Collaborative Hypertext of Radiology

achondroplasia

most common type of short limbed dwarfism; caused by defect in enchondral bone formation => shortening of tubular bones with normal shaft caliber

x-ray features:

short extremities and ribs v. trunk length
"ball-in-socket" epiphyses
pelvis: squared iliac wings and narrow sacrosciatic notch ("champagne glass")
hands: fingers widely opposed and equal length ("trident hands")
skull: enlarged vault and mandible, small f. magnum
spine:
- narrow AP diameter with concave posterior surface and spinal canal only 1/2 normal depth
- decreased lumbar interpediculate distance
- hypoplastic ("bullet nose") T-L vertebrae

Brian Funaki, MD - 6 February 1995
Last updated: 1 October 2013