Chronic, non metabolic bone disorder
Characterised by increased bone resorption, bone formation and remodelling
Rare < 40
1 – 3 % population over 60
M > F
Unknown
Paramyxovirus implicated
- measles
- RSV
- canine distemper virus
Electron Microscope
Disproportionate dwarfism with a short trunk
Problems with dwarfism, spine, vision and hearing
Primary involvement of vertebrae & epiphyseal centres of limbs
Resulting short-trunk dwarfism
- Limb are short, but trunk is even shorter
(cf Metaphyseal Chondrodysplasia - Short limbed Dwarf)
Dysproportionate dwarfism
- short limbs and normal trunk
- rhizomelic
DDx
- physeal dysplasia (SED, MED)
FGF Receptor 3
- point mutation
- decreases endochondral ossification
- normal intramembraneous ossification
- FGFR3 is found in all pre-bone cartilage & in CNS
- FGFR3 inhibits chondrocyte proliferation in the proliferative zone
Deformity of proximal femur with neck-shaft angle <125°
Characterised by
- coxa vara
- decreased femoral anteversion
- limp / trendelenberg
- stress fractures
- early OA
"ACDDC"
Acquired
2° to underlying disorder
- rickets