19. Fractures of the os femoris, though seldom very distressing, in common cases, from any accidents that immediately accompany them, are sometimes rendered so, by inconveniences which are the consequences of them, when they are oblique. Celsus declared, that a shortening of the limb, more or less considerable, was always the result of such fractures. Most authors have copied and repeated this assertion, and, even at the present day, the opinion is advocated by a great number of practitioners. It must be acknowledged, that, if we compare the natural powers that are engaged in producing displacement (10 ... 15), with the artificial resistance made by most of our forms of apparatus, we will perceive that there is between the two forces so great a disproportion in point of strength, that the former can never yield to the latter. But, is it in the nature of all forms of apparatus to be unable to overcome the force of the displacing powers? Cannot an equilibrium be established, so as to retain the fragments in contact? The remainder of the present memoir will throw some light on this problem, which will become less difficult of solution, if we call to mind, that the action of muscles, though very powerful at first, diminishes afterwards by degrees, in consequence of their being kept in a state of permanent extension; that even a weaker power may, by acting constantly, accomplish ultimately, what could not have been effected at once, by another power much stronger, if only momentarily applied; and that compression made by circular bandages, tends also to diminish the force and prevent the action of muscles. Desault has cured, at the Hotel-Dieu, a vast number of fractures of the os femoris, without the least remaining deformity, and there are but few of his pupils who have not witnessed his success, some instances of which will be cited in this memoir. 20. It is, above all, from the well combined use of these two means, the extension and compression of the muscles, that that success was derived. The advantage of extension, in diminishing muscular force, is evident, particularly in the reduction of certain luxations, those of the humerus, for example, where we are frequently unable to succeed, till after having extended the muscles for a longer or shorter time. Fractures of the rotula and of the olecranon, prove equally the utility of compression in effecting the same purpose; for, when the muscles are not compressed by a bandage, they draw the fragment upwards with a double and even treble force. 21. Accidents relating to complications of the fracture, such as splinters, wounds, &c. are to be classed with compound fractures in general, and cannot be treated of in this place. § V. OF THE REDUCTION. 22. Two great indications enter into the treatment of fractures in general, and of that of the os femoris in particular; namely, to bring the fragments into proper contact, and to maintain them so. Let us examine each of these in all their details.