CHAPTER 30
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The Child with a Limb Deficiency
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There remains a difference of opinion about the benefit in
fitting the acquired juvenile amputee in the immediate postop-
erative 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 psychological benefits from placing the child imme-
diately in a postoperative prosthesis. This also aids in edema
control diminution of phantom pain.
Prosthetics
In the prosthetic fitting of the pediatric amputee, the single-
most important guiding principle is that functional concerns
always override cosmetic ones. When dealing with the adult
population, overall biomechanical forces resulting from pros-
thetic alignment can do relatively little damage to skeletal
integrity. This is not the case for the pediatric patient, in whom
skeletal development is ongoing. Incorrect alignment can have
long-term and often pronounced negative results.
Role of the Prosthetist.
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 inter-
vention at all if indicated. The skilled prosthetist can 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. 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 communication
skills to timely direct the flow of knowledge to the other team
members and parents, so that realistic expectations can be
identified and achieved. Routine maintenance of the prosthesis
is extremely important so that extensive repairs will be mini-
mized and the need for a new prosthesis recognized. Children
are generally not happy to be without their prosthesis.
Fitting Techniques.
The technique will vary, on the
basis of prosthetist experience, team philosophy, integration
of ever-changing technology, and severity of the deficiency.
Physiologically, the child is in a constant state of growth and the
prosthetic device must be designed both to permit weight bearing
and to allow for the greatest amount of growth without compro-
mising fit and function. Most congenital lower extremity ampu-
tees are able to bear some weight on the distal end of the residual
limb, allowing the prosthetist to achieve a slightly less intimate fit
of the prosthetic socket than might be the case for the acquired
adult amputee. Unlike the adult, the child’s skin has greater toler-
ance 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 fluid
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 child with limb deficiency leads to unique issues
not normally seen in the adult population. Knee disarticulations
can 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 non-
distal weight bearing) because of problems with soft-tissue con-
tainment and diapers in infants. Location of bony landmarks is
obscured by fatty 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:
1.
CASTING
of the residual limb.
2.
TEST FITTING
of the modified interfacing socket.
3.
DYNAMIC ALIGNMENT AND GAIT TRAINING
.
4.
DELIVERY
of the completed prosthesis.
Socket Design and Suspension Systems.
The cast
or impression forms the foundation for the prosthetic design
(216). 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 fabri-
cated 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 the 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 modifica-
tions can be made to the scanned shape to allow for increased
or decreased weight-bearing areas. The finished design is trans-
ferred 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 (217). 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 (218).
During dynamic alignment in the crawling infant, the
prosthetist initially focuses on creating a prosthesis that will
