8. In common, the first mode of division is by a true counter-stroke, similar to that which fractures the clavicle, the ribs, &c. In the second mode, the fracture is always direct. The middle part of the bone is generally broken in a counter-stroke: wherever the direct stroke is received, that is the place of the fracture which it produces; the division, most frequently oblique in the first case, is sometimes perpendicular or transverse in the second. From a counter-stroke result most commonly simple fractures, while compound ones are usually owing to a direct stroke.
§ III.
OF THE SIGNS AND THE DISPLACEMENT.
9. In whatever manner a fracture of the os femoris may have occurred (7), its existence is characterized by the following signs: severe local pain at the instant of the accident; a sudden inability to move the limb; a preternatural mobility occurring in some particular part; a crepitation sometimes distinct, when the two fragments are rubbed against each other; and a deformity, which may be considered under the threefold relation, of length, thickness, and direction.[22] These signs, being common to most fractures, exhibit but few circumstances peculiar to those of the os femoris, except that of the deformity. Respecting this circumstance, in particular, it is essentially necessary to possess accurate ideas, because, having an incessant tendency to recur, especially in oblique fractures, it must constitute a primary object of attention during the treatment.
10. It may be laid down as a general principle, that all fractures of the os femoris are accompanied with some deformity; the exceptions to this rule are too few to be worthy of notice. If this deformity be considered in relation to length, it will be found that, in oblique fractures, the limb is always shorter than that of the opposite side, a circumstance which plainly points out an overlapping of the fragments. But, on examining the place of fracture, it is easy to discover, that this overlapping arises from the inferior fragment mounting upwards on the superior one, which itself remains immoveable. Now, what power, but the contraction of the surrounding muscles, can communicate to the inferior fragment a motion from below upwards? Attached, on the one hand, to the pelvis, and on the other to this fragment, to the rotula, the tibiæ, and the fibula, these muscles have on the former their fixed, and on the latter their moveable points, and, drawing the leg, the knee, and the inferior portion of the thigh upward, they produce the displacement and shortening either mediately or immediately. In this displacement, the adductores, the semi-tendinosus, the semi-membranosus, the rectus anterior, the rectus internus, &c. are the principal agents.
11. The following case communicated to Desault by a surgeon, who had been formerly his pupil, proves how great the influence of this cause is; a cause which is indeed generally acknowledged, but not sufficiently attended to by practitioners, with a reference to permanent extension. It is this that induces me to relate the case.
Case I. A carpenter falling under the ruins of his scaffold, was immediately taken up and carried home, where a surgeon discovered an oblique fracture of the os femoris, but without any displacement. The thigh, which appeared even a little longer than the other, was fixed in an apparatus too slack to prevent muscular action. Next day, the length of the thigh was the same, but the whole extremity was in a paralytic state, accompanied by an entire inability to discharge urine.
The moxa was proposed. The patient being placed in the position directed by Pott, for fractures of the os femoris, the fire was applied; some movements were the consequence; the application being repeated on the sixth day, the muscles instantly recovered their power of action, and then the shortening of the limb became evident, and still returning immediately after being removed by extension, rendered it necessary to have recourse to an apparatus calculated for permanent extension.