Chapter X: Some General Principles in the Re-Education of the Disabled 145 (2)

A U-shaped cord _a_ passes through a hole in the bracket C and is
attached at each end to the cross piece T; it limits extension. The
two ends of the word enter the thigh piece by two apertures in the
posterior surface, between which is fixed a metal ball which projects
2 cms. The extending spring is the rod _b_ which is fixed to this ball
and to a socket in the upper surface of the bracket. Figs. 54 to 57
show the parts of this spring: a tube, a spiral spring, and a rod with
cup-shaped head. When the spring is in the tube and the rod in the
spring (Fig. 57), it will be seen that pressure upon the head of the
rod increases the tension of the spring.]

In the knee shown in figures 58 and 59 the _extending mechanism_ is as follows. Directly behind the axis of the joint is a metal crossbar, upon which fits the grooved upper extremity of a piece of wood, the other end of which rests (like a lance) in a pocket which is suspended in the leg piece by an elastic band (the latter being kept stretched to a greater or less extent by a lace which emerges from the calf).

The elastic being slightly stretched when the knee is extended, it will be seen that the crossbar turning round the axis of the knee becomes lowered as the knee flexes, so that the elastic is stretched and consequently opposes flexion; but when the knee is bent to a right angle the axis of the joint, the crossbar and the wooden rod are in the same vertical line; the mechanism is at a dead point just as we have already seen in the Marks knee, and the tension on the elastic presses the leg directly downwards without tending either to flex or to extend it.

Leather pads deaden the noise of the impact.

Extension is limited, as will be seen by comparing figures 58 and 59, by the vertical wooden rod meeting flat surfaces in the thigh and leg pieces simultaneously.

3. _Extending slings._[6]--To the sling which passes over the shoulder on the side of the artificial limb, is attached a strap which passes down in front of the thigh piece and is attached to the upper third of the leg.

[6] This is an old French method used in Fouilloy's appliance, which has, however, only become generally used in the suspending braces of the American appliance.

When the patient raises the leg from the ground, the weight of the appliance makes it slip down the stump, tension is thus produced upon this strap and as a result the knee is extended. By an adroit movement of the shoulder this extension can be carried out actively.

When the limb rests upon the ground the weight of the body presses the stump down into the bucket, the tension on the strap is released and consequently the knee is free to flex.

On pages 44 to 48 will be found figures showing the principal points in this extending brace.

The braces, whether they have or have not an extending strap, may be constructed in three ways:

_a_. To ease the constant pressure exerted on the shoulders by the strap which is stretched by the weight of the artificial limb, the brace may be made of elastic like the ordinary trousers brace. But the limb they carry is heavy, so they rapidly become overstretched and it is difficult to keep them properly adjusted.

_b._ The stretching is naturally diminished if the upper part of the brace is not elastic but an elastic section is inserted in its lower third, in front and behind.

_c._ But the patients almost always say that better command of the limb is obtained with inelastic braces. If the strap is wide on the shoulder, the pressure is well borne, and the lower attachment may be made narrower, consisting of a leather thong (Fig. 64).

Fig. 61.

Fig. 62.

Fig. 63.

Fig. 60.--Fouilloy's Braces. Figs. 61 to 65.--Marks' braces.
Fig. 61.--General construction of the braces. Figures 62 and
63.--Attachment at the sides of the thigh piece. Figures 64 and
65.--General view of the apparatus as worn.]

To attach extension braces to the front of the leg piece the old and simple method adopted by Fouilloy may be used. It consists in attaching an elastic strap to the brace which passes over the shoulder on the side of the amputation (and which is fixed to the top of the thigh piece alongside of the other brace). The elastic strap ends in a bifurcated leather thong each branch of which (held in place by a loop of leather) descends obliquely alongside of the patella surface to be attached to the corresponding side of the leg in its upper third (Fig. 60).

In Marks' method the braces end below in loops made of a leather thong (Fig. 61). These are held against the thigh piece by passing under leather bands; they reach as far down as the upper third on the inner and outer sides of the thigh (Figs. 62 to 65).

To each of the loops, gliding on them by means of a pulley, is attached a leather strap which descends vertically to the upper third of the corresponding surface of the leg, being held in place by passing under a leather band. These two straps are attached to each other in front by a lace, which draws them towards the middle line, and in this way brings their line of action forwards. The tighter the lace is drawn the more powerful will be the extending force.

Instead of attaching the extension brace to the leg piece it may be made to pass under a pulley in the interior of the knee. What actually happens is that the thigh piece drops, owing to its weight, when the limb is swung free; this throws a strain on the brace which is transmitted to the leg piece by the following mechanism. The metal stop described on page 39 which limits extension of the knee during the period of weight bearing, is prolonged upwards and forwards beyond the hole through which the axis of the knee passes, this prolongation being furnished with two wooden pulleys (Fig. 69). The loops attached to the braces enter the front of the thigh piece, each by a separate opening, turn under the corresponding pulley and emerge again posteriorly (Figs. 66 to 68).

This mode of attachment has the advantage that when the limb is swung the movement does not take place upon the shoulders--which easily become chafed by the ordinary suspenders--but upon the pulleys upon which the leather thongs work.

The mechanism shown in figures 69 to 71 is interesting. When the metal lever moves around the axis of the knee joint, its lower end and the pulleys at the upper end travel in opposite directions: in flexion the pulleys move downwards and forwards, the lower end upwards and backwards; in extension they move in the opposite direction. Therefore when the limb is swung and the knee bends (Fig. 71), the thigh piece drops of its own weight, the braces tighten, raise the pulley and consequently make the lower end of the lever move downwards and forwards, thus extending the knee joint.

D. _Mechanism to secure rigidity of the knee during weight hearing._--During the time that the healthy limb is raised from the ground and carried forwards there must be complete rigidity of the artificial limb in the extended position. This is secured by mounting the foot in the equinus position. When it has been swung forwards, in taking a step, the limb comes in contact with the ground heel first; then, as the leg becomes vertical the entire sole lies flat on the ground; if the foot is in equinus this position is only possible with the knee hyperextended, or with full extension it may be possible for a very short period. So that it is the weight of the body that locks the limb in the extended position, the sole of the foot sloping obliquely downwards and forwards; and the weight being taken on the toe. There is always a tendency to hyperextension, and to avoid straining the limb in this direction (as occurs in a living knee which is forced into the position of genu recurvatum by a talipes equinus) it is as well, as we have already said, to oppose it by some passive resistance, either in the form of a simple popliteal check cord or by a stop fixed to the front of the leg.

Fig. 73.

Fig. 74.

Fig. 75.

In Figure 72 the foot is fixed, the weight comes upon the point of the
foot, and pressure upon the axis AB tends to close the angle ABC, i.e.
to produce a genu recurvatum, and so to lock the knee in extension.
If the foot is articulated, equilibrium is secured in the same way.
Figures 73 to 75 are intended to show that in order that the axis ABC
may not be vertical (Fig. 73) the axis B of the knee must be behind
the perineal concavity in the bucket, and it is better if at the same
time the axis of the ankle joint C is carried forward.]

This extension is unlocked automatically at the moment when the weight is thrown forward on the healthy limb, the artificial limb rising on its toe and the knee commencing to bend because the braces are relaxed.

E. _Movable ankle._--We have taken as our type a limb with a fixed foot. There are, however, a number of methods of attaching a foot with a _movable ankle joint_. The general principles and the mechanism for securing stability are those which we have already studied, but the gait is more supple, at the price it is true of somewhat delicate articulations and therefore of simplicity.

The foot is made of a single piece of wood; it is divided transversely at the level of the middle of the metatarsal bones, and the anterior part (shaped like toes) is attached by two pieces of leather, dorsal and plantar, between which are two indiarubber cylinders which keep the toe piece extended 15° to 20° when at rest, and which allow, when the foot is pressed on the ground, an extension to 45°.

This foot is mounted on the leg at an angle of 45° beyond the right angle, with an interposed rubber cylinder, which allows of the diminution of the angle to 25° or 30° but no further. It is important that flexion to a right angle should not be possible. In fact, a slight degree of equinus is essential in order to secure the locking of the knee in extension, exactly as with the fixed foot (compare figures 73, 74 and 75 with figure 72), and as on the shoe there is always a heel which makes us walk normally in slight equinus, the two feet will be similar in appearance, the slight movement of the artificial foot being sufficient to allow a rolling movement of the sole upon the ground (Figs. 77 to 86).

The figures 76 and 76A show the simplest and best known mechanism. On the upper surface of the foot two cavities are hollowed, one in front and one behind the bolt of the ankle joint, in each of these is placed a cylinder of rubber; the posterior cylinder is about twice as thick as the anterior. Above them the leg piece is fixed, it ends in front in a short instep which lies within the cavity hollowed out in the foot.

The foot is attached to the leg piece by a bolt made as follows: a steel tube fitting into two corresponding grooves in the leg and foot, is attached to the leg by being prolonged upward into a vertical rod, which is secured by a nut inside the leg piece.

Upon the steel tube moves a brass rod shaped like an inverted U, the two ends of which pass through the foot and fasten beneath it by two nuts (Fig. 82).

Raising the point of the foot further compresses the anterior piece of rubber, lowering it relieves the pressure upon this piece and compresses the posterior piece. But the tension and the size of the pieces of rubber are such that they are under slight compression in the position of rest, the foot being in 30° of equinus. So that this foot is never loose. When pressure is made on the point of the foot it may come to within 15° or 20° of a right angle, but it returns to its angle of 30° as soon as the pressure ceases.

Contact of the sole with the ground in normal walking. Heel first then
toe, with progressive dorsiflexion of the ankle joint. Compare with
the contact of the artificial foot in figures 82 to 86.]

With boots on, with heels of 2·5 centimetres the two feet are in the same position when the soles are flat on the ground.

The forepart of the foot (representing the toes and the anterior part of the metatarsals) is kept in this position (Fig. 76) in slight extension by a piece of rubber, compression of which allows an increase of extension of 15° to 20°.

When a step is taken, the heel of the foot first meets the ground, the leg pointing downwards and forwards. Then the whole sole comes to lie flat on the ground, the degree of equinus being increased, the posterior rubber compressed and the anterior relaxed (Figs. 82 and 83), but when the limb is vertical the sole still being flat on the ground, compression of the posterior diminishes and that on the anterior increases (Fig. 84). This remains unchanged up to the moment when the foot leaves the ground, whilst the heel rises and the weight is borne on the toe piece of the foot, which is forced into extension (Figs. 85 and 86).

FIG. 83.

FIG. 84.

FIG. 85.

FIG. 86.]

This method of using rubber cylinders is the simplest. Another method, good but more delicate, is shown in figures 87 and 88. In the leg below the calf are two cross pieces of wood; the lower placed transversely supports the upper which is antero-posterior and so increases its resistance to the cords which are attached to it.

The shape of these pieces of wood can be seen in the figures and require no further explanation. The bolt of the ankle joint is the same as in the foot last described. To the antero-posterior cross piece are attached two cords, which pass through the foot and are attached beneath it, one under the heel, and the other about the level of the midtarsal joint. The posterior cord is inelastic and stops dorsiflexion of the foot. The anterior has a section of elastic in it; it prevents the dropping of the foot whilst the limb is being swung. A small pad of rubber placed in front beneath the anterior part of the leg piece allows, by its compression, the partial correction of the equinus when the sole is pressed flat on the ground.

Some appliances allow the foot a little _lateral mobility_, by rotation around an antero-posterior axis, so that it may adapt itself to irregularities of the ground. We here illustrate the "Duplex foot," which is very ingenious but which has the defect that after a time the mechanism grates. The ankle attachment is carried out in the same way as in the limbs last described (in this particular limb it is attached by cords), but the foot piece is divided as in a sub-astragaloid amputation; the lower surface of the astragaloid piece bears a median antero-posterior projection, tapering posteriorly and enlarged into a knob anteriorly, this lies in a corresponding groove in the heel piece; alongside this are two rubber cushions which are alternately compressed and relaxed as the foot inclines to one or other side.

_Combined mechanism for knee and ankle joints._

This very ingenious combination, which, however, necessitates a rather complex mechanism, was devised by Palmer in 1850. It is carried out in the limb made by Frees, the mechanism of which will be seen to resemble that of the articulated foot shown on page 54 in figures 87 and 88.

Above the axis of the knee joint and at right angles to it is a wooden cross piece, to which are attached three cords, two behind the joint, one in front; these cords emerge from the thigh piece through an opening in its lower end (Figs. 90 to 92).

The posterior of these cords, made of hemp, ends inside the upper third of the leg. It limits the extension of the knee, exactly as described in the Marks leg.

The other two cords extend down to the foot, which is attached in a manner very similar to that shown on page 54, but with a single rubber cylinder behind, and with the instep cut obliquely so that when the joint is in the resting position of equinus there is an opening in front amounting to an angle of 15° to 20°. The posterior cord, of hemp, is attached in the heel; the anterior, made of catgut with an indiarubber section, enters the foot obliquely and is fixed a little in front of the middle of the sole.

When the knee flexes, the wooden cross piece tilts, its posterior end becoming lower, its anterior higher (Figs. 91 and 92), the elastic of the anterior cord is tightened, thus raising the front of the foot, whilst at the same time the heel cord is relaxed. Thus the mechanism which produces extension of the knee acts at the same time upon the foot; when the knee is straight the foot is plantar flexed to 20°, when the knee flexes the foot comes to a right angle. Thus the foot becomes dorsiflexed at the same time as the knee flexes, as in ordinary walking.

If the action in walking is watched, it will be seen that as the limb is swung forward, the toe is raised so as to clear the ground.[7]

[7] The mechanism of this artificial leg resembles that of the "tendon leg," which was in such common use in England before the present war that it is often called the English pattern.--(ED.)

FIG. 91.

FIG. 92.--(FIGS. 90 to 92. Foot and Knee of Frees.)]

In the sitting position the anterior cord is not relaxed, there is no dead point, so that the knee always tends to extend. This is somewhat inconvenient.

_Conversion of the articulated peg leg into the leg with free knee
movement and vice versâ._

Whatever advantage it may be thought to possess, in our opinion the artificial leg with free knee joint is only suitable for sedentary occupations; it is not suitable for manual labourers and particularly for agricultural labourers who are obliged to get about on rough ground. Hence it is not uncommon for a patient who has been provided with an American leg to come and ask for a peg leg. In figures 93 to 95 it will be seen that it is a simple matter to transform the limb into an articulated peg. It is only necessary to attach the stirrup-shaped fork of the peg to the thigh piece by the knee bolt, and to add the double lock. To this peg may be added, if desired, the show calf and foot described on page 32. The full artificial leg can be rebuilt whenever it is wished.

On the other hand, an articulated wooden peg leg, such as we have described under the name of the Federation leg, can be easily adapted for walking with a free knee. It is only necessary to unlock the knee joint and to add the artificial muscle or accumulator of elastic shown in figure 98. This supplies the extending force, the value of which we have shown on page 36. We consider that this appliance is excellent and we know patients who almost always walk upon the peg, but who sometimes use a free knee for short walks. The conversion is simple and requires no special care. Under these conditions the fixed foot is almost always used; there is nothing to prevent the fitting of an articulated foot, but we have already seen that there is no great difference in walking between the old-fashioned fixed foot of the Marks leg and the more or less complicated articulated feet of more recent design.

FIG. 97.

FIG. 98.]

II. Limbs without bearing upon the Ischium

_For amputations through the condyles of the femur, and similar
amputations_ (_disarticulation of the knee and very short stumps below
the knee_).

Certain orthopædists do not know how to fit an artificial limb to an amputation through the condyles of the femur; they come therefore to the conclusion that this is a bad operation, and ought to be replaced by an amputation above the condyles.

The two objections raised to this amputation are:--

1. That it is impossible to fit a wooden bucket because the bone at the lower end of the stump is larger than it is at a higher level.

2. That it does not leave enough room to fit an artificial knee joint at the right level.

These two objections are not valid, and, on the other hand, this amputation allows us to fit an artificial limb with complete end bearing, and this is a great advantage.

1. _Fitting of the bucket._--The first difficulty is easily got over. All that is necessary is to cut away the front of the lower half of the bucket, and to cover in this opening with a lacing piece of leather. The stump passes into the top of the bucket, comes out of this opening and then falls back into the enlarged lower end where it takes a direct bearing (Fig. 99).

2. _Level of the knee joint._--It is clear that if the stump is too long it is impossible to fit a knee joint with a bolt right through at the same level as the opposite knee. The thigh piece would have to be prolonged downwards in order to allow of the insertion of this bolt.

This arrangement would not affect walking, but would be unsightly in sitting because of the inequality in the length of the thighs.

It is easy to overcome the difficulty by attaching the leg by two independent lateral hinge joints, without a bolt right through, using the stirrup-shaped fork and the double lock, if a peg is used. This method, as we have already stated, is not so strong, but this is to a large extent compensated for by the possibility of getting a direct end bearing.

3. _Direct end bearing and suspension._--If the stump is well covered with a good anterior flap and if the lower end of the bucket is accurately moulded upon it with an interposed layer of felt, the patient can walk directly upon the end of the stump, without it being necessary to carry the bucket up against the ischium, simple braces being used as the means of suspension.

4. There is nothing special about the braces or about the extending strap if the knee is free, nor about the method of attaching the foot.

These limbs for long stumps do not require any spring to extend the knee, if one is wanted an artificial muscle is quite easily fitted.

We have taken as our type an amputation through the femoral condyles.

The covering of the stump is excellent, and pressure is taken upon tissues which are naturally adapted to it (the thick skin and fibrous tissue over the patella), specially if it has been possible to keep the patella in the flap and fix it across the cut surface of the femur (Gritti's operation).

The mechanical points in the fitting of an artificial limb for an amputation through the knee joint are the same. But this amputation seems to us to be inferior to that through the condyles. The sacrifice of three centimetres in length is of no importance in an appliance with direct end bearing; and, on the other hand, disarticulation has several disadvantages:--

1. The enlargement of the femoral condyles, without any compensating advantage.

2. The bearing upon the two condyles, separated by a groove.

3. The insufficient covering of the condyles by the thin skin of the front of the leg.

The principles of fitting a limb are the same in amputations of the leg in which we are obliged to make the patient walk upon the bent knee (too short a stump, the position of the scars, persistent osteitis, the impossibility of straightening the knee when it is ankylosed or stiff in a flexed position), as in the old-fashioned kneeling pin leg.

A posterior transverse band, passing over the bent stump helps to hold the limb on.

_CHAPTER IV_

ARTIFICIAL LIMB FOR DISARTICULATION AT THE HIP JOINT

Attempts have been made to attach to the pelvis, by means of a waist belt or braces, a wooden artificial limb whose upper end is fitted directly on to the tuberosity of the ischium. So far these have met with little success. In our opinion, the only really practical method is to enclose the whole stump and pelvis in a regular corset, and to attach the artificial limb to this corset.[8]

[8] Amongst English limb makers this moulded corset with the steel hip attachments is usually known as the "tilting table."--(ED.)

The moulding of this corset upon the stump must be accurate.

The tuberosity of the ischium is the only bony point in the stump upon which pressure can be taken. The corset may be made of leather, but, until a new order is issued, the material of choice is celluloid, moulded upon a plaster of Paris cast, in spite of the disadvantage mentioned on page 4.

The limb is an articulated peg leg, with convertible knee joint and double lock, exactly the same as in the limb for amputation through the thigh.

It is attached to the pelvis (_i.e._ to the tilting table), as shown in figures 100 and 101, by a joint with a double anterior lock, which allows the patient to sit down by flexing the hip.

FIG. 101.]

This general description and an examination of figures 100 and 101 will suffice to explain this appliance. It is comparatively rarely required, and its construction is difficult; we consider that the forms shown in the illustrations are the best. It is only possible to fit such an appliance when the conditions are good, when the scar is above and in front of the ischium, and when the latter is well covered.

_CHAPTER V_

ARTIFICIAL LIMBS WITH FREE KNEE JOINT FOR AMPUTATION THROUGH THE LEG

If the leg stump is ten centimetres long, if the knee joint is freely mobile and capable of complete, or almost complete, active extension, and if there are no adherent scars around the tuberosities of the tibia, the American apparatus with free knee joint should be adopted.

_Walking on the bent knee_ (as stated on page 63) with the "poor man's peg" may be allowed as a temporary measure, but the patient must be advised to give his knee a rest frequently in order to lessen the risk of stiffness in a flexed position.

There are two methods of fitting, corresponding with those we have described for the thigh.

1. For the ordinary amputations with bearing upon the top of the leg.

FIG. 102.--Limb fitted upon the patient. Note that he
stands upon the toe, and that the knee is flexed. ]

FIG. 103.--Posterior view of the same limb.]

FIG. 104.--Anterior view of the same limb.]

2. For amputation very low down with end bearing upon the extremity of the stump.

I. APPLIANCES WITH BEARING UPON THE TUBEROSITIES OF THE TIBIA

An artificial limb for amputation through the leg with a free knee joint is composed of two parts: a leg piece (with foot) which is fitted to the bony prominences around the top of the stump and supports them; and a suspensory apparatus which consists of a lacing thigh corset.

A. LEG BUCKET.--The points on which the top of the bucket must be fitted are the internal tuberosity and the anterior tubercle of the tibia, and the head of the fibula, so that hollows corresponding to these must be carved out.

Pressure upon the head of the fibula is often painful, and a deep concavity is therefore carved out for it. The pressure then comes upon the external tuberosity of the tibia which, however, ordinarily bears little weight.

Whenever possible direct end bearing upon the termination of the stump should be used as an accessory to relieve the weight upon the tuberosities of the tibia; this is obtained as described on page 7. It is only possible if the scar is lateral and if there is a good thick posterior or external flap (in the upper third of the leg). An anterior flap is the least satisfactory.

It is also advisable--

That the inner surface and the anterior border of the tibia be divided obliquely, and that the fibula be divided at a higher level than the tibia.

The fibula must not take weight, it is too slender. In high amputations it has a tendency to tilt outwards, causing the double inconvenience of widening the stump and of projecting through the skin. If only 4 or 5 cms. of the fibula remain it is perhaps best to disarticulate and remove it.

With a fitting arranged in this way, we consider that the convenience of walking with a free knee can be assured to patients whose stumps measure only 10 cms. from the lower border of the patella.

These principles can be applied to a limb constructed either of wood or of leather.

_The leather appliance_ (French method) is formed of a leather cylinder, strengthened by two laternal steels which articulate at the level of the knee joint with two similar steels in the thigh corset. Its upper edge may be strengthened anteriorly by a metal plate, but in practice the latter cannot be made to fit with precision the bony prominences enumerated above. It is actually the edge of the leather, adjusted by lacing, which supports tibial tuberosities, and therefore the precision of the fit is soon lost.

For this reason, for amputation below the knee, the American method of construction with a wooden bucket is demonstrably superior.

These limbs are infinitely more durable than the French. They may last three years, whereas the French limb used by a young and active patient is worn out at the end of the first year, and it was for this reason that a limb with a free knee joint used to be considered a luxury.[9]

[9] That is the reason that amputation at four fingers' breadth below the knee used to be called for the working class, amputation at "the seat of election," a name which is no longer applicable and which is liable to mislead the operator.

This wooden bucket is shaped very accurately to the bony prominences, and by passing the fingers over its inner surface the three hollows corresponding to the points of pressure enumerated above can be distinctly felt.

It is important to describe the shape of the upper edge of the bucket in order to guard against two points which may interfere with flexion--

I. Pinching of the tissues behind the knee.

II. The tendency of the stump, when it is short, to tilt forward
in the bucket (Fig. 108).

_Pinching of the flesh behind the knee_ in flexion takes place between the edge of the leg piece and that of the thigh corset.

If the top of the bucket is horizontal, it must inevitably occur, even if the edge of the thigh corset is well cut away (Fig. 106).

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.[10]

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

[10] 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.[11]

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).

[11] 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.)

Certain limb makers consider these operations are bad for the same two reasons that we have already refuted in connection with amputation through the condyles of the femur, viz.--

(1) The stump being enlarged at its lower end will not fit into a wooden bucket.

(2) The stump is too long to allow an artificial foot to be fixed below it.

From this it simply follows: 1. That complete enclosure of the stump in a wooden bucket is impossible; 2. That pressure must be placed directly and exclusively upon the end of the stump.

The latter condition is only possible if the state of the soft parts allows the cutting of a thick plantar flap to cover the cut surface of the bone and if care be taken to resect the posterior tibial nerve in the flap.

We therefore draw special attention to the excellent elliptical supra-malleolar amputation with posterior flap (Guyon's method) in which it is sufficient to retain a bare finger's breadth of skin from the plantar surface in front of the point of the heel. It bears direct pressure well, perfectly if a layer of the os calcis is cut with the scissors from the area adjacent to the tendo-Achillis and applied under the cut end of the tibia.

For all these amputations the anterior flap is bad. The thin dorsal skin of the foot is incapable of withstanding the direct pressure which is indispensable for this method of fitting.

Even if it were true that under these long stumps it is impossible to insert an artificial foot for lack of space, the operations which we have enumerated above should be recommended if the flap can be cut in the way we have indicated.

Their great advantage--and the reason for retaining as much length of bone as possible--is that they allow walking directly on the stump without an apparatus. It is sufficient to have a circular shoe made by any shoemaker consisting of a heel more or less thickened surmounted by a lacing gaiter reaching halfway up the leg. Guyon's amputation constitutes the limit up to which this "elephant boot" is possible.

It is an unsightly apparatus, but its simplicity and cheapness should be taken into consideration, for it is quite possible that a manual labourer, especially a countryman, to whom an artificial foot and an "elephant boot" are given, will reserve the former for Sunday and use the other for his daily work.

APPLIANCES WITH ARTIFICIAL FOOT.--The wooden piece which partly encloses the stump consists of a block carved to the shape of the stump and padded with felt, it is prolonged in front by an instep reaching to the level of the middle of the metatarsus, and above by a grooved piece which reaches halfway up the leg and encloses the anterior half of the latter. A leather gaiter is fixed at the sides and back and extends up the leg, being laced in front over the wooden piece as a field boot is laced over the leather tongue. The foot may be mounted at right angles to the leg, but it is better mounted slightly in equinus.

The sole and toes are of rubber as described on page 35.

In studying figures 120 and 121 the following should be noted:--

1. The shape of the leg bucket in which an aperture behind permits the introduction of the stump which is enlarged at its lower end.

2. The mechanism by which the posterior gaiter laced in front fixes this leg bucket.

3. The articulation of the foot on a transverse axis.

_CHAPTER VI_

PARTIAL AMPUTATIONS OF THE FOOT

This name should be applied to amputations in which the mobility of the ankle joint is retained, _i.e._ Chopart's amputation (midtarsal disarticulation), Lisfranc's amputation (tarso metatarsal disarticulation), amputation of several toes with their metatarsal bones, or amputation of all five toes.

1. _The amputations of Chopart and Lisfranc._--Chopart's amputation has a grave defect: the anterior muscles have not sufficient leverage to oppose this gastrocnemius and soleus, and the posterior tarsal bones tilt forward so that the patient walks, not on the lower surface of the os calcis and the plantar skin, but on the head of the astragalus and of the os calcis and on a painful cicatrix. If certain precautions are taken (careful preservation of the fibrous plantar flap and suture to it of the anterior tendons) this defect is not invariably present, and it is an exaggeration to say that Chopart's amputation "has never given anything but disappointment." It should, however, only be practised if the technique is well understood, and even then it is rarely indicated, because it demands almost as much plantar skin as Lisfranc's amputation.

Nevertheless I have seen some good Chopart stumps the result of operations by myself or by other surgeons; they should be fitted like the stumps resulting from Lisfranc's operation.

With regard to the latter, they can be easily and comfortably fitted, provided that the scar is dorsal and is not stretched over prominent bones.

If the first cuneiform is not well covered it can simply be removed, no functional disability results. It is mainly upon the plantar surface of the stump that pressure is borne, but pressure comes also upon the anterior surface when the foot is tilted downwards.

The fore part of the foot which constitutes the prosthetic apparatus consists of a block of wood, which reaches forward as far as the middle of the metatarsus and ends in a vertical plate in front of the stump. This block of wood is carved to the shape of the stump and lined with felt. It is attached to the leg by a leather gaiter which laces in front.

Anteriorly it is prolonged into an artificial toe piece similar to that already described for the artificial limb for amputation through the thigh.

This appliance is not indispensable. It is sufficient to use a piece of cork shaped to the anterior surface of the stump and filling up the anterior part of the boot, its advantage, however, is that once the patient is fitted with this appliance he can wear an ordinary boot.

2. _Partial Amputation of the Fore Part of the Foot._--These are--

Transverse amputation through the metatarsal bones.

Disarticulation of one or more toes with their metatarsal bones.

Disarticulation of one or more toes.

For any of these amputations all that is required is an ordinary boot, fitted with a cork, which is shaped to fit the stump and which fills up the space left by the amputation.

In order that the patient may walk well the scar should be dorsal and should not be tense.

We consider that the difficulty of maintaining equilibrium after removal of the head of the first metatarsal, or even of the whole of this metatarsal bone, has been much exaggerated.

Removal of a marginal metatarsal bone (either alone or with its neighbour), tends to make the foot tilt into varus or valgus; so that the boot needs to be stiffened and the sole thickened to avoid this.

_CHAPTER VII_

ARTIFICIAL LIMBS FOR AMPUTATION THROUGH THE FOREARM

The constituent parts of an artificial arm are the same in principle as for those of an artificial leg, they are--

1. A means of attachment preventing the appliance from dropping as the result of its weight.

2. A socket, fitted to the stump and articulated with the last named at the elbow.

3. The terminal appliance, intended to replace as far as possible the amputated hand and, if possible, resembling it in appearance. In the case of the upper limb the advantages that wood possesses in giving strength and accuracy of fit do not apply, and the arm and the forearm pieces are made of leather, with lateral steels articulated at the elbow: this joint is active in the case of amputations of the forearm but purely passive in amputations of the arm.

We will commence by describing the appliance for amputation through the forearm, taking as our type amputation in the lower half. This will furnish an example which illustrates all the principles that should guide us, the ends we should have in view, and the means by which we can attain them.

When once we have studied the apparatus by means of which the functions of the hand can as far as possible be replaced, a short description will suffice to explain what can be done when the loss of movement of the elbow and then a shorter and shorter stump in the upper arm oblige us to diminish the utility of the appliance.

We must study in turn: (1) The attachment of the upper arm socket; (2) the joint between this and the forearm socket; and (3) the appliances attached to the extremity of the forearm whether these take the shape of a hand or not.

1. POINTS OF ATTACHMENT

1. SUSPENSION.--In the exceptional amputation very low down, in which the roots of the thenar and hyperthenar eminences remain, the enlargement thus formed at the extremity of the forearm may be used for the attachment of a wristlet which may suffice to support the artificial appliance, provided that the latter is not intended for heavy work. In the latter case an attachment from the elbow at least must be added.

This method would evidently be out of the question in the usual class of case, viz. ordinary amputations through the forearm.

In these the attachment may be made in two ways:--

(1) To the humerus above the condylar enlargements, the epicondyle and the epitrochlea, the latter being much the more prominent.

(2) To the top of the shoulder, _i.e._ to the surface over the acromion and clavicle.

A. _Attachment to the Elbow._--The simplest method of attachment is that in which pressure is exerted upon the condyles of the humerus (Fig. 124). A leather armlet laced in front is furnished with two lateral steels, curved in above the condyles and articulated at the level of the centre of rotation of the elbow joint with two similar steels in the forearm piece (the socket).

FIG. 123.--The three regions used as points of support, the
shoulder, the elbow and the wrist.]

FIG. 124.--Suspension from the elbow. The side steels of
the arm piece are curved in to fit upon the supra-condylar ridges of
the humerus. A good method of suspension for long stumps, when the
appliance is not to be used for heavy work. It should be supplemented
in other cases by direct suspension from the shoulder.]

This direct method of attachment is sufficient for a low amputation, in cases where the patient does not do hard work. But if the stump is short and if the patient has to carry fairly heavy weights the appliance is only prevented from slipping by a considerable constriction of the arm, which results in a serious interference with muscular action.

B. _Attachment to the Shoulder._--For this reason it is usually advisable to supplement this by an indirect attachment to the acromion and clavicle by means of a shoulder cap.

The firmest and strongest pattern consists of a piece of blocked leather, moulded to the shoulder, including the pectoral, supra-clavicular and scapular regions. This is kept in place by a strap which passes under the opposite axilla. It is cut away on the outer side of the acromion, the anterior and posterior borders being continued downwards on either side of the deltoid as two tapering straps to which the armlet is attached. In this way full liberty of movement is allowed to the shoulder (Fig. 125).

This pattern is strong, but cumbersome and heavy. It can be lightened by reducing it to an antero-posterior strap, 6 or 7 centimetres wide, over the clavicle and spine of the scapula, ending in front and behind at the level of the axillary folds in triangular enlargements. In the upper and inner angles of these are attached the ends of the axillary strap, to the lower and outer angles, prolongations from the armlet (Figs. 126 and 127).

The lightest method, but obviously also the least secure, consists in suspending the armlet by two straps, anterior and posterior, which cross above the clavicle and then pass in the form of a loop under the opposite axilla (Fig. 128).

The choice between these three methods of attachment depends upon the profession of the patient and the strength required by it.

2. RESISTANCE TO UPWARD PRESSURE.--The artificial limb should be capable of resisting upward pressure, when a thrusting force is exerted by the hand. This is secured in the following three ways, the hand being presumed to hang vertically with the elbow straight:--

(1) By pressure of the end of the stump in the socket (in amputations low down with a palmar flap--for example, in disarticulation at the wrist joint).

(2) By pressure of the top of the forearm socket on the enlargement of the forearm below the elbow.

(3) By pressure of the inner side of the upper edge of the armlet against the axilla.

But, in actual work, thrusting movements are nearly always made with the elbow bent to a right angle or almost so, then the pressure transmitted through the forearm piece is borne almost entirely by the steels of the armlet.

3. RESISTANCE TO ROTATION.--A well-adjusted artificial arm cannot rotate on the limb because--

(1) The forearm is elliptical in section and not circular, this is specially so in the lower third.

(2) Flexion of the elbow is only possible if the artificial joint is in the same plane as the axis of the elbow joint--that is, the sagittal plane.

(3) The axillary strap of the shoulder attachment prevents rotation.

FIG. 129.--The three regions used as points of resistance to
upward pressure.]

FIG. 130.--The three regions at which rotation of the
apparatus may be prevented. ]

2. ELBOW JOINT