by which they become more or less fixed and beyond voluntary control of the patient. This condition has been described by Sayre as “muscles on guard.” It is a significant feature, and has as much to do with active joint disease as has abdominal rigidity with surgical intra-abdominal conditions. Swelling will be proportionate to the acuteness of the case. Tenderness is nearly always extreme, especially along the articular line. The joint capsule is frequently distended to its extreme and the normal contour of the part completely obliterated.
The most common position in which limbs are held is midway between extremes; thus when the knee is involved the leg will become flexed upon the thigh, at about 75 degrees. If the shoulder be at fault the arm is maintained close to the body. In disease of the elbow the forearm is carried midway between the right angle and complete extension. This is partly due to the fact that the flexors are always stronger than the extensors, as it represents a compromise between the antagonism of the opposing groups of muscles.