Anatomical characters of the acute arthritis of the knee.—On examining the interior of a knee-joint which had recently been the seat of acute inflammation, we find that the synovial fluid has accumulated in the cavity of the joint, and that it is mixed with purulent matter; when this is removed, we perceive that the synovial sac has been widened and enlarged, and that the subsynovial tissue is much infiltrated, causing the synovial mem brane to be raised up above the level of the articular cartilages. We have seen the syno vial membrane or subsynovial tissue as red as the conjunctiva oculi in acute purulent ophthal mia. In these cases the articular cartilages lose much of their natural white silvery lustre, become yellowish, and are found softened at their edges or circumference, where the ele vated and inflamed synovial membrane is in contact with them. We have found the card lage of the patella softened and partially de tached from the bone, even in very recent cases. In cutting down to the joint we have noticed an alteration in the natural colour of the muscles ; and outside the synovial sac we often encounter abscesses containing true pus. Generally speaking this sac is of an intensely red colour, and covered here and there with a green but not very consistent layer of organi zable lymph. Some fragments of thinned shreds of exfoliated articular cartilage, with serrated edges, hang into the cavity of the joint, and some portions are altogether free, and float about loose in the interior. We have found the minute capillary vessels of the car tilages faintly traced in red lines, and have also discovered that these vessels admit the colour ing matter of our injections. The vascularity of the cartilages under the influence of acute inflammation seems to be fully proved. We have it on the authority of Sir B. Brodie that he had been able to detect with the naked eye vessels in articular cartilage filled by blood ; and it is fresh in the recollection of the profes sion that Mr. Liston has lately laid before the Medico-Chirurgical Society important obser vations on this subject.—The periosteum of the bones in the immediate vicinity of the knee is usually found to be of a red colour, thicker than natural, and easily detached from the bone ; the bones themselves occasionally pre sent a reddish or pink hue externally, and a section of them spews, by its bright red colour, an increase in the number or size of the capil lary vessels, admitting red blood, which per vade their medullary membrane and cancellated structure.
Example of acute arthritis genu.—Michael Roche, twenty-seven years of age, was admitted into the Richmond Hospital in April 1832. He had an emaciated appearance, a dry tongue, and some fever. He complained of severe pain in the left knee, which completely inter rupted sleep, and of frequent spasmodic start ings of the limb. The limb was so much swollen that measurement of it showed an in crease of six inches in its circumference over the sound one. The superficial veins were di lated, the patella was thrown much forwards, and the leg and foot were oedematous ; the in teguments were red and thinned, and a fluctu ation of matter in the joint was very evident. He stated this violent attack to be of five weeks' duration, having commenced with a very severe rigor, and attributed it to his having lain for some hours on wet grass. Three years previ ously he had had an attack of acute inflamma tion of the knee, which, however, quickly sub sided, but leaving a stiffness of the joint. An opening was made with a lancet into the part of the knee-joint which was red and thinned, and eight ounces of purulent matter were let out, but no relief was afforded. Some super ficial inflammation was observed, in the course of the lymphatics to the groin, from the wound, as also swelling of the inguinal glands. The spasmodic startings of the limb became more urgent, and the oedema increased. On the 17th of April Dr. 111‘Dowel amputated the limb. The incision passed through a sinus which he thought it necessary to dissect out. The muscles did not retract. On the following day the report from the man was that he rested well at night. But on the fourth day after the operation his countenance was flushed, his pulse feeble-96, and he complained much of the pain of the stump. On the 22d of April, the fifth day after the amputation, he had a rigor followed by a hot and sweating stage : his pulse amounted to 144. For some days subsequently he had frequent rigors. The stump was not doing well; the muscles were shrinking away daily and leaving the bone un covered. The edges of the wound had a sloughy appearance, and towards the end of the month he was attacked with diarrlicea which in a few days proved fatal.
On an examination of the knee-joint all the structures entering into its composition exhi bited evidence of their having been the seat of recent high inflammatory action. The bones
and synovial membrane presented a very great degree of vascularity and redness; purulent matter and flakes of lymph were contained in the interior of the joint ; a fragment of one of the semilunar cartilages alone remained, and the articular cartilages were in many places removed altogether ; in other situations these latter were thinned very much, and in one or two places a number of minute perforations were seen in the articular cartilage investing the lower end of the outer condyle of the femur. The minute vessels of the joint were rendered evident by a previous injection of fluid size coloured by vermillion. The syno vial membrane was much thickened and raised above the level of the cartilages; it presented a red pulpy appearance, and productions from it passed from the side of the femoral condyles and were loosely folded over the articular carti lages; and wherever this loose membrane was in contact with the articular cartilages, these seemed to have been absorbed. Depressions in the cartilages exactly corresponded in form with this vascular membrane, which was lodged in these superficial depressions. The articular cartilages were thinned, and when elevated from the bone a red pulpy membrane, very similar in appearance to the free surface which the synovial membrane presented, was seen. The minute pores and perforations in the articular cartilages already noticed were evidently formed by the action of a pulpy membrane subjacent to them, and causing their absorption, evidently in the same manner, it appears to us, as we find an exfoliation from a flat bone of the cranium to be perforated by the absorbing powers of the granulations proceeding from the bone beneath it. In examining this preparation, and reflect ing on the history of the case, it would appear that when the limb was amputated, the com plete destruction of the articular cartilage was in progress. On the free surface towards the cavity of the joint, the cartilage was evidently absorbed by the villous productions from the inflamed synovial membrane; on the osseous surface the cartilage was acted upon by a pulpy membrane, which existed here also, and it was this membrane which was produced from the bone and caused the number of minute perfo rations already alluded to, having partially removed the articular cartilage.* The hones were in a condition of hyperxmia. This newly formed membrane seems to be endowed with a power of absorbing, by its villi, the cartilage with which it comes in contact ; for we must agree with Mr. Key that these vascular fimbri or tufts are often buried into excavations in the cartilage, and the convexity of the villous mem brane seems sunk into fovea: formed in the cartilage, so as to leave no doubt of the vital mechanism, if we can so say, of the process, which seems quite analogous to the absorption of the sequestrum of a cylindrical bone, or the exfoliating piece of a flat bone. The writer presented to the Pathological Society of Dub lin a recent specimen and a drawing of the knee-joint of a man aged seventy, William Walsh, who died the day previously (13th Dec. 1839) in the House of Industry, of an attack of acute arthritis genu which had supervened on a chronic disease of the joint of long standing. The synovial sac of the joint had been much distended and was more capacious than usual. It was greatly thickened, and presented on its internal surface an intense scarlet colour. Ex tensive deposits of a yellowish green lymph were noticed over the entire of the synovial sac : the strong contrast in colour between the green lymph and the red villous synovial mem brane is well seen in the preparation. The cru cial ligaments were partially removed, and it was found on dissection that the internal and external lateral ligaments had lost all their dis tinctness as fibrous bands ; both seemed to be resolved and spread out into thin membranes or fascia, which but little restrained the move ments of the knee, and allowed of a motion of rotation being communicated to the joint. The articular and sem ilunar cartilages were removed, and the denuded porous surfaces of the bones of the tibia, femur, and patella presented nu merous small red spots, as if they had been sprinkled with red sand. An abscess contain ing about two ounces of yellowish green pus, of a laudable consistence, was found under the crurceus muscle, just above the synovial sac of the joint: this abscess was isolated, and had no communication whatever with the interior of the sac of the joint. The fluid in the interior of the articulation was more of a thin sanies ' than pus, hut was abundant in quantity, and had made its way externally by a large sloughy looking opening in front of the leg, about two inches below the knee.