[28] A motion or sweep describing the arch of a circle.
Trans.
[29] That which forms the superior boundary of the longitudinal fracture by which the condyls are separated from each other.
Trans.
[30] For an account of an improvement of the splint, represented in this plate, projected by Dr. Physick, and now used in the Pennsylvania hospital, see Article II. of the Appendix.
Trans.
[31] A case of luxation of the head of the os femoris in a forward direction, but differing in some respects from the above, occurred lately in the Pennsylvania hospital under the care of Dr. Physick. The doctor reduced this luxation in the amphitheatre, in the presence of his class, by a process which was also somewhat different from that adopted by Desault.
In the case of Desault’s patient the luxated limb was shorter than the sound one: in that of Dr. Physick’s it was evidently longer. This was no doubt owing to the head of the os femoris having, in the former case, passed farther up towards the superior rim of the os pubis than it had in the latter. In both cases the protuberance formed by the head of the bone in the groin could be readily felt.
For the purpose of making counter-extension, Desault passed a strap between the scrotum and the thigh of the sound side: Dr. Physick, for the same purpose, passed the strap between the scrotum and the affected thigh. He conceived that by this mode he could act with more effect on the pelvis, and more effectually prevent the acetabulum of the affected side from being drawn in any measure downward by the extending forces. It would seem, that by making counter-extension, in such a case, on the sound side, the pelvis is made to rotate, so to speak, on its own axis, in the direction in which the counter-extension is made. The necessary effect of this rotation must be, a slight descent of the acetabulum of the affected side. But to retain the acetabulum firmly up is the true and only end of counter-extension. Dr. Physick appears therefore to have availed himself of the greatest mechanical advantage of which the situation of the parts admitted.
Again: Desault placed the strap on which extension was made just above the ancle: Dr. Physick placed the strap intended for the same purpose above the knee. His object in this was, to have the leg free and unincumbered, in order that he might be able to use the limb with more advantage, as a lever of the first kind, to assist in moving the head of the os femoris towards the acetabulum. The fulcrum of the lever into which the limb was thus converted, was a strap passed round the affected thigh a few inches below the groin, and drawn laterally with great force in a direction opposite to that in which the bone was displaced.
In this case extension and counter-extension were made by means of powerful sets of pullies. Notwithstanding this, these forces were not alone sufficient to subdue the resistance of the muscles. The reduction was not completed till muscular contraction had been weakened, and the patient reduced almost to a state of syncope, by the loss of nearly two quarts of blood. This copious evacuation, co-operating with the fatigue which the muscles of the limb necessarily sustained, in consequence of the powerful extension to which they were for some time subjected by the action of the pullies, overcame all resistance and the head of the bone was finally replaced. To exhaust the energy of the resisting muscles by forcible and permanent extension, and to weaken the action of the system generally, by copious blood-letting, appear to be the two most effectual modes of ensuring success in the reduction of all obstinate cases of luxation.
Another point of difference between these two cases of luxation remains yet to be mentioned. In Desault’s case the head of the os femoris was, as he tells us, displaced in a direction “upward and forward.” In Dr. Physick’s case, the direction of the displacement was downward and forward. This was proved beyond all doubt, by the circumstance of the affected limb being longer than the sound one.
Trans.
[32] I know not of any English term equivalent to this. T.