The Child with a Limb Deficiency

The child with an amputation is essentially
different—something that no child wants to be. However, almost all
children are different in various ways. Some differ in physical
appearance, some in physical ways that are not immediately visible, and
some in personality and intellectual development. The more children
perceive themselves to be different from peers, the more they
understand their disability. Children’s understanding of their
disability is general and incomplete at 6 years of age, but within a
few years, around the age of 8 or 9 years, they come to a much more
complete understanding of their handicap (17).
Therefore, if parents have not discussed this with the child, they can
expect the more difficult questions from their child to begin at around
this age.

All children with disabilities are vulnerable to social
isolation. This, in turn, can have negative effects on the development
of self-esteem, body image, and the child’s identity, which are
developed through the interaction with parents, teachers, friends,
classmates, and others. As children develop these interactions, the
issue of “first appearance” becomes important because it serves as a
clue to perceived personal characteristics, and can be an obstacle to
further healthy interaction. Children in peer groups tend to devalue
those with handicaps, a factor that may greatly interfere with these
relationships (18). Parents especially understand this and fear for their child in this regard.

There has been a great deal of study on the
nonhandicapped child’s reaction to various handicaps, showing that
children prefer other children without handicaps, and that they dislike
some handicaps more than they dislike others (19,20,21).
In addition, it is known that young adults show signs of anxiety when
face-to-face with a handicapped person. However, there is some evidence
that young children do not share their parents’ values toward various
handicaps when young, but between the ages of 6 and 18 years, they
gradually develop values almost identical to those of their parents (20).
This would suggest that these values may be subjected to modification
among young children and emphasizes that organized discussions with
classmates in school about the child’s handicap may be of great value.

Despite the negative “first impression” that physical
differences hold for children, there is evidence demonstrating that the
age of the patient, the gender, the degree of limb loss, or
socioeconomic status are not predictors of low self-esteem or of
depressive symptoms. Rather, social factors, for example, stress and
hassle, parental discord, and social support from classmates, parents,
and teachers, along with the child’s own perceptions of competency and
adequacy, gained through peer acceptance, scholastic achievement, and
athletic accomplishments, play the largest role in the development of
self-esteem (22,23,24).

The importance of this information for parents,
physicians, therapists, prosthetists, and teachers is that although
limb deficiency is the visible problem and is subject to little
modification, the important factors in the development of self-esteem
are independent of the deficiency and can be positively affected.

The difference between the juvenile amputee and the
adult amputee are as different as are the child and the adult. Acquired
amputation in the adult is usually of the lower extremity and involves
only one limb. In the child, it is most often congenital and more
frequently has upper- and multiple-limb involvement.

The more important difference, however, lies in the fact
that children are born dependent and are naturally in the process of
becoming independent, whereas adults and older children are independent
and far less changeable. The child with a congenital amputation or
congenital deformity requiring an amputation will adapt far better to a
missing limb than will an older child or adult who suddenly loses a
limb. In addition to their adaptability in the physical arena, they
will have far more adaptability in the psychosocial arena.

Similar differences apply to congenital and acquired
juvenile amputees. The congenital amputee has a difference; the
acquired amputee must adjust to a loss. The difference is dependent on
the age and the deficiency. A child born with bilateral amelia will
learn to use the feet for all activities of daily living, as will a
child with traumatic loss of both upper limbs at an early age. However,
bilateral upper-extremity loss in the older child who has functioned
with both hands for years will not be so well compensated for by use of
the feet.

It has been observed that the percentage of shortening
in a congenital limb deficiency remains relatively constant. This
principle has been established for congenital short femur (28,29,30), and fibular hemimelia (31,32).
Clinical experience indicates this to be true for the tibial hemimelias
also. It is important for the clinician and the parents to be aware
that this percentage difference will translate into significant
differences as the limb grows. Therefore, in discussing centimeters of
shortening and planning treatment, it is important to calculate what
the discrepancy will be at maturity.

Because the percentage of shortening remains relatively
constant, it is possible to calculate the ultimate discrepancy in
centimeters at an early age. Knowing the percentile height of the
child, the length of the femoral and tibial segments of the normal limb
can be estimated from the Green and Anderson growth charts (33) (Tables 31.2 and 31.3).
Then, knowing the length of the normal segments and the percentage by
which the affected segments are short, the length of the affected
segments at maturity can be estimated.

Although the preceding method of calculating the
eventual discrepancy at maturity is clinically valid, the clinician
should be aware of the effect that surgical procedures could have on
the growth of the limb. Following amputation, the epiphysis of the bone
may not grow at the normal rate. Christi et al. showed that in 20 B-K
amputations in children, only three tibias grew at the expected rate (34).
The congenital group of tibias grew to 36% of what would have been
expected, and the acquired group grew to 53% of the expected level.
Various reasons for this may be the lack of stress across the growth
plate, the decreased blood flow to the bone, or the result of the
congenital insult that produced the limb deficiency.

The timing of an amputation in a congenital
limb-deficient child is best understood in the context of the purpose
of the amputation in an already limb-deficient child and the
development of the child. The amputation is done for two reasons: to
correct a severe discrepancy in length or to enhance prosthetic fitting.

In general, elective lower-extremity amputations,
designed to aid prosthetic fitting of congenital deficiencies, are
performed at the time the children are ready to walk, as indicated by
their pulling to stand. For children with tibial and fibular
deficiencies who will be treated with amputation, pulling to stand and
cruising are the signals that the child is ready to begin walking. This
would be the time for an amputation and prosthetic fitting, so that the
child can maintain a normal developmental sequence. In some unusual
cases in which the deformed extremity is interfering with crawling and
other prewalking activities, amputation may be performed earlier.
However, prosthetic fitting should wait until it will be of some value.
It is very difficult to keep a prosthesis on a crawling child.

In other cases (e.g., PFFD), prosthetic fitting will
usually be done when the child is ready to walk, but definitive
surgical treatment to permit a more functional prosthesis will be done
later for technical reasons.

Finally, there will be cases in which leg lengthening is
the treatment of choice, but the difference in length must be
compensated for before lengthening at a later age. Occasionally, it
will be necessary to fit such patients with nonconventional prostheses,
when shoe lifts are not sufficient.

Although it is poorly documented, there is the
impression among both parents and surgeons that with early amputation
the child does not experience the loss in body image that accompanies
amputation at a later stage. Also important is that as a general rule,
the earlier the amputation, the better the adaptation of the child’s
neurologic plasticity to the alteration.

Bony overgrowth at the end of the residual limb is the
most common problem in juvenile amputees. Its occurrence is reported to
be between 4% and 35%, and depends on the cause of the amputation, the
age of the patient at the time of amputation, and the bone involved (35,36,37).
It occurs most commonly following traumatic amputation or elective
amputation through a bone. It is seen in congenital amputations because
of amniotic band syndrome but not in those due to failure of limb
development. It is not seen in amputations through joints (38).
Overgrowth occurs most often in below-knee amputations, with the
problem being present in the fibula more often than in the tibia, and
in transhumeral amputations. Recurrence is common and is felt by some
to be more common during periods of rapid growth when bone turnover is
high (e.g., adolescence).

Contraction of the soft tissue and growth of the bone, pushing it through the skin, were originally thought to be

responsible for bone overgrowth. Aitken disproved these theories when
he demonstrated by implanting metallic markers that the overgrowth took
place distal to the end of the bone (35,39).
The new bone is formed by periosteal and endosteal bone. Overgrowth
results from the typical process of wound contracture as has been
demonstrated by Speer (40). Following
amputation through a bone, the periosteum continues to grow. As it
grows over the end of the bone, it grows over the open medullary canal,
where it contracts and is drawn into the canal from which it can
continue to grow, producing the overgrowth at the end of the bone.

The patient will often notice pain on weight bearing or
prosthetic use. An antalgic gait with decreased stance time may be
noticed. Decreased range of motion, to limit pulling

of
the skin at the end of the limb, is an additional symptom. Clinically,
the patient presents with tenderness and pain at the end of the
residual limb. There may be inflammation, bursal formation, or the bone
end may be protruding through the skin. Commonly, the bony spike can be
palpated within a small, tender bursa. Careful medical supervision can
often anticipate the problem, which in turn allows the patient to plan
for surgical correction. Prosthetic adjustments may help delay surgical
revision, but will seldom be sufficient with significant overgrowth.

In an effort to disrupt the pathologic sequence of
overgrowth, various plastic and metallic devices have been used to cap
or plug the end of the bone. However, these techniques have been
abandoned because the results were not as good as with the use of
biologic material (41,42). Marquardt reported in the mid-1970s, in the German literature, on the

capping of the bone end with a cartilage-bone graft. More recently,
Tenholder et al. reported comparable results with the use of a
polytetrafluoroethylene felt pad (43).
Various reports for both acquired and congenital amputees indicate
generally favorable results, with most revisions being for technical
reasons (41,42,44,45).

When a patient presents with pain and bursa formation,
prosthetic modification and other conservative measures should be used
first unless a bony spike is felt. If revision surgery is necessary, a
capping procedure should be considered. In the case of a primary
amputation, it is advisable to use available parts from the amputated
portion of the limb to cap the end of the bone, if conditions permit.
The most common procedure is the use of the proximal fibula to cap the
tibia. As in any revision, adequate resection of the bone is essential
to provide a healthy soft-tissue envelope. (Fig. 31.2).

Following surgery, the therapist should supervise and
educate the child and parents in edema control to hasten return to
prosthetic use. In addition, range of motion and strengthening
exercises hasten, and may even be necessary to regain, full function of
the prosthesis. Users of myoelectric prostheses may need readjustment
of their electrodes and, for a while, may have difficulty activating
the prosthesis. This is because of swelling and reshaping of the limb,
which may alter the optimal sites for electrode placement.

In some patients with either congenital or acquired
amputation, the residual limb will be too short for satisfactory or
comfortable prosthetic fitting. In such cases it may be possible to
lengthen the residual limb. Watts has written an excellent review of
this subject and reports his experience with 32 limbs in 27 patients (46). Alekberov et al. report on six patients who had successful lengthening of 3.4 to 8.4 cm in congenital below-elbow segments (47). The remainder of the literature to date is largely case reports.

The lengthening of residual limbs is fraught with
complications, and careful consideration needs to be given to the
potential benefits versus the possible complications. Skin problems are
frequent and often limit the length to be gained. Tissue expanders
generally do not provide the solution. Free tissue flaps may be used
when skin coverage is

inadequate.
Free flaps often remove sensation from the end of the residual limb,
and especially in the upper limb this can affect the function of the
limb both with and without the prosthesis. The child will be without
the use of the prosthesis for a prolonged period, an especially
difficult problem when the lower extremity is involved.

The term “phantom limb” was coined by the neurologist
Silas Weir Mitchell in the middle of the 19th century. He described
these sensations as replicas of the lost limb, some being painful and
some not. Phantom sensation of the limb is often described by patients
as the feeling that they can move the part, tell how the part is
positioned, or feel it itching or tingling. Phantom pain, however, is
perceived by the patient as just that—painful. It often is the same as
the pain before an amputation or may be cramping, shooting, burning, or
of any other characterization.

It has been a general idea that children born without
limbs do not have sensations of them; nor do these children experience
the phantom pain or phantom sensation seen in the acquired amputee (48). Recent reports call this commonly accepted truism into question (49,50).
Whatever this pain is, those who care for children with limb
deficiencies will recognize that these children do not have the same
problem as the true chronic phantom pain seen in adult amputees.

Melzack et al. reported that phantom limb was present in
at least 20% of children with congenital limb deficiency and in 50% of
those who underwent amputation before age 6 (50).
In addition, 20% of the congenitally deficient group described the
sensations as painful, whereas 42% of the acquired amputees described
them as painful. To explain the phenomenon of phantom limb in a child
who has never had a limb, Melzack et al. have proposed that there is a
genetically or innately determined neural network that is distributed
in the cortex (not focal), which is responsible for the representation
of the limb, even though the limb bud development was not normal.

Phantom pain and distal residual limb pain are also
associated, and in general seen to be associated with, other pains;
such as, headache, bone, or joint pain (49,51).
The phantom sensations may occur frequently or rarely. They are often
triggered by a wide variety of stimuli. Feeling nervous or happy, not
wearing a prosthesis, being cold, or being ill are frequent triggers.
Fortunately, these sensations do not interfere with the child’s usual
activity, and most say they just try to ignore the sensations (52).

There is no single highly successful treatment for
phantom limb pain, most likely because there is usually not one single
cause. Because many of these problems resolve with prosthetic
alterations or physical therapy modalities, a multidisciplinary
approach has proven to be the best intervention in evaluating and
properly treating the phantom limb phenomenon when it becomes a problem.

A properly fitting socket, with appropriate suspension and sock thickness, is the best and first treatment of choice (52,53).
A heavy, tight shrinker, either worn inside the prosthesis or when the
prosthesis is off, may provide relief. Physical therapy interventions,
including weight bearing and graduating pressures such as tapping,
rubbing, and massage to the residual limb, have been reported to give
temporary or permanent relief. Rubbing and massaging the uninvolved
limb at similar points to those in which they are experiencing the
phantom limb sensation may provide relief. Various physical modalities
have been utilized in the treatment of phantom sensations in children,
including transcutaneous electrical nerve stimulation (TENS),
biofeedback, ultrasound, and the physical agents of heat and cold (54).

For the occasional adolescent amputee who has problems
with phantom pain following an amputation, gabapentin (Neurontin,
Park-Davis) has proven a useful medication for some patients.

The child with unilateral absence of the arm will be
less likely to fully accept a functional prosthesis than those with
lower levels of amputation. If body-powered components are used, the
patient has difficulty in controlling the devices because there is no
lever arm. Externally powered prostheses are heavy. The weight and
increased body heat due to the necessary suspension make this a
difficult prosthesis to wear. When coupled with the problems of
function in using an artificial shoulder, elbow joint, and hand, the
child will usually choose to function without the prosthesis.

Many children with amelia of the upper extremity are
affected bilaterally. The choices for these children are to help them
develop their lower extremities to substitute for the upper
extremities, to fit them with prostheses, or to attempt a combination
of both. There is universal agreement that there is no place for
attempting to limit the child’s use of the feet or attempting to
provide all of the child’s upper-extremity function with prostheses.
The feet are the best substitute for the hands. Children with bilateral
amelia and relatively normal lower extremities can usually master all
ADL, while leading full lives with family, children, and employment.
Until the physician becomes acquainted with a child or, preferably an
adult, with bilateral amelia, she or he cannot understand the extent to
which the legs and feet can substitute for the arms and hands. Most of
these children will reject prostheses.

The question of prosthetic fitting most often arises in
the child with bilateral amelia and significant lower-extremity
anomalies that limit their substitution for upper-extremity function.
In such cases, unilateral fitting may be indicated, but is likely to
gain limited acceptance, and then only after many years of struggle.

Children with bilateral amelia will often walk late.
They will need help in pushing to stand. In addition, the fear of
falling, because they cannot protect themselves, comes early. Helmets
or some protective headgear are needed until the child is independent
in gait. Therapy is directed at trunk control and strength, along with
training in the use of their feet for all activities. These children
are also prone to develop a progressive scoliosis, often before
adolescence. This presents a difficult problem. Bracing restricts the
use of their feet in activities of daily living. Surgical fusion does
the same. However, often these curves will require fusion, and in such
cases, as short a fusion as possible should be done.

In phocomelia, the distal portion of the extremities
appear to attach directly to the body. There are wide variations in
this deficiency. In some, the hands may be close to normal, with some
remnants of the arm bones, whereas in others the hand may be no more
than a single functionless digit with little residue of the arm.
Patients with phocomelia usually have some mobility in their residual
limbs, and therefore differ in one significant way from the child with
bilateral amelia—they have a sensate limb often capable of some
grasping function. The function of these limbs depends on the function
of the hand, the length and function of the arm itself, and the ability
to bring the hands together at the midline or to the face.

Those children who cannot bring their hands to the midline or to the mouth will use their feet to substitute in the ADL (Fig. 31.16 A,B,C,D).
They should be encouraged from an early age to develop their foot
skills and the body strength that is necessary to use the feet. In
those children with better function and length, little else than
adaptive equipment to aid in dressing and so on may be necessary (Fig. 31.16E).

Therapy to increase the range of motion of the scapula
and limbs and to strengthen any muscle power in the residual digits may
prove of benefit. Adaptive equipment to aid in the use of the residual
limbs can be very useful for some activities such as feeding, dressing,
and so on. The residual limbs can manipulate switches for powered
prostheses, and therefore, the temptation to find for a prosthetic
solution to their problem arises. However, like the child with
bilateral amelia, these children will function in most activities by
substituting foot function for what they cannot do with their upper
extremities. Fitting the older child with a unilateral prosthesis for a
specific function may be indicated, but routine wear is not common.

There is little published experience in this deficiency.
Although some children with unilateral above-elbow amputation will
develop surprising facility with a prosthesis, they will often wear it
only for specific activities, such as sports, or for cosmetic reasons.
If there is a humeral segment of any reasonable length, the
humeral-thoracic pinch provides useful assistance for the normal
opposite extremity. Prosthetic use will be in accord with the patient’s
functional needs, and will generally relate to specific tasks. These
may be as limited as riding a bicycle or full-time use at school. These
patients should be offered the opportunity for prosthetic fitting.

Patients with bilateral congenital transhumeral
deficiencies are more inclined to use their own body, rather than a
prosthesis. These children may benefit more from assistive devices than
from prostheses. Such patients will often prefer prosthetic fitting on
one side, where they use the humeral-thoracic pinch, with intact
sensory feedback on the other side and in their feet. Again, it is
important to make the distinction between the congenital and acquired
amputee. The congenital amputee will be less inclined to

use prostheses, and the traumatic amputee will be more inclined.

For the patient with bilateral above-elbow transhumeral
deficiencies, Marquardt has recommended an angulation osteotomy of the
humerus (160). The osteotomy angles the distal
3 to 5 cm of the humerus anteriorly by 70 to 90 degrees. This allows
for suspension of the prosthesis without the usual shoulder cap, makes
it easier to put on, permits better shoulder motion, and gives better
control of rotation. This procedure should only be performed if the
humeral length is sufficient and there is a need for a unilateral
prosthesis.

The congenital below-elbow amputation is the most common
of all of the upper-extremity deficiencies. It is more often the left
arm (Fig. 31.17). It is sporadic and without
known cause. Children with this deficiency present the most ideal
upper-extremity deficiencies for prosthetic fitting. Children with this
deficiency are unlike those with a transverse amputation through the
carpal bones, which usually have partial grasping function with
sensation. They are also unlike the above-elbow deficiencies in that
they have a normal shoulder and elbow that allow accurate placement of
a relatively light prosthetic terminal device.

Despite the fact that congenital below-elbow amputees
are ideal candidates for prosthetic use, not all children will remain
good prosthetic users during their childhood. Scotland and Galway
reviewed the experience at the Ontario Crippled Children’s Center, and
found that 32% had stopped using their prosthesis, upon follow-up of 7
to 17 years (161). How many of these may resume use of the prosthesis in the work environment is unknown. They, like Brooks and Shaperman (162), noted greater acceptance of the prosthesis if fitting was done before the age of 2 years.

In the congenital group of Brooks and Shaperman (162),
22% of those fitted before 2 years of age, and 58% of those fitted
after, had stopped using their prosthesis. However, of those who
continued to use their prosthesis, there was no difference in the
extent of use between the two groups. The most common age at which
patients discontinued use of their prosthesis was at 13 years, and the
most common reasons they gave were that the prosthesis was cosmetically
unacceptable and that they could do everything without it. Sorbye (163)
reported that, of the patients in their clinic who were younger than 24
years, 87% were using their myoelectric prosthesis, and 65% of these
used it all day and for all activities. Hubbard et al. (164),
reporting on the Toronto experience, found that 70% of the below-elbow
amputees were using their prosthesis, whereas 30% had rejected it.

With this and other evidence, it is now the usual
practice to recommend fitting around the age of 4 to 6 months with a
passive hand to aid in normal development. It is in this age range that
the child brings his or her hands to midline

while
supine, props on the elbows while prone, and then props on extended
arms while sitting and rolling over. This lightweight prosthesis is
used to have the child become comfortable with a prosthesis, and to
acquaint the child with the two-handed activities that a normal child
would perform, in an effort to develop the central cortical pathways
for bimanual dexterity.

Depending on the child’s acceptance and use of this
passive prosthesis and the choice of a terminal device, a more
functional terminal device is fit between 15 and 18 months (27,165). Today, there are a number of terminal devices available (166).
There are two choices to power the device: battery (myoelectric) and
body (cables). Although there will be many factors to consider in the
selection (cost and funding, clinic philosophy, and parent choice),
virtually all centers today in North America are fitting most children
with myoelectric-powered terminal devices (Fig. 31.17). Table 31.4
compares the advantages and disadvantages of myoelectric and
body-powered terminal devices for the child with a congenital
below-elbow amputation.

The congenital transcarpal amputation is the second most
common deficiency of the upper limb and occurs in a characteristic
pattern, with some or all of the proximal row of carpal bones
preserved. The existing flexion of the carpals on the radius allows for
limited grasping function, which along with normal sensation, makes
this an assistive hand for which no prosthesis can substitute (Fig. 31.18).
Occasionally, children will benefit from a volar opposition post for
certain activities. They will usually wear it only for certain tasks,
for example, as a guitar pick adapter or to grasp the handle bars on a
bicycle.

The authors’ experience with such children is that they
have much more difficulty with the cosmetic aspect of their deficiency
than do those children with transverse amputations at higher levels. In
the older child and adolescent, it may be wise to explore the desire
for a cosmetic hand that would be used in certain circumstances or
would provide a psychosocial benefit. Some cosmetic hands have a
passive spring grasp to provide limited function.

Generally, upper-extremity prostheses and their control systems can be subdivided into three categories: passive, externally powered, or body-powered devices.
The Ballif arm (circa 1400) was the first body-powered prosthesis to
introduce the use of prosthetic hand operation by transferring

shoulder movement to activate the terminal device (167).
A harness over the contralateral shoulder is connected with a thin
cable and housing to a terminal device. Through the use of scapular
abduction, the fixed cable is stretched over a greater distance and
causes the prosthetic hook or hand to open or close, depending on the
configuration of the terminal device. A good analogy is the braking
system on most bicycles. Most parents prefer the cable-operated
prosthetic hand over the cantered hook for cosmetic reasons.
Unfortunately, the hook is far superior in function, but has fallen
from favor because of the desire to have the prosthesis look as natural
as possible, even at the sacrifice of function. Most hooks are canted
in design, and this allows a full field of view of the device while
using it, compared to the mechanical hand that obstructs the view and
results in awkward arm positions to grasp objects.

The externally powered prosthesis can be further subdivided into switch control or myoelectric control.
In both systems, a battery, relay switch, electric hand, and electronic
control system are present. It should be noted that the myoelectric
hand is the only terminal device available for children using the
externally powered prosthesis. In the myoelectric prosthesis (Fig. 31.19),
an electrode placed on the surface of the skin acts to pick up the
electromyographic (EMG) signal, which in turn is amplified with the
help of an electronic relay switch, and this, in turn, operates the
electric hand (168). The entire system is
generally referred to as a one-site or two-site system. This denotes
the number of electrodes that are used for signal recognition.

The one-site system can be further categorized as
voluntary opening—automatic closing, rate-sensitive, and
level-sensitive. The first fitting of a myoelectric arm occurs at
younger than 2 years and utilizes a voluntary opening— automatic
closing (cookie-cruncher) configuration. The muscle signal opens the
electric hand, and relaxing of the signal causes the hand to close
automatically. This system is used for children under 4 years of age.
The rate-sensitive and level-sensitive control systems use one muscle
to control two functions, and are generally fitted to children over 4
years of age, when two sites are not available. The choice of a system
depends on the muscle signal strength, muscle control, and prosthetic
design factors (27).

In the two-site system, each electrode operates a specific task. Children can often operate this more complex

system by 3 to 3½ years of age. The EMG signal of the flexors is used
to close the hand, whereas the EMG signal of the extensors is used to
open the hand. This system is used when children have established good
control and good use of their myoelectric prosthesis and have
demonstrated the ability to control both the flexors and extensors
independently of each other.

Patients with a higher level of upper-extremity
amputation are generally good candidates for switch-controlled
externally powered prostheses. The electrode is replaced with a
miniature switch that can be of a push-pull configuration, a
force-sensing resistor, or of a simple on-off design. The incorporation
of these switches into the prosthesis depends primarily on the level of
amputation and the design of the prosthetic socket or frame.

Management of the patient with multiple-limb
deficiencies, involving both the upper and lower limbs, is a challenge
that requires a team with experience to achieve the maximum function
for the patient. The problem of bilateral upper-extremity amputation
has been covered earlier. Children with one upper and one lower
extremity pose no problems beyond the management of each individual
limb. Children with bilateral knee disarticulation or transtibial
amputations will walk without support, and therefore a unilateral
upper-extremity amputation in association poses no special problem,
other than donning and doffing the prostheses. With bilateral
amputations above the knee disarticulation level, however, walking
without support is problematic; upper-extremity function is needed, and
a wheelchair may be required for long distances and to conserve energy.

A special caution needs to be given in regard to those
children with bilateral upper-extremity amputation and lower-extremity
anomalies that might ordinarily be treated with amputation and
prosthetic fitting. No amputations of the lower extremity should be
performed until it is certain that the child will not require the use
of the feet for grasping activities.

One of the most common types of patients seen in the
pediatric age-group with this problem is the quadrimembral amputee
resulting from meningococcemia. In these patients, it is often
necessary to cover the residual extremities with split-thickness skin
grafts to maintain length. These grafts, if not adherent to bone, do
very well in the prosthesis, and are not a hindrance to fitting.
Treatment must be individualized for each patient with certain general
guidelines. The first is to help the patient maximize function with his
or her residual limbs. This is especially true with the upper
extremities, in which sensation is so important to function. Although
these children will become proficient in the use of bilateral
upper-extremity prostheses, if their residual limbs are long enough,
they will usually perform many of their daily activities, especially at
home, without their prostheses.

A common mistake is to attempt to fit all four
extremities of these children with quadrimembral loss at the same time.
Although the pressure to do so is enormous, it may result in actual
delay in functional recovery and rejection of the prostheses. In most
situations, it is best to first fit the lower extremities and achieve
ambulation. After this is accomplished, the upper extremity is fit.

In the child with a congenital quadrimembral deficiency,
there will usually come a time when the parents, and perhaps the child,
desire prosthetic fitting. Again, it is best to avoid fitting all four
extremities at once, but rather focus on meeting specific needs.
Although experience shows that most of these children will use their
prosthetic devices in a limited fashion, if at all, they and their
parents need and are entitled to this experience at least once (Fig. 31.20).

Children may undergo an amputation for a variety of
reasons. Although there are no good statistics, trauma is the major
cause of amputation in childhood (169). In this
group, power lawnmowers lead the list of causes, and most commonly, it
is a child riding with a family member. Motor vehicle accidents, farm
injuries, and gunshot wounds follow in that order (170).
In war-torn countries, land mines may be the leading cause of
amputation. Because amputation of the digits is most often caused by
machinery, upper-extremity amputations are more common than those of
the lower extremity. Boys are affected about twice as often as girls.

Tumors, vascular occlusion caused by meningitis or
vascular catheterization, and burns are additional causes, and each has
its own unique set of circumstances. Indeed, the differences in
acquired amputation defy a detailed analysis. Some are semielective and
allow for some preparation of the patient and the parents, whereas
traumatic amputations do not. It is possible, however, to discuss the
common principles that are applicable to acquired amputations in
children.

When the surgeon is faced with an acutely mangled
extremity, it can be difficult to decide on amputation versus limb
salvage. The usual criteria and classifications that are applied to
adults are not easily transferred to children. It is often necessary to
gain the input of a vascular surgeon and others to make the best
assessment, while always remembering the tremendous healing and
adaptive capacity of the child, compared with the adult.

When dealing with feet mangled in a power lawnmower, it
is often wise to attempt salvage at the first surgery. However, in the
case of a mangled leg that will require vascular and nerve repair,
along with bone reconstruction and free tissue transfer, the decision
needs to be made more realistically. The more energy expended in saving
the limb, the higher the parents’ expectations of the result.

The surgeon rarely will have options regarding the level
of amputation in trauma. The lack of preparation, coupled with the
parents’ expectations, usually dictates saving as much of the limb as
possible. This often results in a less functional level of amputation
than one that is more proximal. The most obvious example is
preservation of the talus and calcaneus, which the parents and child
may see as saving at least part of the foot, whereas the result may be
a worse gait, worse cosmesis, and more prosthetic problems than with a
Syme amputation.

In the child, it is usually advisable to save as much
length as possible in amputations of the long bones. This is especially
true in the femur, in which 70% of the growth

of
the bone occurs from the distal physis. A 5-year-old child with a
midthigh amputation will have less than ideal length as an adult. In
the leg, however, little is lost, so long as an adequate portion of
proximal tibia, in which most of the growth occurs, is preserved, and
in fact, shortening the bone to achieve good soft-tissue coverage may
be the best course.

The common teaching, that skin grafts do not make
suitable coverage for a residual limb that will bear weight in a
prosthesis, is not applicable to children, especially very young ones.
In children, skin grafts do make good coverage so long as they are not
adherent to the bone. Split-thickness skin grafts are frequently needed
to preserve length in meningococcemia, burns, and some cases of trauma.
In older children with traumatic amputations, free vascularized flaps
can provide excellent coverage.

Where possible, disarticulations will prevent the
problem of bony overgrowth. It is not necessary, or perhaps even
advisable, to remove the cartilage from the bone end. Tapering of the
bone ends, at the distal tibia, for example, is not necessary unless
the child is approaching adulthood. The bony prominences will not
develop to adult proportions, and therefore do not present a prosthetic
fitting problem. If a young child has a through-bone amputation, it may
be possible to salvage a portion of bone and cartilage from the
amputated part for capping the bone. This is similar to performing a
Marquardt procedure, and has the potential to substantially reduce
problems of overgrowth.

It is important not to forget the child during the acute
phase of the amputation. Often the surgeon has enough problems dealing
with the parents’ emotions, and can easily forget that the child also
needs emotional as well as physical attention.

In many circumstances, the amputation will be elective.
Such is the case with children who have posttraumatic injuries, and are
electing surgical modification for better function and prosthetic
fitting. Children with gigantism, Klippel-Trenauney-Weber syndrome, and
malignant tumors not suitable for limb salvage also are in this
category. In many cases the need is obvious, and the child and parents
have come to their decision after careful consideration.

In the case of tumors, however, it is usually not so
easy, and generally there is not complete acceptance of what is in fact
a life-saving procedure. In all cases, the more preparation by the
professionals and opportunities for the parents and patient to talk
with other patients, the better. It needs to be emphasized that the
challenge is to live, and that the surgery is necessary for that. The
options revolve around the functional and cosmetic aspects of the
different procedures.

There remains a difference of opinion as to whether it
is worthwhile to fit the acquired juvenile amputee in the immediate
postoperative period. In the young child with a congenital deficiency,
there seems little to be gained. However, in the older child,
especially when the amputation is caused by trauma, there can be large
psychologic benefits from placing the child immediately in a
postoperative prosthesis. This also aids in the control of edema and
phantom pain.

The role of the prosthetist is to ensure that the
highest level of functional need of the patient is met through
prosthetic intervention, or through no intervention at all if
appropriate. The skilled prosthetist is able to assess anatomic and
functional deficiencies and recommend socket design and component
selection. In recent years, there has been a tremendous increase in the
prosthetic innovations and components available for the pediatric
amputee. Current knowledge of these components and their appropriate
use will generally be the responsibility of a prosthetist with special
interest and experience with children. In addition, he or she must
possess the clinical skills, medical knowledge, and the ability to
communicate that will enable timely and appropriate flow of knowledge
to the other team members and parents, so that realistic expectations
can be identified and achieved. Routine servicing of the prosthesis is
extremely important so that extensive repairs will be minimized and the
need for a new prosthesis recognized. Children are generally not happy
to be without their prosthesis.

The technique will vary, on the basis of the experience
of the prosthetist, team approach, integration of ever-changing
technology, and the severity of the deficiency. Physiologically, the
child is in a constant state of growth and the prosthetic device must
be designed to permit weight bearing and allow for the greatest amount
of growth without compromising fit and function. Most congenital
lower-extremity amputees are able to bear some weight on the distal end
of the residual limb, and the prosthetist is able to allow for a
slightly less intimate fit of the prosthetic socket than might be the
case for the acquired amputee. Unlike the adult, the child’s skin has
greater tolerance to skin breakdown. The increased activity levels of
the child amputee place tremendous expectations on the prosthetic
devices and the components. All of these factors

are
constant challenges to the prosthetic prescription, and emphasize the
need for a nonstructured approach to fitting. What may be suitable for
one child may be unsuitable for a different child with the same
anomaly. Rigid time schedules are discouraged, and developmental levels
should be used only as a rough guideline to aid the practitioner.

Fitting the pediatric amputee leads to unique issues not
normally seen in the adult population. Disarticulations lead to long
residual limbs with knee centers lower than on the sound side. Ischial
containment sockets are not normally recommended (unless needed because
of hip instability or nondistal weight bearing) because of problems
with soft-tissue containment and diapers in infants. Location of bony
landmarks is obscured by fatty baby tissue, and casting is difficult
and nonexact.

The various stages involved prior to fitting a
prosthesis are generally standard within the profession. Upon referral
to a clinic, the child is assessed by the team, and a treatment
protocol is established. The stages involved in prosthetic fitting
include:

The cast or impression forms the foundation for the prosthetic design (171).
It is only after a well-fitting and comfortable socket-skin interface
is achieved that the additional components can be added and expected to
function as designed. Casting usually involves the placing of a casting
sock on the residual limb, marking all landmarks and wrapping
circumferentially with plaster or synthetic bandage. This becomes the
negative impression. It is then filled with molding plaster and
stripped, forming the positive cast ready for modification. This
positive cast is then modified to distribute forces and relieve
pressure in the socket for proper hydrostatic control of the residual
limb.

Through the use of a clear test or diagnostic socket
fabricated over the positive mold, the practitioner is able to
ascertain the areas of high and low pressure and to ensure that they
are directed over the appropriate areas. Common fitting problems can be
flagged and corrected before final socket design.

Computer-aided design/computer-aided manufacture
(CAD/CAM) has been used as an alternative tool to plaster casting and
modification of the prosthetic socket. In its most simplified form, a
residual limb is scanned with an optical laser. The information is
relayed to a computer, with which modifications can be made to the
scanned shape to allow for increased or decreased weight-bearing areas.
The finished design is transferred to a computerized milling machine to
form a positive model. This, in turn, is used to fabricate the finished
device. Slowly, CAD/CAM is becoming more widely used within the
profession, because of advantages of design reproducibility, record
keeping, and flexibility in remote locations (172).
Its advantages in the pediatric setting have yet to be proven. All
current CAD/CAM systems rely on surface topography of the residual
limb, and therefore disregard crucial data such as tissue density,
tissue mobility, and underlying skeletal structures (173).

During dynamic alignment in the crawling infant, the
prosthetist initially focuses on creating a prosthesis that will aid
the infant in preparation for ambulation, transitioning from crawling
to standing, with little consideration of gait at this point.
Sutherland concluded that mature gait patterns were established by 3
years of age (174), whereas others place the
time frame closer to 6 years of age. Early infant gait patterns are, in
fact, the processes of suppression of primitive reflexes and the
acquisition of postural responses (175).
Dynamic alignment is the manipulation of relative position of the
socket to the foot and knee while the prosthesis is moving through the
various stages of gait. Through the use of alignment mechanisms in the
components, the prosthetist is able to shift, tilt, and rotate the knee
and foot in relation to the socket. Once independent gait is
established in the infant, refinement to gait can be achieved through
further prosthetic alignment.

The design and fitting of lower-extremity prostheses
encompasses numerous biomechanical principles and their application to
the residual limb-socket interface, and it is the successful
manipulation of these forces that ensures a patient’s comfort and
function. The accommodation for differences in tissue compressibility,
pressure tolerance, underlying bony structures, and vascular integrity
are factors taken into account prior to socket design. Dynamic forces
exerted through ground reaction forces and resulting moments, including
torque and shear forces, increase the vulnerability of the skin-socket
interface.

It has been estimated that more than 100 prosthetic knees are commercially available, and the number is growing each year (178).
Although most are for adults, recently there are a number of new knees
available for children. The prosthetic knee is composed of the knee
mechanism or frame, and may contain a control unit. The control unit
consists of a pneumatic, hydraulic, or mechanical system, or some
combination of these three. The control unit responds to changes in
cadence and dampens sudden, abrupt changes.

The
faster a hydraulic or pneumatic unit is compressed, the faster the
energy is released, and this helps to regulate the lower shank of the
prosthesis. The prosthetic knee unit can be further subdivided into
single axis and polycentric types.

The maturation of gait from infant to adult carries with
it the need for sound practice in selecting the appropriate knee, on
the basis of amputation level, functional level, and body size. In
general, the single-axis internal knee without any control unit is the
first knee to be used on the child, because of its light weight, short
lever arm, and simplicity. In the single-axis knee joint, the lower
shank rotates around a single point in relation to the socket.

A polycentric knee was introduced in 1998 for the infant and toddler, and it may be used if space permits.

Internal polycentric knees move around a center of rotation that varies with the flexion angle of the lower shank (168). The four-bar linkage knee is the most common polycentric knee and the most widely used by prosthetists (179) (Fig. 31.26).
The inherent stability during stance, the fluid knee-flexion movement,
and the mechanical design to give more ground clearance during flexion
increase patient and practitioner confidence in the unit (180).

Changes in design and technology have now widened the
boundaries and age distinctions for the prescribing of specific knees.
Traditionally, an articulating knee would be introduced in a congenital
amputee at approximately 3 to 4 years of age. This age was determined,
in part, by the limitations in the size and function of the components.
In the experience at the authors’ center, as well as others,
introduction of a prosthetic knee without a locking feature can be used
as the first prosthesis when the child first pulls to stand. A recent
report demonstrated the benefits of early fitting with articulated
knees in children as young as 17 months. All children learned to walk
with an articulated knee, despite their age differences (129).

As the child develops and grows, more sophisticated
control systems (e.g., hydraulic knees) can be incorporated into the
prosthesis. Most components carry specific weight guidelines, and many
children reach these ranges well before adulthood. For example, an
adult hydraulic polycentric knee is routinely used on 8-year-old boys
whose weight has surpassed 100 lb. This does not mean that every child
of a certain age and weight should have a particular knee. Placing a
sophisticated knee and control system on an individual who has neither
the hip range, muscle strength, nor residual limb length to activate
the knee often results in contralateral hip and lower back pain as well
as patient frustration.

Variations in the materials, design, and alignment of
the foot can have profound effects on the performance of the
prosthesis. Functionally, prosthetic feet can be categorized into five
main groups (181):

The solid ankle cushion heel (SACH) foot [Therapeutic
Recreation Systems, Inc. (TRS)] contains no articulating parts, and
foot motion depends on the various compressive properties of the
materials used between heel-strike and

toe-off (Fig. 31.27A).
It is generally considered when amputees require maximum late-stance
stability because of weak knee extensors, knee-flexion contractures, or
poor mid- to late-stance balance (182). The
SACH foot is used in pediatrics when the foot size is below 12 cm. The
Little Feet is a bolt on type SACH foot designed with unique energy
dynamics (Fig. 31.27B). The toes are very
flexible because of the use of an elastomer that more closely mimics
the child’s foot. A special removable heel core allows the foot to be
used “barefoot.”

The single-axis foot usually contains rubber bumpers
that allow passive dorsi- and plantar flexion. By changing the hardness
of the bumper, the prosthetist is able to effectively change the
properties of the foot. The single-axis foot does not come in a size
suitable for the child amputee. This foot is best suited for the
transfemoral amputee, in whom full-foot contact with the ground is
necessary to increase stability. The multiaxis foot allows passive
dorsi- and plantar flexion, inversion, and eversion. The multiaxis foot
was once thought best suited for the amputee who because of uneven
terrain or a lifestyle that includes golfing or various sports requires
flexibility and some rotational control: It has now found its way into
the pediatric population. The multiaxial foot (College Park Truper
foot) (Fig. 31.27C) allows controlled
resistance in all planes—inversion/eversion, dorsiflexion and plantar
flexion, and transverse rotation about the ankle joint. This class of
foot has gained wide acceptance within the pediatric arena, in part
because of its ability to absorb forces at the ankle and reduce
transmission of these forces to the socket. This is particularly useful
when fitting a very short residual limb.

Once the child’s activity level warrants a
higher-functioning foot, the prosthetist can move the child into a
dynamic-response foot. This group of feet is distinguished by a spring
mechanism in the keel that deflects during gait (Fig. 31.27D).
The dynamic-response foot has found its way into competitive-level
sports as well as day-to-day activities. Although the variety of
componentry for children is still much less than for adults, there is a
wide variety of feet with different performance characteristics
available. It is important to use

components that will maximize performance, and at the same time be appropriate for the patient (183).

At slower walking velocities, there is little difference between the dynamic-response foot and the SACH foot (184).
Generally, children are not fitted with the highest-performance
dynamic-response feet, because of constant growth and weight changes
and the high costs associated with foot replacement. The involvement in
competitive sports is usually a good benchmark to initiate fitting
adolescents with the highest-performance dynamic-response feet.

In the transfemoral amputee, it is crucial to properly
choose a foot that will enhance gait, but also to choose the
complementary knee that will aid in controlling the foot during all
aspects of the gait cycle. A common mistake is to prescribe a
dynamic-response foot with a simple, friction-controlled knee that is
incapable of preventing uncontrolled heel rise. The same is true of the
transtibial amputee, who lacks the muscle strength to control the foot,
often resulting in premature muscle fatigue. In the selection of
multiple components, the prosthetist must marry the characteristics of
all components, so that maximum benefit can be available to the amputee.

The choices left open to the prosthetist are numerous
and, at times, controversial. Where some clinics maintain rigid
protocols for terminal device selection, other clinics rely more on
patient and parent input, combined with historic

success
rates for device types. Clinics that maintain very high caseloads for
myoelectric devices, for example, will most likely have far more
experience in fitting externally powered prostheses, compared to a
clinic that may only see a handful of potential myoelectric candidates.

In simple terms, the terminal devices can be divided
into hands and hooks, and they can be body-powered (cable and harness)
or externally powered (electric). Hands and hooks can be either
voluntary opening or voluntary closing. Patton lists the functional and
prescription criteria for the various terminal devices (166).

The initial fitting of a child with upper-extremity limb
deficiency begins at 4 months of age in a passive prosthesis with a
stylized passive hand. There are several hands manufactured for this
age range (Fig. 31.29A). This allows for equal
arm lengths for the development of propping up on the amputated side
and greater acceptance by the parents. Following initial sitting
balance, the clenched-fist terminal device is exchanged for a small
infant passive hand. When the infant begins to reach out (at
approximately 15 to 18 months of age), the clinic team begins to assess
the need for either body-powered or externally powered prostheses. If

body-powered prosthesis is recommended, a cable-operated Hosmer 12P plastic-covered hook (Fig. 31.29B) or an ADEPT infant hand (Fig. 31.29C)
will be prescribed. The canted design of the 12P hook allows for
greater visual feedback to the wearer. In the event that a myoelectric
device is warranted, the Variety Village 0-3 (VV 0-3) electric hand (Fig. 31.29D) or the Otto Bock Electrohand (Fig. 31.19)
is used. In the pediatric VV 0-3 hand, the thumb and opposing two
fingers operate to form a three-point chuck grip. In the Otto Bock 2000
hand, the same principle is applied, except that from the open to
closed position, the thumb sweeps from a lateral position to meet the
two opposing fingers upon close.

Progression from this starting point through the various
component sizes and versions allows for a relatively smooth transition
into adulthood. Prescription criteria are reviewed during each clinic
visit, and changes are made on the basis of the child’s changing needs.
In today’s environment of active children and sports activities, the
use of sports or other adaptive terminal devices is essential for the
amputee. TRS has developed numerous devices for use in sports and
recreational activities. These can be interchanged on the prosthesis,
so that only one socket is required.

The structure or construction of a prosthesis is
referred to as an endoskeletal (internal structure) or exoskeletal
(external structure) prosthesis. Generally, transtibial, partial foot,
and transradial prostheses are constructed exoskeletally, and
transfemoral, knee disarticulation, hip disarticulation, transhumeral,
and shoulder disarticulation levels of prostheses are constructed
endoskeletally.

Exoskeletally finished prostheses are more durable and
better suited to the growing child. There are various techniques and
materials used in the construction of the exoskeletal prosthesis.
Generally, following the completion of dynamic alignment, the
ready-to-be-finished prosthesis is placed within a transfer jig that
allows the socket to be separated from the foot, while maintaining
alignment. A rigid polyurethane foam is added, and the prosthesis is
cosmetically shaped to equal the sound limb. The structure is then
laminated with acrylic resin forming the outer “shell.” The advantages
of this construction are its increased durability, and that it is easy
to clean and structurally strong. The major disadvantages are the lack
of further alignment capabilities, and that they are less cosmetically
acceptable than some other types.

Endoskeletal design was initially used in the immediate
postoperative period as a temporary method to initiate ambulation,
while maintaining the ability to alter the alignment. This quickly
became the norm for fitting in the adult population, and has been used
primarily for knee disarticulation or transfemoral prosthesis. The
prosthesis is modular and composed of a pylon (tube) and connecting
hardware, and it allows for quick changing of damaged components. In
the event that realignment is necessary, the endoskeletal design
incorporates alignment jigs within the attachment couplings, and only
the cosmetic soft cover needs to be removed for adjustment. For these
reasons, advanced components for use by children tend to be engineered
for use in this system. The disadvantages of the endoskeletal system
are lack of durability of the cosmetic cover, increased maintenance,
and increased costs. This is outweighed by the increase in function and
ease of adjusting length.