Limb deficiencies or limb reduction defects are a spectrum of musculoskeletal disorders characterized by the absence or severe hypoplasia of a limb or part of a limb 1,2.
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Terminology
Currently (c. 2024) the preferred terminology for limb deficiencies is based on the anatomic classification. Terms such as hemimelia, aphalangia, and adactyly, many of which were popularized by the Frantz and O'Rahilly classification of skeletal limb deficiencies, are commonly adopted, but their use is discouraged because they are often imprecise 1.
Some terms used to describe limb deficiencies are also currently (c. 2024) considered pejorative, such as phocomelia and lobster claw 1.
Epidemiology
Congenital limb deficiencies occur in 2 to 7 per 10000 live births 3,4.
Associations
Limb deficiencies are associated with other congenital anomalies in up to a third of the cases 3.
Some of these are:
VACTERL 1,2
Fanconi anemia 1,2
trisomy 18 1,2
Diagnosis
The diagnosis can be made during antenatal ultrasound or clinically, with radiography being used to better characterize the malformation.
Pathology
The upper limb is slightly more affected than the lower limb 3,4.
Classification
Two classification systems are commonly used:
anatomic classification (recommended)