SOME GENERAL PRINCIPLES IN THE RE-EDUCATION OF THE DISABLED 145
INDEX 159
ARTIFICIAL LIMBS
_CHAPTER I_
GENERAL CONSTRUCTION OF AN ARTIFICIAL LIMB
A prosthetic apparatus for any amputation is composed of two parts:
1. The artificial limb.
2. The attachment of this limb to the trunk.
The artificial limb itself is divided into two parts:
1. A conical socket.
2. A part which replaces the missing limb and is in fact a terminal
functional appliance.
Two conditions must be considered, whether or not there remains
attached to the trunk a segment of the limb capable of being fitted
into the base of the artificial limb, to which it gives support, and
to which, in addition, it can communicate movement. Accordingly the
artificial limb differs essentially for:
1. Disarticulation of the shoulder and of the hip.
2. Amputation of the arm and of the thigh.
In the first case we attach to the trunk an instrument which is
entirely passive.
In the second we attempt to turn to account the active movements of
the stump.
These various parts do not lend themselves to a general description
applicable at once to the upper and lower limbs. Not only are
the modes of attachment and the functional artificial limb quite
different, but the bucket does not serve the same purposes.
_The position of the scar._--The stump, which fits the bucket exactly,
transmits to it two kinds of force:
1. The force of vertical pressure.
2. Lateral force corresponding to the angular movements of the joint
above.
The lateral force is transmitted by the whole of one surface of the
stump to the corresponding lateral surface of the bucket: by the
anterior and posterior surfaces only in the case of hinge joints such
as the elbow and the knee: by all surfaces in the case of joints with
movements of circumduction such as the shoulder and the hip.
Vertical pressure exercised upwards or downwards may cause the limb to
press upon the bucket at two points: (1) on the summit of the cone,
_i.e._ on the extremity of the stump; (2) on the base of the cone,
_i.e._ on the bony prominences around the last remaining joint. The
adjustment is never sufficiently accurate for the relief due to the
fitting of the stump in the bucket to be of much importance.
We should take it as a general rule that a scar cannot stand pressure
or friction; and that in consequence, when we amputate under
favourable conditions, we should arrange to place the scar in such a
position that from our knowledge of the suitable prosthetic apparatus
these two evils will be avoided. It should be added, however, that
after perfect primary union, the narrow and mobile scar is very
tolerant, but it must also be remembered--especially as will be
seen in the lower limb--that this condition is rarely realised in war
surgery.
The length of the stump is often estimated by reference to that of the
other limb; amputation at the upper, middle, or lower third of the
thigh, of the leg, of the arm, or of the forearm. This is convenient,
starting from a certain minimum length, but there is an _absolute
minimum length_ below which the stump has insufficient leverage and
tends moreover to escape from the bucket.
_Temporary and permanent apparatus._--For the irregular amputations
of war surgery which have suppurated, more often than for those of
civil practice, it is generally advisable, particularly in the lower
limb, to use a temporary apparatus, of fairly good fit, for several
weeks or even months before the permanent apparatus of more precise
fit. The stump has to soften and shrink gradually; only when this has
occurred can we make an accurately fitting bucket, by means of a cast
if necessary.
_Materials for making the bucket._--The first method of construction
is that of _leather reinforced with metal_; a sheath strengthened
with metal supports, is laced around the stump; the supports further
give attachment, if there is room, to the artificial joints. This
is an excellent principle, either for stumps which are still likely
to diminish in size, or for the upper limb where exact fit is of
secondary importance.
For buckets accurately fitted on a cast we employ:
_Blocked leather_, which loses shape and ought to be abandoned for
artificial limbs for the lower extremity.[1]
[1] This we have attained at the _Fédération des Mutilés_, having
forced the makers to abandon their routine. It seems to us therefore
that the same result might be attained for the appliances furnished by
the State, which are still made of leather.
_Celluloid_ is the material of choice, but it has the defect of
requiring the hand of an artist; commercial attempts on a large scale
have so far yielded mediocre results.
_Metal_ (zinc, sheet steel, aluminium), the defect of which is that
the apparatus, particularly for the lower limb, is noisy. This is also
an inconvenience in the metal joints of lateral steels of leather
appliances and of the spiral springs in certain wooden apparatus,
for this reason indiarubber is more often relied on for springs and
accumulators.
_Wood_, for many years used for the commoner types of limbs for the
lower extremity, is now, as the result of American influence, utilised
for the making of apparatus hitherto termed "de luxe," but to-day
serviceable, thanks to this technique.[2]
[2] Working in wood, to hollow out of a log of wood a bucket which
fits the stump accurately, is no novelty. Some sixty years ago two
Frenchman, Bailly, then Xavier, succeeded in such construction. But
these appliances, like the common, cheap unshaped peg leg, split
easily and were only made strong when the Americans conceived the
idea of covering the outer surface with a layer of raw hide: strong,
and therefore practical, for though we may resign ourselves to the
frequent renewal of a peg leg at 25 francs, it is another matter with
an appliance costing 300 to 400 francs. (Prices in peace time.)
(In England the standard patterns of artificial legs have for many
years been made out of wood.--ED.)
The adjustment to the stump is very exact; the contact with the
surface where there is friction is soft and comfortable without
padding; the appliance is light, strong and silent. The best woods
appear to be English willow and lime. The bucket should not present
any flaw or knot, this can be seen on the inner uncovered surface.
But we must emphasise the general fact that _standardisation is
impossible when the bucket is made of wood_. For the other parts it
is possible but not for the bucket, which must be made specially for
each patient, hollows being made for each bony point, which must be
marked out and felt for with the fingers. A plaster cast would appear
more exact: but by this means we do not mark out the bony points. Good
results cannot be obtained, if, as certain people have tried, linear
measurements are sent to a workshop whence an apparatus is forthwith
despatched to a patient whom the maker has never seen.
_CHAPTER II_
GENERAL PRINCIPLES OF FITTING FOR THE LOWER LIMB
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.
_CHAPTER III_
ARTIFICIAL LIMBS FOR AMPUTATIONS THROUGH THE THIGH
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.
_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.
[Illustration: FIG. 100.
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.
[Illustration:
FIG. 102.--Limb fitted upon the patient. Note that he
stands upon the toe, and that the knee is flexed. ]
[Illustration:
FIG. 103.--Posterior view of the same limb.]
[Illustration:
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.
[Illustration:
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.
[Illustration:
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.
[Illustration: FIG. 109.]
[Illustration: FIG. 110. FIG. 111.]
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.
[Illustration: FIG. 112.
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.
[Illustration: FIG. 114.]
[Illustration: FIG. 115.]
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).
[Illustration: FIG. 116.]
[Illustration: FIG. 117.]
[Illustration: FIG. 118.]
[Illustration: FIG. 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.
[Illustration: FIGS. 120 and 121.]
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.
[Illustration: FIG. 122.]
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).
[Illustration:
FIG. 123.--The three regions used as points of support, the
shoulder, the elbow and the wrist.]
[Illustration:
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.
[Illustration: FIG. 125.]
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).
[Illustration: 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).
[Illustration: 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.
[Illustration:
FIG. 129.--The three regions used as points of resistance to
upward pressure.]
[Illustration:
FIG. 130.--The three regions at which rotation of the
apparatus may be prevented. ]
2. ELBOW JOINT
1. _The Concavity of the Armlet._--At the elbow joint the pinching of
the anterior soft parts on flexion is liable to take place in just the
same way as occurs at the back of the knee in amputations through the
leg. To avoid this it is necessary--
(1) That the axis of the joint should lie in a prolongation of a line
passing through the epicondyle and the epitrochlea.
(2) That the armlet and the forearm socket should be cut away in front
in crescent-shaped concavities.
[Illustration: FIG. 131.--Limb for amputation in the middle
third of the forearm.]