Harness Patterns for Upper-Extremity Prostheses
Robert J. Pursley, Lt., USA (MSC) *
The comparatively recent development of
more functional components for artificial arms has made it necessary to analyze
in greater detail the requirements of harnessing the power needed for effective
operation. Just as an automobile is helpless without a well-designed and
well-built engine and transmission system, so an arm prosthesis is helpless
without a well-designed and well-constructed harness. To build a successful
harness system requires not a knowledge of some long-lost art but, instead, a
careful appraisal of the wearer, of the device to be worn, and of the available
tools to be put to work. Since the modern body harness constitutes a dynamic
coupling between a human being and a mechanism designed to replace a living
extremity, the problem of devising it is also one of dynamics and of what some
call "human engineering."
Many illustrations of typical harness
patterns are presented later in this article. But it is not enough for the
harnessmaker simply to reproduce what is shown in these drawings of typical
patterns or to superimpose on an individual amputee a generalized harness
pattern of any particular type. He must first understand the purpose of the
harness, the requirements of the particular prosthesis involved, and the body
motions available, and he must then apply his own skill and judgment in making
appropriate modifications to suit the individual case. It is, of course, far
more important to produce a harness that will give the desired functional
results than it is to produce one that looks exactly like any one of the
drawings. The illustrations are therefore intended as general guides only, not as a
detailed description applicable to every case of amputation at the indicated
level. When planning and making any harness, the prosthe-tist should examine the
location of each element to ensure proper function with the expenditure of
minimum effort on the part of the particular wearer concerned.
The first and most simple requirement of
any harness is that it must hold the prosthesis securely on the stump. The
second is that it must be comfortable to the amputee. Generally, suspension, as
such, is easily obtained, but to suspend the prosthesis properly and at the same
time to assure maximum comfort for its wearer is more difficult. If either of
these requirements becomes a matter of choice, then comfort must be the more
important consideration. If the harness is not comfortable, or at least
tolerable, the person for whom it was intended will soon hang it politely on a
suitable nail. Since almost no harness can be constructed satisfactorily without
a few compromises at first, it is unwise to promise complete success on the
first try.
The third and all-important requirement
of functional body harness is that it must supply a source of power for the
operating components of the prosthesis. This means simply that residual body
motions must be harnessed to replace lost functions of the natural member, but
to provide controls that are operable in an effective and yet inconspicuous
manner poses a complex problem. It requires an examination of the body motions
that can be utilized by the harness without detracting from the usefulness of
the remaining normal hand and without introducing unduly awkward gyrations of
parts of the anatomy not ordinarily involved in arm activity. The higher the level of
amputation, the greater the control requirements but the fewer the sources of
control. The problem is further complicated by the need to maintain the proper
balance between adequate suspension, acceptable comfort, and worthwhile
function, for each of these needs is often satisfied only at the expense of the
other two. A look at the background of harnessing for upper-extremity prostheses
reveals that, when devices were generally passive in
nature, so was the harness. As devices have increased in function, so has the
harness also. Today the development of devices has in general surpassed the art
of harnessing them. With the proper approach, however, and using a common-sense
analysis both of the amputee's capabilities and of the requirements of the
prosthesis, an accomplished limbfitter can in almost every case turn out a very
acceptable harness that will meet functional needs to a surprising
degree.
Harnessing for the Below-Elbow
Cases
The prosthesis for the unilateral
below-elbow case is unquestionably the simplest to harness. For the reason that
the below-elbow amputee retains his own elbow, and therefore usually requires
replacement of prehension only, he can almost without exception be harnessed
successfully. At least three feasible control motions are to be had. In order of
decreasing usefulness, they are arm flexion on the amputated side, shoulder
depression on the amputated side, and scapular abduction. The choice and extent
of use of these three motions, singly or in combination, is largely a matter of
personal preference depending on the area in which the terminal device is
required to operate. With the elbow flexed to 90 deg. and with the terminal
device located slightly above the level of the head, for example, arm flexion is
almost completely spent. Using scapular abduction under the same circumstances,
however, the below-elbow amputee can still operate the terminal device
satisfactorily. Successful wearers of below-elbow prostheses develop their own
individual patterns of operation and subconsciously learn to operate the device
in all areas in which it is called upon.
The problem of transmitting the force and
excursion of body motions from the source to the point of use has in the past
involved a wide variety of materials. Rawhide thongs and leather laces are only
two of many that have been used, even as late as only a decade ago. The flexible metal cable and wrapped-wire housing adopted from the aircraft
industry is currently the most widely used and is the most satisfactory
available today. It is based on the Bowden principle (Fig. 1), which makes it
possible to transmit force and excursion from the body to the terminal device
regardless of elbow angle.
Fig. 1. The principle of the Bowden cable
for transmitting tension forces applied at one end. Although point C is
brought closer to point A when rotation occurs about B, the
housing D prevents slack in cable E by preserving the effective
path length A to C. A counter-force is required at the opposite end
to return the flexible cable to its original position. Other types of Bowden
cables are based on the torque principle, as used in speedometer cables, or the
push-pull principle, as used in the temperature controls of the automobile
heater.
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Utilizing any or all of the three useful
body motions, together with the Bowden-cable transmission system in every case,
two alternate harness patterns are available for the below-elbow amputee with a
stump of medium length. The first is known as the "figure-eight" harness, the
second as the "chest-strap" harness. In addition, there are two special
modifications, one for the very long and another for the very short below-elbow
stump. These are, respectively, the "double-axilla-loop" harness and the
"dual-control" harness. Finally, there is the special harnessing arrangement
using the biceps cineplastic muscle tunnel to provide force and
excursion.
The Below-Elbow Figure-Eight
Harness
The Harness Pattern
The figure-eight pattern, of which Fig. 2 presents a typical example, is the harness most commonly used in the
unilateral below-elbow case, the axilla on the sound side being the site of
anchor for capturing the relative motion. The front view of Fig. 2 shows the
suspension portion of the harness. The front harness strap, passing over the
shoulder at the pectoral interval on the amputated side,
buckles to the inverted Y-strap supporting the leather triceps pad, which in
turn supports the socket through the flexible elbow hinges. The back view shows
the transmission system from harness to terminal device. The general path of the
control cable is such that sharp bends and curves of small radius are avoided as
much as possible.
Fig. 2. The below-elbow figure-eight
harness. A simple webbing loop passes around the sound shoulder, the front
portion being used for suspension, the back for attachment of the control cable.
The inverted Y-suspensor. triceps pad, and flexible elbow hinges are constructed
of 4 to 6-oz. strap leather and lined with 4-oz. pearl horse-hide or equivalent.
The proximal retainer on the triceps pad is of the flexible leather type to
improve cable life. The three circled inserts show possible variations in
individual cases. Circle A illustrates the leather half-cuff as used in
combination with rigid elbow hinges and a single billet. Circle B shows a
hall-cuff with two billets, again in combination with rigid elbow hinges. Circle
C shows the inverted Y-strap as made from fabric instead of leather. Any
of the combinations shown may be used as required to furnish the necessary
stability depending upon occupational needs, level of amputation, and other
factors.
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The chief purpose of the control system
is to transmit force and excursion to the terminal device. When, however, the amputee must
pick up loads with forearm extended, the cable is expected to assist in support
whenever the load is of any appreciable magnitude. This, then, is an example of
what is meant by the proper balance of forces that is needed to meet amputee
requirements. Both suspension and control system should be so constructed and
adjusted as to be comfortable and yet be able to meet a reasonable load-support
requirement without unnecessary displacement of the prosthesis. Tests for
determining allowable displacements and other important factors have been set
forth by Carlyle.
As shown in Fig. 2, the harness is
padded and protected under the axilla, and the control cable is so adjusted that
it cannot come into contact with the amputee's back. For maximum excursion, the
cross of the harness should be below the cervical vertebrae and not more than 1
in. toward the sound side of the vertebral spine. The control attachment strap
(i.e., the strap attached to the flexible control cable) should lie at
the midscapular level. In the course of constructing the harness, visual
observations of all these details should be made while the wearer goes through
the movements to be expected in normal use.
Because of the simplicity of the
figure-eight harness, minor deviations usually are not serious. Occasionally,
indeed, exceptions to the normal placement of the harness cross are necessary
and desirable to improve comfort. The figure-eight harness can be worn
successfully by the majority of below-elbow amputees with ordinary duties, it is
easy to construct and there is little chance for error, and it is functional and
comfortable in most cases. Together these advantages generally represent the
reason why it is so widely used. It readily adapts itself to vocations that are
clerical in nature and to individuals requiring medium duty, such, for example,
as the lifting that might be required of a stockroom worker.
Below-Elbow Cliffs, Pads, and
Hinges
To furnish suspension and socket
stability, three types of cuffs and pads, with and without fillers, are
available, and any of several types of hinges, some flexible and some rigid, may
be used. The circled inserts A and B of Fig. 2 show some of the variations giving
greater and greater stability as needed in the individual case. The choice of
cuff and hinge combination is strictly a consideration for the prescription
team, the rule being to provide maximum stability with the absolute minimum of
harness. Prescription criteria and suitable templates for cuffs are described in
considerable detail in Section 5.6 of the Manual of Upper Extremity
Prosthetics. It should be remembered that many combinations of hinges
and cuffs are available and that no one cuff must necessarily be accompanied by
any particular type of hinge. Moreover, the prescription for any given amputee
should take into account his own individual requirements and personal
preferences.
There are at least two ways of making
cuff suspension systems, material selection being the principal distinguishing
factor. The preference of the limbmaker may enter into the choice of technique
largely because of the fabrication facilities that happen to be available.
Leather has long been used in the limb industry, and it is readily adaptable
because of its molding characteristics. Although the ability of leather to
conform readily to the shape of the arm represents something of an advantage
over webbing straps (circled insert C of Fig. 2), its tendency to
absorb perspiration and thus to deteriorate, as well as to acquire unpleasant
odors, is considered by many to be a distinct argument against its use in arm
cuffs. The webbing strap, while perhaps less stable, offers the advantage of
being easily washed and quickly replaced. Modern synthetic fabrics now available
commercially can be laundered without undue shrinkage and may be reapplied
without stretching under load.
The below-elbow cuffs and pads usually
are made of 4- to 6-oz. strap leather and are lined with horsehide or similar
material. The fabrication of this component calls for the cutting, sewing, and
fitting skills of the limbmaker. To make the Y-shaped leather suspension strap,
a paper pattern is first cut to conform to the amputee's arm. When the template
lies smoothly against the arm above the bulge of the biceps and will reach
properly from the triceps pad or cuff to the webbing suspension strap passing over the shoulder at the
pectoral interval, its shape is reproduced in 4- to 6-oz. strap leather or
equivalent. The lower legs of the leather suspension strap are then riveted to
the cuff or pad in such a position that the "V" lies smoothly against the arm
and will support axial loads.
The webbing inverted Y-suspensor is
prepared by folding a piece of 1/2-in. webbing back on itself in such a way as
to form a "V." The apex of the "V" is then sewed directly to the front suspensor
strap of the harness at such a level as to give a smooth transition from the
harness to the cuff or pad. The lower attachments to the cuff or pad are made by
means of 1/2-in. buckles.
Again, material selection is the chief
factor determining technique. When leather is used, it is hard to determine the
proper length of the legs of the "V" and to assure proper alignment without
later adjustments. Moreover, unless leather components are coated with nylon
or similar material, the effects of perspiration will soon become
apparent. Conversely, the webbing Y-suspensor offers easy adjustment of
alignment and also resistance to perspiration by virtue of its washability. When
fitted properly, both systems are acceptable, and hence personal preference is
an influencing factor.
The Below-Elbow Chest-Strap
Harness
Although the figure-eight harness is
suitable for most below-elbow cases, it does not meet all vocational
requirements. Heavy-duty activities, such as those of a farmer, requiring
frequent lifting of loads greater than 50 lb., can best be accommodated by a
below-elbow chest-strap harness. Fig. 3 shows a typical example. By the
addition of the shoulder saddle to reduce unit stresses on the shoulder and
opposite axilla, the load-supporting capabilities and amputee comfort can be
greatly improved, but to obtain a satisfactory result with the chest-type
harness presents a greater challenge to the harnessmaker.
Fig. 3. The below-elbow chest-strap
harness The two suspensor straps running through D-rings are attached to a
leather shoulder saddle Improved stability and reduced unit stresses over the
shoulder offer greater ability to lift axial loads. Normally, the below-elbow
chest-strap harness, used on amputees requiring heavy-duty service. is
constructed in combination with half-cuff and rigid elbow hinges.
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It has been said that some
limbmakers construct the chest-strap harness simply because they do not know how
to make the figure-eight design. There ap pears to be no real evidence to prove
which type really is the older, but it is generally
accepted that the chest strap was the forerunner of the figure-eight. Regardless
of priority, both patterns are acceptable, and each offers advantages and
disadvantages.
As shown in Fig. 3, there are basically
three elements in the below-elbow chest-strap harnessâ€"the chest strap to hold
the harness on, the shoulder saddle to serve as an anchor for suspending the
prosthesis, and the control attachment strap for operating the terminal device.
To connect the shoulder saddle and to suspend the prosthesis, two lengths of
1/2-in. leather or webbing are used. They originate on the back of the shoulder
saddle, thread through D-rings on the cuff, and then buckle to the front of the
saddle. This arrangement distributes the load on four points of the saddle and
two points of the cuff and offers the inherent self-equalizing effect by virtue
of the D-rings.
The control attachment strap is connected
to the chest strap and utilizes arm flexion and scapular abduction on the
amputated side. Since no definite anchor is involved, neither scapular abduction
nor shoulder flexion on the sound side can be harnessed, so that, unlike the
case with the figure-eight harness, in the chest-strap design these body motions
cannot be used as a source of reserve excursion. Although this basic difference
is responsible for the improved comfort of the chest-strap harness, lack of a
positive anchor not only robs the amputee of a third control motion but actually
permits the harness to rotate upon the chest when excessive forces are applied
to the control cable.
The indications for and advantages of the
chest-strap harness lie in its improved comfort and greater lifting capacity.
The chief reasons for its selection over the figure-eight arrangement are
concerned with vocational considerations, relief of unavoidable discomfort in
the opposite axilla, and amputee preference based on his past experience. Both
the figure-eight and the chest-strap harness may be used with almost any
combination of hinges and cuffs. It may not be desirable to use a triceps pad
and a shoulder saddle in combination, but there is no law against this
possibility. The rule, as always, is to try for maximum stability with a minimum amount of harness. This
being the case, the figure-eight harness should be tried first.* If
it is not satisfactory, then the more complicated chest-strap harness may be
resorted to. For detailed discussions of fabrication techniques for both
harnesses, reference may be had to Section 5.0 of the Manual of Upper
Extremity Prosthetics .
The Double-Axilla-Loop Harness
The increased frequency of successfully
fitted wrist-disarticulation cases has led in such instances to a departure from
the typical below-elbow harness pattern. A very simple and useful harness has
been reported by the Naval Prosthetics Research Laboratory for use
with transcarpometacarpal cases, and the technique is also adaptable to
wrist-disarticulation cases. As shown in Fig. 4, a double axilla loop
originates the initial body motion on the sound side and provides its own
reaction point on the amputated side. A solid piece of Bowden cable extends from
the proximal reaction point located on the axilla loop on the amputated side to
the distal reaction point located on the arm socket. The cable housing is covered with a piece of
plastic tubing to prevent pinching of flesh and pulling of hair on the subject's
arm.
Fig. 4. The double-axilla-loop harness
for wrist disarticulations and transcarpometacarpal amputations. The loop on the amputated side serves as the reaction point, relative motion being produced when
the sound shoulder is flexed. The control cable continues to the distal reaction point on the arm socket ([link5]) The auxiliary elastic strap indicated by dotted lines may or may not be needed. Courtesy U S Naval Hospital, Oakland, Calif.
.
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It should be pointed out that the
double-axilla-loop harness is only a means of supplying terminal-device operation. Suspension
must be inherent in a well-fitted socket, which usually must be split to
facilitate donning, the condyles of the wrist being the principal means of
retaining the socket on the stump (Fig. 5). Wrist disarticulations can be fitted
by this technique at first. If it proves to be unsuccessful for any reason, the
harness may easily be replaced with a conventional below-elbow figure-eight
harness.
Fig. 5. Wrist-disarticulation socket for
use with the double-axilla-loop harness. Control cable extends to the proximal
reaction point located on the axilla loop on the amputated side ([link4]).
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The Below-Elbow Dual-Control
System
As opposed to the problem of fitting the
wrist disarticulation and other long below-elbow stumps, there is the one
involving the fitting and harnessing of the very short below-elbow slump. Use of
the split-socket type of prosthesis furnishes a means of increasing the range of
elbow flexion through a mechanical step-up. Thia expedient greatly improves the
versatility of the below-elbow prosthesis and in the majority of cases proves to
be very satisfactory when using the below-elbow figure-eight harness based on
the single-control principle.
For marginal cases with insufficient
torque about the elbow to lift the prosthetic forearm, another departure has
been made from the usual pattern of control. The below-elbow dual-control
system, shown in Fig. 6, uses a forearm lever loop and a split-housing cable
system. Since in this case the cable housing is in two separate pieces, the
effective distance between the reaction point on the arm cuff and that
constituted by the lever loop on the forearm shell is no longer independent of
elbow angle, so that arm flexion produces forearm flexion. When used with the very
short below-elbow stump, the dual-control system thus provides an assistive lift
for forearm flexion, sometimes especially needed when forearm flexion is begun
from full forearm extension. Ordinarily the short below-elbow case has enough
torque about the elbow to stabilize the forearm, so that no elbow lock is
required. When the forearm socket is stabilized by the stump, the force from the
harness is transmitted to the terminal device.
Fig. 6. The below-elbow dual control
using the split-socket type of prosthesis for the short below-elbow case. Since
the cable housing is in two pieces, arm flexion assists in lifting the
prosthetic forearm. The stump is then used to stabilize the elbow for
terminal-device operation, no elbow lock being needed. The design of the step-up
elbow hinges has been discussed in detail by Alldredge and Murphy
(1).
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The familiar rule of first trying the
less complicated harness should be applied at this level also. If the forearm
cannot be flexed by the stump without unnecessary fatigue, or if forearm flexion
is painful, then the dual system is indicated. Amputees fitted with the dual
control should be checked periodically to see whether the residual muscles have
hy-pertrophied enough to be adequate for unassisted forearm flexion, in which
event the single control may be substituted. No harm is done by using the
below-elbow dual-control harness when its necessity is questionable, but again
the usual desirability of simplicity of harness would suggest discard of the
assist lift when adequate function can be obtained without it.
The Below-Elbow Biceps-Cineplasty
System
The Case for Cineplasty in
General
Since World War II, there has been,
especially in the United States, a considerable revival of cineplastic surgery
to produce muscle tunnels capable of harnessing for the
operation of artificial arms. Practically all available muscles of the arm and
two major muscles of the chest (the pectoralis major and minor) have been
harnessed by various means to operate arm prostheses. Two basic philosophies
have developed in the use of the cineplastic muscle tunnel. First established
was the idea of using the muscle motor to power the terminal device. The
advantages of this means of independent terminal-device operation, without
relying upon body motions, were readily apparent, to say nothing of the
possibility of eliminating body harness completely in some cases.
Some authors, for example Mount
and Bernberg, discuss the
advantages of an increased sense of pressure and generally improved sense of
perception when a muscle motor is harnessed to a terminal device. Mount and
Bernberg say "The results generally indicate that the two Ss [subjects] using
cine-plastic prosthesis distinguished, compared and recognized given objects
with greater skill and precision than the Ss [subjects] using prosthesis of the
harness type." Although further scientific tests to support this observation
have not been conducted, subjects successfully fitted with both a conventional
and a cineplastic prosthesis indicate that they have a better sense of pressure
or feel with the latter.
In the second philosophy developed, the
pectoral tunnel is used to operate the elbow lock in the
shoulder-disarticulation case. Obviously, the advantage in this case lies in the
provision of the additional source of control.
It may be stated, without reservation,
that of all the possible arrangements involving cineplasty, the greatest degree
of success has been obtained using the biceps muscle tunnel to power
terminal-device operation in the below-elbow case. This does not mean that the
combination of other muscle tunnels and other levels of amputation may not be
successful in individual cases. Spittler and Fletcher, Kessler
, Alldredge et al., and Taylor report other
muscles and other levels of amputation successfully fitted
with cineplastic prostheses. Because, however, the other cases have not yet been
proven clinically in the general sense, the discussion of the fitting of
cineplasty is here restricted to the below-elbow biceps system.
In the below-elbow biceps case, fitting
is greatly simplified because the muscle tunnel is above the first sound joint
in the amputated stump. The socket may thus be made to harness residual
pronation and supination, and it does not require window-type construction
since the tunnel is once removed in the upper arm.
Because the biceps tunnel in the
below-elbow case is able to avail itself of the physiological characteristics of
muscle, adequate force and excursion are to be had. Since normally
muscles are contracted to produce prehension, contraction of the biceps muscle
tunnel should effect closing of the terminal device. For this reason it is
generally accepted that a voluntary-closing device is most desirable for use
with cineplastic amputees. Of course if the improved sense of pressure is to be
had, then it may be best to use the voluntary-closing terminal device.
Regardless of all data presented here and elsewhere, however, many biceps
tunnels have been successfully harnessed in the below-elbow case with the
voluntary-opening terminal device.* This circumstance can only suggest that the
prescription of the terminal device in cineplasty is largely in the same area as
is the prescription of the terminal device in the conventional case using body
harness.
The back-and-forth discussion of these
factors is endless. It is therefore useful to have a look at the indications for
cineplasty as seen from the point of view of the amputee. Needless to say that,
in the growth of prosthetics clinic teams, new amputees are seeing more and more
the types of prostheses worn by other amputees. Usually when the wearer of a
conventional arm prosthesis sees a cineplastic type he feels that a "Cadillac"
version of an artificial arm is available for him. No doubt personal choice, or
the individual desire for a cineplastic type of prosthesis, is the major
consideration. Amputees who were not too favorable at the time of discussing the
cineplasty procedure have not obtained the same degree of success and training
as have those who indicated their preference for cineplasty from the
beginning.
Another important factor relates to
vocation. If a below-elbow amputee desires to do, for example, mechanical work
on an automobile, he often finds himself lying on his back on a dolly. In this
position, he is quite restricted in body motions for using a shoulder-harness
prosthesis. For the wearer of a conventional prosthesis to operate his terminal
device in this position involves the use of many body motions other than those
ordinarily involved.
Although no real criterion has yet been
developed for the selection of individuals for the cineplasty type of
prosthesis, it can be stated categorically that the personal preference of the
individual and the vocational considerations are of prime importance and should
therefore be discussed thoroughly with the patient before reaching a
decision.
The Two Established
Systems
Prosthetic fitting and socket
construction for a biceps-cineplasty below-elbow prosthesis are very similar to
the conventional techniques. The socket must provide stability and a means of
attaching a terminal device. Suspension of the prosthesis may be handled in
various ways. Two power-transmission systems have been developed, one at the University of
California at Los Angeles and the other at the Army Prosthetics Research
Laboratory. A comparison of the efficiencies of the two systems has revealed
that they have quite similar characteristics.
The UCLA Below-Elbow Biceps-Cineplasly
System.
The power-transmission system of UCLA consists of a muscle-tunnel
pin, a dual-cable power-transmission system, and a twin cable mounting harnessed
to the terminal device. All parts of this system, shown in Fig. 7, have been
available commercially for some time, and the arrangement has received wide use
in the field. Three types of cuffs are available for suspension in the UCLA
system. The epicondyle cuff (Fig. 8 and Fig. 9), the epicondyle clip (Fig. 10), and
the epicondyle strap (Fig. 11) may be used with any selection of either flexible
or metal double- or single-axis elbow hinges. The method of installing the UCLA
system is described in detail in Section 10.0 of the Manual of Upper
Extremity Prosthetics.
Fig. 7. The UCLA below-elbow
biceps-cineplasty system with epicondyle cuff and rigid elbow hinges. The twin
cable mounting is connected to the yoke to allow positioning for adequate
operating excursion.
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Fig. 8. Pattern for the UCLA epicondyle
cuff.
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Fig. 9. Alternative design of the UCLA
epicondyle cuff, constructed of stainless steel and covered with horsehide, the rigid hinges being attached to the cuff before covering. The cross strap at the
top helps to stabilize the cuff on the arm.
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Fig. 10. The UCLA epicondyle clip,
constructed of stainless steel and covered with horsehide. Conventional
baseplates are attached to be used as the proximal retainers for the dual cable
system. The clip can be used with or without the auxiliary elastic strap as
needed to maintain the clip in position when the arm is flexed. The epicondyle
clip has also been constructed of a semirigid plastic such as
Royalite.
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Fig. 11. Typical pattern for the APRL
epicondyle strap, reduced to exactly half the size needed to produce a strap for an arm with a circumference of 10 1/2 in. Placed as drawn on the grain side of
the selected leather, this template makes a left or a right strap depending on whether the amputee prefers to have the strap buckle toward the medial or toward
the lateral side of the arm. To produce a strap buckling in the reverse
directions, the template is turned over and placed on the grain side of the
leather. The dotted lines indicate a modification to accommodate a biceps tunnel located low on the upper arm when it is desirable to save space in the anterior
fold of the elbow.
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The UCLA system is quite adequate and
very simple to harness and provides easy pre-positioning and ready adjustment of
effective cable length. It has met with a very large degree of success
throughout. Compared to the APRL system, it offers the advantage of
being applicable to a wider selection of terminal devices inasmuch as the
control system may be mounted either on the top or on the bottom of the arm
socket (Fig. 12). It offers also the advantage of allowing pre-positioning of
terminal devices with less friction throughout the cable system.
Fig. 12. Alternate locations of the twin
cable mounting for various terminal devices in the UCLA below-elbow
biceps-cineplasty system. If it is desirable to interchange between the
voluntary-opening hook and the voluntary-closing hand, two snap portions of the
twin cable mounting may be used, one toward the lower side and another on the
top side of the socket.
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The APRL Below-Elbow Biceps-Cineplasty System. The APRL system, as it appears in the Manual of Upper Extremity
Prostheticshas been revised to improve function. The principal
modifications (Fig. 13) have been to adopt flexible leather hinges and
to discard the so-called "transit elbow hinges." Since these changes, indications have pointed to a greater
degree of success when the biceps tunnel is used with a voluntary-closing
terminal device.
Fig. 13. Completed installation of the APRL below-elbow biceps-cineplasty system. The epicondyle strap is used in
conjunction with flexible leather hinges, the hinges being adjustable by means
of strap-type buckles placed at the points of attachment on the arm socket. The ox-bow tunnel pin, fitted with "Dot Fasteners" for joining to the sheave-type cable equalizer, is recommended for use with the APRL system. A flat cable-extensor mechanism is used to allow cable adjustment within the system and to permit interchangeability of terminal devices. Insert shows a variation in
pin design that is available commercially.
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Although both the voluntary-closing and
voluntary-opening hands and hooks are recommended routinely for use with biceps
tunnels in below-elbow amputees, experience has shown that voluntary-closing
devices have offered a number of special advantages. The available excursion can
be increased by utilizing spring forces in the terminal device to recover
excursion, thereby stretching the biceps tunnel into pre-tension beyond the rest
length of the muscle. Moreover, the improved ability to select
prehensile forces at the finger tips makes it possible for amputees to handle,
say, an ice-cream cone without crushing it or to wield a hammer or other heavy
object without dropping it. Expressed amputee reaction seems to indicate,
furthermore, that a considerable amount of pressure appreciation is realized
through the use of the voluntary-closing terminal device, where the biceps is
contracted for gripping an object. Of course, some pressure appreciation is lost
when the voluntary-opening device is used, for then the biceps is contracted to
open the device against the tension of the spring or rubber band, and the
grasping force is exerted by the spring or rubber band upon relaxation of the
muscle. Although no published data are available to support the claim of
improved pressure appreciation with the voluntary-closing device, there are
sound indications from active users that such a cue to the pressure exerted is
of definite advantage.
Since no published instructions for
installing the APRL below-elbow biceps-cineplasty system are available, a
simplified set is included here. The first step is to cut and check a paper
template for the epicondyle strap in order to assure proper size and shape
before proceeding to make the finished strap. The typical size and shape are
indicated in Fig. 11. The pattern should be placed around the arm and examined
for comfort, both with the patient's elbow extended and in maximum flexion (Fig. 14). If the biceps tunnel is located low on the arm, the template should be
shaped as indicated by the dotted lines in Fig. 11 to allow for maximum
passive stretch. By thus lowering the front portion of the epicondyle strap,
comfort, as well as excursion, is improved.
Fig. 14. Procedure for checking the paper
template when making the epicondyle strap.
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With the epicondyle strap fastened in
place, the normal elbow center is marked on the projecting hinge tabs. Standard
baseplates are located as close to these points as possible and are held in
place with a clamp on the upper edge (Fig. 15). They are then so aligned that
the cable housings will follow smooth curves from the tunnel pin through the
elbow center to the two distal retainers on the arm socket. Notation should be
made of the approximate angles shown in Fig. 11.
Fig. 15. Placement of the baseplates on
the epicondyle strap. They should be so positioned that the cable housings pass
through gentle curves from the muscle tunnel to the distal baseplates on the arm socket.
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The extending ears adjacent to the rivet
holes on the two proximal baseplates should now be bent, as shown in Fig. 16,
to follow the contour of the epicondyles, thus giving greatly improved comfort
as well as added stability in supporting axial loads. The baseplates are then
riveted to the epicondyle strap by means of the top rivets only.
Fig. 16. Bending the ears of the proximal baseplates to conform to the contour of the epicondyles. This detail gives added stability in supporting axial loads and improves amputee comfort.
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Two pieces of 4-oz. strap leather 5/8 in.
wide are now cut long enough to connect the epicondyle strap to the arm socket.
A piece of nylon or vinyon strap is attached by rubber cement to the inside of
the leather straps, and the whole is stitched along each side. One end of each
of these two flexible hinges is then laid under one of the lower ears of the
proximal baseplates and the lower rivets are driven in.
With the epicondyle strap fastened in
position, the arm socket is placed on the patient, and the proper length of the
flexible hinges is determined. Finally, the positions of the distal hinge
attachments are marked, and the hinges are riveted to the socket, adjustment
being provided for by the two buckles.
The arm socket and epicondyle strap are
now put in place, the cable-housing retainers are attached to the baseplates on
the epicondyle strap, and the cable housings are continued through the elbow
center in such a way as to maintain a gentle wave to a point approximately 2 in.
below the top of the arm socket (Fig. 13). The arm is then removed from the
patient, and the baseplates are riveted in position on the socket. The male end
of the cable lengthener is now attached to the terminal device, the lengthener
is extended to the full-open position, and the other end of the lengthener is
attached to the sheave equalizer.
Next the cable housings are installed and
adjusted to obtain maximum elbow flexion and extension without compression or
stretch of the housings. The ends of the housings are trimmed so that, when the
ferrules are installed, the housings will terminate flush with the rivets on the
baseplates. The ferrules are then pinched slightly with a diagonal
cutter.
A female snap-on attachment is now
fastened to one end of a length of cable, and the attachment is snapped to the
pin. The free end of the cable is fed through one cable
housing, down through and around the sheave, and back up through the other cable
housing. The terminal device is opened, the muscle tunnel is pulled into passive
stretch, and the cable length is measured. The cap fitting is installed
according to manufacturer's instructions. Normally, the cable will be a little
too long. Adjustment may be made by taking up on the cable-length
adjuster.
After a period of use of the prosthesis,
the amputee may find that the adjuster can no longer remove slack from the
system. This development can be expected in some cases. It is only an indication
that the tunnel has stretched with use. In this event, the control cable should
be detached, shortened, and reattached as in initial cable
installation.
The APRL system as described here has
been used experimentally with a great deal of success, but the lack of
commercial availability of components in the past has limited its use in the
field. It is designed primarily to be used with the voluntary-closing type of
terminal device. Furthermore, the frictional losses in pre-positioning are
greater than in the UCLA system, and unless the sheave equalizer is placed on
the top of the socket use is limited to voluntary-closing terminal devices. This
circumstance makes interchange-ability of a voluntary-closing hand and a
voluntary-opening hook quite impractical. The APRL system is primarily
recommended for use with the epicondyle strap, which normally gives ample
support for axial loads without appreciable displacement of the
socket.
A distinct advantage of the APRL system
over that of UCLA is that the effective cable links between the equalizer and
the muscle tunnel may be adjusted while at the same time maintaining equalized
forces. To adjust the effective cable links between the twin cable mounting and
the muscle tunnel in the UCLA system requires a turnbuckle, which in effect
changes the links of the cable housing, thus increasing frictionai losses within
the system.
Harnessing for the Above-Elbow
Cases
Basically, two functional requirements
must be met in above-elbow cases. Not only must prehension be provided for but it
must be usable at various degrees of forearm flexion. Experience has shown that
satisfactory prehension can best be obtained through a normal range of forearm
flexion when provision is made for stabilizing the forearm at the selected level
of operation. Thus, to the two basic functions there must be added the
requirement of elbow lock. The body motions easily accessible and available for
controlling these three functions in the above-elbow prosthesis are arm flexion,
arm extension, and scapular abduction.*
At present there are three satisfactory
harness patterns for the above-elbow case, two based on the so-called "dual
control" and the third based on "triple control." The two dual-control
systemsâ€"the above-elbow figure-eight harness and the above-elbow chest-strap
harnessâ€"utilize arm flexion for forearm flexion and terminal-device operation,
elbow lock being effected by arm extension. In the triple-control harness, arm
flexion is used to produce forearm flexion, arm extension gives elbow lock, and
terminal-device operation is obtained by shrug of the sound shoulder. Each of
the three systems has its own advantages and disadvantages, and each therefore
has indications and contraindications in individual cases.
The Above-Elbow Figure-Eight
Harness
From the wearer's point of view, the
above-elbow figure-eight harness (Fig. 17) constitutes the easiest way of
meeting the requirements of the above-elbow case. It is simply a modified
below-elbow figure-eight design with provisions for the added functional
requirements. Although in the below-elbow case it is essential mechanically to
maintain a constant effective distance between the proximal and distal reaction
points of the terminal-device control cable (Bowden principle), in the
above-elbow case two functions may be obtained from a single cable by splitting
the cable housing and substituting for the distal reaction point a lift lever on
the forearm shell.
Fig. 17. The above-elbow figure-eight
harness. The basic structure consists of a loop about the opposite axilla, the
front portion supporting the arm and the rear portion attaching to the control
cable so that arm flexion gives forearm flexion and terminal-device operation.
The piece of elastic inserted in the front portion provides for relative motion
for elbow locking by arm extension, the elbow-lock control being attached to the
nonelastic portion. Suspension is improved by the lateral support strap and
indicated auxiliary straps when necessary. As in the below-elbow dual control
([link6]), the cable housing is split so that arm flexion gives forearm lift when
the elbow is unlocked, the leather lift loop on the forearm shell serving as the
distal reaction point. If it is difficult to start the forearm into initial
flexion, two baseplates may be used on the arm socket. The length of the leather
lift loop on the forearm shell should be such that, when the forearm is
extended, the distance from the center of the cable to the center of the elbow
is equal to the distance from the center ot the forearm to the center of the
cable housing. This arrangement reduces the amount of force needed to start the
forearm into initial flexion without increasing the excursion required for full forearm flexion.
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This arrangement couples forearm flexion
and terminal-device operation to produce the dual control as used in the case of
the very short below-elbow stump. Motion in the control source elicits
terminal-device operation or forearm flexion depending on whether the elbow is
locked or unlocked.
In the dual-control system, arm flexion
is used as the source of control for forearm flexion and terminal-device
operation, sometimes augmented by scapular abduction at large elbow angles, such
as when the terminal device is near the mouth. A piece of elastic-webbing is
substituted for the nonelastic front attachment strap of the below-elbow
figure-eight harness. It is attached at the level of the clavicle and extends to
the adjustable buckle on the arm socket, a minimum of 6 in. being desirable for
easy operation of the elbow lock. The elbow-lock control cable is attached
to
the nonelastic portion of (he front
attachment strap by means of a piece of 1/2-in. webbing bearing a 1/2-in.
adjustment buckle. Arm extension thus produces relative motion between the
elastic webbing and the nonelastic control strap in such a way as to induce
elbow locking. Thereafter arm flexion controls terminal-device operation. With
proper training and practice the amputee can become very adept in effecting
smooth operation of all three prosthetic controls.
Suspension is improved by adding a
connecting strap, known as the "lateral support strap," above the cross on the
amputee's back. It extends laterally across the shoulder to a buckle on the
lateral side of the arm socket. Proper adjustment of the lateral support strap
controls alignment in the abduction-adduction plane. With these modifications,
the below-elbow figure-eight harness is adapted to become the figure-eight for the above-elbow
case. In summary, the alterations include insertion of the elastic webbing in
the front to help suspend the socket and to provide for relative motion for
elbow-lock control, addition of the lateral support strap over the shoulder to
contribute to socket stability, and the use of the two-piece cable housing to
give forearm flexion when the elbow is unlocked.
The two optional straps indicated in
Fig. 17 together improve suspension, increase the available excursion, and
assist in maintaining the control attachment strap on the shoulder when the arm
is raised. The over-the-shoulder strap forms a webbing network to support axial
loads and to stabilize the lateral support strap and front attachment strap on
the shoulder. The cross-back elastic strap not only gives greater excursion both
in scapular abduction and in arm flexion but it helps to prevent the control
attachment strap from riding over the shoulder during extreme arm flexion, such
as when the amputee is working in areas over his head. But again, following the
rule of simplicity whenever possible, the above-elbow figure-eight harness
should be tried first without the two optional straps. If that proves
unsatisfactory, then the extra straps may be added.
For a detailed description of the
technique of fabricating the above-elbow figure-eight harness, reference may be
had to Section 6.7 of the Manual of Upper Extremity Prosthetics or
to the report of the NYU Committee on Above-Elbow Harness. It will
suffice here to describe some of the common errors often leading to
difficulties. Careful observation should always be made to be certain that the
elastic straps are not too short and that the proximal end and distal buckle of
the front suspensor strap are properly positioned. A minimum of 6 in. of elastic
is required to give sufficient excursion for operation of the elbow lock and to
provide adequate length for adjustment of tension in the strap.
Placement of the proximal end of the
elastic suspensor not lower than the clavicle enables the amputee to feel the
elastic stretching over the deltopectoral interval during the elbow-lock
operation, thus furnishing an additional cue to ensure reliable elbow
function, and it permits the minimum of 6 in. of elastic to be used without
bringing the attachment too far down on the socket. Normally the harness cross
should lie approximately 1 in. toward the sound side of the vertebral spine.
Crossing the harness at this point usually brings the control attachment strap
over the lower third of the scapula, where maximum excursion may be utilized.
The cross should be below the seventh cervical vertebra, thus avoiding the
discomfort caused when the harness rides up. If the cross is more than 1 in.
toward the sound side, the axilla loop is unduly decreased in size, with
consequent increase in discomfort at the axilla.
The control attachment strap should not
fall so low as to prevent arm abduction, and the lateral support strap should
not ride too high on the neck. If the cross is farther to the amputated side,
the control attachment strap may ride too high. Placement of the lateral support
strap 1/2 in. forward of the acromion is found to result in optimal
stabilization of the prosthesis on the stump without causing rotation.
Attachment of the lateral support strap should be 2 in. below the acromion. When
it is attached at a lower point, the strap rolls back and forth over the
shoulder, and higher attachment results in poor cosmesis because of the
interference of the buckle with the shoulder pad of clothing. Placement of an
adjustable buckle at the junction of the front support strap and elastic
suspensor provides optimal position for adjustment of the elbow-lock control
cable.
The placement of the elastic suspensor
strap markedly influences the effectiveness of the elbow-lock control motion. If
excess slack is left in the elbow control cable, it must be taken up by the
control motion before the lock will operate, and consequently the total
excursion will then be greater than necessary. At the same time, there must be
sufficient slack in the cable to permit relaxation of tension for resetting the
elbow-lock mechanism.
The Above-Elbow Chest-Strap
Harness
The chief advantages of the above-elbow
figure-eight harness are that it is functional and simple and will satisfy the
needs of most vocational activities. As in the
below-elbow case, however, if there is a requirement for the harness to lift
heavy loads, then another type is indicated. Again as in the below-elbow case,
the chest-strap harness (Fig. 18) is recommended for the above-elbow amputee
whose activities commonly involve heavy-duty work. By supplying a shoulder
saddle and thus reducing the unit stresses over the shoulder, the above-elbow
chest-strap harness provides greater comfort, and hence greater loads can be
accommodated.
Fig. 18. The above-elbow chest-strap
harness using for suspension a leather strap threaded through a D-ring on the
lateral wall of the socket and attached to a leather shoulder saddle at two
points, The strap for the control cable may be attached either to the shoulder
saddle, as shown, or to the chest strap at the midspine position. As in the
below-elbow case, this type of harness improves lifting ability and reduces unit
stresses over the shoulder on the amputated side. The elbow-lock control cable is attached to the front of the shoulder saddle, and again a piece of elastic is
used as the front suspensor between shoulder saddle and arm socket.
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The shoulder saddle has taken two forms,
the leather type and the webbing type. The leather type is precisely like that
used in the below-elbow chest-strap harness. Fig. 19 and Fig. 20 illustrate
webbing-type shoulder saddles that furnish adequate suspension on the lateral
side of the arm socket and provide for the relative motion needed for elbow lock
and for dual control. The operational pattern of body motions is identical to
that used with the above-elbow figure-eight pattern. Arm flexion manages dual
control (i.e., forearm flexion and terminal-device operation),
and arm extension controls the elbow lock.
Fig. 19. The above-elbow chest-strap
harness with webbing shoulder saddle. The functional arrangement is identical to
that in the above-elbow chest-strap harness with leather shoulder saddle ([link18]). The leather has simply been replaced with a webbing saddle designed to give
the same function. The technique is best used on individuals who perspire freely
but who nevertheless need the chest-strap type of harness for heavy
lifting.
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Fig. 20. An alternative construction of
the webbing shoulder saddle for use with the above-elbow chest-strap harness.
Beginning at the point of attachment on the front of the arm socket, the
principal strap passes over the shoulder on the amputated side, continues across
the amputees back, goes under the opposite arm, crosses the chest, again passes
over the shoulder on the amputated side, and buckles to the rear portion of the
socket. This arrangement equalizes the forces when axial loads are encountered.
A Y-type construction is used to connect the control cable to the chest strap at
the midspine position and at the point where the chest strap crosses the
shoulder. A similar construction is used in front, the lower leg of the Y"
being made of elastic to permit the relative motion needed for elbow-lock
control.
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The above-elbow chest-strap harness has
as its chief advantage the ability to lift axial loads with lower unit stresses
over the shoulder. Its primary disadvantage lies in its characteristic tendency
to rotate about the chest owing to lack of a positive anchor. Again as in the
below-elbow case, the simpler figure-eight design should be applied to the
above-elbow case whenever it can be made to serve the amputee satisfactorily.
The above-elbow chest-strap harness should be adopted only when the simpler
figure-eight harness proves to be inadequate in any given case.
The Above-Elbow Triple Ccontrol
In the above-elbow triple-control harness
(Fig. 21), arm flexion produces flexion of the forearm, arm extension provides
elbow-lock control, and extreme flexion of the sound shoulder (shrug) gives
terminal-device operation. Although the control system is quite simple, it
requires the amputee to distinguish between arm flexion on the amputated side
and extreme flexion of the shoulder on the opposite side to yield two separate
controls. Above-elbow amputees with long stumps can usually make this
distinction readily enough; those with medium to short stumps find it very
difficult.
Fig. 21. The above-elbow triple-control
harness. It differs from the dual-control pattern in that three body motions are
required. The axilla loop uses shrug of the opposite shoulder to operate the
terminal device, so that in this case the chest strap is separated at
approximately the midspine position. Relative motion takes place between the
axilla loop on the sound side and the reaction point located on the portion of
the harness on the amputated side. A supporting shoulder saddle is constructed
of a webbing network, and the control attachment strap for forearm flexion is
attached at a point over the superior spine of the scapula on the amputated
side. Arm flexion then lifts the forearm. Arm extension is harnessed as usual, a piece of elastic being used as the front suspensor strap to provide for the necessary relative motion.
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The advantage of triple control lies in
the possibility of operating the terminal device without first locking the
elbow. But the complexity of fabricating the triple-control system has been a
major disadvantage and has discouraged its use. It is recommended for amputees
requiring versatility in the use of the prosthesis, but it should be approached
cautiously by the harnessmaker.
Harnessing for the
Shoulder-Disarticulation Cases
To provide adequate functional harness
for the shoulder-disarticulation amputee has always been especially difficult
because of the lack of the control source otherwise available from humeral motion. In the absence of an
arm stump, it has been to date, for all practical purposes, impossible to
provide any satisfactory voluntary motion of the prosthetic arm about the
shoulder, and consequently a substitute must be sought for arm extension, the
control source commonly used by the above-elbow amputee for operation of the
elbow lock. The alternatives are to use manual operation of the lock by the
sound hand or else to harness some residual control source ordinarily remote
from arm function.
Since in any case manual control is
undesirable because it interrupts two-handed activities, the trend has been to
utilize other body motions such as those of the head or shoulders. The nudge
control, with the operating button located on the shoulder
cap of the prosthesis, was designed to be operated by pressure from the chin.
But this system leads to such awkward appearance in use that it has since been
more or less superseded by harness designs utilizing shoulder motions.
The perineal strap, with function based on
relative displacement between shoulders and pelvis, is disliked by most amputees
and therefore has been used less and less except where special complications
prohibit other arrangements. The most practical system worked out to date
involves use of a waist band or equivalent. At the present time, there are four
satisfactory harness patterns for the male shoulder-disarticulation case and two
suitable for the female. For the male, there are three dual-control systems, all
operated by scapular abduction, elbow lock being accomplished in the first case
by shoulder elevation on the amputated side, in the second by flexion of the
opposite shoulder, and in the third by shoulder extension on the amputated side.
The fourth system for the male utilizes the triple-control principleâ€"scapular
abduction to provide forearm flexion, elevation of the shoulder on the amputated
side to give elbow lock, and shrug of the opposite shoulder to operate the
terminal device. Since all four of these systems involve a chest strap unsuited
to the female, two special arrangements have been worked out for women. Both are
built around a brassiere, and both utilize dual control, in the one case
operated by scapular abduction, in the other by motion of the opposite shoulder.
In both cases, elbow lock is effected by elevation of the shoulder on the
amputated side.
Harness Patterns for Men
Dual Control with Shoulder-Elevation
Elbow Lock
Of the four shoulder-disarticulation
harness systems for males, the one most often used with the least trouble
involves scapular abduction for dual control of forearm flexion and
terminal-device operation, elbow lock being managed by elevation of the shoulder
on the amputated side. As in all dual-control systems, excursion of the control
source, in this case bilateral abduction of the scapulae, produces either
terminal-device operation or forearm flexion depending on whether the elbow is
locked or unlocked.
Fig. 22 presents the basic details of
this harness pattern. A webbing chest strap attaches to the front of the
shoulder cap, passes under the axilla on the sound side, crosses the back at the midscapular level so as to
utilize the maximum available excursion, and attaches to the control cable
positioned on the back of the shoulder cap. An elastic suspensor strap extends
from the top of the shoulder cap, diagonally across the back, and attaches to
the chest strap at a point just toward the sound side of the vertebral spine.
The length of the chest strap is so adjusted as to permit full terminal-device
operation without bringing the cable into contact with the skin.
Fig. 22. Shoulder-disarticulation harness
using scapular abduction for dual control, elbow lock being operated by shoulder
elevation on the amputated side. After Pursley , by permission of
Orthopedic and Prosthetic Appliance Journal.
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Elbow-lock operation by shoulder
elevation is provided for by linking the elbow control cable to a waist strap
encircling the trunk below the thoracic cage, thus establishing an anchor to
oppose shoulder elevation. Although adequate force for elbow locking is usually
available, care is taken to position the cable reaction points in such a way as
to eliminate as much frictional resistance as possible.
This system offers several distinct
advantages over other methods of harnessing the shoulder-disarticulation case.
It involves the minimum amount of harness needed to operate the three basic
controls, and it has the inherent advantage of avoiding any possibility of
interference between elbow locking and the other two functions. Thus training is
simplified considerably, and the success of the individual harness may be
determined at the time of fitting.
Dual Control with Opposite-Shoulder
Elbow Lock
A second shoulder-disarticulation harness
system seen frequently also uses scapular abduction for dual control of forearm
flexion and terminal-device operation, but elbow lock is effected by a forward
rotation of the sound shoulder. The arrangement for dual control is precisely
like that just described, the difference in the harness as a whole being
concerned with the method of elbow locking (Fig. 23). In addition to the chest
strap and the elastic suspensor strap, there is provided for the sound shoulder
a webbing saddle, the cross-back extension being attached to the elbow control
cable near the point of stabilization on the back of the shoulder cap. Again the
lengths of the straps are so adjusted as to permit adequate excursion without the
cables touching the flesh.
Fig. 23. Shoulder-disarticulation harness
using scapular abduction for dual control, elbow lock being operated by flexion of the shoulder on the sound side. After Pursley, by permission of
Orthopedic and Prosthetic Appli~ ance Journal.
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Although this system eliminates the need
for the waist strap, it obviously introduces more complicated harness about the
shoulders, and it offers the inherent disadvantage of the possibility of
inadvertent locking or unlocking of the elbow in the course of forearm flexion
or terminal-device operation. If, however, care is taken to keep the chest strap
at the mid-scapular level while making the opposite-shoulder loop as high as
possible, and if the amputee is thoroughly trained, the two operating body
motions can usually be separated satisfactorily.
Because in this system the elbow-lock
control cable traverses a comparatively long path, and also because the
associated harness moves across the entire surface of the back, the frictional
forces involved are sometimes such that the alternator spring in the
elbow is not strong enough to return the
control cable to the relaxed position. When this is the case, an additional
spring may be added on the inside of the arm section (Fig. 24). Since this extra
spring force makes the elbow lock more difficult to operate, it has the
incidental advantage of making it easier for the amputee to separate
opposite-shoulder shrug from scapular abduction, thus helping to avoid
inadvertent elbow action. If difficulty is still encountered, separation of
controls is sometimes made easier if the opposite-shoulder loop is adjusted to
require an extreme flexion of the sound shoulder before elbow locking is
induced.
Fig. 24. Installation of the elbow-lock
cable, showing arrangement when auxiliary spring is needed to return cable to
relaxed position. The additional spring force makes it easier to separate the
elbow-lock control motion from scapular abduction. After Pursley, by permission of Orthopedic and Prosthetic Appliance Journal.
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In any event, a considerable period of
practice is usually required before the average amputee can manage separation of
controls systematically and with the necessary confidence. Training is thus more
prolonged than is the case with the shoulder-elevation elbow lock, and consequently the dual-control
harness using opposite-shoulder lock offers the further disadvantage that the
ultimate success in any given case is difficult to determine at the time of
initial fitting.
Dual Control with Shoulder-Extension
Elbow Lock
Fig. 25 presents the dual-control
shoulder-disarticulation harness utilizing shoulder extension to lock and unlock
the elbow. The lower leg of the front attachment strap contains a piece of 1-in.
elastic, the front elbow-lock control being connected to the
nonelastic part of the chest strap. Thus shoulder
extension produces a relative motion for elbow locking.
Fig. 25. Shoulder-disarticulalion harness
using scapular-abduction dual control, elbow lock being operated by extension of
the shoulder on the amputated side The chest strap terminates in front in a
forked arrangement for attachment to the socket. A piece of 1-in. elastic is
inserted in the lower leg of the fork, and the elbow-lock control cable is
attached to the base portion of the chest strap just beyond the elastic, thus
providing for relative motion upon extension of the shoulder on the amputated
side.
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To operate the prosthesis starting with
forearm extended, scapular abduction is used to produce forearm flexion. While
maintaining enough force on the lift cable to hold the forearm in the desired
position, the amputee extends his shoulder on the amputated side to lock the
elbow. Thereafter scapular abduction operates the terminal device.
Although this system may be used on any
shoulder-disarticulation case, amputees retaining the humeral neck are the most
successful. Patients without the humeral neck experience difficulty in
coordinating the two body motions. In any event, the length of the elastic and
the position of the wide attachment are both critical. Normally a piece of 1-in.
elastic 1 1/2 in. long is used as a start. If the elbow is difficult to operate,
the elastic portion is made longer. If the elbow operates inadvertently,
the elastic is shortened so as to require
more definite shoulder extension to lock and unlock. Although this type of
shoulder harness is quite new, experience to date would suggest consideration of
new elbow mechanisms especially designed for use with it. An obvious advantage
is elimination of the waist band and opposite-shoulder loop used respectively in
the other two dual-control systems.
Triple Control
In the triple-control system for shoulder
disarticulation, as in the triple control for above-elbow cases, the three
necessary functions are provided by three control sources, one for each. The
usual and generally most successful pattern utilizes scapular abduction for
forearm flexion, shrug of the sound shoulder for terminal-device operation, and
elevation of the shoulder on the amputated side for
control of the elbow lock. The basic pattern (Fig. 26) involves a minor
modification of the chest strap seen in Fig. 22 and Fig. 23, an elastic suspensor
strap also similar to that seen in Fig. 22 and Fig. 23, an opposite-shoulder loop
with an extension passing over the seventh cervical vertebra or slightly below
it, and a linkage between elbow control cable and waist band.*Although the triple control requires more harness than do the other three patterns
for shoulder disarticulation, it offers certain advantages not to be had from
dual control. Separation of terminal-device operation from forearm flexion
offers improved control over prehension, since during forearm flexion no force
or excursion is introduced affecting the terminal device. Likewise, as in the
case of the dual control with shoulder-elevation elbow lock, the triple-control
system overcomes the difficulty of separating elbow lock from the other two
functions, so that inadvertent elbow locking or unlocking is avoided. The result
is, again, simplified training and the possibility of determining the success of
the harness at the time of initial fitting.
Fig. 26. Shoulder-disarticulation harness
utilizing triple control. Scapular abduction provides forearm flexion; shoulder
on sound side operates terminal device; elbow lock is operated by shoulder
elevation on the amputated side. After Pursley, by permission of
Orthopedic and Prosthetic Appliance Journal.
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Harness Patterns For Women
Since the chest strap, common to all four
harness patterns for male shoulder-disarticulation cases, is unsuited for most women,
harness designs for female shoulder-disarticu-lation amputees are best based on
some other principle. The most satisfactory method found to date for eliminating
the chest strap is to utilize as part of the harness a brassiere made of sturdy
material.* As shown in Fig. 27, a strip of 1-in. webbing is sewed
around the lower edge of the brassiere known to bra designers as the "diaphragm
band." The shoulder cap is so designed as to project in front below the breast
on the amputated side to provide an anchor point (B) to which the
diaphragm band is attached. An elastic sus-pensor strap attaches to the top of
the shoulder cap at A, passes diagonally down the back, and is sewed to
the diaphragm band at C somewhat toward the sound side of the vertebral
spine. For ease in adjustment and to provide for ready laundering, a buckle
is used at D, a clip-type disconnect
is installed at E, and attachments at B and A are made with
snap fasteners. The arrangement for control of the elbow lock utilizes the waist
band* in the same way as in the corresponding pattern for the male
(Fig. 22).
Fig. 27. Harness for female
shoulder-disarticulation cases, made integral with bra but detachable from arm
socket for laundering. Scapular abduction provides dual control of forearm lift
and terminal-device operation, while elbow lock is effected by shoulder
elevation on the amputated side. After Pursley, by permission of
Orthopedic and Prosthetic Appliance Journal.
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Although in this harness design the
diaphragm band crosses the back somewhat lower than the midscapular level
desired with the chest strap, adequate excursion is usually available from
biscapular abduction, which, as in the male patterns of Fig. 22, Fig. 23 and Fig. 25,
provides dual control of forearm flexion and terminal-device operation. Shoulder
elevation provides control of elbow locking.
A problem encountered with the design
shown in Fig. 27 is that in flat-chested persons or in those with comparatively
small breasts it is sometimes difficult to get adequate stability, so that
operation of the dual control causes the brassiere to rotate upon the chest.
When such a situation prevails, use may be made of the modification shown in
Fig. 28, where the brassiere is called upon to provide suspension only, the
loop about the sound shoulder furnishing the dual control. Here, as in Figure
27, attachments A, B, and D are made with snap fasteners so that
the entire harness can be removed from the arm socket for laundering, the
elastic suspensor being sewed to the diaphragm band at C.
Fig. 28. Alternative harness for female
shoulder-disarticulation cases in which the simpler arrangement of Figure 27
proves too unstable. Here the bra is used for suspension only. The loop over the
sound shoulder provides dual control of forearm lift and terminal-device
operation, while elbow lock is effected by shoulder elevation on the amputated
side After Pursley, by permission of Orthopedic and Prosthetic A
ppliance Journal
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Some Special Cconsiderations
A distinguishing characteristic of the
shoulder-disarticulation amputee is that the available control sources are for
the most part of comparatively high force but of low excursion. Most
commercially available terminal devices require an average of 1 3/4 in.
of excursion for full operation, and normally 2 to 3 in. of excursion are needed to produce
full forearm flexion of 135 deg. Generally, the total exceeds the excursion
available from scapular abduction. This means that if, in a dual-control system
with a voluntary-opening hook, where the excursions for forearm flexion and for
terminal-device operation are additive, the amputee is to be able to open the
hook at the mouth, some means must be found for obtaining the extra excursion.
The only other alternatives are to use a voluntary-closing hook, in which case
the excursion used in forearm flexion is regained for hook operation, or to use
triple control, in which case forearm flexion and terminal-device operation are
obtained from two separate sources. But many shoulder-disarticulation amputees
do not care for voluntary-closing terminal devices, and others, for this reason
or that, are not always able to manage the triple control. Since in general the
force available from scapular abduction far exceeds that needed for forearm lift
and prehension, some of the force may be sacrificed in the interest
of obtaining an increase in excursion. The "block-and-tackle" cable system shown
in Fig. 29 and Fig. 30 provides a two-to-one step-up in excursion at the expense
of surplus force. It may be used with any of the six harness systems whenever
added excursion is needed either for forearm flexion or for terminal-device
operation. In Fig. 23, for example, it is applied to the dual control. In
[link26], it is used to step up forearm flexion in the triple control. It could
equally well be installed in the system of Fig. 22, should that prove to be
necessary in any given case. Conversely, when excursion step-up is not required
for the patterns of Fig. 23 and [link26], an external cable routing may be used, as
in Fig. 22. In any case, careful analysis of the excursion available and of
that required for the terminal device prescribed forms the basis of judgment as
to whether the step-up system is indicated or not.
Fig. 29. Cable system for reducing the
amount of excursion needed in the shoulder-disarticula-tion dual control. After
Pursley, by permission of Orthopedic and Prosthetic Appliance
Journal.
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Fig. 30. Installation of the
excursion-reducing cable system shown in Figure 29. After Pursley ,
by permission of Orthopedic and Prosthetic Appliance
Journal.
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Although the six harness patterns
described here represent the most generally successful designs now in common use
for the shoulder-disarticulation case, no one of them provides a voluntary
control source for motion of the upper arm about the shoulder. This deficiency,
of course, imposes upon the shoulder-dis-articulation amputee a rather serious
limitation not characteristic of the normal arm. Some provision for arm
flexion-extension is possible by making the arm socket in two pieces, a humeral
section and a shoulder cap, and using the so-called "sectional plates"
. But this arrangement is intended for manual pre-position only.
Recently a shoulder-disarticulation arm has been designed with a
shoulder joint giving a combination of flexion and abduction to permit
comfortable sitting at a table or desk, but again arm lift is manual, there
being no satisfactory control source for voluntary flexion-abduction about the
shoulder cap. Development of an additional voluntary control source to simulate
the motion of the normal glenohumeral joint is now perhaps the most pressing
need of the shoulder-disartic-ulation amputee.
Harnessing for Bilateral Arm
Amputees
As compared to the unilateral case, the
prosthetic requirements of bilateral arm amputees are magnified many fold.
Experience shows that the unilateral subject uses his prosthesis chiefly to
hold, carry, or assist in activities requiring two hands. Bilat-erals, on the
contrary, are required to rely wholly on their arm substitutes for both
one-handed and two-handed activities. The prescription criteria and techniques of
fitting are therefore modified for the bilateral in an attempt to provide
general operation in areas where the unilateral uses his normal hand. Bilateral
arm amputees must, for example, have access to the pockets, both shirt pockets
and side and hip trouser pockets if possible. They must be able to brush the
teeth, comb the hair, use a buttonhook to manage button
closures, and perform a great variety of other essential activities in the
course of daily living. In general, all of these functions require action close
to the body, behind the back at waist level, or at face, neck, or above the
head. The prescription criteria for bilaterals therefore require special
attention to personal as well as vocational needs, and consideration must be
given to such special items as easily operable wrist disconnects and
wrist-flexion units. Fabrication techniques are altered to provide for greater
strength, and socket margins must be carefully determined in order to assure
maximum socket stability for improved control.
In below-elbow cases, residual pronation
and supination is, of course, priceless. In every step of amputee care, every
effort should be made to maintain forearm rotation. Attention should be paid
this matter from the time of the original amputation and should continue through
prescription, socket fitting, and fabrication of the harness.
A matter of the greatest importance to
the bilateral arm amputee is that of being able to get the harness and
prostheses on and off without help from others. Bilateral above-elbow and
shoulder-disarticulation amputees can almost always manage to get their
prostheses off without help, but they sometimes require assistance in putting
the arms on. Special brackets mounted on a wall in a bedroom are often needed to
help amputees otherwise unable to perform independent donning. If, for example,
a bilateral with short above-elbow stumps cannot control his prostheses while
reaching for the harness cross on his back to remove the harness by pulling it
over his head ("skinning-the-cat"), he hangs the cross over the wall hook by
simply backing up to it. He then bends his knees to lift the straps over his
head. Leaving the harness cross on the hook, he then removes the prostheses by
holding the terminal devices, one at a time, each with the opposite foot. Thus
the arms are left hanging in such position that the stumps can again be inserted
into the sockets and the harness slipped back over the head.
Control in the bilateral amputee is at
best difficult. Because the number of controls required is doubled, less
effective control motions must be brought into use, and independence of control
becomes a problem. At present, six control functions, three for each arm, are
about all that can be manipulated conveniently and efficiently. Even so,
interaction between controls is noticeable.
The Bilateral Below-Elbow
Harness
The easiest way to describe a bilateral
below-elbow harness (Fig. 31) is to start by supposing that a unilateral
below-elbow amputee has lost his remaining good arm below the elbow and has
asked that his old figure-eight harness be used to make the new bilateral
harness. The first step would be to cut the axilla loop on what was formerly
the sound side. The front portion of the cut
strap would then be attached to the inverted Y-suspensor of the new prosthesis.
The back portion of the cut strap would be turned back upon itself and attached
to a buckle. It thus would become the control attachment strap for the new
prosthesis.* Arm flexion on either side then gives terminal-device
operation.
Fig. 31. The bilateral below-elbow
figure-eight harness. A webbing inverted Y-suspcnsor with triceps pad and
flexible leather hinges is shown on the right side, while a leather inverted
Y-suspensor with full cuff and rigid hinges is shown on the left. Similarly, one
type of hook is shown on one side and another type on the other. In the
bilateral case, prescriptions should be written independently for the two sides
with a view toward providing as much utility as possible. As in the
corresponding unilateral cases, the choice of cuffs, pads, hinges, terminal
devices, and other details is made on the basis of the individual
characteristics of the stump for which the prosthesis is intended.
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The cross on the back may be lowered by
loosening the inverted Y-straps in front and taking up the slack in the control
attachment straps. The reverse procedure moves the cross up. Should the cross be
too far to one side, it may be moved horizontally by loosening the inverted
Y-strap and control attachment strap on that side and taking up the slack on the
opposite side.
An important consideration is the choice
of materials best suited to the individual case. In Fig. 31, the right
Y-suspensor is made of vinyon, while the left is made of leather. If the amputee
finds that getting the harness on and off is a major problem, then the tendency
of leather to maintain its shape makes it easier to slip the stumps through the
suspensors. If excessive perspiration is a problem, then vinyon tape may be more
suitable.
Although the combination of one leather
and one vinyon Y-suspensor is shown in Fig. 31 primarily to suggest the two
possibilities, it is not inconceivable to consider the arrangement for actual
use. In the bilateral below-elbow cases, the choice of cuffs and hinges is made
independently for each side on the basis of such factors as stump length,
muscular tone, and elbow mobility. In some cases, it might be well to consider
using flexible hinges on one side to encourage the use of residual
pronation-supination while applying full cuff and rigid hinges on the other to
provide stability. A bilateral so fitted would thus have the added versatility
provided by an enhanced function of one kind in one arm and an enhanced function
of a different kind in the other.
In Fig. 31, a wrist-flexion unit is
installed on the left prosthesis. Although in exceptional cases the bilateral
fitting of wrist-flexion units might be desirable, ordinarily only one flexion
device is necessary. When only one wrist-flexion unit is used, amputee
preference, or simply prosthetic dominance of one extremity over the other, is
probably the best criterion for determining the side to which wrist flexion
should be applied.
The Bilateral Above-Elbow
Harness
The unilateral below-elbow figure-eight
harness has been adapted for bilateral above-elbow cases as well as for the
bilateral belowelbow amputee. It is essentially the same
as for the below-elbow cases but with added suspensory harness and means of
operating the elbow locks. A typical pattern is illustrated in Fig. 32. If
allowance is made for the increased need for function in the bilateral case,
then fabrication of the bilateral above-elbow harness is similar to that of the
unilateral above-elbow figure-eight pattern. Use is made of the same methods of
harness adjustment as in adjusting the harness for the below-elbow
bilateral.
Fig. 32. The bilateral above-elbow
figure-eight harness. As in the bilateral below-elbow case, here too the choice
of components for the two sides is made independently with regard for individual
stump characteristics and with the intention of providing as much useful
function as possible.
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Before attempting the fabrication of the
bilateral above-elbow harness, the harness-maker must understand the above-elbow
figure-eight harness for unilaterals. He should then discuss with his patient
any special vocational or personal activities requiring modification of harness
design. When the harness is completed, the prosthetist should make it a point to
follow up progress in training to make sure that the bilateral amputee can soon
become self-sufficient in all necessary activities. If attention is paid to
these few details, and if each bilateral amputee is treated as an individual
problem, surprisingly good results may be obtained in practically all bilateral
cases.
The Bilateral Shoulder-Disarticulation
Harness
Because the bilateral shoulder
disarticulation and the bilateral above-elbow/shoulder combination represent
comparatively rare and highly specialized instances of upper-extremity
amputation, it has thus far not been possible to establish any set harness
pattern for these cases. Although in general the bilateral
shoulder-disarticulation harness is a sort of combination of two
shoulder-disarticulation harnesses for the unilateral, every amputee requiring
such harness must have meticulous attention to details in the individual case.
In any event, it is obvious that, in the bilateral shoulder-disarticulation
amputee, the goal of the prosthetist is to obtain as much function as possible
regardless of necessary deviations from ordinary practice. Although experience
with extreme cases of this kind has to date been limited, the Case Study at the
University of California at Los Angeles (page 61) has accumulated some useful
information. At present, the knowledge gained at UCLA probably offers the most
important guide for management of the individual bilateral
shoulder-disarticulation case.
Conclusion
To the student of the art of harnessing
upper-extremity prostheses, it will now have become perfectly plain that here,
as in almost every other published source, the harness designs presented are
principally those applicable to the comparatively young, healthy, adult male
amputee. Included, furthermore, are only those systems for which there has been
accumulated enough clinical evidence to prove their validity for use with
presently available arm components. Noticeably missing are special patterns and
fabrication techniques for the very young, for the very old, for the
debilitated, for the special cases involving other complicating handicaps, and, with
two exceptions, for the female.
The reason for this situation lies in the
fact that, inspired as it was by the desire to aid the veteran returning from
the wars, the Artificial Limb Program, sponsored by the Veterans Administration
and the Department of Defense, has quite naturally placed emphasis upon the type
of amputee to be expected from the battlefield. But it is not fully appreciated
by the general public that there are produced annually from disease or
accidentsâ€"in the home, on the highway, in the factoryâ€"many, many more amputees
than are ever produced in military campaigns. Such causes of amputation play no
favorites with age or sex.
Fortunately, the basic principles
involved in the harnessing of the adult male are more or less fully applicable
to the juvenile amputee. Recently, for example, an armamentarium chart defining
child amputee types and offering suggestions for prescription for children
of age three and a half to ten years has been prepared under the auspices of the
Michigan Crippled Children Commission. Two columns of this reference
document are devoted to "harness type" and "control type" respectively. Except
for the omission of the below-elbow dual control and of the above-elbow and
shoul-der-disarticulation triple controls, at every level of arm amputation in
the child the recommended harness and control systems are identical with those
used for the corresponding level in the adult male. The only significant
modifications are concerned with the use of 1/2-in. instead of 1-in. webbing,
according to the size of the child, and with the twofold recommendation that the
harness be worn over a T-shirt and that the younger children be provided with
two harnesses, one to be worn while the other is laundered. Since in general
young children do not possess harnessable forces as large as are usually to be
had in the adult, the unit stresses produced by the narrower webbing are
acceptable to the small child, and hence, following the rule of minimum
permissible harness in all cases, it is obviously advisable to use the 1/2-in.
material whenever it can serve the small fry satisfactorily. The need of
children generally for a frequent change of clothing deserves no further comment
here.
In any event, it will be recalled that
some twelve-year-olds are actually larger and stronger than some adults, and
consequently the determining factor in any given child is his own particular
size, which in turn determines whether 1/2-in. or 1-in. material will provide
the more comfort. Other features of harness fabrication for children are
essentially the same as for adult harnessing.
As for the adult female, generally the
harness for the adult male is applicable, with the exceptions that the
chest-strap designs usually are not desirable and that commonly more emphasis is
placed on cosmesis. Most women, for example, prefer to have a choice of wearing
"V" necklines instead of being restricted to Peter Pan collars or other high
necklines. The figure-eight harness pattern is adequate for both above- and
below-elbow female amputees. In high-above-elbow cases and shoulder disarticulations, the patterns
of Fig. 27 and Fig. 28 usually serve satisfactorily.
Elderly amputees, amputees with multiple
limb losses, and those with additional complications such as blindness or
deafness all present such highly specialized problems that no single harness
pattern can be more than partially satisfactory in all cases. Some evidence
seems to indicate that there may even be an age limit beyond which most
individuals begin to feel that bothering with an artificial arm at all is no
longer worth the effort. But no really scientific evaluation has yet been made
of the needs of the aged amputee. Circumstances in the individual case must
therefore dictate the course to be taken. As in the case of children, some
geriatric patients are healthy, strong. and dynamic; others are ailing, feeble,
or lethargic. In the elderly amputee, therefore, as in all special cases,
personal factors prevent the recommendation of any generalized harnessing
system.
In the two illustrations of typical
harnessing for bilateral arm amputees (Fig. 31 and Fig. 32), the subjects are shown
as having amputations at approximately the same level on the two sides. In
actual clinical practice, of course, bilateral arm cases present all possible
combinations of above- and below-elbow amputations. In all such cases, the
problem of devising suitable harnessing combinations presents a special
challenge to the prosthetics clinic team. Similarly, in the case of amputations
complicated by other mental or physical handicaps, special assessment of the
individual patient must be made to determine, first of all, whether use of a
prosthesis is actually feasible and, if so, what if any departures from
conventional harness patterns are indicated. In all such unusual instances, the
considered judgment of the clinic team is indispensable in the development of a
specialized harness pattern suited to the needs and abilities of the individual
concerned,
It may now be reiterated that, even in
the so-called "standard" cases, it does not suffice to supply a "standard"
harness. The reference chart of Table 1 is appended here only for the
convenience of the clinic team in selecting the basic kind of harness applicable
to any given case. It is, in the end, the responsibility of the prosthetist to see that the details are
properly custom-matched to the wearer and that, after adequate amputee training,
the harness chosen actually fulfills satisfactorily the needs of the wearer for
whom it was intended. Less meticulous avenues of approach lead ultimately to
failure.
Table 1. (For a larger image of this table, please refer to the PDF link at the top of the page.)
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Finally, cognizance should be taken of
the understandable circumstance that the harness patterns presented here have
all been developed specifically for use with existing mechanical devices. The
above-elbow and shoulder-disarticulation systemsâ€"the dual-control figure-eight,
the dual-control chest-strap, and the triple-control patternsâ€"have, for example,
all been designed around existing elbows. Because heretofore the art of
harnessing has lagged behind the development of arm components, it has been
necessary in recent years to design the harness systems to fit the mechanical
parts rather than vice versa. A more logical arrangement would have been first
to analyze the available body control motions, to design the harness for maximum
utilization of these motions in the least awkward way, and then to design the
other parts of the prosthesis in such a manner as to be operable by control
patterns best suited to amputee characteristics. Future research in harnessing
can be expected to influence redesign of desirable operational characteristics
of the mechanical devices now available and to encourage the development of
wholly new and improved arm components.
Acknowledgment
With the exception of the photographs and
of Fig. 12, the illustrations appearing in this article are the work of George
Rybczynski, free-lance artist of Washington, D. C.
References:
- Alldredge, Rufus H., and Eugene F. Murphy,Prosthetics research and the amputation surgeon, Artificial Limbs, 1(3):4 (September 1954).
- Alldredge, Rufus H., Verne T. Inman, Hyman Jampol, Eugene F. Murphy, and August W. Spittler, The techniques of cineplasty,, Chapter 3 in Klopsteg and Wilson's Human limbs and their substitutes. McGraw-Hill, New York, 1954.
- Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Technical Report 5424, Comparison of UCLA and APRL cable transmission systems for B.E. biceps cineplasty arm, 21 June 1954.
- Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Technical Report 5526, Shop instructions for cable and sheave equalizer systems (below-elbow cineplasty APRL), 8 August 1955.
- Carlyle, Lester, Artificial arm checkout procedures,Artificial Limbs, January 1954. p. 25.
- Carlyle, Lester, Fitting the artificial arm, Chapter 19 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954.
- Carnes, W. T., U. S. Patent 1,046,966, December, 1912.
- Carnes, W. T., U. S. Patent 1,046,967, December, 1912.
- Carnes, W. T, U. S. Patent 1,402,476, January, 1922.
- DeFries, Myron G., and Fred Leonard, Bacterio-static nylon films, Applied Microbiology, 3(4):238 (1955).
- Fletcher, Maurice J., and A. Bennett Wilson, Jr.,New developments in artificial arms, Chapter 10 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954.
- Hitchcock, William E., Abduction for shoulder disarticulation prosthesis, Orthop, Pros. Appl. J., September 1955. p. 23.
- Inman, Verne T., and H. J. Ralston, The mechanics of voluntary miscle, Chapter 11 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954.
- Kessler, Henry H., Cineplasty, Charles C Thomas,Springfield, Ill., 1947.
- Langdale-Kelham, R D., and George Perkins,Amputations and artificial limbs, Oxford University Press, London: Humphrey Milford, 1944.
- Leonard, Fred, T. B. Blevins, W S. Wright, and M. G. DeFries, Nylon-coated leather, Ind Eng. Chem., 45:773 (1953).
- Marks, George E., A treatise on Marks' patent artificial limbs with rubber hands and feet, A. A. Marks, New York, 1889.
- Mary Free Bed Children's Hospital and Orthopedic Center, Grand Rapids, Mich., Child amputee types and suggestions for prosthetic prescription, 3 1/2 years to 10 years (a chart), 1955.
- Mount, George E., and Raymond E. Bernberg,A preliminary comparison of perception undet cineplastic and harness prostheses, Am. J. Psychol., LXII(1):106(1949).
- New York University, Prosthetic Devices Study, Committee on Above-Elbow Harness [Hector Kay, Chairman], Report of conference, The above-elbow figure-eight harness a guide to procedures and principles, September 23, 1954.
- Northrop Aircraft, Inc., Hawthorne, Calif., Subcontractor's Final Report to the Committee on Artificial Limbs, National Research Council, Artificial arm and leg research and development, February 1951. Sections 1.6.1 and 1.6.1.1, p. 92.
- Northwestern Technological Institute, Evanston,Ill., Subcontractor's Final Report to the Committee on Artificial Limbs, National Research Council, A review of the literature, patents, and manufactured items concerned with artificial legs, arm harnesses, hand, and hook; mechanical testing of artificial legs, 1947.
- Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. & Pros. Appl. J., March 1955. p. 15.
- Spittler, August W., and Maurice J. Fletcher,Technique of cineplastic surgery and prosthetic appliances for cineplasty, Am. Acad. Orthopaedic Surgeons Instructional Course Lectures, Volume X, Edwards, Ann Arbor, Mich., 1953.
- Taylor, Craig L., The biomechanics of the normal and of the amputated upper extremity, Chapter 7 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954.
- Taylor, Craig L., Control design and prosthetic adaptations to biceps and pectoral cineplasty, Chapter 12 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954.
- University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952.
- U. S. Naval Hospital, Oakland, Calif., Artificial Limb Department, Blueprint 811, Carpometacarpal {harness controlled) prosthesis, September 22, 1952.
- Wilson, A. Bennett, Jr., and Robert J. Pursley,Fitting the wrist disarticulation case, Orthop. & Pros. Appl. J., September 1952. p. 17.
Reference | 18. | Mary Free Bed Children's Hospital and Orthopedic Center, Grand Rapids, Mich., Child amputee types and suggestions for prosthetic prescription, 3 1/2 years to 10 years (a chart), 1955. |
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Footnote | While this hypothetical case suffices to describe the harness, it carries the faulty implication that the bilateral harness is simply two unilateral harnesses. No such implication is justified, for, as already pointed out, the functional requirement is magnified many fold, there is the complication of effecting separation of controls, and in addition there is the problem of getting into and out of the harness. |
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Reference | 12. | Hitchcock, William E., Abduction for shoulder disarticulation prosthesis, Orthop, Pros. Appl. J., September 1955. p. 23. |
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References | 25. | Taylor, Craig L., The biomechanics of the normal and of the amputated upper extremity, Chapter 7 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Footnote | When the waist band is disliked by the female amputee, the elbow control strap may be anchored to a girdle or pantie girdle, just as it may be anchored to the trousers in the male. |
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Footnote | Not chiffon or lace! |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Footnote | Use of the waist band, as in Figure 22, is largely a matter of personal preference. Some amputees like it, some do not. When the amputee wishes to dispense with the extra waist strap, the elbow control may be anchored to an item of clothing such as a button at the top of the trousers near the fly, as in Figure 26. The control strap then passes out of the shirt between buttons, so that no special opening is needed. But of course when this arrangement is used, the prosthesis is inoperable when the wearer is unclothed. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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Reference | 23. | Pursley, Robert J., Harness for shoulder disarticulation amputees, Orthop. &Pros. Appl. J., March 1955. p. 15. |
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References | 11. | Fletcher, Maurice J., and A. Bennett Wilson, Jr.,New developments in artificial arms, Chapter 10 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. | 25. | Taylor, Craig L., The biomechanics of the normal and of the amputated upper extremity, Chapter 7 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Reference | 20. | New York University, Prosthetic Devices Study, Committee on Above-Elbow Harness [Hector Kay, Chairman], Report of conference, The above-elbow figure-eight harness a guide to procedures and principles, September 23, 1954. |
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Reference | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Footnote | It may be noted that the techniques for harnessing the above-elbow amputee can be applied equally well to articulated braces for flail arms. |
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Reference | 13. | Inman, Verne T., and H. J. Ralston, The mechanics of voluntary miscle, Chapter 11 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 4. | Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Technical Report 5526, Shop instructions for cable and sheave equalizer systems (below-elbow cineplasty APRL), 8 August 1955. |
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Reference | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Reference | 3. | Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Technical Report 5424, Comparison of UCLA and APRL cable transmission systems for B.E. biceps cineplasty arm, 21 June 1954. |
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Reference | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Reference | 3. | Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Technical Report 5424, Comparison of UCLA and APRL cable transmission systems for B.E. biceps cineplasty arm, 21 June 1954. |
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Footnote | Although common-sense logic might lead one to suppose that improvement in pressure appreciation would be obtainable only were the terminal device voluntary-closing, it turns out that considerable improvement is to be had also from muscle tunnels harnessed to voluntary-opening devices. The tests conducted by Mount and Bernberg were, for example, all made with amputees wearing voluntary-opening hooks. How does the amputee so fitted estimate the amount of force being exerted at the hook fingers? He measures holdback and subtracts it mentally from the known total force exerted by the hook when no restraint is applied. (Ed) |
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Reference | 13. | Inman, Verne T., and H. J. Ralston, The mechanics of voluntary miscle, Chapter 11 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 26. | Taylor, Craig L., Control design and prosthetic adaptations to biceps and pectoral cineplasty, Chapter 12 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 26. | Taylor, Craig L., Control design and prosthetic adaptations to biceps and pectoral cineplasty, Chapter 12 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 2. | Alldredge, Rufus H., Verne T. Inman, Hyman Jampol, Eugene F. Murphy, and August W. Spittler, The techniques of cineplasty,, Chapter 3 in Klopsteg and Wilson's Human limbs and their substitutes. McGraw-Hill, New York, 1954. |
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Reference | 14. | Kessler, Henry H., Cineplasty, Charles C Thomas,Springfield, Ill., 1947. |
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Reference | 24. | Spittler, August W., and Maurice J. Fletcher,Technique of cineplastic surgery and prosthetic appliances for cineplasty, Am. Acad. Orthopaedic Surgeons Instructional Course Lectures, Volume X, Edwards, Ann Arbor, Mich., 1953. |
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Reference | 19. | Mount, George E., and Raymond E. Bernberg,A preliminary comparison of perception undet cineplastic and harness prostheses, Am. J. Psychol., LXII(1):106(1949). |
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References | 2. | Alldredge, Rufus H., Verne T. Inman, Hyman Jampol, Eugene F. Murphy, and August W. Spittler, The techniques of cineplasty,, Chapter 3 in Klopsteg and Wilson's Human limbs and their substitutes. McGraw-Hill, New York, 1954. | 14. | Kessler, Henry H., Cineplasty, Charles C Thomas,Springfield, Ill., 1947. | 24. | Spittler, August W., and Maurice J. Fletcher,Technique of cineplastic surgery and prosthetic appliances for cineplasty, Am. Acad. Orthopaedic Surgeons Instructional Course Lectures, Volume X, Edwards, Ann Arbor, Mich., 1953. | 26. | Taylor, Craig L., Control design and prosthetic adaptations to biceps and pectoral cineplasty, Chapter 12 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 29. | Wilson, A. Bennett, Jr., and Robert J. Pursley,Fitting the wrist disarticulation case, Orthop. &Pros. Appl. J., September 1952. p. 17. |
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Reference | 28. | U. S. Naval Hospital, Oakland, Calif., Artificial Limb Department, Blueprint 811, Carpometacarpal {harness controlled) prosthesis, September 22, 1952. |
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Reference | 28. | U. S. Naval Hospital, Oakland, Calif., Artificial Limb Department, Blueprint 811, Carpometacarpal {harness controlled) prosthesis, September 22, 1952. |
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Reference | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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Footnote | Except, of course, in those cases where extremely heavy duty is a requirement from the beginning. |
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Reference | 2. | Alldredge, Rufus H., Verne T. Inman, Hyman Jampol, Eugene F. Murphy, and August W. Spittler, The techniques of cineplasty,, Chapter 3 in Klopsteg and Wilson's Human limbs and their substitutes. McGraw-Hill, New York, 1954. |
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Reference | 2. | Alldredge, Rufus H., Verne T. Inman, Hyman Jampol, Eugene F. Murphy, and August W. Spittler, The techniques of cineplasty,, Chapter 3 in Klopsteg and Wilson's Human limbs and their substitutes. McGraw-Hill, New York, 1954. |
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References | 10. | DeFries, Myron G., and Fred Leonard, Bacterio-static nylon films, Applied Microbiology, 3(4):238 (1955). | 16. | Leonard, Fred, T. B. Blevins, W S. Wright, and M. G. DeFries, Nylon-coated leather, Ind Eng. Chem., 45:773 (1953). |
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Reference | 27. | University of California (Los Angeles), Department of Engineering, Manual of upper extremity prosthetics, R. Deane Aylesworth, ed., 1952. |
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References | 5. | Carlyle, Lester, Artificial arm checkout procedures,Artificial Limbs, January 1954. p. 25. | 6. | Carlyle, Lester, Fitting the artificial arm, Chapter 19 in Klopsteg and Wilson's Human limbs and their substitutes, McGraw-Hill, New York, 1954. |
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Reference | 21. | Northrop Aircraft, Inc., Hawthorne, Calif., Subcontractor's Final Report to the Committee on Artificial Limbs, National Research Council, Artificial arm and leg research and development, February 1951. Sections 1.6.1 and 1.6.1.1, p. 92. |
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Reference | 1. | Alldredge, Rufus H., and Eugene F. Murphy,Prosthetics research and the amputation surgeon, Artificial Limbs, 1(3):4 (September 1954). |
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References | 7. | Carnes, W. T., U. S. Patent 1,046,966, December, 1912. | 8. | Carnes, W. T., U. S. Patent 1,046,967, December, 1912. | 9. | Carnes, W. T, U. S. Patent 1,402,476, January, 1922. | 15. | Langdale-Kelham, R D., and George Perkins,Amputations and artificial limbs, Oxford University Press, London: Humphrey Milford, 1944. | 17. | Marks, George E., A treatise on Marks' patent artificial limbs with rubber hands and feet, A. A. Marks, New York, 1889. | 22. | Northwestern Technological Institute, Evanston,Ill., Subcontractor's Final Report to the Committee on Artificial Limbs, National Research Council, A review of the literature, patents, and manufactured items concerned with artificial legs, arm harnesses, hand, and hook; mechanical testing of artificial legs, 1947. |
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Robert J. Pursley, Lt., USA (MSC) | Chief, Research Limb Section, Army Prosthetics Research Laboratory, Walter Reed Army Medical Center, Washington, D. C. |
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