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CHAPTER 30
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The Child with a Limb Deficiency
and foot anomalies as part of the tibial deficiency ectro-
dactyly syndrome, which is inherited as an autosomal
dominant trait (166). Treatment in these cases is knee dis-
articulation and removal of the segment of distal femur in
poorest alignment.
Etiology and Epidemiology.
Femoral deficiencies are one
of the teratogenic effects of thalidomide. In the modern age,
femoral deficiencies are sporadic, unless they are part of a larger
syndrome such as femoral hypoplasia–unusual facies syndrome,
which exhibits an autosomal dominant inheritance pattern.
Clinical Features.
The appearance of patients with femo-
ral deficiency is classic and should be easily recognized. It will
be bilateral in 15% of the cases. The femoral segment is short,
flexed, abducted, and externally rotated. The hip and knee
joints exhibit flexion contractures. The proximal thigh is bul-
bous and rapidly tapers to the knee joint (Fig. 30-32). Fibular
deficiencies are so common in association with PFFD that the
valgus foot and other characteristics of fibular deficiency are
almost a part of PFFD. PFFD is associated with fibular defi-
ciency in 70% to 80% of cases (167). In addition, approxi-
mately 50% of the patients will have anomalies involving other
limbs (158, 167).
Examination of the hip joint is difficult because of the
bulbous thigh and short femoral segment. Pistoning may be
apparent because of associated hip instability. The knee is
always unstable in the AP direction.
Radiographic Features.
Most of the radiographic features
were covered in the description of the Aitken classification. In
patients with a congenital short femur, the only finding may
be slight coxa vara and an anterolateral bow in the femoral
shaft. In addition, the findings of fibular deficiency are often
evident, as up to 50% of these patients have concurrent fibular
deficiency.
Other Imaging Studies.
Recently, an MRI classification
of femoral deficiency has emerged, which partially addresses
the difficulty of the unossified proximal femur on plain
radiographs (168). The authors demonstrated that the carti-
lage anlage in the proximal femur region was well-visualized
with MRI and correlated to the plain radiographic appear-
ance over time to the initial MRI. They suggest that an MRI
classification should be used in lieu of a plain radiographic
classification.
Pathoanatomy.
There are few anatomical studies of
patients with femoral deficiency. Most of what we know
about the pathoanatomy are based on imaging studies. There
are pathologic changes throughout the entire limb of varying
severity. The acetabulum can exhibit mild dysplasia and retro-
version in mild cases, and it can essentially be absent in severe
cases. The proximal femur can have delayed ossification and a
varus deformity in the intertrochanteric region or there can be
a pseudarthrosis. In severe forms, it is completely absent. With
regard to the knee, findings can range from mild anterior/pos-
terior laxity to complete absence of the cruciate ligaments to
severe flexion contracture. As mentioned previously, the lower
leg can be normal, but often exhibits fibular deficiency, pos-
sibly with severe foot deficiencies that occasionally go along
with that disease process.
Pirani et al. (169) recently described the MRI appear-
ance of the musculature around the hip and proximal femur.
Most muscles were hypoplastic, except for the obturator exter-
nus and the sartorius, which were hypertrophied. In addition,
the obturator externus coursed in an abnormal direction in
more severe cases. In describing their MRI classification for
PFFD, Maldjian et al. (168) showed, in patients who do not
develop pseudarthrosis of the proximal femur, that there is a
cartilaginous anlage that attaches the proximal femur to the
femoral head.
Natural History.
Regardless of the severity of the femoral
deficiency, children will usually walk at the normal develop-
mental age. Children with a mild congenital short femur walk
with a slight Trendelenburg gait and have a mild limb-length
discrepancy. They often compensate with varying degrees
of hip, knee, and ankle flexion on the contralateral side if
FIGURE 30-32.
This photo of a 12-month-old girl who is pulling to
the standing position demonstrates the clinical features of PFFD: a
very short and bulbous femoral segment, which is flexed, abducted,
and externally rotated.
