The moist glistening membrane lining the abdomen (peritoneum) and that lining the chest (pleura) are similar to the synovial sac between the bone ends at joints or the synovial sheaths of tendons.
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.