PATHOLOGICAL CONDITIONS OF BURSIE MU— COSX.—Bursw mucosw, .superficial as well as deep, are not unfrequently the seat of inflamma tion, resulting either from external causes, such as cold or local injury, or from constitutional causes. In the majority of cases inflammation in these structures assumes a chronic form, and its ordinary effects are either to increase the quan tity of the synovial fluid, to determine the effusion of a turbid serum loaded with flakes of lymph, or to end in the formation of matter.
The general phenomena of bursal inflamma tion may be studied with most advantage in the large subcutaneous bursa in front of the knee joint : it is more frequently inflamed than any other in the system. This, however, is not owing to any peculiarity of structure predis posing it to disease, but merely to the accidental circumstance of its situation, which exposes it more than any other to external injury. In those persons who continue for a long time in the kneeling attitude, in devotional exer cises for example, and still more remarkably in those whose occupation obliges them not only to support the body but also to move upon the knees (as carpenters, housemaids, and others), inflammation of this bursa is very frequently met with. In many instances it occasions little general or local disturbance, merely causing an increased effusion of the proper synovial secretion, without producing any change whatever in its natural properties. In other cases the fluid is not only increased in quantity, but becomes changed likewise in quality ; it assumes the appearance of a turbid serum, with numerous flakes of lymph floating in it; or where the disease has been of long standing, the fluid is frequently found loaded with a number of loose bodies, almost of the consistence of cartilage, and of a flattened oval form. Sir Benjamin Brodie compares their appearance not inaptly to that of melon-seeds, and he considers them as portions of lymph originally of an irregular shape, but which, by the motions and pressure of the surrounding parts, have had their angles worn off, and assumed by degrees a firm consistence. They have been found likewise in the smaller bursce. Monro has seen upwards of fifty extracted from the small bursa of the flexor pollicis longus tendon, where, by excessively distending the surrounding parts, they had produced severe pain. When the great vaginal bursm of the flexor tendons have,become the seat of effusion, a very remarkable appearance may present itself, at once explicable, however, by referring to the anatomy of the part. The fluid can by pressure be forced downwards under the annular liga ment, and into the palm of the hand, and thence upwards again into the forearm. Some authors have deemed it proper to designate by a par ticular name this termination of the disease by effusion, and the words thygroma and ganglion have been applied with a good deal of con fusion by different persons; but it appears to us that there exists no necessity for a specific name to refer to this accidental mode in which inflammation terminates.
A much more important termination of the disease is that in which, owing to local or con stitutional causes above alluded to, the inflam mation, having run a severer course, ends in suppuration. Sir Benjamin Brodie has in this case observed that the matter may take either of two courses : it may come directly to the surface ; or, without pointing forwards, it may penetrate the side of the sac, and so become extensively diffused through the surrounding cellular membrane, involving the whole anterior and lateral portions of the joint. In such a case the practitioner is very liable to be de ceived as to the true character of the abscess, and to confound it with those which originate in the cellular membrane.
There are certain cases in which acute inflam mation of a bursa becomes even a more serious disease than that just alluded to. In the syno vial sheaths of the flexor tendons, for example, the progress and termination of the inflamma tion are often modified in a remarkable manner by the anatomical peculiarities of that part. In that form of the paronychia affecting the ante rior part of the finger, and seated in the synovial sheath of its flexor tendon, the inflamed mem brane is closely bound down by a dense and unyielding fibrous layer : hence not only death of the contained tendon may be produced, but even extension of the disease to the bone itself.
Such are the morbid changes usually met with in the contents of inflamed burs; but if the disease have been of long standing, changes scarcely less remarkable are produced in the structure of the bursa itself. Instead of the delicate synovial membrane we have above described, it is frequently found converted into a firm gristly substance, sometimes half an inch in thickness. In such cases no tact, how ever delicate and experienced, could, previously to operation, have detected the presence of matter.
Monro seems to regard, in certain cases at least, the communication above alluded to be tween certain burs and the neighbouring joints as the result of rupture or of friction : he even considers it remarkable that in such instances neither lameness nor pain had been complained of during the lifetime of the individual. It ap pears to us, however, much more probable that in those instances the synovial membrane of the joint and that of the bursa have been ab initio but different parts of one and the same structure; at least, in our dissections of the subcrureus bursa in young subjects, we have more than once observed it communicating freely with the joint.