Part 16

It can be avoided by cutting away these two edges into concavities opposite each other.

FIGS. 105 and 106.--Limb in which the upper edge of the leg bucket is almost horizontal; in the sitting position (Fig. 106) the flesh at the back of the thigh is pinched even if the lower end of the thigh corset is well cut away.]

In the French limbs made of leather it is usual to make the leg piece very high in front, i.e. as high as the middle of the patella. This is quite useless. The posterior border is cut down to a depth of two fingers' breadth below the axis of the joint. Pinching is thus avoided, but the posterior support is insufficient, the stump tilts forward as described above and the bucket gapes in front (Fig. 108). If the top of the bucket is horizontal--as in certain American limbs--there is, as we have already said, pinching of the popliteal tissues and compression of the popliteal vessels and nerves (Fig. 106). A concavity is therefore necessary, but one reaching to one finger's breadth below the axis of the joint is sufficient. In front the edge of the bucket reaches up to the joint line, this is quite sufficient to enclose the bony prominences (Fig. 109).

The posterior concavity of the leg piece is combined with a concavity in the thigh piece varied in accordance with the thickness of the popliteal soft parts.

FIGS. 107 and 108.--If the leg bucket is hollowed out too much at the back, the stump is tilted obliquely forward (Fig. 108), the knee loses contact with the bucket, and the flesh at the back of the thigh is pinched.]

To diminish further the tendency of the stump to tilt forward the posterior edge of the bucket is flattened so that the shape of the top of the bucket is triangular with curved sides and angles much rounded (the anterior angle over the tuberosity of the tibia being obtuse). This is the natural shape of a section of the top of the calf. In this way the posterior muscles are flattened and no longer tend to escape from the bucket when the knee is flexed. In figures 110 and 111 are shown two ways in which this flattened posterior margin may be shaped.

B. SUSPENSION APPARATUS.--The leg is attached (a) by a thigh corset taking its hold on the femoral condyles, and (b) by braces over the shoulders.

(a) The thigh corset is made of leather laced in front. Two lateral steels curving in sharply against the upper part of the condyles (Fig. 112) form the most effective part of the support. At their lower ends they are articulated with two steels passing up from the top of the leg to which they are attached. The joint (Fig. 113) is composed of a nut, A, into which fits a screw. Around the nut is a copper ring made to move with the femoral steel by means of a stop-notch. When the knee flexes and extends the wear comes upon this copper ring. The steels remain intact. If the joint works loose it is sufficient to renew the ring.

FIG. 113.

FIG. 112.--The thigh steels, curved in above the condyles, hold the limb on very securely.

FIG. 113.--Details of the joint at the knee.]

In this illustration the joints are placed too low. They should be opposite the centre of rotation of the knee joint, i.e. a transverse line passing through the femoral condyles. (ED.)

(b) The braces are a very useful addition which French orthopædists should employ systematically.

They increase the stability of the limb and allow the thigh piece to be laced less tightly, so that contraction of the thigh muscles is facilitated.

Support may be given by a strap from a waist belt as shown in figure 117, but proper braces are better. These braces pass over the shoulder of the sound side and are attached either to the thigh corset or to the leg piece of the artificial limb. Attachment to the thigh corset is made by a single strap either in front and behind (Fig. 114) or on either side of the front lacing, the ends of the strap crossing in front of the groin (Fig. 115). It is a simple matter to add to the brace an extending strap, such as we have described for the artificial limb for amputation through the thigh (page 44). It is only necessary to terminate the brace in a strap from which two branches pass down in an inverted V and are fixed to the sides of the front of the leg piece (Figs. 116 and 117). This is unnecessary if the stump is long, for its leverage will then be good. It is, however, very useful for short stumps which give little power to the action of the quadriceps. In the case of patients with a long stump an attempt has been made to abolish the thigh piece and suspend the limb exclusively by braces. This method, we believe, is inadequate even if it is completed by a transverse band above the knee (Figs. 118 and 119).

C. THE FOOT.--The foot, usually articulated, is fixed in exactly the same way as in a limb for an amputation through the thigh, i.e. it is mounted in the equinus position. But in this case, however, precautions must be taken against stretching of the posterior ligaments of the knee joint, because the equinus mechanically produces hyperextension of the knee, and a genu recurvatum may result. For this reason a strap must be fixed posteriorly between the thigh corset and the leg piece to prevent full extension of the knee (popliteal check cord). This means that we make the patient stand and walk with slight flexion of the knee and with a corresponding elevation of the heel of the shoe (2-3 centimetres).

II. APPLIANCES WITH END BEARING ONLY

These appliances are suitable for certain amputations very low down in the leg which we must first define.

The orthopædist should consider the following operations as very low amputations of the leg, allowing of walking with end bearing only, and suitable for the same type of appliance:--

Supra-malleolar amputation.

Disarticulation at the ankle joint.

Sub-astragaloid amputation.

Osteoplastic amputations through the os calcis (or amputation in which the os calcis is retained entire after removal of the astragalus).

In England, of course, this is always called Syme's amputation. It constitutes the type par excellence of the end-bearing stump. Upon a good Syme stump a patient may be able to walk ten miles without an artificial foot, wearing simply an "elephant boot." Amputations above the Syme level are not end bearing, however long the stump may be. The other amputations in this region seen in English war surgery are the various types of osteoplastic amputations in which a part of the os calcis is retained (Pirogoff's amputation, etc.). These have the following defects:--

(1) There is often sepsis between the tibia and the os calcis, necessitating re-amputation. Osteoplastic amputations are unsuitable for septic surgery.

(2) Ankylosis between the os calcis and the tibia is often imperfect so that the bulbous end of the stump is unstable.

(3) The stump is too long to allow of the fixation of a good artificial ankle joint beneath it. A Syme's amputation leaves two to two and a half inches clearance between it and the ground.

I have not yet seen a sub-astragaloid amputation in war surgery, and only once a disarticulation through the ankle joint, the latter could not bear pressure and it was necessary to convert it into a Syme's amputation. In fact, in this region there is Syme's amputation and a number of other far inferior amputations which should never be considered when a Syme's amputation is possible. (Ed.)