FRACTURE OF THE NECK OF THE FEMUR. IMPACTED FRACTURE OF THE BASE OF THE NECK, WITH EVERSION. THE injury known as the "impacted fracture of the neck of the thigh-bone" has been well described by various writers. When it occurs, the neck, broken at or near its broad insertion into the head of the shaft, is driven into the loose cancellated tissue of the latter, and so fixed there that it sometimes requires a considerable force to withdraw it. That it may be a severe lesion, especially in the latter part of life, the numerous recent specimens to be found in museums sufficiently attest. In my own observation, while it is at least as frequent among elderly people as fracture of the neck within the capsule without impaction, the accident is comparatively common in middle life, and even later; and the bone is sometimes capable of uniting after a few months, with little deformity. This fracture is characterized by shortening and eversion of the limb, sometimes so inconsiderable that we are obliged to accept a diagnosis based upon an almost imperceptible eversion, and a shortening of half an inch or less, by careful measurement. The Museum of the Medical School of Harvard University contains a valuable collection of impacted fractures of the hip; and having through these specimens become familiar with the eversion exhibited by them in various degrees, I had my attention more carefully directed to the subject by the following not unusual case. A gentleman slipped upon the ice before his door, and fell upon his hip. He walked up stairs with assistance, and was placed upon his bed. His attending physician, in the absence of any obvious shortening or eversion of the limb, entertained some doubt in regard to the nature of the injury, but after ten days, finding no improvement in the symptoms, -the pain and soreness having in fact increased, requested me to see him. The local tenderness and pain on motion, together with a very slight eversion,- best seen on attempting to invert comparatively the two feet, and a shortening of less than half an inch, led me to the conviction that the bone was slightly impacted; and I conceive this view to have been corroborated by callus subsequently felt about the trochanter, and by the length of time required for the recovery, the patient having been confined to his bed a little more than two months, and unable to walk without crutches until after the lapse of four months. Since that time I have had sufficient opportunities to satisfy myself that though this accident may be serious when it occurs late in life, it is by no means so to a middle-aged and healthy subject; that the impaction is sometimes slight, and its indications proportionably so; and that the following signs may be relied on as generally pathognomonic, disability; pain and tenderness resulting from local violence, especially when applied laterally, as in a fall upon the hip; shortening and eversion, however slight; absence of crepitus; and lastly, the rotation of the trochanter through an arc of a circle of which the head of the bone is the centre, instead of upon the axis of the shaft, as in detached fracture of the neck. The practical importance of readily identifying this fracture lies in the fact that its progress, as regards both time and good union, is in general more favorable than that of the unimpacted fractures; that though it is a comparatively common and disabling accident, it may exhibit little deformity; and lastly, that the object of extension in its treatment is to steady the limb, and not to draw it down. The following details of the ana tomical structure of the femur sustain the foregoing statements in respect to the shortening and eversion incident to this lesion. ANATOMICAL STRUCTURE OF THE Let a well-developed femur be placed in a vice with its back toward the observer, in its natural upright position, but obliquely, as if the legs were widely separated, the shaft being so far inclined that the neck is horizontal. Let a first slice be now removed from the top of the head, neck, and trochanter by a saw carried horizontally through the neck. Let a second and third slice be removed in the same way, so that the neck shall be divided into four horizontal slices of equal thickness.1 FIG. 1.2 It will be found that the upper section exhibits the anterior and posterior walls of nearly equal thickness; but that as we 1 If the head of the bone be now vertically transfixed by a wire, the sections may be spread for examination like a fan. 2 Fig. 1 exhibits a bird's-eye view of a horizontal section of the neck of the femur, showing the posterior wall plunging beneath the intertrochanteric ridge, at the angle where the neck joins the shaft. The posterior wall is of the thinness of paper, and here impaction occurs. The anterior wall, on the contrary, is seen to be quite thick, and forms by its fracture a hinge which is very rarely impacted. approach the lower surface of the neck the anterior wall becomes of great thickness and strength, while the posterior FIG. 2.1 wall remains thin, especially at its insertion beneath the posterior intertrochanteric ridge, where it is of the thinness of paper. ROTATION. The result of this conformation is obvious. In impacted fracture, the thin posterior wall is alone impacted, while the thick anterior wall, refusing to be driven in, yields only as a hinge upon which the shaft rotates to allow the posterior impaction. This phenomenon, varying a little with the injury, is constant in every specimen of simple impacted fracture I have examined; and in fact it must be so from the arrangement of the bony tissues, which at once invites and explains the eversion.2 SHORTENING. The hinge before alluded to is oblique, following the anterior intertrochanteric line. Were it vertical, by bending this 1 The same as Fig. 1. The section of the shaft near the lesser trochanter shows the lower extremity of the septum, where the wall is thicker and changes its direction. (From a photograph taken in 1861.) 2 M. Robert, in a memoir upon impacted fractures of the neck of the femur, attributes the posterior impaction to the supposed fact that the tangential plane of the external surface of the trochanter is inclined obliquely backward to the axis of the neck, and that a force applied to its centre would tend to increase the obliquity of this angle, and thus to produce outward rotation of the shaft. The shortening of the limb he attributes to the fact that the impaction is greatest at its lowest part. (Mémoire sur les Fractures du Col du Fémur accompagnées de Pénétration dans le Tissu Spongieux du Trochanter. Par Alphonse Robert, Professeur Agrégé, etc. Mémoires de l'Académie de Médecine, tom. xiii. p. 487.) hinge we should produce rotation without shortening. On the other hand, if it were horizontal and transverse, bending it would produce shortening without rotation; but as it stands at an angle of 45°, the shaft rotating upon this broken interval is shortened in proportion to its rotation,—or, what is the same thing, the neck is reflected upon its hinge downward and backward till its axis normally oblique may become even transverse, with great outward rotation of the shaft and a shortening of perhaps two inches. This is probably the most common cause of shortening, although the head of the bone may be otherwise depressed.1 TRUE NECK. Upon examining the lower of the above sections in a wellmarked bone, the posterior or papery wall of the neck will be seen to be prolonged by radiating plates into the cancellous structure beneath the intertrochanteric ridge. That the thickest of these (Fig. 1) is a continuation of the true neck may be shown in another way. Let the whole of the posterior intertrochanteric ridge, including the back part of both trochanters, be removed by a narrow, thin saw. (Fig. 3.) The bone being now laid upon a table, let a chisel, or what is better a gouge, be held perpendicularly upon the cancellous structure thus exposed, and lightly twirled until the friable and spongy tissue is removed and the instrument arrested by the septum, or wall, alluded to. To expose its inner surface, the shaft should be split by a vertical and curved section behind this wall, and the cancellous structure removed in the same way. The septum will then be distinctly seen as a thin, dense plate of bone continuous with the back of the neck and reinforcing it, plunging beneath the intertrochanteric ridge in an endeavor to reach the opposite and outer side of the shaft. At its lower See pp. 157, 161, 163. |