2. • Clinical presentation
Achondroplasia is the most common cause of short-limb
dwarfism. Patients are of normal intelligence and motor function,
presenting with delayed motor milestones.
• Pathology
Mutation to the FGFR3 gene (fibroblast growth factor gene 3 ) in
achondroplasia is a gain of function mutation with constitutive
activation of an inhibitory signal. All bones that form by endochondral
ossification are affected. Bones that form by membranous ossification
are not affected, thus allowing the skull vault to develop normally.
3. Radiographic features
Horizontal acetabular roof
(decreased acetabular
angle), small squared
(tombstone or mickey
mouse ear) iliac wings and
champagne glass type
pelvic inlet
4. • Rhizomelic dwarfism, with relatively short
femora
• Bilateral genu vara.
• Metaphyseal flaring (widening), most
evident at the lower femora, giving
trumpet bone type appearance
• Relatively long fibulae.
• V shaped growth plates, most evident at
the upper tibia.
5. • The skull vault is enlarged, with small
skull base.
