Congenital malformations - Edocr

Chapter 45
Limb Reduction Defects
PRAVEEN KUMAR
INTRODUCTION
Limb reduction defects (LRD), also known as
congenital limb deficiency (CLD), are a diverse
group of birth defects which are characterized
by congenital absence of either part or all of one
or more limbs. These rare but very visible congenital
malformations are potentially devastating
for both patients and parents since they can have
significant adverse impact on everyday function
and quality of life. These defects can present as
either isolated malformations or as part of a complex
of multiple congenital anomalies due to
syndromes, sequences, and associations.
Many different classification systems have
been proposed to describe limb reduction defects
which pose considerable difficulty in comparing
data from different studies. Frantz and
O’Rahilly proposed a classification system in
1961 which is still widely used and is particularly
helpful in describing longitudinal deficiencies. 1
They first divided all limb deficiencies into either
terminal or intercalary deficiencies. Terminal deficiencies
are those in which all skeletal elements
are absent beyond a given point; intercalary deficiencies
are characterized by absence of the
proximal or middle segment of a limb with all or
part of the distal segment being present. Both
terminal and intercalary deficiencies can be further
subdivided into either transverse or paraxial
defects. In a transverse defect, the entire width
of a limb is affected while in a paraxial defect either
the preaxial or postaxial part of the limb is
involved. In 1991, the International Standards
Organization (ISO) and the International Society
for Prosthetics and Orthotics (ISPO) proposed a
new classification to improve consistency. In this
classification, all limb deficiencies were divided
into either transverse or longitudinal and missing
bones were described as either complete or partial.
Many studies have used the following EU-
ROCAT (a European network of population-based
registries for the epidemiologic surveillance of
congenital anomalies) classification which assigns
each limb reduction defect to one of the following
six categories: 2
1. Terminal transverse: absence of all distal
structures of the affected limb; the proximal
structures can be normal or deficient. The
following types are included:
a. Ectrodactyly: total or partial absence of
all phalanges, metacarpals/metatarsals,
or full hands/feet.
b. Amelia: total absence of entire extremity.
c. Hemimelia: total absence of entire forearm/foreleg
and hand or foot irrespective
of the presence of digit-like structures at
the end of the limb.
2. Intercalary: absence or severe hypoplasia
of the proximal part of the limb with hand
or foot normal or near normal.
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