Dwarfism with Horizontal Acetabular Roof

Catherine C. Roberts, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Helpful Clues for Diagnoses

Achondroplasia
- Short, thick tubular bones
- Short trunk with short ribs
- Large skull with narrow foramen magnum
- Short, flat vertebral bodies lacking normal widened interpediculate distance caudally
- Posterior vertebral body scalloping
- Square iliac wing with horizontal acetabular roof
- Hemispheric femoral head
- Overgrown fibulae
Achondrogenesis
- Short tubular bones and long bones
- Short ribs
- Minimal mineralization of vertebral bodies
- Short iliac wing
- Nonossified sacrum and pubis
Chondrodysplasia Punctata
- Short long bones
- Punctate calcifications in cartilage and periarticular regions
- Coronal clefts of vertebral bodies
- Delayed brain myelination, cortical atrophy
Thanatophoric Dwarf
- Large “cloverleaf” skull with small face and frontal bossing
- Long trunk with small chest
- Short ribs with cupped costochondral junctions
- Short, bowed limbs, “French telephone receiver femurs”
- Flared metaphyses
- Platyspondyly with rounded anterior vertebral bodies
- Short, small iliac bones with horizontal acetabular roof
- Lethal shortly after birth
Asphyxiating Thoracic Dystrophy of Jeune
- Bell-shaped thoracic cage
- Handlebar clavicles
- Horizontal, short ribs with bulbous ends
- Short iliac bones with spur of sciatic notch
- Horizontal acetabular roof and trident acetabular margin
- Hands with cone-shaped epiphyses