CASE X. The corpse of a man of forty, was brought into the amphitheatre of Desault, soon after he became a public teacher. One of the pupils, on preparing to dissect the body, discovered a preternatural mobility in one of the condyls. The knee was examined. A double fracture was found, accompanied by a separation of the two condyls. On inquiry it was ascertained that the corpse came from the Hotel-Dieu. It was further discovered, with certainty, that the injured subject, in jumping through a window, had alighted on his feet, and that he experienced instantly a severe pain in his knee, and fell on the ground, unable to support himself. Here, no doubt but the condyls, by being violently pressed between the weight of the body and the articulating surfaces of the tibia, had been fractured by a counter-stroke. § XIX. OF THE SIGNS. 121. But whatever may be the precise form and figure of the fracture, its signs are easily comprehended: a very perceptible separation oftentimes exists between the two condyls, increasing the transverse diameter of the knee. The rotula, sinking into this chasm between the condyls, renders the part more flat from before backwards, than it is in its natural state. If the rotula be pressed in a backward direction, the condyls are separated still further from each other. If, on the other hand, pressure be made on each side of the lower part of the os femoris, the condyls are brought together, and the knee resumes its usual shape. If we take hold of a condyl in each hand, it will be easy, by moving them alternately backward and forward, to make them rub against each other, and produce a crepitation which characterizes the fracture beyond a doubt. 122. If the upper fracture be oblique, a shortening of the limb more or less perceptible is always the effect of it: this appears to be principally owing to the weight of the body which pushes the upper fragment down, and to the action of the muscles which draws the lower ones up (10 ... 14). In this case, the superior fragment, being forcibly pushed against the integuments, has sometimes lacerated, and even passed through them, giving rise to consequences of a serious nature. Desault has published a case of this kind. A similar effect has been produced, though more rarely, by the inferior fragment, in which case much mischief has arisen from the admission of air into the joint. 123. Sometimes when the upper fracture extends through the whole thickness of the os femoris, the extremity of the bone is turned round, so that the external condyl lies behind, the internal before, and the rotula on the outside, while the foot points in the same direction. A case of this kind is recorded in the Journal of Surgery. The body of the bone, being pressed into the chasm or interval between the two condyls, may prevent their reunion, by pushing them asunder, and thus give rise to various accidents.