Part 7

FIG. 3.

In the upright position the rami of the pubis and ischium, between which stretches the perineum, slope downwards and backwards at an angle of about 45° with the horizontal. The tuberosity of the ischium bounds the perineum posteriorly, and is its lowest point. The rami of the pubis and ischium, corresponding to the genito-crural fold, mark the boundary between the thigh and the perineum. These bones are unable to stand the pressure of an artificial limb.

If the top of the bucket is narrower than the circumference of the top of the limb, measured below the ischium, it may be circular and still give support to the ischium, which will not slip into it. If the ischium does slip into the bucket, the result will be that it no longer serves as the support, the pressure coming instead upon the rami of the pubis and ischium and upon the perineum.

The constriction thus exerted upon the top of the stump may easily become insupportable. The correct solution of the problem is to cut down the upper border of the bucket opposite the perineum, letting it rise again posteriorly beneath the tuberosity of the ischium, and gain a good support there.]

The same slope may be given to both edges of the bucket (Fig. 5). This obliquity in the posterior part serves no useful purpose: it is better on the contrary to lower the posterior border combining this semioblique fitting with a rise beneath the ischium and a depression under the perineum (Fig. 6).

These conditions are easily carried out in a well-made wooden bucket, represented in figures 8 and 9, in which it may further be seen that from the front it is convex outwards; from the side, convex forwards (Fig. 9). This form, which is that of some good American appliances, ought to be generally used.

The curve outwards, by drawing away the soft parts from it, frees the region of the ischium and allows the tuberosity of the ischium to press upon the bucket (Fig. 8).

If the thigh piece is curved forwards, and particularly if the limb is built with a very slight flexion of the knee, the stump remains slightly flexed at the hip and the patient feels as if he is sitting in the apparatus.

When the thigh piece is straight, an uncomfortable pressure is produced by the edge of the bucket against the ischium. It may be added that extension of the hip is very often impaired, particularly in patients with a short stump: The extensor muscles being divided, the flexors cause contraction into a flexed position, the more so the shorter the stump is. If the thigh piece is straight, the short stump cannot follow the movement of extension necessary in walking; it slips out of the bucket if the anterior lip of the latter is too low.

The principles are the same for the leather bucket, known as the French pattern.

FIG. 5.

FIG. 6.

FIG. 7.

FIG. 8.

FIG. 9.

Figure 4 shows the circular bucket (almost always too large) of the poor man's peg leg, attached to the body by a belt which is fastened to a projection upwards from the outer side of the bucket.

Figure 5 shows the oblique bucket, with symmetrical anterior and posterior borders. Figure 6 one with the anterior border oblique, the posterior border being cut away. Figure 7 shows the double obliquity, downwards and backwards, of the bucket. The convexities of the bucket and thigh piece, in the type which we consider to be the best, are shown in figure 8 (convexity outwards), and figure 9 (convexity forwards).]

In this the thigh piece is strengthened by two lateral steels (to the lower end of which is fixed the leg piece) joined posteriorly by a semicircular cross piece on which the ischium should rest (Fig. 13).

The usual form hitherto has been that shown in figure 10. The cross piece was horizontal and formed simply a posterior semicircle; the lateral steels were straight. Consequently in this pattern these steels form a cone, in which the soft parts are not compressed on the inner side, nor drawn outwards, as in the apparatus previously described. Further, as long as the stump is not shrunken, the ischium covered on its inner side by soft parts sinks into the bucket, and it is the perineum which becomes the point of pressure (Fig. 11). Made of leather, the perineal concavity soon loses its shape and really no longer exists. Finally the bucket is circular, with the faults inseparable from that shape (Fig. 12).

In cases where it is felt necessary to employ leather, all these faults are easily corrected, by giving the cross piece the shape which we have described for the wooden bucket, and by prolonging it forwards through two-thirds of the corresponding circumference, in the shape of an oblique bucket. (Dotted line in Fig. 12.)

If it is not strengthened, an oblique border of leather gives way, and after a few months' use allows rotation. The leather which extends from the termination of the metal ascends very steeply towards the trochanter, whilst the posterior border of the bucket, which is horizontal, curves downwards on the inner side to form the perineal concavity.

FIG. 13.

FIG. 14.

The ordinary leather bucket is mounted upon two lateral steels, which are joined by a posterior cross piece (Fig. 13). This framework is shown in figure 10, and covered with leather in figure 12. If the lateral steels are straight and divergent, this has all the defects of the straight circular bucket. The concavity for the perineum, cut out of the leather, soon loses its shape. It is, however, easy to shape the cross piece as shown in figure 14, with a perineal concavity and the anterior border oblique, following the dotted line in figure 12. By doing this and curving the steel uprights appropriately, the correct form of the wooden bucket can be copied exactly in a leather and steel apparatus. Such a correct apparatus is shown in figures 15 to 18.]

In figure 14 is seen the metal framework; in figures 15 and 16 that of the apparatus covered with leather; in figure 17 the support upon the ischium; and the possibility of making this appliance identical with the wooden bucket will be observed (Fig. 18).

II. MODE OF SUSPENSION

Suspension of the thigh piece is essential, and is all the more important when the stump is short and consequently more liable to slip out of the bucket. For this purpose support may be taken either from the waist, upon the prominence of the iliac crests, or from the shoulders by means of braces. In the case of a long stump (amputation below the middle of the thigh) only one of these methods is necessary, we shall describe the usual methods:

The waist belt (French system) for leather appliances.