Synovial bursa

Bursae. A bursa, which is a sac lined with serous membrane, placed over a joint or other prominent part for protection, is also quite similar. All of these membranes are smooth and moist, giving lubrication to movable parts, thus: the peritoneum covering the intestines, permits of their easy worm-like action within the abdomen; the pleura makes for the free rise and fall of the lungs; the synovial sacs  of joints allow the bones to ride smoothly one upon the other; the synovial sheath  of a tendon acts like a silken sleeve in which the tendon slides up and down and, lastly, pressure over a bony point causes the member to move aside because of the slipping of the walls of the bursa, one upon the other, when compressed.

Injuries and Diseases of Bursae

Synovial bursae  exist normally in connection with tendons or with certain joints, and may be developed by continued friction or pressure at certain parts of the body. Deep bursae are sometimes connected with the joints, or are in very close relation with them.

Injuries of Bursae. Wounds of bursae may be either contused, incised, lacerated, or punctured, and, if they become infected, may prove most serious injuries. Wounds of bursae should be thoroughly disinfected and drained; they usually heal with obliteration of the sac.

Acute Bursitis. This affection usually results from an injury or from continuous irritation of a bursa, and is characterized by tenderness, pain, redness of the skin, and swelling or distension of the bursa. If suppuration occurs, the inflammation is apt to extend to the surrounding cellular tissue, or, if in close proximity to a joint, the latter may be involved. Bursitis can usually be diagnosed from other affections by the rapidity of development of the inflammatory symptoms, the location of the swelling in relation to certain tendons or joints, and its globular shape.

Treatment. This consists in elevating the part and putting it at rest on a splint, and in the application of cold or pressure. If, however, the pain and swelling due to effusion continue, and there is evidence of suppuration, the bursa should be freely opened and irrigated, and subsequently packed with sterilized or iodoform gauze. Under this treatment the cavity soon becomes obliterated as healing occurs. The bursae most commonly involved are the prepatellar  and that over the metatarsal joint of the great toe.

Chronic Bursitis. This affection may result from acute bursitis which does not terminate in suppuration, or may develop slowly from long continued irritation or pressure, or from tubercular infection of the bursae and is accompanied by little pain.

The most marked feature in chronic bursitis is the distension of the sac with fluid, and in some cases the walls of the sac become so thickened that the bursa is converted into a solid tumor. Chronic bursitis of the prepatellar bursae is not infrequent, and is commonly known us Housemaid's knee, resulting from long continued pressure upon the knee occurring in those whose occupation causes them to constantly bear pressure upon this part.

Gumma of the prepatellar bursa is very common, and should be suspected in every case of suppuration of this bursa without assignable cause. It often results in extensive sloughing.

Hernial protrusion of a portion of a bursa is sometimes seen after injuries of bursae.

Treatment. The treatment of chronic bursitis, if the sac is distended with fluid, consists in removal of the fluid by aspiration, or by making an incision and introducing a drain. The greatest care should be observed to keep the wound aseptic. The bursae may be removed by dissection. This is the only treatment which is likely to be of use in cases where the bursa is very thick or is converted into a solid tumor. In removing these growths by dissection, great care should be exercised to avoid opening the neighboring joints.

Bunion. This is a bursal enlargement over the metatarsophalangeal articulation of the great toe, which is very frequently observed with hallux valgus, this being the most universal cause. The part is swollen and tender upon pressure, and if suppuration occurs the pain is severe, and cellulitis is apt to develop, involving the surrounding parts, or the joint may be involved, caries of the bones of the articulation resulting.

Treatment. If suppuration has not occurred, the part should be protected from pressure by a circular shield of felt or plaster; if suppuration has taken place, the part should be incised and drained, and if the joint is found diseased it should be curreted and dressed with an antiseptic dressing; if malposition of the toe exists, its position should be corrected by amputation of the head of the metatarsal.

Inflammation of Synovial and Serous Membranes. When the serous and synovial membranes are attacked by inflammation, the stage of congestion is accompanied by exudation of serum and fibrin from the surface, and the endothelial cells become swollen and detached in large numbers. The serous exudation may be sufficient to fill the entire cavity involved. There is a form of dry or fibrinous inflammation, without fluid exudate, in which the surface of the membrane loses its polish, becoming dry and red, and adhesions readily form wherever the surfaces are in contact.

In suppurative inflammation, pus is produced by emigration, and also by the detached endothelial cells. If fibrin is present, false membranes form on the surface and the membrane itself appears to be greatly thickened. At a later stage the proliferating cells invade these layers of fibrin and they become organized into connective tissue, and new vessels develop on them. Their tendency, however, is to disappear after a time, and the membrane returns to its original condition, unless the inflammation has been very intense, in which case the new connective tissue becomes permanent. Chronic inflammation of these membranes is marked by general thickening of all the layers, the formation of dense connective tissue in the fibrinous membranes, strong adhesions, and sometimes complete obliteration of the cavities, their endothelial lining disappearing entirely.