Prosthetics Research and the Amputation Surgeon
Rufus H. Alldredge, M.D. *
Eugene F. Murphy, Ph.D. *
Except in abnormal circumstances, man is
born into his world with four mobile members which extend from his trunk like
branches from a tree. These so-called "limbs" he uses in manifold complex
patterns, first to serve his immediate personal needs and second to shape his
own environment as best he can. Although in early life man reveals the history
of the race by crawling about on all fours, he shortly assigns to two of the
limbs chiefly, but not exclusively, the functions of supporting the body and of
moving it from place to place. The "legs" thus become the principal
weight-bearing members and the generally accepted means of
locomotion.* To the more versatile "arms" man assigns most of the more complex functions of daily living and of creative activity. No doubt to this "division of labor" can largely be attributed the rather remarkable development of art and science and literature and industry and most of the other
creative manifestations of human life.
Because, however, the limbs extend from
the body proper, they are particularly susceptible to damage, either from lack
of nutrition and disease or by external forces of one kind or another. Since the
limbs are not "vital" organs in the same sense as, say, the heart or the liver, it is possible under favorable conditions to remove one or more without loss of the whole living organism, especially since the advent of modern surgery, anesthesia, and the newer drugs
and blood substitutes. That is to say, a man has a chance of living on, though a
natural member be discarded. We thus have as a result of war, accident, and
disease a sizable number of individuals lacking part or all of one or more
limbs, and to these must be added those persons born with malformed or missing
limbs. All these people, now known generally as "amputees," are obviously
handicapped, to greater or lesser degree, in the performance of all those
functions ordinarily carried out by the arms and legs, and in extreme cases
there may be no residual function at all. To restore lost functions in as great
a measure as possible has long presented a challenge to certain people, mostly,
as might have been expected, to amputees themselves.
The Background
Early amputations undoubtedly were more
often than not traumatic events leading to a prompt death. Occasionally,
however, history records amputees who survived their bloody and painful
experiences. One famous example was Hegesistratus, who, captured and chained by
the Spartans, amputated his own foot in order to escape. With the
slow development, over the centuries, of surgery in general, amputations came to
be performed more frequently. Typically they were desperate efforts to save
life. Such works as those of Pare, of the sixteenth century,
described the techniques. In some cases, a tight tourniquet was applied and left
intact until the distal portion was lost by spontaneous amputation. In others,
the amputation was conducted with knife and saw, and bleeding was
controlled by cauterization.
From the beginning it seemed obvious that
the amputation should be as distal as feasible in order to conserve the maximum
bony lever. Many surgeons, however, preferred a disarticulation at a joint
whenever that was possible. For they had found that infection was relatively
unlikely to enter the bone through the normal surfaces which could be retained
with disarticulation, whereas, in the days before aseptic surgery, osteomyelitis
was all too common when the marrow cavity was opened by amputation through the
shaft of a bone.
Roughly a century ago the introduction of
anesthetics made prolonged surgery possible, and not long after that the germ
theory and antiseptic and aseptic surgery greatly increased the chances of
surviving either accidental wounds or surgery. These factors made possible the
comparatively long and complicated amputations now taken for granted, the
revision of otherwise unsuitable stumps, and the elective amputations in cases
of serious disease or deformity.
At about the same time, wars involving
European powers, and especially the American Civil War, led to large numbers of
surviving amputees. Also, and again more or less simultaneously, the rapid
development of heavy industry and of railroading resulted in many traumatic
amputations in civilian life, especially in the United States. All these factors
increased interest in amputation surgery and in limb-making for the large
numbers of surviving amputees.
Amputation Surgery and the Art of
Prosthetics
Artificial limbs of one kind or another
date from antiquity. Particularly during the fifteenth, sixteenth, and
seventeenth centuries, crudely functional artificial arms came to be made,
chiefly by armorers, who were already experienced in a related field. Of many
known examples, the arm and hand made about 1509 for Goetz von Berlichingen
is by far the best known (Fig. 1), numerous copies having
been constructed for museums. In this and others of the period, joints were
flexed by the other hand and locked by ratchets. Springs returned the joints
when the ratchets were released by pressure on a projecting knob. In all such
armorlike arms and hands, iron was used, sometimes with holes punched to reduce
weight. Leather doublets or sockets, often with laces, commonly were used for
several centuries.
Near the end of the eighteenth century,
Klingert introduced an above-elbow arm with most of the natural
motions controlled by ten catgut cords fastened to a vestlike garment and moved
individually by the sound hand. Since in most cases the sound hand might better
have performed the intended action, this impractical prosthesis was a classic
pioneer in exceeding what some nowadays call the "hardware tolerance" of the
amputee. In 1818, Peter Ballif of Berlin developed the first
voluntary control by use of trunk and shoulder muscles. His hand was of the
voluntary-opening type with springs to close the fingers and
thumb. To the Dutch sculptor, Van Peeterssen, is attributed the first
above-elbow prosthesis with harness control permitting voluntary flexion of the
artificial elbow joint.
As the art of armormaking declined,
limb-making on the Continent came to be carried on usually in conjunction with
the making of braces, and consequently the artificial legs produced there
typically evidenced steel sidebars and molded leather corsets similar to those
used in braces. At the time of the Napoleonic Wars, the wooden leg, used from
earliest times, was provided, for example, by Potts of London for the Marquis of
Anglesey and others. Wood reinforced by rawhide was used
customarily in the United States, although a variety of other structural
materials has been suggested in the journal literature and in
patents.
Comte de Beaufort invented a
number of artificial arms as well as legs, some of which were approved for
French veterans of the Crimean and Italian campaigns. In 1858, he presented to
the French Academy of Medicine a hand with an alternator mechanism and a
double-spring hook. Dorrance introduced in America the
well-known voluntary-opening split hook with rubber bands to close a movable
finger against a rigid one. He and others rapidly produced a variety of hook
shapes intended for specific trades.
World War I
World War I led to a revival of interest
in amputations and in artificial limbs, notably in Germany, Belgium, and
England. All these countries had rather extensive programs involving the
cooperation of surgeons, limb-fitters, and engineers. Publications based on
World War I experience indicated considerable progress
in understanding of amputation techniques, of the need for prompt rehabilitation
of amputees, and of the importance of fit and alignment of the prosthesis. The
development of many new devices and components for artificial limbs for both
upper and lower extremity was described perhaps most impressively in
Ersatzglieder und Arbeitshilfen. Martin's second book , prepared for the International Labour Office, and Little's text were particularly useful because they offered critical analyses following
impartial descriptions of prostheses and mechanisms.
The wooden leg came to be used widely
throughout the Continent as well as in England and in the United States.
Aluminum, introduced by Desoutter in England in 1912, was used
particularly in England and to a lesser extent elsewhere. The fiber leg was used
by a substantial number of limbmakers, particularly in the United States.
Despite the large number of knee locks and ankle joints permitting lateral
motion, described in patents and in medical and technical literature, most
above-knee amputees used a simple uniaxial hinge for the knee joint and a
single-axis ankle joint. Rubber bumpers were used widely in place of the tendons
popular in the nineteenth century. It is interesting to note that in 1922 Little
remarked that most leg amputees had to use at least one
stick.
For the upper extremity, a great many
artificial arms, hands, and working tools were developed during World War I, as
can be seen from the major books on prostheses of the period
. American designers generally used the split mechanical
hook closed by rubber bands and separated from the forearm by a rubber washer
which provided stability by friction but which at the same
time permitted pronation-supination by means of the other hand. Europeans
generally preferred passively operated clamps and special tools so designed as
to be interchangeable by a disconnect at the wrist. Either a clamp, as on a
machine tool, or a locking bolt engaging any one of a series of holes in a disc
was used to fasten the tool in the selected position of pronation or supination.
For working purposes, the attachment for the tool was often placed at the end of
the socket, far above the normal hand level, so as to decrease the leverage of
the load on the stump. For dress wear, a cosmetic forearm and terminal device
could be attached in place of the tool.
Various wooden hands, usually with
spring-loaded or voluntarily controlled thumbs, were shown in the literature of
many countries. Generally, it was assumed that such hands were for dress and for
light office use only, either bare or covered with a leather or fabric glove.
Often the fingers were curved permanently to carry a briefcase. The Carnes arms
and hands, patented in 1912, 1922, and subsequently, were
widely sold in the United States for many years. During World War I they were
widely admired abroad and were described in detail by Schlesinger and to a lesser extent by Martin and by Little.
Similar devices, under the general name
"Germania," were built in Germany after entrance of the United States into
hostilities. Most authors admired the dexterity achieved by the Carnes
devices-particularly because of their ingenious construction, the passively
adjustable wrist flexion, and the possibility of coordinating supination with
elbow flexion to assist in eating-but criticism was leveled at complexity,
relatively heavy weight, lost motion, and the restriction against interchange of
a hook for the hand.
World War II
Surgical authorities during World War II
advocated typical "sites of election" Fig. 1 and Fig. 2) based upon
the extensive practical experience of the surgeons as well as on the advice of
many of the more active limb-fitters, who were notably successful in fitting
good stumps at these "sites of election" but who had encountered serious difficulty in
fitting such stumps as the wrist disarticulation, the very short below-elbow
stump, the knee disarticulation, or the Syme stump. Typical prostheses for the
so-called "sites of election" are shown in Fig. 3, Fig. 4, Fig. 5, and Fig. 6.
It will be noted, for example, that all
levels of forearm amputation, from the wrist disarticulation to the short
below-elbow, were fitted with the same type of forearm composed of a molded
leather socket, usually laced, extending into a cosmetic shell and reinforced by
volar and dorsal metal sidebars which formed a crosspiece at the wrist
supporting a screw thread or bayonet-type attachment for the hook or artificial
hand. Typically, the terminal device could be rotated passively by
the opposite hand against the friction of a
rubber washer but could not be pronated or supinated actively. The metal
sidebars were hinged in line with the humeral epicondyles to permit elbow
flexion in relation to a buckled or laced cuff about the upper arm. Usually the
terminal device was operated by a leather thong which passed over a pulley or
through a short length of helical wire housing at the elbow joint so as to be
independent of elbow flexion. Since the prosthesis did not provide for
pronation-supination, whatever of this function was originally available in a
stump amputated at the "site of election" soon disappeared owing to muscular
atrophy.
The elbow lock for above-elbow arms
generally was operated, in the case of a unilateral amputee, by the opposite
hand, or, in the bilateral arm amputee, by pressure against the body or against
a table. It usually consisted of a sliding bolt engaging one of three or four
holes in a metal strap surrounding the carved wooden elbow portion below the
molded leather or fiber humeral socket. Cotton webbing and rather heavy leather
shoulder saddles were commonly used in the arm harness, and leather thongs
transmitted forces to flex the elbow and to operate the terminal
device.
During the period of World War II, the
typical unilateral leg amputee in the United States, including many
hip-disarticulation cases, walked without the aid of a cane, although the
above-knee amputee usually walked with the relatively fixed cadence for which
the fixed friction about the knee bolt was adjusted. Any attempt to walk faster
or slower led to excessive heel rise or to a tendency to drag the toe. The
below-knee artificial leg was often carved from a wooden block by
trial-and-error fitting. Alternatively, a leather socket, molded over a modified
plaster replica of the stump, was inserted into a fiber, metal, or
occasionally a wooden shank. Sometimes, in an effort
to increase conformity to the stump, a certain degree of softness or of ability
to flow plastically was imparted by a thin lining of felt, wax, or relatively
pliable leather.
The above-knee leg was occasionally held
to the body by suspenders, but by 1945 a large percentage of above-knee amputees
used a pelvic band and metal hip joint. Usually the hip joint permitted the leg
to swing in one plane only, although in some designs an additional axis
permitted abduction and adduction. In England, and rarely in the United States,
a third axis, substantially vertical, also
permitted a limited amount of rotation, although about an axis outside the body
several inches from the ball and socket of the natural hip joint.
Era of Antobacterial
Techniques
During World War II, blood, plasma, and
antibiotics came to be used widely to increase the chances of survival at the
time of injury as well as to permit more extensive surgery. The Surgeon General
of the U.S. Army ordered open amputation exclusively, to be followed by skin
traction until a revision operation could be performed. This flat order
unquestionably reduced the incidence of infection and gangrene from
combat injuries to U.S. Servicemen in World War II, as compared to experience in
previous wars or to the experience of certain other military forces. It
undoubtedly led also to the conservation of many stumps which, under other
circumstances, would have been reamputated at the "site of election" above the
next joint in order to avoid rapid spread of infection and gangrene. According
to Veterans Administration records, for example, the U.S. forces had over two
thirds of their lower-extremity amputations below the knee, whereas during the
American Civil War and among the Filipino Scouts and guerrillas and
the Yugoslavian guerrillas in World War II, it was estimated that at
least half of all lower-extremity amputations were above the knee. Little, in a sample of 1030 amputations among the English forces in World
War I, found only 219 "leg" (below-knee) and 441 "thigh" (above-knee) stumps in
a total of 723 lower-extremity amputations.
On the other hand, there is no question
that the order for open amputation, followed by traction and a second, or
revision, operation, led to prolonged hospitalization for some cases which safely could have been performed
primarily as closed amputations, particularly as antibiotics became available
late in World War II. Furthermore, many of these "military" amputations,
performed as they were far behind the lines, were really essentially civilian in
nature. It seems very questionable that there would be a need for performing as
many open amputations in civilian practice where risk of infection and gas
gangrene is relatively low. The surgeon has a responsibility to use open
amputation and traction when there is a clear risk, yet to consider prudently
the much shorter care which will be needed with a primary closed amputation when
it is feasible medically.
New Concepts in Rehabilitation
The large military amputation centers in
World War II provided an excellent opportunity to study the entire problem of
amputee rehabilitation. Although civilian surgeons generally had been
in the habit of dismissing the patient when the amputation scar had healed,
leaving him to search for limbfitting services with only the guidance of the
classified telephone directory and the perplexing visits of amputee salesmen and
demonstrators, the military Services reawakened the responsibility of the
surgeon for more complete rehabilitation through the stages of prosthetic
fitting, training, and subsequent follow-up. Similarly, the Services assumed
responsibility for the necessary vocational guidance and counseling.
Wartime Problems
Because of the dramatic concentration of
hundreds of amputees in a single hospital, however, the large military
amputation centers drew considerable public attention-both favorable and
unfavorable and generally over-dramatic. In operating their limbshops, they
encountered difficulties because of the scarcity of experienced personnel (P).
This problem was partially corrected, though never completely solved, by
diligent effort to locate limbfitters who had been drafted and to see that they
were reassigned to limbshops at amputation centers. In every case, however, the
bulk of the limb-shop staff was necessarily made up of men who perhaps had
mechanical aptitude but who were without previous training or
experience in the limb industry.
At the same lime the commercial
artificial-limb industry was kept very busy with its private cases from civilian
life and with the veterans from previous wars, while some of its younger men
were drafted into the Services. Besides this, the generally good business
conditions during and immediately following World War II, together with the
manpower shortage, led to the employment or advancement of a great many amputees
who, during the previous depression, had had great difficulty in finding and
holding jobs. Many of these people wished to procure new limbs, thus further
overloading the commercial limb industry.
To add to the difficulties, the industry
was then neither certified nor licensed, and it consisted, as it does today, of
several hundred relatively small workshops. While some of its members had had
formal education in other fields, there had never existed in this country any
means for formal training in the arts and sciences basic to limbmaking and
limbfitting. The sudden release, within a limited number of months, of some
21,000 veterans from military amputation centers imposed upon the industry an
exceptional burden. These men had been fitted in the military centers with a
serviceable, adequate, but admittedly "temporary" prosthesis, with the
understanding that soon after their release the Veterans Administration, through
civilian contractors, would provide a permanent prosthesis. Indeed, an
additional or spare permanent prosthesis also was provided as a matter of
policy.
The confused state of affairs about the
end of World War II, and during the year or so immediately thereafter, was further
complicated by a series of sensational stories in some of the newspapers
concerning difficulties with the limbs provided by the military
centers and covering a series of indictments and trials of certain members of
the commercial limb industry for alleged violation of the Antitrust Acts. The
rather emotional atmosphere then prevailing in regard to amputees led to
dramatic stories but in many cases to neglect of the basic
difficulties.
Casualities From Korea
Substantially all factors concerned have
since been greatly improved, so much so in fact that there were no difficulties
of this type over the treatment of amputees returning from the Korean conflict.
The relatively calm and orderly handling of these casualties, with the close
cooperation of all concerned, was a tribute to the progress which had been made
since 1945 in both technical and administrative aspects. Much of this change has
been due to the fine cooperation of the commercial limb industry, now emerging
into a prosthetics profession. It also has been influenced by the greater
interest of surgeons in amputations and amputee rehabilitation, by the
development of the team concept in this area as in so many other areas of
medicine (and indeed in science generally), by the contributions of many sound
administrators, and by the results of much hard work in the research and
development laboratories.
Some of the major changes which have
influenced the amputation surgeon have been proven clinically by experience with
casualties from Korea. Concepts of level of amputation and certain of the
techniques of surgery have been affected. Perhaps most important, there is now a
greater interest in postoperative care and in the rehabilitation
responsibilities of the medical profession.
Level of Amputation and Modern Prosthetic
Replacement
The surgeon's first decision in
amputating is the selection of the site. Perhaps the influence of the Artificial
Limb Program, sponsored by the Government and coordinated by the Committee on
Artificial Limbs of the National Research Council, can be shown
most dramatically by a review of the changes in recommended level. From a few
definite "sites of election," the development of new principles and devices has
made possible reaffirmation of the policy of "save all possible
length." Every level, with the possible exception of the below-knee amputation,
has benefited, particularly in the upper extremity, where it is now possible to
define at least nine amputee types (Fig. 7), all of which can be fitted
successfully. In many cases the new devices not only permit satisfactory fitting
of longer stumps but often replace additional functions beyond the important
increase in bony lever.
The Upper Extremity
The Below-Elbow Cases
The Wrist-Disarticulation Case.
The wrist-disarticulation prosthesis is a good example of the development of
a simpler appliance which yet permits better appearance and additional function
than did the conventional prosthesis of 1945. At the end of World War II, the
wrist disarticulation, if retained at all and not later reamputated at a higher
level, was fitted with a laced, molded leather socket supported by steel
sidebars jointed at the elbow, quite similar to that shown in Fig. 3, with
rather bulky harness and a leather thong for power transmission. Elbow flexion
and terminal-device operation were the only functions provided,
pronation-supination being prohibited by the single plane in which the elbow
hinge operated. The entire appliance was bulky, the uncoated leather soon
absorbed perspiration and became objectionable, and the almost complete encasing
of the forearm made the prosthesis uncomfortable in warm weather. Because of the
screw thread attaching it to the wrist, the terminal device, whether hook or
mechanical hand, projected appreciably beyond the opposite natural hand,
resulting both in limited function and in undesirable appearance. No cosmetic
covering faired the gap between the mechanical hand and the
wrist.
In contrast, there has been developed
under the program of the Advisory Committee on Artificial Limbs a light and
sanitary plastic-laminate prosthesis (Fig. 8) which covers only the distal
portion of the stump and extends only a short distance up the radial side
to support tipping loads while still permitting pronation and supination. Extending farther up the ulnar aspect, the socket provides adequate
leverage and bearing area to permit comfortable resistance to large loads on the
terminal device which tend to tip the socket about the stump when the forearm is
in the horizontal position. The snug, "screw-driver" fit of the bony prominences
at the wrist into the terminal portion ensures rotation of the socket and
terminal device as the radius glides around the ulna. Since this rotation
decreases progressively up the forearm until, at the elbow, there is no relative
displacement, it is necessary to cut away as much as possible of the radial
aspect from the socket. But removal of socket material decreases both the weight
of the prosthesis and discomfort in warm weather. The plastic-laminate socket and
nylon coating of any leather used in this or any other prosthetic or
orthopedic appliance will prevent absorption of perspiration and the consequent
development of odors.
Very simple harness is adequate. For the
rare amputee requiring only an extremely light-duty prosthesis, the socket can
be held on the bulbous stump by a strap like that for a wrist watch to close a
keyhole slot so as to clamp the socket firmly just above the bulging styloids.
In this case, the only harness necessary is the cable and loop about the
opposite shoulder. Practically all amputees, however, require a somewhat more
secure, yet still minimum harness, as shown in Fig. 9, with a light triceps
pad held by an inverted Y-strap whose fork is higher than the fully tensed
biceps. A very simple figure-eight harness is used, and the steel Bowden cable
transmits energy quite efficiently without stretching and without catching the
shirt sleeve.
To shorten the prosthesis markedly in
order to match the length of the opposite arm, the proximal wall of the APRL No.
4C hand may be fastened to a plate built into the distal wall
of the plastic-laminate socket, as shown in Fig. 8. Thus the plastic cosmetic
glove can readily bridge the gap between the hand and the prosthesis and extend
up under the shirt or coat sleeve of the wearer. A similar plan can be followed
with the APRL hook by removal of the stainless-steel stud and
plate by which the hook case is normally fastened to the wrist disconnect. On
other types of hooks, the stainless-steel stud can be removed or shortened and a
suitable fastening plate added by welding or brazing. For wrist friction, thin
rubber 0-rings may sometimes be used instead of thicker rubber washers, thus
further decreasing length.
In many cases, it has been found entirely
feasible, both technically and economically, to supply two sockets, one laminated to a
hand and the other to a hook, to be worn interchangeably. The added length due
to a conventional wrist disconnect and stud is thus avoided. Snap fasteners
between the flexible leather elbow hinges and the forearm socket, plus the
disconnect feature of the control-cable attachment post, permit interchange of
prosthesis without changing the harness. Thus the amputee can make the
interchange from hand to hook simply by rolling up his sleeve, it being
unnecessary for him to remove his shirt.
The Long Below-Elbow Case.
In many
shorter below-elbow stumps, a similar type of prosthesis, but without the bulges
for the styloids, can be applied to permit the amputee to use his remaining
pronation and supination. The key factors are flexible elbow hinges and the
"screw-driver" fit of the end portion of the stump in the socket with
increasingly loose fit proximally. The fact that pronation and supination may be
retained encourages the surgeon to make every effort to avoid fusion of the
radius and ulna owing to bone spurs or similar causes and to instruct the
amputee to participate in physical therapy designed to redevelop muscular
control.
The Medium Below-Elbow Case.
In
the medium below-elbow stump, the limited amount of pronation and supination is
worth retaining, yet it is inadequate to permit direct control of the
prosthesis. Accordingly, the step-up type of rotation device (Fig. 10) has been
developed. Early attempts at an automatic lock were frequently disappointing,
particularly if the amputee tended to snap the prosthesis when used with a
wrist-flexion unit, because the high inertia forces jammed the locking surfaces
and caused permanent dents which thereafter caused chattering or even
failure to lock. Instead, a simple lock has been
supplied on an experimental basis, some mechanical problems remaining to be
solved. A simple bolt in the stabilized outer socket engages one of a series of
holes in the rotating portion of the wrist whenever the elbow is flexed more
than a few degrees but is withdrawn at maximum elbow extension (Fig. 10,
detail). This device is particularly desirable even with a short, almost conical
below-elbow stump which, with elbow extended, participates in humeral rotation
from the shoulder. The entire extremity rotates within the triceps pad and outer
socket, which are stabilized by the harness. With the socket and terminal device
rotated to the desired position, the amputee returns his stump to its normal
position with the elbow axis parallel to the mechanical elbow hinges, flexes the
stump, and thus locks the wrist in the desired position.
In such applications, step-up gears are
normally provided to increase the rotation of the terminal device in relation to
that of the socket. A lock is desirable partially to transmit torsional loads on
the terminal device through the elbow hinges to the open humeral cuff,
but it is particularly desirable with outside
Bowden-cable control of the terminal device to permit the torsional component of
tension in the cable, when it spirals about the forearm, to be transmitted to
the upper arm without stress upon the stump. The mechanical advantage of torque
at the terminal device or control cable over the stump is due, of course, to the
step-up gearing used to increase rotation of the terminal device.
The Short Below-Elbow Case.
For
rather short below-elbow amputations, a geared poly-centric hinge (Fig. 11) has
been developed. In some cases, it permits easier fitting of
the socket and may hold the socket more firmly on the stump. For still shorter
stumps, the socket may be attached to the link connecting the two axes of
rotation, while the forearm is attached to the lower geared segment (Fig. 12),
thus providing a fixed ratio of 2:1 between degree of flexion of the
artificial forearm and degree of flexion of the below-elbow stump and socket. It
has been found, however, that this fixed ratio has only limited
application.
The short below-elbow stump is another
example of the new principle of saving all possible length. Formerly, most
surgeons and limbmakers would have agreed that such short below-elbow stumps
could not be fitted satisfactorily. Such a stump tends to slip out of the
conventional socket and also may exhibit no useful control of the elbow joint.
Frequently, it was advised that such cases be reamputated at the "site of
election" in the humerus. Late in World War II, however, both in Canada and in
at least one U.S. Army amputation center, hinges were developed, similar to
those shown in Fig. 13, which permitted a step-up of forearm movement as
compared to stump movement, a variable ratio compensating roughly for the
resistance encountered and the strength of the stump at various
positions.
As seen in Fig. 14, the short below elbow, biceps are feasible.* Since there is no appreciable pronation-supination at this level, the biceps tendon
remains in a fixed position rather than tending to migrate from medial toward
lateral as it does when a longer stump moves from pronation to supination. The
posterior rim of the socket is carried as high as possible, substantially to the
olecranon. In some cases it is possible to hook the socket brim over the
olecranon to help pull the stump into the socket during flexion.
The middle pivot of the step-up hinges is
substantially opposite the humeral epicondyles, which define the anatomical
elbow axis. The lower hinge moves in its slot during elbow flexion, as indicated
in Fig. 13. The lower proximal end of the forearm shell must be cut out in
order to clear the short stump at extreme elbow flexion. But since this type is
used on short below-elbow stumps, there is no serious protrusion of the stump
beyond the general line of the forearm socket and, therefore, no appreciable
bulge in the coat sleeve.
Customarily, an auxiliary lift for the
forearm is provided by an above-elbow type of harness, with two separate pieces
of cable housing attached to the forearm and to the triceps cuff but bare cable
running from a space between the two separated pieces of housing, as shown in
Fig. 14. By voluntarily controlling the position of the stump, the amputee can
effectively "lock" the forearm as if by a mechanical elbow lock and can thus
operate the terminal device by increased tension on the control cable without
causing further flexion of the forearm. By means of stump action, he also can
press downward firmly enough on the forearm to perform functions such as
holding papers on a table or holding a fork to
stabilize a piece of meat while it is cut by a knife held in the opposite
hand.
The Elbow-Disarticulation
Case
The elbow disarticulation was for many
years frowned upon because of the difficulties of fitting it with a conventional
prosthesis with laced molded-leather socket and elbow lock and joint requiring a
bolt extending the full width of the elbow. In such a design, of course, the
mechanical lock was necessarily fitted below the end of the stump, thus making
an overly long humeral section and a correspondingly short forearm section,
usually preventing the amputee from reaching his mouth with the terminal device,
as well as creating an awkward appearance and difficulty in using the amputated
elbow as a support on the desk top, and the like. Capable of end-weight-bearing,
the elbow-disarticulation stump, however, is useful as a support without the
prosthesis, as in rolling over in bed. Its bulbous and irregular shape serves as
a key to stabilize the prosthesis against rotation about the long axis of the
humerus.
To conserve these functions, therefore,
the external lock shown in Fig. 15 and Fig. 16 was developed to fit on the
outside of the socket in line with the humeral epicondyles and the
anatomical axis. The artificial forearm can thus be of a conventional length,
and the terminal device can be brought to the mouth readily. The locking circle
is, however, necessarily of a smaller diameter than would be available in a
conventional above-elbow type of prosthesis, so that in the present model the
number of locking positions is reduced to five (Fig. 16). Although numbering
more than in the earlier conventional above-elbow or brace locks, the five
positions are less than the 11 or even infinite number of positions provided by
above-elbow locks which have been developed in the ACAL research
program.
The APRL-Sierra outside-locking elbow
hinge has another special application in the very short below-elbow stump where
range of motion is insufficient to operate a forearm through a step-up elbow
hinge but where a small residual motion is adequate to operate the locking
mechanism diagrammed in Fig. 16. In the arrangement shown in Fig. 17, elbow locking is effected by stump motion rather than by motion of the
shoulder, thus giving a more natural appearance and more freedom than could be
obtained with an elbow disarticulation or an above-elbow stump.
The external elbow lock has already been
used occasionally for applying artificial-arm principles to arm braces. The
situation in that entire field should improve rapidly in the near future.
Occasionally, patients have requested, or surgeons have recommended, amputation
of an arm when disease or injury have left a flail elbow. It has seemed that
improved artificial arms would actually provide the patient with more function.
It must be remembered, however, that the damaged arm provides at least some
support and perhaps sensation, and consequently every effort should be made to
replace the lost functions of stability, control, and voluntary movement by
suitable bracing. Polio cases, retaining sensation and an erratic distribution of
muscle activity, offer a special challenge.
The outside-locking hinge of Fig. 16 is
normally fitted as shown in Fig. 15 and Fig. 17 for control from the proximal
joint. Presumably, though, it could be inverted and controlled from the distal
end of the arm if some portion capable of even a little voluntarily controlled
movement with very nominal forces were available in the hand or wrist. A ring on
a finger or extreme hyperextension of the wrist could, for example, be used to
trigger the elbow lock, thus simplifying the harnessing, particularly if the
shoulder were also weakened.
It may be noted parenthetically that some
work has been done both by rehabilitation centers and by
prosthetists and orthotists to drive paralyzed fingers with mechanisms adapted
from the artificial-hand field or to hyperextend a paralyzed hand on a "cock-up"
wrist splint and substitute a hook on a rotary or even on a ball-and-socket
mounting on the volar aspect of the wrist. Even with a
quadriplegic there has been enough control of shoulder movement to provide the
necessary voluntary control for the hook, supplementing at least a weak biceps
action for forearm flexion and supination. The relatively heavy hook extending
from the volar aspect of the wrist will provide by gravity forearm
extension and a tendency toward pronation. Since the degree of paralysis and of
loss of sensation may be so variable, in the entire field of arm bracing the
role of the doctor is even more important than it is in rehabilitation after
amputation. Correspondingly, there is an even greater challenge to the ingenuity of the
prosthetist, the engineer specializing in prosthetics, and the manufacturer in
adapting or developing special appliances for the individual case and to the
patience of the therapist in redeveloping even faint voluntary movements which
might control triggers for locking mechanisms.
The Above-Elbow Cases
In the above-elbow stump, as much as
possible should be saved consistent with the nature of the injury or disease.
Even a very short above-elbow stump may be useful as an anchor point, and in
experimental work on electric arms such a stump has been used to
control the necessary switches and clutches (Fig. 18). A stump of nothing more
than the head of the humerus helps to round out
the shoulder and to provide a much more secure stabilization of the
"shoulder-disarticulation" socket.
Nevertheless there remains a challenge to
the engineer and prosthetist in providing improved shoulder-disarticulation and
very high-above-elbow arms with passive or voluntarily controlled humeral
flexion and abduction. A number of designs were shown in the literature
after World War I, but none appears to have been practical. The sectional
plates used in the ACAL research program have facilitated
independent construction of the socket and remainder of the prosthesis and their
subsequent alignment. Sometimes they have been provided with rotation to
facilitate donning of clothing with the humeral section flexed, followed by
return of the humerus to a vertical position. Such joints of the humeral section
to the shoulder cap have not permitted abduction, however, and have not normally
permitted voluntary or passive forward flexion of the humeral section about the
shoulder joint to bring the elbow forward and permit the terminal device to
reach the mouth.
The conventional sectional plates have
been solid and thus have been suited only for a true shoulder disarticulation,
but it should be feasible to leave an opening through which a very short stump,
such as the head of the humerus and its surrounding socket, could protrude into
the hollow humeral section. Provision of a sector of a complete circular track,
rather than the elongated D-shape which has been used, would also result in
better cosmetic appearance when the artificial humeral section is flexed
forward. Possibly a simple lock to stabilize such humeral flexion could be
controlled by a very short above-elbow stump, even if passive adjustment with
the other hand, or by gravity in connection with torso movement, were necessary
because of the weakness of the stump.
Attempts to provide voluntary control of
humeral abduction and rotation have been reported in the literature. Alderson
developed an experimental arm of the
shoulder-disarticulation type in which shoulder lift against the anchorage of a
groin strap generated either elbow flexion followed by humeral abduction or
humeral abduction alone, depending on whether the elbow were free or locked. At
least one commercial limb manufacturer recently has experimented with a
"universal shoulder joint" permitting a combination of actively and passively
controlled motions including upper-arm rotation by means of a turntable located
in the humeral section.
The Lower Extremity
In the lower extremity, although there
have been definite changes in techniques and devices, the influence of the
Artificial Limb Program has not as yet markedly changed the levels of
amputation. Work is, however, going forward rapidly, particularly at the
Lower-Extremity Clinical Study operated at the University of California using
facilities of the U.S. Naval Hospital at Oakland. It is to be expected that in
the next few years more definite changes can be recommended.
Meanwhile, the principal effects of wartime experience and of the ACAL
research program have been increased emphasis on the Syme and knee
disarticulation and a better understanding of muscle functions,
particularly in relation to the suction socket for above-knee
amputees.
The Below-Knee Cases
The Syme Amputation.
While the
Syme amputation is more than a century old, it has until recently been
considered controversial, with firm advocates and bitter opponents. In some
cases, criticism has rightly been directed toward very long below-knee stumps
which, however, were not true Syme amputations with the normal heel flap and
capable of full end-weight-bearing. Experience at military amputation centers
during World War II seems to have confirmed the successful results which have
been reported by the Canadians ever since World War I. A recent Canadian
report on the Syme amputation describes surgical precautions,
conventional and experimental Syme prostheses, and clinical
experience.
Although the Syme amputation requires
meticulous surgery, in the absence of sepsis, and careful attention to all
details, a successful result provides much greater freedom of action for the
amputee and enables him to remain on his feet for long periods. The broad
surface of tissues anatomically adapted to weight-bearing offers the Syme
amputee a great advantage over the below-knee amputee with limited areas
offering a wedgelike support for the stump and pressing upon tissue which has
not been accustomed to weight-bearing.
The prosthesis for the Syme has been
improved, on an experimental basis, by the Canadians (Fig. 19) and, more
recently, by the Prosthetic Testing and Development Laboratory of the Veterans
Administration (Fig. 20). Both types use a plastic laminate in place of molded
leather for greater sanitation as well as for greater strength with decreased
weight and bulk. Both use Fiberglas extensively for high strength.
Considerable success has attended efforts
to reduce the bulk at the ankle by eliminating the steel sidebars which, in
earlier prostheses, projected beyond the malleoli on the medial and lateral
aspects, thus adding thickness to a zone already the broadest portion of the
ankle. The steel sidebars had, in any case, been mechanically rather ineffective in
sustaining bending loads, as when the weight of the amputee is supported on the
ball of the foot, because the material was close to the neutral axis or central
portion of the bars. In the newer designs, this portion over the
malleoli is relatively thin, but bending moment is resisted more effectively by
the most anterior portion, ahead of the tibial crest, and by the posterior
portion at a greater lever arm than was available in the older, narrow, metal
bars. To avoid fatigue failures, special care must be taken to achieve a smooth
posterior cut in the shell-like prosthesis. The bulbous malleoli are introduced
into the prosthesis by opening a posterior portion, which may then be closed
either in trap-door fashion by a hinged portion of the shell or by a fabric- or
nylon-coated leather portion held by a slide fastener, laces, or adjustable
straps.
The shell-like combination socket and
shank section, with the end-bearing pad, is molded over a plaster model of the
stump to attain uniform fit. A slightly soft lining may be used throughout the
socket. Relief is provided along the sharpest portion of the tibial crest so as
to maintain comfort when weight is carried on the ball of the artificial foot
and there is a tendency for the socket to press sharply on the upper portion of
the tibia. Under such conditions, firm counterpressure, distributed comfortably,
is also required just above the malleoli on the posterior portion of the tibia
and fibula. Ankle action may be provided by a laminated sponge-rubber heel which
is compressed at heel contact, giving the equivalent of plantar flexion, or by a
rubber-block ankle joint with a shallow V-shaped section removed to accommodate
the long stump.
The Short Below-Knee Case.
Short,
badly scarred, below-knee stumps have heretofore sometimes been reamputated
above the knee or have been used in a permanently flexed position in the
so-called "bent-knee" or "kneeling-knee" prosthesis reminiscent of pirate tales.
In either case, the advantages of voluntary control of knee-joint movement are
lost.
The U.S. Navy below-knee "soft" socket, an outcome of recent research, consists of a plastic lining backed by a thin layer
of sponge rubber and a rigid or, recently, a rather flexible shell (Fig. 21). An
improvement on earlier commercial sockets with felt or wax lining, it may be
fitted to any below-knee stump, but particularly it has permitted conservation
of short, sensitive, badly scarred stumps. The weight-bearing impression of the
stump dipped in plaster yields a much more accurate replica than do most wrapped
plaster-bandage impressions. In general, it seems reasonable to believe that any
technique for making a socket from a cast is likely to produce a more accurate
fit more rapidly and with less discomfort than is a trial-and-error carving
process. The thin sponge-rubber lining giving the "soft" socket its
name seems to be only one of several factors contributing to its
usefulness.
Careful location of the mechanical knee
joints is always important. The work of the University of Denver
indicated the possibilities, for below-knee amputees in general, of improved
fitting of conventional legs with single-axis knee joints by more careful
location of the knee joints. Particularly recommended were fixtures and tools to
ensure that the mechanical joints on opposite sides of the prosthesis are on a
common axis. Poly-centric joints did not seem necessary. The report considered,
however, the possibility of a mechanical joint of the single-axis type at the
knee, but mounted high up on the thigh corset by a pivoting joint of limited
angular range, in place of rigidly riveting the upper joint bar to virtually the
full length of the corset. This idea has been proposed in the German literature. In such a case, probably a reinforcing band should be mounted in
the thigh corset to ensure that the upper joints are kept on a common
axis.
The very short below-knee stump, with the
tibia amputated in the broad condylar area and with trabecular bone structure,
is often suited to take a high fraction of weight-bearing on the distal end, in
contrast to the usual below-knee stump of much smaller diameter, limited bearing
area, and with thick, hard cortex surrounding a medullary canal. If the
thickness of pads at the end of the stump is gradually increased, particularly
if the pad in contact with the stump end is carefully molded to the
irregularities of the stump, an increasing fraction of end-weight-bearing may
often be tolerated.
These circumstances deserve careful
investigation before any thought is given to re-amputation above the knee, which
in the past has often been suggested for such stumps. End-weight-bearing is both
more nearly normal with respect to mechanical characteristics, promoting
calcification, and is desirable in avoiding any tendency toward lordosis. The
very short below-knee stump often can be fitted successfully by very careful
forming of the socket. Special care is needed in shaping the posterior brim to
accommodate the hamstring tendons, yet to rise into the popliteal space as much
as possible without cutting off circulation. The "slip" socket, elastically
supported to stay in contact with the stump during the swing phase, is an old
idea often indicated for short stumps.
Even if a very short below-knee stump
cannot take appreciable weight-bearing on its end and on the flaring tibial
condyles, it may be fitted with a long, ischial-supporting thigh corset and the
sturdy external mechanical joints which would be used in a knee-disarticulation
prosthesis. In this case the below-knee amputee, like the above-knee amputee,
must rely upon mechanical stability of the prosthesis during the stance phase
with the knee in full extension, but at a
minimum he has proprioceptive sense of knee position and usually some limited
ability to control slight knee flexion to return the knee to full extension,
thus saving himself from some falls. Partial control of heel rise at the
beginning of the swing phase and of knee extension at the end of the swing phase
permit a more graceful gait and a better range of cadence than generally can be
attained with above-knee prostheses.
The Knee-Disarliculation Case
The knee disarticulation, an old type of
amputation, typically has been fitted with a molded leather socket provided with
a lacer to permit the entry of the bulbous end of the stump. This type of
prosthesis has mechanical joints and sturdy metal sidebars similar to those in
the below-knee prosthesis. Normally, no mechanical friction has been used, and
consequently gait tends to be limited to a single cadence. Any attempt to walk
more rapidly leads to excessive heel rise and to "slamming" of the artificial
shank into full extension just before heel contact. Normally,
extension is limited by thongs similar to the back-check in a below-knee
artificial leg. Since the knee cannot be extended or stabilized voluntarily, the
joints are arranged to give mechanical stability at full extension, as in an
above-knee leg.
Many prosthetists have objected to the
knee disarticulation as a level of amputation because of discomfort of the long,
molded, leather socket, tendency toward breakage of the sidebars, and the lack
of mechanical friction. Amputation at a higher level has frequently been
advocated. The knee disarticulation, however, provides definite advantages over
the above-knee amputation. If the end of the stump is properly fitted, a broad
weight-bearing area is available. Normal transmission of weight through the
shaft of the femur minimizes the tendency toward the lordosis often developed in
above-knee amputees as the result of weight-bearing on an ischial support
located back of the normal hip joint. Clearly, disarticulation
offers the maximum bony lever of any amputation at or above the knee.
A recent informal survey of some of the
knee-disarticulation cases performed under supervision of one of the authors
(R.H.A.) at Thomas England General Hospital during World War II has indicated
satisfaction of the patient with this type of amputation and prosthesis. In
spite of the gait deficiencies noted, these knee-disarticulation amputees feel
that they walk well, continue to prefer this level of amputation, and refuse any
consideration of reamputation above the condyles to become more conventional
above-knee amputees. Although some knee-disarticulation prostheses providing
knee friction are reported in the literature, much more needs to be
done in this respect.
The Above-Knee Cases
In the above-knee amputation, at all
locations as much length as possible should be conserved. Gritti-Stokes and
similar end-bearing stumps have in many cases been fitted successfully with the
suction socket, although attachment of the muscles is then
particularly important to avoid development of excessive negative pressure owing
to displacement of muscle bulk in the necessarily limited clearance volumes
available with long stumps and end-bearing pads. Some have found difficulties in
fitting such cases with the suction socket and have preferred to rely on a
conventional pelvic-band suspension, perhaps with a second hinge permitting
abduction. In either case, the longer the above-knee stump the
better.
As regards the above-knee case, the
principal development thus far of the Artificial Limb Program has been the
reintroduction of the suction socket, with many far-reaching effects on stump
shape, muscle conservation, socket fit, and alignment, accompanied by increased
need for the cooperation of many disciplines and the launching of a program of
education and certification. As for the first of these, the suction-socket
program shifted emphasis from the excessively flabby, conical stump (Fig. 22)
desired for the so-called "plug" fit to a more nearly cylindrical stump with
firm muscles stoutly attached to the bone. In the suction socket, the muscles
are needed both to control the newly found freedom about the hip
join and to provide a gripping action by
bulging against the walls of the socket, thereby decreasing the negative
pressure required to carry the weight of the prosthesis. Similarly, introduction
of the suction socket led to replacement of the typical conical socket of
triangular or circular cross section (Fig. 23) by a more nearly rectangular
socket (Fig. 24). The latter, developed in Germany within the last generation,
has a better basis in physiological and anatomical fact, appears to be a
necessity with the suction socket, and has, of course, also been used
successfully with an increasing number of pelvic-band conventional limbs without
use of suction.
As for alignment, introduction of the
suction socket has forced the prosthetist to pay more attention to details,
since, unlike the case of the conventional above-knee leg, errors in alignment
cannot here be concealed by trial-and-error bending of the pelvic band and
metal, single-axis hip joint which forced conventional legs to swing in a single
plane regardless of their inertia and the gait of the amputee. With the suction
socket in correct alignment, the amputee balances his weight completely on the
leg, since he has no pelvic band and hip joint to lean against for support.
Conversely, however, attention to better alignment has led to decreased stress
in the hip joints and pelvic bands of those legs which, for one reason or
another, are still fitted with pelvic bands. If one thinks of the suction socket
as being fitted with an imaginary hip joint carrying zero stress, it is apparent
that a comparable alignment will result in minimum stress in a real hip joint
and pelvic band of a conventional leg and, therefore, to greatly reduced risk of
breakage.
In a very short above-knee leg, the
suction socket plus auxiliary suspension, either the Silesian bandage
(Fig. 25) or the conventional hip joint and pelvic band (Fig. 6), has permitted
conservation of greater effective stump length than would be possible
with the same stump in a conventional leg with hip joint and pelvic band but
with a "plug" fit. In donning the suction socket, the flesh is pulled into
the socket with stockinet, in contrast to the
tendency of the conventional stump sock and "plug" fit to push the soft tissues
upward and out of the socket. The auxiliary suspension provides greater control
and stability than would be available in a pure suction socket. The more logical
anatomical fit of the quadrilateral shape, including some ischial support,
avoids the roll of flesh in the adductor region and the skin irritations and
furuncles so commonly seen with the "plug" fit. Thus, some very short above-knee
stumps fitted with this combination of suction socket and auxiliary suspension
can function as if with a conventional above-knee leg without the necessity of
flexing the stump permanently in a tilting-table type of socket such as would be
used for a hip disarticulation.
Extremely short above-knee stumps, with
little more than the neck of the femur, can be fitted in some cases with the
"saucer" type of socket |
