14. Hence the method generally employed by most practitioners, recommended by almost every author who has written on the subject, adopted by Petit, Duverney, Heister, &c. and which consists in placing the knee between the shoulders of the patient, as a point of resistance, by the aid of which the shoulders may be drawn backward, fulfils only half of the indication of cure; because at the time that the humeral extremity is drawn backward, it is not directed sufficiently outward. Hence a difficulty of replacing the bone sometimes occurs, a difficulty always removed, when, pursuant to the method employed by Desault in fractures of the clavicle (see Desault’s method), the arm is made to serve as a lever of the first kind, to carry backward and outward, the head of the bone, which is displaced in the opposite directions, when the luxation is forward. This method possesses the advantage, not only of giving the powers of extension a proper direction, but also of increasing them to a degree even beyond what is necessary for effecting a reduction, by removing them further from the resisting force. Hence it is unnecessary to adopt any particular measures for restoring and preserving the form of the part, as the extension is alone sufficient for that purpose. These principles, evidently applicable in effecting a reduction, are still more strikingly so in the means destined for retaining it. Let us apply what I have just said, to a case of dislocation in a forward direction. It will be easy to transfer it afterwards to the other kinds of luxation. § V. OF THE MEANS OF RETAINING A REDUCTION. 15. Few luxations are so speedily reduced, but few are more easily displaced again, than that of the clavicle. This disposition is the reverse of that of most other luxations, which are reduced indeed with difficulty, but seldom afterwards suffer a displacement. The cause of this we find, 1st, in the extreme mobility of the clavicle, to which all the motions of the arm are communicated; 2dly, in this further consideration, that most of the muscles, which have their insertion towards the shoulder, tend to draw this bone inward, when the ligaments, in consequence of being either broken or distended, as happens in this accident, do not offer a sufficient resistance. 16. From this two-fold cause of displacement, arises a two-fold indication in the arrangement and application of the apparatus. These are, 1st, to render the clavicle immoveable, by restraining every kind of motion in the shoulder and arm; 2dly, to retain the extremity of the clavicle outward, a direction opposed to that in which it has a tendency to be displaced. But if to those indications we compare the forms of apparatus hitherto used, we will readily perceive that they are insufficient to fulfil them.