Rhizomelic Limb Shortening

► [Shortening of the proximal segments of the extremities (humerus, femur)]

By far the most common form of rhizomelic limb shortening is seen in patients with achondroplasia (OMIM 100800), an autosomal dominant disorder with complete penetrance. Although shortening can affect any of the tubular bones, including those in the hands and feet, in patients of all ages, it is most prominent in the proximal segments, especially those of the upper extremities (humerus more involved than femur). In infancy, the proximal femur and humerus have a characteristic appearance of oval areas of lu-cency,while the distal femur is medially slanted, owing to defective or delay ossification of the lateral femoral condyle. In later years, abnormalities of the distal femur include metaphyseal flaring, a V-shaped appearance, small epiphysis, and a ball-in-socket epiphyseal configuration (Langer et al. 1967). These radiographic changes are noticeably more severe in early lethal ho-mozygous achondroplasia, an exceedingly rare skeletal dysplasia that shares similarities with thanatophoric dysplasia (Langer et al. 1969). In pseudoachondropla-sia (OMIM 177170) the body proportions resemble those of achondroplasia, with a long trunk and short extremities, the proximal segments being primarily affected. It differs from achondroplasia in that the skull is not affected and clinical manifestations are not present at birth, not developing until the 2nd year of life or later (Heselson et al. 1977). Additional distinguishing features include epiphyseal dysplasia, meta-physeal widening and irregularities, the type of vertebral alterations (short pedicles with posterior scalloping in achondroplasia; marked end-plate irregularities and central tongue-like protrusions in pseudoachon-droplasia), and a specific pelvic appearance (round iliac bones, flat acetabula, narrow sciatic notches in achondroplasia; markedly irregular pubic and ischial bones in pseudoachondroplasia). Partial restoration of normal vertebral shape occurs during adolescence. The capital femoral epiphyses are small and irregular and are followed by early osteoarthritis in adults. Chondrodysplasia punctata, rhizomelic type (OMIM 215100) features severe shortening and metaphyseal splaying of the proximal segments of the extremities. Calcific stippling of hyaline cartilage is seen at the ends of the humeri and femurs, adjacent to the spine and pubic/ischial bones, near the patellas and ribs, and in the carpal and tarsal bones. In contrast to the Con-radi-Hunermann type of chondrodysplasia punctata, the stippling has a symmetrical distribution (Gilbert et al. 1976). Severe metaphyseal splaying of the humeri and femurs, coronal clefts in the spine, symmetrical shortening of metacarpals (especially the 4th), and hypoplastic distal phalanges are additional characteristic features of the rhizomelic type of chondro-dysplasia punctata (Silengo et al. 1980). Opsismodys-plasia (OMIM 258480) is a very rare autosomal recessive dwarfing disorder characterized by rhizome-lic micromelia with marked metaphyseal flaring and cupping, and severe platyspondyly with hypoplas-tic or absent vertebral bodies and normally ossified posterior elements (Maroteaux et al. 1984). The epi-physeal appearance is severely retarded. Additional features include narrow thorax with short ribs, very

Sensenbrenner Syndrome

Fig. 5.24 a-c. Omodysplasia, autosomal recessive, in a newborn girl. a Note severe limb shortening, with predominant involvement of the proximal segments (rhizomelic dwarfism). Note also bilateral pterygia in the upper extremities. The face is flat, with short upturned nose and long philtrum; the nipples are widely spaced. b Severe shortening of the humerus, radio-ulnar diastasis, and flared metaphyses. c Severe shortening of the femora, with clubbed upper ends, and short lower legs, with tibias shorter than fibulas. (From Masel et al. 1998)

Fig. 5.24 a-c. Omodysplasia, autosomal recessive, in a newborn girl. a Note severe limb shortening, with predominant involvement of the proximal segments (rhizomelic dwarfism). Note also bilateral pterygia in the upper extremities. The face is flat, with short upturned nose and long philtrum; the nipples are widely spaced. b Severe shortening of the humerus, radio-ulnar diastasis, and flared metaphyses. c Severe shortening of the femora, with clubbed upper ends, and short lower legs, with tibias shorter than fibulas. (From Masel et al. 1998)

Limb Shortening

short tubular bones in the hands, and unossified skull base (Zonana et al. 1977). Omodysplasia (OMIM 164745), a term introduced by Maroteaux in 1989 (Maroteaux et al. 1989),is used to mean a type of skeletal dysplasia with a characteristic facies (flat face, depressed nasal bridge, long philtrum, large ears), severe rhizomelic limb shortening (especially involving the humeri), and radioulnar diastasis at the elbows. The humeri are short, with hypoplasia of their distal portion and anterior dislocation of the radial head at the elbow. The femurs are also short, with club-shaped proximal ends (Fig. 5.24a-c). Occasional findings include low-set, widely spaced nipples, inguinal hernias, microphthalmia, micrognathia, maxillary hypoplasia, and brachycephaly. Inheritance can be either autosomal dominant or autosomal recessive (OMIM 258315),the latter with generalized involvement of the limbs and severe dwarfism (Baxova et al. 1994; Al Gazali and Al-Asaad 1995). Femorofacial syndrome (OMIM 134780) is a rare association of bilateral femoral hypoplasia/aplasia and a characteristic facies with short nose and elongated philtrum, thin upper lip, micrognathia, upslanting palpebral fissure, cleft palate, and ear deformities. Hypoplasia of the femur at one side can occur in association with absence of the contralateral femur. The acetabula are hypoplastic. Short humeri, short or hypoplastic fibulas, radio-humeral or radioulnar synostosis, Sprengel deformity, rib anomalies, vertebral anomalies, foot deformities, and renal, cardiovascular, and gastrointestinal anomalies are additional features (Daentl et al. 1975). The inheritance pattern is unknown. This syndrome is clearly separate from proximal femoral focal deficiency, a relatively common, unilateral skeletal anomaly that occurs as an isolated defect. Cranio-ecto-dermal dysplasia (Sensenbrenner syndrome, OMIM 218330) is an autosomal recessive condition characterized by defects of ectoderm-derived structures and characteristic bone anomalies, notably dolichocephaly and rhizo-melia. Growth deficiency, sparse fine hair, delayed psy-chomotor development, microcephaly, photophobia, short thorax, heart defect, chronic renal failure, and abnormal calcium homeostasis are inconsistent manifestations (Amar et al. 1997; Levin et al. 1977). Weisenbach-er-Zweymuller syndrome (OMIM 277610), which now is recognized to be the same as the heterozygous form of OSMED (nonocular type III Stickler syndrome, OMIM 184840), is characterized by a neonatal type of rhizo-melic dwarfism with neonatal micrognathia and meta-physeal widening of the long bones and vertebral coronal clefts. Regression of bone changes with catch-up growth in the subsequent 2-3 years is a striking manifestation (Chemke et al. 1992).

Rhizomelia has been reported in association with variable skeletal and nonskeletal defects (Verloes et al. 1997; Faye-Petersen et al. 1991; Urbach et al. 1986).

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Responses

  • mathias ebersbach
    Can long philtrum and widely spaced nipples be isolated findings?
    7 years ago
  • antonina
    What is shortening of proximal segment of extremeties?
    4 years ago

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