Meromelia is defined as the partial absence of a free limb (excluding the girdle). It can refer to the proximal, middle or distal segment of the upper or lower limb. The deficiency may be transverse, implying that the absence extends across the width of the limb, or it may be longitudinal, extending parallel to the long axis of the limb and involving pre-axial, central or post-axial components. Intercalary (within a limb) deficiencies involve absence of the proximal or middle segment(s) of a limb with all or part of the distal segment present. Terminal deficiencies are defined as the absence of all skeletal elements of a longitudinal ray beyond a given point. Because only a single ray exists in the proximal segment of the limbs all terminal deficiencies of the humerus and the femur are also transverse deficiencies.
Careful measurement of the long bones and comparison with normal values as well as with the corresponding contralateral bone may help in assessing the size of the absent component and the degree of limb shortening. The presence of associated anomalies (both in the skeletal and in other systems) may also give a clue as to the presence of a syndrome (see associated syndrome listing).
There is a long list of syndromes with meromelia as a feature. Relatively subtle limb shortening as in mesomelic dysplasia may be difficult to differentiate. Bilateral meromelia may also be difficult to assess accurately because of the lack of a contralateral normal for comparison.
Partial absence or shortening of the affected long bone- usually restricted to single long bone or ray (see also radial ray defects and meromelia associated syndromes listing).
- Amniotic bands/ rupture sequence,
- Brachmann de Lange
- Caudal regression/sirenomelia sequence
- CHILD (Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects.)
- Femoral hypoplasia-unusual facies syndrome
- Fetal cocaine exposure
- Fetal varicella effects
- Limb deficiency – thoracic dystrophy – unusual facies
- Oromandibular-limb hypogenesis (Moebius) sequence
- Roberts- SC phocomelia
- Splenogonadal fusion-limb deficiency
- Thalidomide embryopathy
- Tibial aplasia
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