Removal of a marginal

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.

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.]

The depth of these concavities is estimated when the limb is fitted.
Both the arm and the forearm may be cut away freely without any
resulting inconvenience, provided that the stump is long; but if the
stump is short and includes only the upper third of the forearm, it
is impossible to cut away the forearm socket sufficiently without
depriving the stump of a proper hold in the socket, so that movements
are not transmitted to the forearm lever with their proper force.
Consequently the socket for the forearm must be cut away very little,
and must be carried up to the level of the fold of the elbow when the
joint is flexed. The flesh in front of the elbow will not be pinched
if, the forearm being fitted very accurately, the muscles of the
upper arm are allowed free play, by cutting away the front of the
armlet to half its height, but in this case an indirect attachment to
the shoulder is essential.[12]

[12] Another difficulty in fitting a short forearm stump arises
from the fact that the antero-posterior diameter of the forearm
immediately below the elbow increases considerably when the joint is
flexed, because of the contraction of the muscles arising from the
condyles. If the forearm socket is made to fit closely when the elbow
is extended it will be too small when the joint is flexed and will
prevent full flexion. If it was made to fit with the elbow flexed,
there is risk of the stump slipping out of the socket when the joint
is extended. (Ed.)

[Illustration:

FIG. 132.–Bad apparatus for amputation in the upper third of
the forearm. The front of the arm piece is insufficiently cut away.]

[Illustration:

FIG. 133.–Good apparatus. The arm piece is well cut away,
consequently the flesh does not bulge out.]

2. _Construction of the Joint._–In most cases this is a simple
articulation between the steels of the arm and the forearm pieces by
two hinge joints.

[Illustration: FIG. 134.

FIG. 135.

FIG. 134.–Limb for amputation through the lower third of the
forearm, with elbow joint of strong leather.

FIG. 135.–Details of the joint.]

The objection to this is that the movements of pronation and
supination, if these are present in the stump, are abolished.

(_a_) _Long Stump._–When the stump is long (amputation in the lower
quarter) the following may be used: The steels of the forearm socket
are attached to the armlet, which is not furnished with steels, by two
straight strips of hard leather jointed at each end with rivets to
the corresponding piece of the limb. This allows a certain amount of
torsion so that pronation and supination are to some extent possible.
It is necessary to add an indirect attachment to the shoulder. Not
only must the armlet, not being closely moulded over the condyles, be
even when new laced so tightly as to be unbearable, but in addition
the inevitable loss of shape of the unsupported leather will in every
case soon interfere with proper support direct from the armlet (Figs.
134 and 135).

[Illustration: FIGS. 136 and 137.–Amputation through the
forearm above the upper third. The elbow joint does not flex beyond
the right angle.]

[Illustration: FIG. 138.–Limb for amputation through the
upper third of the forearm. (For a description of the ratchet see page
135.)]

This method is, moreover, scarcely applicable to patients who will
have to carry out heavy work.

(_b_) _Short Stump._–The stump of an amputation in the upper third of
the forearm is too short to be securely held in the forearm bucket.
There is consequently a loss of power in the movements communicated,
particularly in flexion, the arm of the lever being too short; in
addition, the elbow joint in these cases is often a little stiff, so
that flexion beyond a right angle is impossible (Figs. 136 to 138).

The chief functional difficulty depends upon the fact that, with the
elbow at a right angle, the anterior surface of the forearm stump
is too short to support a weight; for example, a basket held by the
handle. The stump escapes partly from the bucket when the forearm
extends. It is therefore well in such cases to fix the elbow at a
right angle by means of a ratchet identical with that used in the
artificial arm for amputation above the elbow (Fig. 138).

3. THE ARTIFICIAL HAND AND APPLIANCES

At the extremity of their forearm almost all patients wish in the
first place to wear something that is shaped like a hand. Many
people–and even many medical men–consider that this “artificial
hand” is really useful. In actual fact, by means of fairly simple
contrivances, it can be used to enable the patient to eat, to write,
to put on and take off his hat, but it is out of the question for it
to do real work. For that an appliance, a tool in fact, adapted for
use and not for appearance is necessary.

The limb, therefore, will, as a rule, end in a hand, but for workmen
this hand will be capable of being unscrewed and replaced easily by
one or more appliances.

Attempts have been made to construct so called universal hands and
forceps which will serve for any sort of work, but up to the present
none of these inventions have given satisfaction. And the practical
solution of the problem in the present state of affairs consists
in devising a special appliance for a particular trade, studying
carefully the movements necessary in this trade.

A workman who in the course of his occupation carries out a number of
different movements may thus have several appliances, which he selects
as he requires them. For example, a locksmith must be able to hammer,
to file, and to drill holes in succession.

We will describe first the hand properly so called, then the
appliances. The former is suitable for clerks, and it is for them that
the various improved patterns that we shall describe are made. The
latter are suitable for manual workers to whom should be given a hand
in which the mechanism is reduced to a spring thumb grip and one or
more special appliances.

These appliances will almost always be constructed to carry out the
movements made by the left hand in the course of the work, because the
first step in the re-education of a patient who has lost the right
hand should always consist in training the remaining left hand to
carry out the work hitherto entrusted to the missing right hand.

A.–THE ARTIFICIAL HAND.

The hand, which is screwed into the end of the forearm socket in such
a way that it is in semipronation when the arm hangs vertical, is
nearly always made of wood, but occasionally of aluminium.[13]

[13] Hands are nearly always made of lime wood, which has the
advantage of lightness, but the fingers are fragile and easily break.
Instead of using hornbeam, which is hard but heavy, as the fragility
only affects the fingers, some makers have overcome this difficulty by
reinforcing the fingers by what they call a “philippeau.”

The finger is divided throughout its whole length by a mortise 1·5
millimetres in width, in which are glued two layers of veneering wood
(mahogany, rosewood, etc., extremely hard woods, or else a layer of
hornbeam).

It may be a simple show hand without any joint. This pattern is no
longer used. It may be jointed in one or in several fingers. We shall
first consider certain principles of construction which we can explain
by describing the chief mechanisms used.

_Simple Spring Grip Thumb._–The simplest and most useful articulation
is that of the thumb, which when at rest is kept by means of a spring
in the flexed position, with the grip against the index finger which
is partly flexed (as are also the other fingers).

In many cases the patient is content with this simple mechanism. He
opens the spring with the other hand and allows it to close on the
object he wishes to grip (Figs. 139-145).

[Illustration: FIGS. 139 to 142.–_Mechanism of the passive
spring thumb._

The thumb turns on the axle D upon a piece which fits by a tapered
extremity C into a hollow cut out in the thenar eminence. The base of
the thumb is rounded. The spring AB flexes the thumb.]

[Illustration: Figs. 143 to 145.–The Beaufort Thumb.

The model shown on page 98 is more mobile than this, in which the
thumb turns on the axis AB, and is fitted directly into the thenar
eminence. But in this type it will be seen that the spring CD which
keeps the thumb flexed, reaches right up to the wrist, and is
therefore longer and more powerful. The thumb is much stronger, and
this is the mechanism usually adopted. It has the inconvenience that
it requires a deep excavation of the thenar eminence, encroaching
upon the root of the index finger, so that it is impossible to
mount the thumb in this way when it is desired to fit a movable
metacarpo-phalangeal joint to the index finger, either with a spring
(Fig. 155) or without (Fig. 148).]

_The Automatic Thumb._–Active opening movement can be produced by the
mechanism shown in figure 146. A cord fixed behind the scapula of
the opposite side by a ring which passes over the clavicle and under
the axilla, extends down the posterior surface of the arm and forearm
pieces, running in pulleys which keep it in place. If the patient
bends the elbow and at the same time brings the arm and both shoulders
forward, rounding his back, the cord is tightened and pulls the thumb
into the position of abduction and extension.

This narrow grip, between the tips of the thumb and index finger only,
is not always convenient. A commercial traveller or a foreman could
not easily hold with it the order book, in which he has to write. But
if the thumb, held by a powerful spring, is parallel to the palm of
the hand and grips against the other fingers, which are stretched out
and not semiflexed, the grip will be strong and convenient, especially
if a mechanism is introduced between the forearm and the hand,
allowing the latter to be rotated at will into any position (Fig. 148).

As in the preceding case the thumb may have either a simple grip or an
automatic grip opened voluntarily by a cord from the shoulder.

The following is a very interesting method which allows a fork or
pen to be held, the automatic thumb being used. The fingers are half
flexed, the index being separated from the middle finger, so that the
handle of a pen can be inserted between them. The grip of the thumb is
not against the tip of the index finger but against the outer side of
the last phalanx of the middle finger, against which in consequence
the handle of the object held will be pressed (Fig. 147).

[Illustration:

FIG. 146–Appliance with automatic thumb. The cord is fixed
to a loop which passes round the sound shoulder. Abduction and forward
movement of the shoulder and flexion of the elbow open the thumb.]

[Illustration:

FIG. 147.–Hand with space between the index and middle
fingers, wide enough to take the handle of a fork, which is held by
pressure of the thumb against the side of the middle finger.]

The extended fingers are better placed for gripping than the
partially flexed fingers, although the latter are convenient to the
patient in certain ways. Ball and socket joints are inserted at the
interphalangeal joints. (Details are shown in figures 152 to 154.)
These are so stiff that they maintain the position in which they are
placed passively, as do the joints of an artist’s lay figure.

[Illustration: FIG. 148.–Articulated hand for commercial
travellers. The thumb, lying parallel to the palm of the hand, takes a
secure hold of such an article as a memorandum book.

FIG. 149.–The usual pattern of hand. The grip is too small.]

[Illustration: FIG. 150.–The index finger is the same length
as the middle finger. The thumb and index fingers are furnished with
nails. A small ball can be picked up.

FIG. 151.–The middle finger being longer than the index, the
latter does not reach the surface of the table and the ball cannot be
picked up.]

If the fingers are rigid and in semiflexion it is possible to
articulate all the metacarpo-phalangeal joints, fitting them with a
spring, which keeps them flexed, and arranging for active extension as
already described for the thumb. All that is necessary is to terminate
the cord by five separate strings instead of one. In certain special
cases this arrangement may be useful (Figs. 155 to 157). It seems to
us useless to render the interphalangeal joints automatic.

As to the attempt which Beaufort appears to have made to give movement
to the wrist also, we do not believe that any practical result has as
yet been attained.

For the relative length of the fingers and the utility of a nail on
the thumb and on the index finger see figures 150 and 151.

_Shape of the Hand._

In the usual pattern (Figs. 149 and 151) the fingers are semiflexed
and the thumb grips against the index finger, which is shorter than
the middle finger as in the natural hand. If it is desired to pick
up a ball, for example (Fig. 151), it will be seen that the middle
finger projects and gets in the way. For this reason it is advisable
that the index finger be longer than the middle, and in addition it is
useful to furnish the thumb and index finger with a little projection
representing the nail (Fig. 150).

In figure 148 will be seen an arrangement which allows the thumb to
grip not by the tip, but by the whole length of its palmar surface (to
hold, for example, a notebook). The fingers of this hand have ball
and socket joints constructed in the way shown in figures 152 to 154.
The joints keep passively the position in which they are placed.
The attachment of the ball of the joint on an intermediate tenon is
similar to that of the thumb shown on page 98. The articulation of the
index finger prevents the sufficient excavation of the thenar eminence
for the insertion of the Beaufort thumb with its powerful spring. The
wrist rotates upon a bayonet joint.

[Illustration: FIGS. 152 to 154.]

The fingers shown in figures 155 to 157 are joined together into a
single piece, which articulates with the metacarpal part of the hand
upon a transverse axis.

They are held in a position of flexion at the metacarpo-phalangeal
joints by four palmar springs and they are opened away from the thumb
by the action of a cord which bifurcates from the thumb cord on the
back of the hand. The pull of this cord is exerted upon the upper
angle of a triangle from the lower border of which four cords pass on
to the back of the phalanges. Figure 156 shows detail of a finger. We
know that attempts have been made to isolate by surgical means the
masses of the extensor and flexor muscles in the end of the stump,
making from them little prominences, perforated with a tunnel which is
lined with skin. The cords pass through the tunnels, and in this way
are worked voluntarily. We are not sure that this is practicable.

[Illustration: FIGS. 155 to 157.–_Automatic fingers._

In figure 155 are seen the cavity in which the finger portion works
and the axis upon which movement takes place, also the four palmar
springs. In figure 157 the arrangement of the cords. In figure 158 the
attachment of the spring to the finger. This pattern, which we have
designed and which is not patented, seems to us to be simpler than
those in which the interphalangeal joints are also articulated and are
automatic. It gives a more accurate grip between the tips of the thumb
and index finger.]

_The Brunet Grip._–The Brunet grip is described here because of its
resemblance to the automatic thumb, both being worked on the same
principles.

[Illustration: FIGS. 158 and 159.]

[Illustration: FIG. 160.]

[Illustration: _Brunet’s Grip._

Below the leather forearm piece, which laces up, the lateral steels
are continuous with each other in the form of an arch, to which the
grip is riveted.

The latter consists of a strong semicircular piece of metal facing
downwards, ending in a pair of wide and thick jaws, like those of a
locksmith’s pliers. When the apparatus is at rest, these are kept in
contact by the pressure of two powerful fixed springs, attached to the
semicircle on the forearm above and to the jaws below. The external
and dorsal spring is attached to the tip of its jaw, the internal and
palmar (the side on which the manipulating cord is attached) to the
base of it.

The pliers are opened in the following way:–

Inside the semicircle to which the jaws are attached, lies a cylinder
with its ends cut obliquely; this rotates about a transverse axis,
and when at rest lies with its longer side upward. To the palmar edge
of the shorter side is attached a transverse eccentric, to which is
hooked a cord actuated as described in figure 146. When this is drawn
upward the cylinder rotates so that the wider side comes between
the jaws of the pliers and opens them; when the cord is relaxed the
springs turn the cylinder back again find the jaws close. Figures 158
and 159 show the appliance at rest and with the jaws open.

This appliance is patented and is made in one piece. We demonstrate in
figure 160 that it would be very easy to make the pliers detachable
from the forearm, with a screw connection, just as is done in the
various other appliances which will be described.]

The grip of the automatic thumb always lacks power, for two reasons.
There is no room in the thenar eminence to fit a powerful spring and
the grip has always a very narrow hold.

The Brunet grip is an actual pair of pliers, shaped like these and
furnished with a powerful spring. It is opened by a cord like that
of the automatic thumb. Figures 158 to 160 explain the mechanism.
It is an excellent appliance with which the wearer can carry out
the majority of the actions of everyday life. It has, however, the
disadvantage that it is not shaped like a hand–a point to which
patients attach much importance–and, moreover, it is a part of
a patented appliance, for which an interchangeable hand is not
manufactured. So that in order to have in addition an artificial hand,
which is capable of being removed and replaced by one or more of the
appliances which will be described later, it would be necessary for
the patient to possess two complete artificial limbs, and changing
from one to the other would evidently be inconvenient.

We generally prescribe this appliance for patients who have lost both
arms, for one side and as a supplementary appliance.

There are other similar models into details of which it is unnecessary
to enter. Those in which the grip is opened by movements of pronation
and supination are obviously only suitable for certain rare cases
(very long stumps, with free movement).

B.–APPLIANCES FOR USE IN PLACE OF THE HAND.

The general principle is to fit to the end of the forearm piece an
attachment which can be screwed on or unscrewed at will and which
carries an appliance which is adapted to the various more or less
specialised movements of the patient’s trade.

Naturally the results thus attained must always be imperfect; but
however little perseverance and ingenuity he may possess, the patient
finds that he is able to educate the remaining arm, even when it
is the left, to replace the amputated one in a way that is often
remarkable. It is to this education that attention must be specially
directed in the workshops for the re-education of the maimed.

1. _Knife and Fork._–The first necessity is to be able to eat, and by
certain very simple devices a fork, spoon or knife may be fixed to a
wooden hand, whether the thumb be mobile or not.

[Illustration: FIG. 161.–Raynal’s fork rest.]

As a general rule if the patient has one arm intact, he uses the sound
hand only for this purpose, but when both forearms have been lost an
appliance is indispensable.

We have already described how in the hand with an automatic thumb,
room can be left between the index and middle fingers for the handle
of a spoon or fork. A direct grip can also be obtained with the hand
shown in figure 147.

The hand with five automatic digits (p. 105) is usually arranged in
such a way that it is possible to hold a tumbler for drinking; but a
patient with an amputation of one hand drinks with the other, and one
who has lost both hands can drink with a straw.

[Illustration: FIG. 162.–The termination of the forearm is a
hemispherical piece of metal, furnished with a screw into which screw
at will the hand, the hook or the ring.]

These appliances have replaced that in which the knife or fork is
attached to a block of wood which can be fitted into the palm of the
hand when required. It is inconvenient to be obliged to carry these
special implements about.

Raynal’s fork-rest has the advantage over the last mentioned that
it fits any fork. Figure 161 shows very clearly its construction and
the way in which it is used. The small special attachment, which is
screwed in place, is not cumbersome and can quite well be carried in
the pocket; it is, however, even more convenient to have an appliance
which is capable of gripping the fork directly like those described
previously.

[Illustration: FIG. 163.–Vine dresser’s hook.
(Gripouilleau).]

[Illustration: FIG. 164.–The branch is held in the grip by a
leverage exerted by torsion.]

2. _Appliances for Workmen._–All the appliances that are attached
to the arms in place of the artificial hand for performing various
kinds of work are elaborated from two simple forms: the hook and the
ring (for catching hold and carrying a parcel, for holding a handle,
etc.). A glance at figure 162 will show the nature of these and the
way in which they are used. But it will also be understood that if
the simple ring and hook are useful for equally simple purposes they
are altogether insufficient for skilled labourers whose work entails
a certain special adroitness, e.g. joiners, locksmiths, agricultural
labourers, etc.

Many makers have realised this and have devised very ingenious
implements, some of which we reproduce, though we are obliged to limit
ourselves to certain types, for they can be varied in countless ways
according to the needs of particular cases. The same workman, as we
have already said, may have several appliances which he uses in turn
as he needs them in the course of his work.

These appliances are constructed in two ways; some are fixed to the
end of the forearm and are immobile, some are attached by means of a
joint or joints and are capable of rotation in various directions.

(_a_) _Fixed Appliances._–We illustrate here an appliance derived
from the simple hook, the _vine-dresser’s claw_, devised some time ago
by Gripouilleau; branches of varying size can be held while the other
hand saws them or cuts them with the pruning shears (Figs. 163 and
164).

This appliance of Gripouilleau, with a series of hooks, forms the
basis of almost all the “pincer hands” constructed by M. Boureau and
characterised by–

(1) The closure of the upper hook which is thus transformed into a
ring, the two appliances being combined in one;

(2) The spring fixed to the straight side of the hook providing the
grip necessary for holding articles. If the free end of the spring is
turned up like the pointed toe of a mediæval shoe a sufficiently large
opening is left between it and the straight edge of the hook to enable
an object which is fixed mechanically or held by the other hand to be
pushed into and gripped by the spring.

The simplest type of this mechanism is the _postman’s hand_ (Figs. 165
and 166).

[Illustration: FIGS. 165 and 166. Postman’s hand.]

The left hand of the postman who sorts letters has for its work to
keep in the proper order the envelopes which are arranged in little
packets; the right hand has only to push the letter into place between
a flat spring, fixed to the wrist, and the back of the hook. If two
or three springs are supplied the postman can arrange two or three
packets of letters at the same time. He can also bind the packet with
string.

The _vine-dresser’s hand_ is provided with this spring to hold
small flat objects, but the second spring is wavy in outline, so
that semilunar spaces are left between it and the first. Into these
branches slip when the spring is pressed against them, and they are
thus held more firmly, whilst being sawn or pruned, than by the
twisting action of the old pattern hook of Gripouilleau (Figs. 167 and
168).

[Illustration: FIG. 167.–Horticulturist’s hand.]

[Illustration: FIG. 168.–Method of holding a branch.]

This thrust to seize the branch is somewhat rough, and is only
possible in holding hard wood which there is no fear of bruising.
For more delicate shoots (grafting vines indoors, preparation of
cuttings), a grip is necessary which can be opened before seizing
hold of the object. This is accomplished by prolonging the spring
towards the forearm as a handle, pressure upon which against the chest
(when standing), or against the knee (when sitting), opens the grip,
in which the graft, for example, is then placed in the opening of the
correct size.

_The packer’s hand_ is very ingenious (Fig. 169). It has the hook
pierced by an eye enabling a thread to be passed through a basket
as with a curved needle. The jaws of the pincers are smooth at the
tips, but further back they have a series of graduated notches in
which tacks of different sizes can be held whilst they are driven in
with the hammer. But of course a workman can only work quickly if he
can hold a number of tacks of the same size in the palm of his hand,
placing one under the hammer, relaxing his hold of it after the first
gentle blow has fixed it, and getting the next ready while he drives
it home.

[Illustration: FIG. 169.–Packer’s hand.]

_The plumber’s hand_ (Fig. 170) is made in the shape of a pair of gas
pliers, and ends in cutting edges with which wires can be cut. With
them a bolt can be held whilst the other hand screws on the nut.

[Illustration: FIG. 170.–Plumber’s hand.]

_The leather-cutter’s hand_ (Figs. 171 and 172) should be able to
hold the skin which the other hand cuts: it consists of a plate with
a rough surface fixed to a ball and socket joint which allows it to
turn in any direction, so that the other hand can follow the line to
be cut which is often sinuous. This appliance may also be used to hold
a drawing paper, a rule for cutting cardboard, or sheets of paper for
binding.

[Illustration: FIG. 171.–Leather-cutter’s hand.]

The examples that we have chosen amongst Boureau’s appliances for
craftsmen will, we believe, be sufficient to explain the principles
of their construction. These consist in studying the movements which
are normally carried out by the passive hand (usually the left hand,
but the right in left-handed people) and to devise an appliance
accordingly, the sound hand always becoming the active hand.

[Illustration: FIG. 172.–Leather-cutter’s hand.]

We could have described many more examples, but we shall only say a
few words about the _mechanic’s hand_, which is simply an adjustable
spanner which can be automatically closed, terminating in toothed
pliers to hold circular objects without the necessity for being
screwed up. As a matter of fact, in all the work of a mechanic
(sawing, filing, drilling, tightening screws, hammering, forging, and
grinding) the left hand is only used for picking up and steadying
the article to be manipulated. M. Boureau rightly considers that it
is better to entrust this rôle to the artificial hand rather than to
contrive to make the latter capable of sawing or of filing by means of
the devices which we shall describe further on (p. 121 and following),
ingenious and interesting though these may be.

From these appliances, adapted to certain particular grips, others
have been devised for chair caning, soldering, and for enabling
factory hands to work starting levers and brakes.

Thus each case must be studied separately and the workman furnished
with one or several appliances according to his needs, making the
necessary modifications from the existing patterns.

Several of these appliances are attached by a ball-and-socket joint
like that described for the leather cutter: this is an intermediate
form between the fixed appliance and the jointed appliances which will
be described later.

Boureau recommends that the length of the forearm should be such that
the artificial appliance reaches only as far as the level of the sound
wrist. The work will then gain in precision. We believe that this
principle holds good even for the true artificial hand, which should
be made 3 to 4 centimetres shorter than the sound hand. But it must be
realised that we shall be met with a difficulty, which we have already
experienced. Comments are made upon the appearance of the arm and the
wearer may sometimes be made to believe that this is due to faulty
construction.

For certain special crafts the subject may be studied from another
standpoint and an actual tool constructed which carries out the
necessary actions like a machine worked by the forearm, so that in
these special cases the artificial hand is the active hand.

At the Valentin Hauy Institute for the blind, where there has long
been a brushmaking workshop, we have seen in use a very ingenious
tool of this description with a combined action for carrying out the
entire manipulation of the thread which fixed the little bundles of
bristles into the holes perforating the back of the brush. Results are
so good that a blind and maimed worker using this apparatus works
more quickly than his comrades who have the use of both hands. It
consists of a two-pronged claw surmounted by a small thimble-shaped
projection and with a small hook, like a crochet hook projecting in
front (Fig. 173). The hook first passes through one of the holes in
the back of the brush, catches up the thread and draws it through
the hole (Figs. 174 and 175). The thread is then looped around the
thimble, whilst the sound hand binds the little bundle of bristles
into a twist of the loop (Fig. 176), and finally the bundle is fixed
into the hole, the claw being used to draw the brush towards the
worker (Fig. 177).

[Illustration: FIG. 173.–Brushmaker’s hook.]

[Illustration: FIG. 174.–First movement. The string is
picked up by the hook.]

[Illustration: FIG. 175.–Second movement. The string is
pulled through one of the holes perforated in the back of the brush.]

[Illustration: FIG. 176.–Third Movement. Catching the bundle
of bristles.]

[Illustration: FIG. 177.–Fourth Movement. The bundle is
fixed in the hole in the back of the brush.]

(3) In place of an actual tool the detachable part may consist of a
clamp on the principle of a ring into which the tool is inserted by
the handle. The two principal methods are the screw and the American
chuck. A glance at figures 178 and 179 will explain how the large
handle of a tool intended for heavy work is controlled by means of a
screw and rings.

[Illustration: FIGS. 178 and 179.–Nyrop’s grip for hammer
and saw.]

At Rouen we have seen the disabled Belgians who had been re-educated
wearing an ingenious T-shaped clamp by means of which the handle of a
tool may be held either in the line of the axis of the forearm or at
right angles to this. This method is specially useful for manipulating
a file which is worked with one hand while the other, in this case
the sound hand, presses upon the free end. Usually the filing is done
backwards and forwards, working from base to tip of the file, but
sometimes, specially for final polishing, the file is held with both
hands and worked from side to side.

The American chuck consists of a pair of metal jaws fixed at their
base into a cylinder and appearing somewhat like the petals of a long
corolla. Another cylinder is screwed over the first to control the
opening and shutting of the jaws. When this cylinder is unscrewed
the jaws open and the handle of the tool can be inserted, when it is
screwed up it closes the jaws and makes them grip the handle.

[Illustration: FIGS. 180 to 185.–_The American Chuck._

The pincers are composed of two jaws with vertical cylindrical grooves
(to fit upon a handle), joined above by a ring (Fig. 185) and coupled
by a spring C which keeps them apart. The pincers fit into a piece
B (Fig. 182) cut on the outer side with a screw thread (Figs. 182
and 183) upon which the piece A is screwed up or down (Figs. 180 and
181). When screwed towards the point of the pincers it presses on the
two jaws and closes them. When screwed in the opposite direction the
pincers open automatically.]

If the jaws open widely, the wooden handle of a tool can be held, but
if the opening is small the unmounted tool must be fitted into them
(Figs. 186 and 187). This method is specially useful for files, as it
frequently happens that several files are required for the same piece
of work and they can be changed rapidly.

[Illustration: FIGS. 186 and 187.–File fitted into the
American chuck.]

It must, however, be insisted upon that the principle of giving a
passive rôle to the artificial hand is to be preferred.

(_b_) _Appliances with Mobile Joints._–In the course of work the
direction of the wrist is changing at every instant, flexion,
extension, pronation, and supination occurring, sometimes in order
to move around the object, sometimes in order to maintain a suitable
position when the movements of the shoulder and elbow vary the
direction of the forearm.

The consequence of this is that the worker learns to turn the piece of
work around with his sound hand. To get over this difficulty passive
joints are inserted at the wrist, which allow the appliance to move
when it is pressed against the piece of work and to take up the
direction which suits the inclination of the forearm.

[Illustration: FIGS. 188 to 190.–Agricultural hook and ring.
(Gripouilleau.)]

[Illustration: FIG. 191.–Combined hook and ring. (Boureau.)]

[Illustration:

FIGS. 192 to 194. 1. Tram driver’s and chauffeur’s bell. 2.
Method of use by a tram driver. 3. Management of a motor car lever.
Pressure at the extremity and traction.]

One of the simplest mechanisms–and one of the oldest, because it was
designed by Gripouilleau–is that of the _agricultural labourer’s
ring_, intended to grip and manipulate the handle of a wheelbarrow
or a plough. The ring is mounted on a transverse axis and moves in a
horseshoe which in its turn revolves on a shank which is screwed into
the forearm. The ring is provided with a screw, which may be tightened
upon the handle if desired, but which is, however, rarely used (Figs.
188 to 190).

The _tram-driver’s bell_, represented in figure 192, is devised on the
same principle. It moves on a transverse axis, and in figures 193 and
194 its utility in managing levers in driving a tram or a motor car
will be easily seen. The rotation of the horseshoe on the axis of the
forearm is not required.

_The “cardan” joint_ also allows movement in every direction: it
consists of two semicircles of metal, placed at right angles, each
working around a transverse axis, these axes being united in the form
of a cross. The construction and working will probably be understood
without further explanation by a study of figures 195 to 198. The
first two represent a system with a ball in the centre, which is well
known commercially. The last two represent the simple universal joint
generally used in orthopædic surgery. It is somewhat more cumbersome
than the previous model.

[Illustration: FIGS. 195 and 196.–Universal joint with ball.]

[Illustration: FIGS. 197 and 198.–Simple universal joint.]

[Illustration: FIG. 199.–Gardener’s cylindrical spade
holder. A universal joint permits movements in every direction.]

The spade holder used at the agricultural centre at Limonest is
mounted on a cardan (Fig. 199).

The joint can be fixed by a compression screw which is easily and
quickly adjusted.

Where several tools are necessary each should be complete with its own
universal joint.

Other methods of terminal passive articulations are–

(1) Ball joints which have already been described in connection with
the fingers and which may be applied to the wrist.

(2) Bayonet joints which are only applicable to certain artificial
hands which are not subjected to any great strain.

[Illustration: FIG. 200.]

Figure 200 explains this mechanism as it is applied to the artificial
hand represented in figure 148.

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