44. The escape of the head of the bone through the ruptured and lacerated capsule, constitutes essentially the displacement under consideration. But, it is never possible to ascertain with precision the place of this rupture: how, then, can the head of the humerus be directed towards it by an artificial force?
45. However well prepared for the purpose the body may be, which is placed under the arm-pit, to serve as a fulcrum, always a chafing more or less troublesome, and oftentimes distensions and serious lacerations are the consequences of its application, when the body is suspended on it, as in the mode by the door, the club, &c. where Petit has seen a fracture of the neck of the humerus occur, and even a laceration, followed by an aneurism of the axillary artery.
46. Every one has not at his command the different means above mentioned (41 and 42), whence the difficulty of procuring them, or of constructing them, and the loss of time, precious in relation to the reduction, which is almost always easily accomplished in proportion to the expedition used; these charges apply, among many other means, to that machine so complicated, and so well known, under the name of the mitten[15] of Petit.
47. Supposing the luxation to be consecutive, how can mechanical means make the head of the bone retrace the route it has pursued in becoming displaced? For example, if to a displacement downwards has succeeded a displacement inwards, it will be necessary for the head to return downwards before it can re-enter its cavity. But, can the direction of the movements be thus varied? This whole apparatus of artificial means, for ever contradictory, oftentimes acts in an inverse direction to that of the muscular action, which is the essential and chief agent in the process of reduction.
Should the luxation take place upwards, the insufficiency of these means must be evident.
48. Perhaps, however, they may be employed with some advantage, when a primitive luxation downwards is quite recent, and the head of the bone is near to its cavity. In such a case the lower edge of the scapula presents to it an inclined plane, along which it can easily glide, when pushed by some external force. It is doubtless to this disposition of the bone to replace itself, that we must attribute the successes, greatly exaggerated, but in part real, on which the inventor of every machine endeavours to found the superior merit of his mode of operating.
