Initially, individuals have shortened limbs with a relatively average-sized trunk (short-limbed dwarfism). As the child gets older and the condition progresses, kyphoscoliosis of the spine develops that decreases trunk height (short-trunk dwarfism). Apparent shortening of the limbs also occurs over time, due to progressive joint contractures.
Face and Skull:
- Average facial features
- Macrocephaly can develop due to potential hydrocephalus
Trunk, Chest and Spine:
- Small and narrow chest
- Pectus carinatum (chestbone sticking out more than average) or pectus excavatum (depressed breast bone)
- Severe kyphoscoliosis
- In infancy, “coccygeal tail” can be apparent, which is a prolongation of the normal tailbone consisting of cartilage material
Arms and legs:
- Signficantly shortened limbs with a characteristic dumb-bell shape bone
- Enlarged joints
- Progressive joint contractures during childhood
What are the x-ray characteristics?
The radiographic features of Metatropic Dysplasia include small, flat, diamond-shaped vertebral bodies in early infancy due to defective ossification. Later, platyspondyly and anterior wedging of vertebral bodies are characteristic. Appearance of a hump-like build-up of bone in both the central and posterior portions of vertebral end plates in the lower posterior and upper lumbarspine. The thorax is narrow and ribs are short in both infancy and early childhood. Limbs are also short with marked metaphyseal flare and epiphyseal dysplasia. Deformed capital femoral epiphyses. Hyperplasia of proximal femoral metaphyses. The capital femoral epiphyses are typically deformed. Hyperplasia of proximal femoral metaphyses is usually observed. Finally, hypoplasia of basilar pelvis with crescent-shaped iliac crests and low-set anteriosuperior iliac spines is characteristic.