curretting the foci

Whether we are dealing with an amputation of the leg or an amputation
of the thigh, the principle function of the artificial limb is to
support the weight of the body. The bucket must therefore give support
to this weight. Three bearing points are thus possible: at the base,
upon the surface and upon the end of the stump.

1. _Bearing upon the base._–The principal bearing is that which
is taken by fitting the upper edge of the bucket under the bony
prominences situated around the last joint preserved, i.e. the
tuberosity of the ischium for the thigh, the head of the tibia for the
leg.

2. _Bearing upon the surface of the stump._–Certain makers attribute
to this an importance which we believe to be imaginary, but which
leads them to erroneous conclusions.

It is evident that if a conical stump which is jointless and which
transmits the weight is fitted exactly, point downwards, into a
conical bucket, supported below by a vertical pillar, the weight is
transmitted by the friction of the part enclosed against the bucket,
without any pressure upon the free end. Whence it may be concluded
that, as the end of the stump should not serve as a bearing point, we
should prefer a terminal scar to lateral scars which might be rendered
painful or even ulcerated by friction against the bucket.

But experience shows us that if the pressure of the bucket at this
point is harmful to the lateral scars, it is not less so for most
terminal scars.

The stump in its bucket is in fact a bone, furnished with soft parts
upon which we cannot exert vertical pressure, without squeezing them
back towards the base of the stump, thus exerting an upward tension
of the terminal soft parts over the end of the bone. This is bound to
occur unless there is a considerable length of soft parts beyond the
end of the bone, that is unless more bone has been sacrificed than was
necessary. In this way we get all the disadvantages of an end bearing
without its advantages.

3. _Direct end bearing._–This is only the principal bearing in
certain special stumps which we shall indicate in due course; in some
of these it is the sole bearing. In the case of apparatus for the
usual amputations, above the epiphyseal enlargements, it is never more
than a complementary or accessory bearing, although a very useful one.

To take pressure upon the end of the stump it is only necessary to
stretch across the bucket at the right height a piece of material
covered with felt. If the apparatus is made of leather, the support is
taken upon a circular band of metal fixed to the lateral steels.

In order that direct pressure upon the stump may be possible, two
conditions are indispensable: that there is no terminal scar; and
that the extremity of the bone is well covered with a thick and
nonadherent flap. Actually walking directly on the stump does not
involve simply support by pressure, but also inevitable friction,
of greater or less importance, caused by the backward and forward
movement. This is only realised under the most perfect conditions if
the skin is adapted by its structure to this movement. This is the
case with the sole of the foot: where the epidermis and dermis are
thick and the subcutaneous areolar tissue and deep fascia, continuous
with it, enclose little cavities filled with globules of fat; these
form a cushion, like little globules of liquid gliding over each
other. The skin of the point and of the posterior surface of the heel
is less suitable anatomically than that of the sole: it is, however,
good, and it is for this reason that after amputation above the
malleoli, it is possible to walk directly upon the cut surface of the
tibia.

Nevertheless skin which is not prepared in this way by its normal
structure can adapt itself to pressure and friction, provided that
it is padded by a thick muscular layer, sheathed whenever possible
with fibrous tissue. A skin which is not so lined, especially in
fair and stout people, with thin and delicate skin, ulcerates easily
as the result of friction or even of simple pressure, and bursæ and
callosities form. See what happens to the skin on the dorsum and outer
side of the foot in the case of talipes equino varus. The muscles of
the flap will not remain over the bone in the condition of muscular
tissue, they become fibrous–but they are useful because:

1. They interpose a fibrous layer of greater or less thickness between
the bone and the skin, so that the latter remains movable over the end
of the bone and is not directly compressed;

2. They adhere to the cut section of the bone forming a tendinous
insertion, which renders their action on the bony lever more powerful.

A flap bears weight badly when the muscles have retracted around the
bone, over which there is then nothing but skin. It is the same when
the flap is stretched tightly across the end of the bone, _the soft
parts must remain soft and free_.

Among the hundreds of cases of amputation of the leg or thigh that
have passed before us in being fitted at the _Fédération des Mutilés_,
there were many in which the presence of a terminal scar rendered the
fitting of an apparatus difficult; we have never found this the case
with a lateral scar; we have never seen the latter ulcerate rapidly as
the result of pressure or friction in a properly made wooden bucket.
So that it cannot be admitted that the proper covering of a stump is
ever a matter of secondary importance.

Consequently we should consider, as a matter of principle, the
circular method of amputating only as a last resort, and we ought to
arrange the section of the soft parts so as to cover the end of bone
as adequately as possible, and to bring the scars to one side.

We realise that in practice war surgery often necessitates deviations
from the ideal. We often find ourselves in a dilemma–either the stump
must be good but too short; or, being long, must be poor or even bad.

In the special case of the thigh, circular amputation in the lower
third when it is carried out through healthy tissue and has not
suppurated can be trimmed and sutured in such a way as to give an
excellent scar, which is transverse and slightly posterior. In this
situation after these routine amputations, a linear scar which is
supple and has healed by first intention, separated from the bone
by a good cushion of muscular and fibrous tissue, causes little
embarrassment, whatever its position; at the end of a few months it
stands pressure and friction without harm. But we are considering
war surgery and consequently we are often called upon to fit stumps
in which the cicatrix is large, hard, and more or less irregular, in
which the bone has suppurated and in which the neighbouring soft parts
are indurated and scarred. These stumps are not, however, the results
of the work of the worst surgeon.

Amputating through infected parts, resigning himself to healing by
granulation and subsequent trimming by operation, he must take time
and trouble to attain in the end a result which is good functionally,
although at first sight unsightly. But it is this surgeon who is on
the right road, rather than he who sends us good stumps which have not
suppurated, because he has amputated through the thigh for a wound of
the middle of the leg, or through the leg for a wound of the foot or
even of the front of the foot.

It is clear, that for the stump effectually to play its part of a
lever in its bucket, a certain definite length is necessary; and we
ought to do everything possible to secure a length of at least 15 to
20 centimetres in a thigh stump, or 10 to 12 centimetres in a leg
stump. But when this length is secured, there is no great functional
difference between, for example, an amputation of the leg in the
lower third or in the lower quarter, particularly if the fitter
understands how to utilise direct end bearing. The knowledge of this
is of capital importance to the surgeon called upon to carry out
secondary operations upon imperfect stumps, in determining whether
it is possible to put an immediate stop to suppuration by drastic
shortening, or whether he must preserve length and lose time by
curretting the foci of inflammation in the bone.

There are two entirely different modes of fitting:

I. For amputations above the condyles, in which weight must always be
borne upon the tuberosity of the ischium through the top of the bucket.

II. For amputations through the condyles (or for disarticulation of
the knee) in which a direct end bearing may suffice.

I. Apparatus with Bearing upon the Ischium

(_Amputation above the condyles._)

In the construction of an artificial limb for amputation through the
thigh two entirely different principles may be used, according as it
is desired to make the patient walk upon a rigid shaft, that is to say
upon a peg, or upon an artificial leg proper, in which the knee bends
in walking (known as the American leg).

But whichever principle is adopted, whatever material is chosen, wood
or leather, and however exact the fit in the bucket may be, certain
common rules govern:–

1. The shape of the top of the bucket by which it is fitted to the
top of the thigh and its bearing upon the ischium.

2. The attachment of the limb to the trunk.

To begin with we shall consider these two questions, and then
temporary and permanent apparatus, the peg leg and the full artificial
limb, will be described.

I. THE SHAPE OF THE TOP OF THE BUCKET

The tuberosity of the ischium is the sole bony point which can prevent
the ascent of the limb when weight is applied. This tuberosity is
situated in the posterior part of the perineum (Fig. 1), the anterior
part of which is unable to stand pressure. It is necessary, therefore,
to clear this part by cutting down the inner border in its anterior
part, forming a _perineal concavity_, which rises posteriorly against
the ischium (Fig. 3).

It is essential that the ischium should not be able to slip inside
the bucket, otherwise the inner border will come in contact with the
perineum: therefore the diameter of the bucket must be less than that
of the limb, so that the ischium may rest upon its upper edge.

If the bucket is too large, the patient abducts the stump, so as
to lower the inner border and prevent pressure on the perineum; he
carries the leg away from the side as he walks, and this is both
unsightly and fatiguing.

When an apparatus is completed, it is very easy to ascertain the site
of the pressure on the ischium. The limb being put on, the ischium
is fixed between the thumb and first finger, and it can then be
ascertained whether it rests on the edge of the bucket or lies within
it. This can be determined more exactly, if whilst the fingers which
mark the position of the ischium are kept within the bucket, the
patient is told to raise his stump.

If the bucket is sufficiently narrow, it may be circular without the
excavation for the perineum (Fig. 2). But this shape is unsatisfactory
for another reason, because it results in a tendency for the limb to
rotate inwards.

At the moment when the artificial limb is coming in contact with the
ground as it takes a step, the pelvis is oblique (the iliac spine of
the sound side lying posterior to that of the amputated side). The
sound limb as it executes its step is carried forwards, and the pelvis
which was oblique in one direction now becomes oblique in the opposite
direction. This movement is transmitted to the femur in the stump, so
that the artificial limb turns inwards relatively to the stump. With
each step this rotation becomes little by little more perceptible,
and after a time the patient is obliged to correct it by turning the
artificial limb with his hand.

If, on the other hand, the front of the upper border of the bucket
slopes downwards and inwards at an angle of about 45 degrees, when as
a result of its weight the bucket turns inwards as the limb is swung,
the base of the stump will come against a higher part of bucket; but
when the pressure of the weight of the body returns, the stump, being
forced into the bucket, will descend again along this slope, that
is to say a passive external rotation of the artificial limb will
be brought about, correcting at every step the tendency to internal
rotation.

[Illustration: AMPUTATIONS THROUGH THE THIGH

FIG. 1.

FIG. 2.

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_.

[Illustration: FIG. 4.

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).

[Illustration: FIG. 10.]

[Illustration: FIG. 11.]

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.

[Illustration: FIG. 12.

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).

[Illustration: FIG. 15.]

[Illustration: FIG. 16.]

[Illustration: FIG. 17.]

[Illustration: 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.

_Braces_ (American system) for appliances of wood.

If the stump is short a combination of the two methods is best.

[Illustration: FIGS. 19 and 20.–Simple pelvic suspension,
with details of the joint at the hip.]

A. SUSPENSION BY MEANS OF A WAIST BELT.–_For the peg leg
made of leather_ the best method consists in placing a pelvic plate,
which is attached to the hip steel, below the iliac crest (Figs. 20 to
24). A belt attached to the extremities of this plate surrounds the
pelvis and passes above the iliac crest on the other side. The thigh
piece is attached to this support, on the outer side, by articulation
of the outer femoral steel with the hip steel; on the inner side, by
a perineal strap. Braces complete the method of suspension of the
apparatus (Fig. 21).

[Illustration: FIG. 21.]

The axis of the metal joint between the outer femoral steel and the
lower end of the T piece should be directly above the great trochanter
(Fig. 20).

The femoral steel often breaks in the neighbourhood of this joint
(Fig. 23); we have got over this difficulty by adding immediately
beneath it a joint which allows of abduction (Fig. 19). A perineal
strap limits this movement.

[Illustration: FIG. 22.

FIG. 23.

_Suspension from the pelvis._

A metal hip piece is fixed below the iliac crest and held in place
by a belt which passes above the iliac crest of the opposite side
(Figs. 20 to 24). This piece is attached to the thigh bucket by a
joint shown in figure 19 (see also Fig. 22), which allows both flexion
and abduction of the hip, and which forms the suspension of the
outer side of the limb. The inner border is suspended by means of a
perineal strap, shown in figures 21 and 22. In figure 21 is shown how
a suspending brace may be easily added. Figure 23 shows the action of
a single hinge joint, allowing only flexion and extension at the hip
joint. On page 27 will be seen similar joints which, however, move on
the pelvic attachment as well as on the thigh piece. The object of
this is to prevent the pinching of the abdominal wall by the top of
the thigh bucket when the patient sits. It is indispensable in short
stumps. On page 21 will be seen a joint which allows abduction of the
hip, and thus relieves the strain upon the hinge joint; without it the
latter is easily broken.]

B. SUSPENSION BY MEANS OF BRACES (American method).–The
American method of suspension has the advantage of leaving the pelvis
free; the patient does not feel the pull of the hip piece. Besides,
when the belt is used, if the patient sits down, the buttock on
the side of the stump is raised, to an extent corresponding to the
thickness of the bucket, an obliquity of the pelvis, which is both
uncomfortable and unsightly, being produced. The braces being relaxed
in the sitting posture, the patient can avoid this inconvenience; for
the stump may be slipped partly out of its bucket, the upper extremity
of which is then beyond the level of the edge of the chair. This
position is very comfortable, because it is normal, but the patient
must replace his stump in the bucket whenever he stands up.

[Illustration: FIG. 24.

FIG. 25.

Braces composed of straps passing over the shoulders and down the
front, attached to the bucket by buckles. Posteriorly they are joined
together by a cross strap between the scapulæ, and beyond this are
continued in the form of elastic straps.]

This form of suspension is essential for those artificial limbs with a
free knee-joint, in which, as we shall see, the braces serve to extend
the joint.

We illustrate here two methods of attaching the braces to the thigh
piece, that which we use in the limb supplied by the Fédération (Figs.
24 and 25) and that which is used in the American limb of Marks
(Figs. 26 and 27).

[Illustration: FIG. 26.

FIG. 27.

FIG. 26.–Braces which end below in looped thongs of leather.

FIG. 27.–These loops, held in to the thigh piece by passing
beneath a loop of leather, pass over two pulleys about the middle of
the inner and outer sides of the thigh piece respectively. The outer
brace tends to abduct the limb if it is tightened.]

C. COMBINED METHOD OF SUSPENSION.–_If the stump is short_
the artificial limb must be attached both by a belt and by braces; the
latter should be 5 to 6 centimetres wide.

[Illustration: FIG. 28.

_Combined suspension for short stumps._

FIG. 28.–Complete appliance.

FIG. 29 and 30 show the value of a flexion pivot between the
hip piece and the pelvic plate. If there is no such pivot, the T piece
undoubtedly rotates upon the belt, but not to a sufficient extent to
prevent the thigh piece in rising and pinching the abdominal wall
(Fig. 29). If there is a double joint the hip piece becomes oblique,
thrusting the thigh piece forward and allowing the patient to sit
erect (Fig. 30).]

In these cases also, to prevent the stump escaping from the bucket
when the hip is flexed, the front of the thigh piece is carried as
high as possible; but if the appliance is furnished with a metal T
piece, such as has been described (Fig. 29, see also Fig. 23), then
this raised border prevents flexion of the hip by coming in contact
with the abdominal wall when the patient sits down. This difficulty
can be got over by making the top of the T piece movable; when the
patient sits down the vertical piece of the T becomes oblique, the
thigh piece comes forward, allows the stump to escape a little way and
no longer presses against the abdominal wall (Fig. 30).

The belt may also be replaced by a leather corselet, having fixed to
it the hip piece that we have just described.

[Illustration: FIG. 29.]

The braces by themselves are a poor method of attachment for a short
stump.

[Illustration: FIG. 30.]

In the sitting position the stump easily escapes from the bucket.

When the patient is standing the stump remains abducted, whilst the
apparatus, as the result of its own weight hangs vertically, in this
swaying position the lower extremity of the stump presses against the
outer side of the bucket, whilst the inner edge of the bucket cuts
into the flesh at the top of the thigh.

III. WALKING ON A PEG LEG AND SIMILAR APPLIANCES

_The rigid peg and the jointed peg._–The peg leg is a rigid rod,
ending in a slight enlargement, which transmits the weight of the
body, resting by means of the ischium upon the top of the bucket,
directly to the ground.

The erect position is thus very secure, and stability in walking is
also very good throughout the time when the artificial limb bears the
weight.

To raise the limb from the ground and carry it forwards, the patient
uses at the same time both flexion of the stump at the hip and
movements of the pelvis (elevation, then rotation inwards) varying to
some extent with his proficiency and with the length of the stump.

_The old-fashioned peg leg_, called the “poor man’s peg,” consists
of a bucket continued into a rigid peg. If the support beneath the
ischium is well made according to the principles described above,
it is an excellent temporary limb.[3] This bucket of common wood,
which is not specially shaped to the stump, is very economical; its
imperfect fit is an advantage in that the stump, which is still
enlarged, cannot bear friction; as the stump assumes its true shape
and diminishes in size, the bucket is packed. We would add that every
patient, who is not rich enough to possess two complete artificial
limbs should have in reserve an emergency peg leg, for occasions when
the artificial limb requires repair.

[3] A number of temporary limbs have been designed, with buckets
of lattice work or of plaster. The old-fashioned wooden peg, which
is easily obtained, avoids all this additional work without any
disadvantage.

As a permanent apparatus, with accurately fitted bucket, the rigid
peg leg has two defects: it has not the appearance of a leg and
foot, and when the patient is sitting the rigid peg is unsightly and
inconvenient to him and to his neighbours. We have therefore designed
and completed a _jointed peg leg_, the principle of which is as
follows:

Below the thigh piece the peg is attached by a transverse joint,
this joint being locked in the extended position when the patient is
upright. The patient sets it free by manipulating the lock through the
trousers, when he sits down; when he gets up again the locking in the
extended position is automatic.

The fitting of this transverse joint may be carried out in two ways.

1. The upper end of the peg ends in a stirrup-shaped fork and the bolt
passes through the two ends of this fork and through the lower end of
the thigh piece (Figs. 31 to 33).

2. The lower extremity of the thigh piece has cut in it a central
mortise into which fits a vertical plate, prolonged upwards from the
middle of the leg piece. The bolt passes through this artificial
tibial spine and through the two sides of the mortise in the thigh
piece. If the hole in the tibial spine through which this bolt passes
is square the hinge works securely (Figs. 34 to 36).

In this form the axle turns with the leg, in the first form this is
also possible. But most often when the forked attachment is used it is
fixed to a leather thigh piece, and each end of the fork is jointed
independently to the corresponding end of the lateral steels of the
thigh piece, without any complete transverse bolt. It is then the fork
that revolves around these two joints.

[Illustration:

FIGS. 31 to 33.–Fixation of the stirrup of the leg (Fig. 31)
by a transverse bolt (Fig. 33), the aperture for which in the thigh
piece is seen in Fig. 32. Double lock (Fig. 32).]

[Illustration:

FIGS. 34 to 36.–Attachment by mortise and tenon, with a
bolt, square in section, passing through the knee. Single lock on the
outer side.]

If there is a complete transverse bolt, the joint can be securely
locked by a single lock at one of its extremities (at the outer
extremity) (Figs. 36 to 39).

If there are two lateral joints the single lock is insufficient, both
joints must be fixed at once; unless this is done, that which is not
fixed has a certain amount of play and is strained.

It is, however, simple, by means of a posterior semicircle, to joint
the two locks and to work them together by a single movement (Fig. 32).

For æsthetic reasons the wooden leg piece may be made in the shape of
a leg and foot. But if the principle of the peg leg has been adopted,
for an agricultural labourer for example, on account of its stability,
it is better to use an appliance in which a “show leg” is fitted
around the simple peg on days when appearance is more important than
work (Figs. 37 to 45). The limb is thus rendered lighter, for the
false calf consists of a simple layer of felt and it is very easy to
replace the enlarged lower end of the peg by a foot.

[Illustration: FIGS. 37 to 40.–Attachment by a mortise, and
show foot.]

We show later two models of this sort, one with an American thigh
piece of wood and a single lock upon a transverse axle, the other with
a leather thigh piece and a double lock. The first (Figs. 37 to 40) is
shown with an attachment by braces, and the second (Figs. 41 to 47)
with an attachment by means of a waist belt; we have already explained
when these two must be combined.

[Illustration: FIG. 41. FIGS. 42 to 47.

_Leather and steel peg leg, with show foot._

Figures 41 to 47 (leather appliance) should be compared with figures
37 to 40 (wooden appliance) which complete them in certain points. It
is unnecessary to refer further to the method of fitting the bucket to
the suspension, or to the method of attaching and locking the knee.

The peg–attached above by a stirrup or by a mortise, it does not
matter which–ends below in a rectangular tenon which fits into a
corresponding excavation in the upper surface of the terminal piece,
whether peg or foot (Figs. 38 and 44). A transverse bolt, square in
section, with a head at one end and a thread at the other, fixes these
two parts together. By taking out this bolt the peg can be replaced by
the foot or _vice versâ_.

If the attachment of the foot is made in the heel, a fixed foot is
used (Figs. 43 and 45), but it is easy, by making the attachment
higher, to use a foot with movable ankle joint (Fig. 40).

The attachment of the show calf piece around the peg is shown in
figures 43 and 45.]

Most often the wooden thigh piece is to be preferred; the limb is
lighter and may last four or five years instead of about two years.

We may add that leather loses its shape and the bucket becomes
enlarged, producing inconveniences already described on page 18.

But _leather_–indespensable for certain stumps which cannot stand
a wooden bucket–has the advantage that it can be employed as a
_temporary fitting_. During the first weeks, sometimes even for the
first months, the shrinking of the stump can be accommodated by lacing
up the bucket, and, when shrinkage is complete, the leg part of this
first apparatus can be attached to a wooden bucket which the improved
condition of the stump now renders possible.

This form is a little more expensive (80 frs.) than “the poor man’s
leg,” but I believe a great deal more comfortable. It may be added,
that it is easy when the foot is fitted at the end of the apparatus
to render flexion of the knee free and to attain the “American walk,”
of which we shall speak later. All that is necessary is to attach in
front an artificial muscle of indiarubber, reaching from the thigh to
the leg and an extending sling like that in the American limbs (see
page 47).

This appliance which we call the “Fédération Leg,” because we designed
it at the _Fédération des Mutilés_, has already been imitated without
its origin being acknowledged.

IV. WALKING WITH FREE FLEXION OF THE KNEE

A. _Design._–The oldest type, which will suffice for studying the
general conditions of stability, is that of Marks, with a fixed
foot shaped out of the same piece of wood as the leg: the ankle
joint–several types of which we shall describe later–does not affect
the question of stability.

The appliance is made entirely of wood; it is strong and light.

Nothing need be added to the description already given of the fitting
and method of attachment of the thigh piece, which ends below in a
curved “condyle,”[4] which fits into the top of the leg piece. It
is transfixed by a metal bolt, from each end of which a metal plate
descends and is riveted into a corresponding groove in the leg.[5]
This forms the axle which rotates in the thigh piece when the knee
flexes or extends. Flexion of the knee is free. Extension is stopped
just short of the straight line (see p. 16).

[4] The bucket and the condylar portion are made of two separate
pieces of wood.

[5] The hole through which the bolt passes being cut in soft wood
(willow or lime), must be strengthened by a cylinder of metal, of
leather, or of harder wood (beech or service tree) in which the axle
revolves.

[Illustration: FIG. 48.–Marks leg with fixed foot.]

[Illustration: FIG. 49.–Construction of the foot.]

The foot is in equinus at an angle of 25° to 30° so that the heel
is 2 or 3 centimetres from the ground (the usual height of the heel
of a boot). The piece of wood which forms the instep and which is
continuous with the leg stops at a point corresponding to the middle
of the metatarsus, and is only half the thickness of the foot. The
rest of the foot is shaped of indiarubber stuck on to the instep
piece; the wood and rubber being enclosed in a sheath of leather.

The foot should also point slightly outwards, as in the normal
standing position.

_To ascertain whether the limb is built so as to ensure equilibrium_,
a thread is stretched against its side so as to pass through the axes
of the knee and ankle joints, if this cuts the ischial bearing point
at its centre the equilibrium of the patient is assured. Equilibrium
will be better still if the cord lies entirely behind the ischial
bearing point, leaving in front of it the greater part of the thigh
piece. The best method of ascertaining if the foot is properly mounted
is to hold the limb in front of one by the thigh piece, with the knee
bent at a right angle; it can then be seen whether the foot turns
outwards at the correct angle.

It is not necessary to say anything more about the shape of the thigh
piece (page 17).

The metal bolt which transfixes the knee must not allow any play; the
hole through which it passes must be lined with hard wood or leather.

The indiarubber sole should be reinforced with several layers of
canvas incorporated in the rubber, as the latter if not so reinforced
perishes and cracks.

The appliance must further be examined after it is applied. The level
of the iliac spines must be compared: the spine on the side of the
amputation should be 2 cm. below that of the sound side.

Examine the position of the point of the foot. Make the patient sit
down, see if the knees are on the same horizontal plane; if the
sound knee is the higher the leg piece is too short. The foot being
fixed in the equinus position the patient must wear boots while the
examination is being carried out.

B. _Mechanism of walking._–In walking, a step being taken with the
artificial leg, the toe of the foot is the last to leave the ground,
the heel being raised and the knee straight. The limb is swung forward
and raised by flexion of the hip: active flexion of the knee is
impossible, but passive flexion occurs, owing to the weight of the leg
piece, as the thigh is raised.

At this moment the leg piece is vertical, forming an angle with the
thigh, from this position it must pass into one in which it is oblique
forwards and downwards, in a straight line with the thigh, _so that
the knee may be fully extended when weight is again borne by the limb_
as the foot meets the ground. If at this moment the knee is flexed the
limb will double up under the weight of the body.

The first contact of the limb with the ground should be at the heel
with, as we have already said, the knee extended. Afterwards as the
limb, which at first points obliquely forward and downwards, passes
into the vertical position in which it must be at the period when it
bears the whole of the weight, this complete extension becomes locked
and transforms the limb into a rigid column.

This is brought about as explained on page 48 by mounting the foot
in equinus, and we must here describe the methods by which the
commencement of the movement of extension may be communicated to the
leg so that the heel may be the first part of the foot to touch the
ground.

These methods may be termed _knee extending mechanisms_. They assist
the passive action of the weight of the leg.

In fact the recurrence of extension is brought about by a pendulum
movement of the leg, which, at first oblique downwards and backwards,
swings into a downward and forward obliquity. But this movement
is slow (the pendulum which marks one second is one metre long)
and incomplete. The patient can make it complete with a little
instruction, by extending the thigh slightly as soon as the foot
touches the ground.

This may be sufficient if the stump is long; the leverage is good, and
while the hip is being flexed a swing can be given to the thigh piece
which accentuates the pendulum movement of the leg.

But with a short stump some special mechanism is essential to make
sure that extension will be complete, otherwise the patient will be
obliged to walk with short and calculated steps, to wait whilst the
pendulum action produces extension of his knee and allows him to put
weight upon his foot.

C. _Mechanism for starting extension of the knee during the time the
leg is swinging._–There are two methods which are generally combined:

1. Elastic traction by an artificial muscle.

2. The extending sling.

1. _Artificial muscle._–The action of an artificial muscle made of
elastic (noiseless) or of a coiled steel spring, is easily understood.

(a) The simplest method (that which is commonly used for infantile
paralysis affecting the quadriceps) consists in fixing an elastic band
divided into two slips, one on either side of the patella between the
front of the thigh and of the leg, about the middle of each. (This is
represented in figure 98 in our convertable leg.)

(b) When the apparatus includes the regular artificial knee the makers
generally place this mechanism in the interior of the thigh and leg
pieces, using methods which are often very ingenious. Of these we
illustrate some on pages 40 onwards, with an explanatory description.

In describing these mechanisms, which may be called intra-condylar,
it is necessary to speak at the same time of the _stop to limit
extension_ because, as will be seen, it is combined with the extending
spring.

We have already said that rigidity in extension when the limb is
vertical is essential, but whilst it is necessary for extension to be
_complete_ at this moment it is also necessary to prevent the knee
being forced into the _hyperextended position_, as this would quickly
strain the joint and render the limb useless.

This limitation of extension can be effected quite easily by the
tension of a popliteal cord (see page 41. The knee in Marks leg), or
by carrying the anterior border of the leg piece upwards in front of
the thigh piece so that it impinges against the latter.

This method is not very good because it is noisy.

Moreover, the repeated impact against the leg piece may split the
wood, so that if this method is adopted the stop must be reinforced by
a binding of several layers of parchment.

We will first describe a mechanism the association of which with the
extending sling will be seen on page 48.

α. _To limit extension of the knee_ all that is necessary is
to prolong the antero-posterior diameter of the knee bolt (which
turns with the leg) by a horizontal wing, which engages with a
corresponding notch in the femoral condyle. We show here (Figs. 50
and 51) a rather more complicated but still simple mechanism which
is interesting because it can be combined with the action of the
extending sling (see page 48).

It consists of a piece of metal curved on the flat, ending above in a
cylinder through which the knee bolt passes, continued below into a
cylindrical tail piece, which fits into a ring which is fixed inside
the top of the calf. During flexion this plate moves in a median
posterior window in the femoral condyle, becoming oblique at the same
time as the tail piece sinks into the ring; during extension the tail
piece rises in the ring and the interior flat surface engages against
a corresponding groove in the femoral condyle (covered with leather to
secure silence).

[Illustration: FIGS. 50 and 51.–Internal mechanism to limit
extension of the knee.]

β. In the Marks knee an internal system of cords and springs
serves at the same time both to limit extension and to produce an
elastic extending force. It is a system which is fairly simple and
much used.

1. _Limitation of extension_ is secured by a U-shaped cord, the
extremities of which are fixed to a wooden cross piece (T), fixed in
the thigh piece three centimetres above the axis of the joint. The
cords leave the thigh through two lateral openings in the back of the
thigh piece, and the loop passes through a ring halfway down the calf.

2. _The extending force_ consists in a coiled steel spring the
mechanism of which is combined with that of this cord. The lower half
of the spring is enclosed in a copper tube lined with chamois leather
to secure silence; its upper half or rather more is coiled around a
wooden pin, which terminates above in a head which is cup shaped:
it will be seen (Fig. 57) that if pressure is made on this head the
spring is shortened and under compression.

This spring is fixed below (by means of a tenon which allows
antero-posterior movement) upon a bracket in the calf which is
continuous with the ring through which passes the check cord. The
cup-shaped upper end is in contact with a ball which projects from
the upper surface of the thigh piece between the two openings for the
check cord (Fig. 53). It will be seen that when the knee is flexed
the spring, the head of which lies below the axis of the joint, will
be compressed at the same time as the check cord is relaxed so that
there is an elastic recoil tending to reproduce extension. The ball
which rests on the top of the spring is fixed in such a manner as to
be in the same horizontal plane as the axis of the knee: that is to
say, it is in the same vertical plane as this axis when the knee is
flexed to a right angle (Fig. 52). Therefore in this position the
spring has no tendency to produce either extension or flexion, that
is to say the mechanism is now at dead point, and when the patient is
sitting flexion to the right angle is maintained without any effort.

[Illustration: _The Marks knee._

FIG. 52.

FIG. 53.

FIGS. 54 to 57.

FIGS. 52 and 53.–O, knee bolt. T, cross piece of wood,
situated in the extended position above the knee bolt, in the flexed
position behind it. C, bracket fixed halfway up the interior of the
calf.

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).

[Illustration: FIGS. 58 and 59.–Elastic spring for extending
the knee.]

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).

[Illustration: Fig. 60.

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.

[Illustration: FIG. 64. FIG. 65.]

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).

[Illustration: Fig. 66. Fig. 67. Fig. 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.

[Illustration: Fig. 69. Fig. 70. Fig. 71.]

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.

[Illustration: Fig. 72.

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).

[Illustration: FIG. 76.]

[Illustration: FIG. 76A.]

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.

[Illustration: Figs. 77 to 81.

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).

[Illustration: FIG. 82.

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.

[Illustration: FIG. 87.]

[Illustration: FIG. 88.]

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.

[Illustration: FIG. 89.–Duplex Foot.]

_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.)

[Illustration: FIG. 90.

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.

[Illustration: FIGS. 93 to 95.]

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.

[Illustration: FIG. 96.

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).

[Illustration: FIG. 99.–Limb with end bearing for amputation
in the region of the condyles of the femur. Anterior part of the thigh
bucket cut away to allow the insertion of the enlarged lower end of
the stump.]

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.

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