CHAPTER 30
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The Child with a Limb Deficiency
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untreated. Children with more severe forms often choose to
walk on the knee of the unaffected side to make up for the
severe limb-length discrepancy during the first few years of life
until the discrepancy is severe and treatment is sought.
Treatment Recommendations
Nonsurgical Treatment.
Most patients will benefit from a
treatment plan that includes surgical intervention, be it length-
ening, amputation, or rotationplasty. However, there are few
reports that demonstrate patient-perceived outcomes of ampu-
tation and prosthetic fitting versus accommodative prosthetic
fitting without amputation have similar function results (170).
Thus, accommodative prosthetic fitting might be an option
for the rare patient who does not want to undergo any surgi-
cal intervention. More often, however, prosthetic fitting is a
bridge treatment instituted when the child is ready to walk
until age 2 1/2 to 3 years of age, when definitive treatment is
planned. This prosthesis is nonconventional in design and is
sometimes referred to as an extension prosthesis or a “prost-
hosis.” It is designed to fit the extremity without any surgi-
cal modification to it (Fig, 30-33). The flexion, abduction,
and external rotation of the proximal segment (the femur) are
accommodated in the alignment. At this young age, the knee
joint of the prosthesis can be omitted.
The treatment of children with bilateral PFFD is predom-
inantly nonoperative. These children do not use prostheses.
Occasionally, if there is asymmetric involvement of the limbs,
a limb-length discrepancy can exist. Treatment is individual-
ized to each patient.
Surgical Treatment.
Surgical treatment aims to compen-
sate for the functional problems the patient experiences.
The most obvious of these is the shortening of the limb.
Less obvious is the problem with hip function and its rela-
tion to the alignment of the limb. Because of the flexed and
externally rotated femoral segment, the knee remains flexed,
and the leg and foot are anterior and lateral to the axis of
the body (Figs. 30-32 and 30-33). Without surgical treat-
ment, the patient must lean laterally and posteriorly during
stance phase on the affected limb to move the weight-bear-
ing line so that the proximal femoral segment will be more
stable. This gait pattern is accentuated because of the addi-
tional muscle deficiency around the hip. The knee will have
varying degrees of instability. The function of the foot will
depend on the severity of any associated deficiencies of the
leg, for example, fibular deficiency.
There are three main treatment strategies for PFFD
patients; knee fusion with foot ablation, Van Nes rotation-
plasty with knee fusion, and limb lengthening. Each strategy
is vastly different from the other, and early decision making
is necessary to put the child on the proper path. Fortunately,
most of these decisions can be postponed until 2 1/2 to 3 years
of age, because this is the best age to perform these surgical
options.
Most authors suggest limb lengthening if the predicted
discrepancy at maturity is <20 cm; the hip is, or can be, made
stable; and there is good knee, ankle, and foot stability and
motion. Such cases require multiple-staged lengthenings in
addition to a contralateral epiphysiodesis and sometimes a shoe
lift. The timing and staging of these procedures depends on
the choice of the physician, but will usually not start before the
age of 3 years. Reports of the functional outcome in patients
followed up to maturity and into adulthood are lacking.
If the discrepancy is predicted to be >20 cm at maturity, or
for any other reason lengthening is not chosen as a treatment, a
decision should be reached about the best approach to prosthetic
fitting. Surgery can make the residual limb a more efficient lever
arm to power the prosthesis. In addition, foot ablation can lead
to a more cosmetic appearance of the prosthesis.
Knee Arthrodesis.
Arthrodesis of the knee joint is a standard
procedure in children with PFFD undergoing prosthetic fit-
ting. It creates a single, longer, and more efficient lever arm,
which is easier to contain within the prosthesis. This will
greatly enhance prosthetic function and reduce energy con-
sumption. The proximal femoral segment deformity (flexion,
abduction, and external rotation) does not need to be compen-
sated for at the time of knee fusion. If the tibia is fused in line
with the femur, subsequent ambulation with a prosthesis will
gradually correct the soft-tissue balance around the hip and
realign the limb with the contralateral side.
Depending on the length of the femoral segment and the
limb as a whole, it is usually desirable to remove at least one of
the growth plates at the knee at the time of fusion. This is usu-
ally the case in Aitken class A, B, and C deformities. Without
removing at least one of the epiphyses and physes at the knee,
the limb will be too long (Fig. 30-34). The reason for this is
that most above-knee prosthesis designs need approximately
7 cm to accommodate a prosthetic knee joint. If the ipsilateral
lower leg segment is normal in length or mildly shortened, as
it often is, then the growth of the lower leg segment alone will
FIGURE 30-33.
Lateral photograph of a patient with an extension
prosthesis that accommodates the retained foot proximal to the terminal
end of the prosthesis. This type of prosthesis can be useful if the parents
refuse foot removal or in the young toddler before definitive treatment.
