be torn from its anterior attachment. The end curled up and floated around in the cavity of the joint. The detached portion and about two-thirds of the circumference of the cartilage was cut away and the joint closed in the usual way. A perfect result was obtained.

Discussion.

DR. LEVINGS, Milwaukee-I have been very much interested in this excellent paper of Dr. Sifton's and I feel myself under obligations to him; and I believe the society is also under obligations to the doctor for bringing this subject before us, because we have not fully and upon all occasions understood this injury. The loosening or the displacement of a semilunar cartilage or cartilages (it is very seldom that both are displaced) is predisposed to in part perhaps largely by the construction of the joint. The knee joint is not a perfect hinge joint by any means. In flexion and extension it undergoes a certain degree of rotation-rotation outward in flexion, rotation inward in extension, and this rotation is attended with a certain degree of gliding motion of the condyles of the femur upon the head of the tibia, and consequently upon the semilunar cartilages. The cartilages are also very loosely attached to the head of the tibia. They do not cover, as the doctor has well stated, the entire articular surface, but only its outer portion. They are attached pretty firmly anteriorly and posteriorly, but at the side by means of the coronary ligaments, only slightly. Often in consequence af this loose attachment, because of the rotation and sliding of the joint, as the result of a sudden, perhaps unexpected movement, these cartilages are torn loose, either in part or in whole, from their attachments, roll up in the joint between the articulating surfaces, give the patient terrific pain, lock the joint, and produce a condition of acute synovitis.

Now there are two conditions from which this injury should be differentiated, one is loose bodies in the knee joint, floating cartilages so-called, which are often also due to an injury, may come from a blood clot, may be due to the breaking of an osteophite, may be due to the breaking off of a portion of the cartilage or a portion of the cartilage and bone. It may come in cases of osteoarthritis; but there is this peculiarity about floating bodies: they produce locking of the joints as do detached semilunar cartilages; but they are constantly appearing and disappearing, constantly making their appearance in new places, at one time upon the inside of the patella, then upon the outside, in front and behind, a condition which never occurs in displacement of the semilunar cartilage. A semilunar cartilage always produces its trouble in the same place, and that place can very often be readily determined. If the cartilage is displaced outward you can feel it, if displaced inwards there is a depression. I had a patient who displaced the external semilunar cartilage, and this is but rarely the case, for nearly always it is the internal cartilage which is displaced; she could see and feel a distinct lump or protuberance directly over the outside of the joint and above the head of the fibula. If the cartilage is displaced there is an area which is always sensitive, and if the cartilage is rolled inwards there will be a vacancy and if displaced outwards there will be a node. The other condition with which displaced semilunar cartilages may be confounded is a sprain.

Now I desire to make this point: These cases I believe have been mistaken for and treated as sprains-they have not been understood-at least very often has this been the case. A person gives the knee a sudden wrench,

he feels a snap, and something give way within the joint, there is terrific pain, the joint is locked, it becomes swollen, there is effusion and synovitis, it is treated for a sprain-no finer diagnosis is made. The knee is bandaged and put at rest for a week or ten days and the patient recovers; but after two or three weeks or a month there is again a second slight inadvertent movement while the limb is in a state of flexion and the same condition recursanother snap, a crack, a protuberance, the joint becomes locked, and synovitis supervenes with decided swelling. This condition recurs over and over again. Now this is not the history of a case of sprain. You seldom get the snap, you never get the locking of the joint, you never get a protuberance, a node or a vacant place at the site of the cartilage; and you never get a certain area which is always sensitive even when the joint is practically not inflamed. I think then there should always be a distinct effort made to differentiate the loosening of a semilunar cartilage from an injury or strain of the ligaments, or of the synovial membranes, or of all the structures of the joint combined, and also from floating bodies in the joint.

DR. SIFTON-Sir William Turner speaks of cases in which the semilunar cartilage apparently is not displaced at all, but where the inner edge of it becomes swollen and thickened by some form of traumatism; it seems to me that this point is well taken. However, the fact that the semilunar cartilage is not greatly displaced from its normal attachment, being simply caught between the articular surfaces of the joint, does not warrant us in saying that the attachments are not torn loose at all. The distinction is really unimportant. If the inner edge of the cartilage gets caught in the slightest degree, you may properly call it a displaced cartilage.

DISSECTING ANEURYSM OF THE AORTA WITH A REPORT OF A CASE*.

BY JOHN L. YATES, M. D.,

Assistant Demonstrator in Pathology,
University of Pennsylvania.

Dissecting aneurysm of the aorta has always been of such infrequent occurrence that the discovery of one post-mortem is apt to excite more than a passing interest, though perhaps more particularly in the minds of pathologists. However, if necropsies were more generally done, especially in cases of sudden or fairly sudden death, or if those examinations that are made were more carefully carried out, the condition would be more frequently discovered. Moreover, the clinical recognition of this lesion is always so manifestly difficult and so frequently impossible, that text books are apt to give it but scant attention. There are but two recorded cases in which the diagnosis was made during life and later confirmed by an autopsy. This is part*From the Pathological Laboratory of the Johns Hopkins Hospital.

ly due to the fact that insufficient attention is given to the clinical history without which it is practically impossible to arrive at the correct conclusion.

It is the object of this report to call attention to the fact that the diagnosis is quite possible in certain instances as well as to record the following case.

Jane R., colored. Age unknown (probably considerable over fifty). Unfortunately no clinical history had been taken. She had been admitted as a pauper to the Bay View Hospital (Baltimore) and up to the afternoon of her death had been in fairly good condition. She then complained of a feeling of weakness and of sharp abdominal pains and was immediately transferred to the medical department. The medical staff was extremely busy at that time, and as she was in no apparent need of immediate treatment and had become quite comfortable, her examination was delayed for more urgent work. Shortly afterwards while sitting quietly by her bed she suddenly cried out and fell forward unconscious, dying quietly within a few minutes.

The following notes were taken from the post-mortem record. Death, Feb. 6, 1902. Autopsy, Feb. 8, 1902. The body was that of a much emaciated old woman. There had been complete destruction of the nasal septum with exposure of the bony palate on the nasal aspect. The buccal surface was quite normal.

The peritoneal cavity contained a small amount of blood-stained fluid. One loop of small intestine was found adherent to a small firm mass lying upon the vertebræ a short distance above the brim of the pelvis. The serous surfaces were otherwise normal. A large hematoma lying in the tissues behind the ascending colon and in the transverse mesocolon extended from the cecum upward and transversely almost to the mid-line of the body. So intimate was the relationship of the hematoma to the large intestine that they were readily dissected out together and remained adherent. The cause of the hemorrhage was not recognized at this time and the exact location of the leakage was not determined. The impression was obtained that the bleeding began in the region of the cecum and that the blood had followed upward in the path of least resistance. The clot became progressively smaller as the dissection followed it upward. The pleural and pericardial cavities were normal. The heart was considerably hypertrophied eccentrically (weight 550 grams). Both the aortic and mitral valves were slightly thickened but not evidently incompetent. Fatty and fibrous changes were present in the myocardium.

The lungs were slightly congested and there was considerable hypostasis. The spleen was small and soft with numerous fibrous adhesions between it and contiguous surfaces. The cut section appeared normal. The liver surface was puckered and scarred with numerous irregular white plaques scattered here and there in the capsule. On section the surface was pale, somewhat mottled, and the lobulations were indistinct. The kidneys were small, the capsule slightly adherent and the superficial vessels injected. A cut section revealed an abnormally thin cortex with distinct striations and easily visible

glomeruli. The gastro-intestinal canal was quite normal throughout. The genitalia were atrophic but otherwise normal.

The aorta was of normal size and shape. Widespread but irregular changes were present over the entire intima. These consisted for the most part of areas of slight thickening, yellow in color and evidently containing considerable fat. There were also numerous fibrous and hyaline nodules particularly about the orifices of the smaller branches. A few of these had become superficially calcareous but none were ulcerated. These plaques and the more diffusely thickened areas were surrounded by narrow and likewise irregular strips and areas of fairly normal looking intima.

Beginning at a point 7 mm. below the septum separating the common carotid and subclavian orifices was the upper end of a laceration in the intima. This extended downward in the direction of the axis of the aorta for 35 mm. ending with a fairly sharp turn towards the left just above and to the right of the orifices of the first pair of intercostal arteries of aortic origin. The upper or proximal 15 mm. of the laceration ended in the tissues of the media. The margins were slightly everted but were firmly adherent to the base which was quite smooth and apparently covered with endothelium. Throughout the distal 20 mm. the margins of the lacerations while still smooth and everted were separated from the deeper structures. At first the dissection extended but a short distance laterally from the torn edges, but in the lower portion of the laceration it broadened abruptly to involve about three-fourths of the entire circumference of the aorta. Proceeding downwards the separation extended up to and in places inside of the line of the right intercostal orifices. On the left side it remained well outside this line. At the level of the inferior pair of inter-costals the aneurysmal channel became rapidly narrower and passed between the right of this pair and the orifice of the cœliac axis, reaching just to the base of the latter. It then began to widen again, involving the right half of the base of the superior mesenteric. Continuing to widen as it extended downward, the channel completely encircled the right renal artery but the left was uninvolved. 14 mm. above the orifice of the inferior mesenteric a still greater widening took place so that the aneurysm here involved all of the wall of the aorta but the narrow strip included between the orifices of the lumbar branches. The conditions here underwent a sharp change. The anterior wall was transformed into a sacculated aneurysm 30x30x28 mm. in size and from the sac sprang the inferior mesenteric artery. On the right side the dissection ended with this sac but on the left it was continued down along the anterior wall of the common iliac as an intra-mural hematoma.

The cavity of the aneurysm throughout the acrta was usually smooth and was apparently lined with a membrane similar to endothelium. Upon this new formed membrane were scattered nodular thickenings identical with typical scleroses in appearance. In certain angles and recesses there were larger and smaller thrombi. Nowhere were the walls found shaggy as seen when the media has been artificially separated. The walls varied in thickness and it was often quite impossible to distinguish just where the separation had occurred. At

The broken lines show the limits of the dissection, areas marked (d) being over the aneurysm. The circle about (An) indicates the limits of the sacculated aneurysm.

C. A. Coeliac axis. S. M. Superior mesenteric artery. R. Left renal artery. I. M. Inferior mesenteric artery. C. I. Left common iliac artery.