Diaphyseal Aclasis / Multiple Osteochondromas
Heritable skeletal dysplasia
AD with variable penetrance (96%)
Incidence of malignant transformation much higher
- 10% overall
- 1 % / year
Chondrosarcoma (CS) > Osteosarcoma (OS)
Disturbance of endochrondral ossification of epiphyses of tubular bones
- preservation of vertebrae (c.f. SED)
Dysproportionate dwarfism with normal trunk
- not as severe as achondroplasia
- usually 145 - 170 cm tall
Characterised by small flattened irregular epiphyses
- symmetrical
- leads to OA by 3-4th decade
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
1. Equal leg lengths
- goal is mild to moderate isolated discrepancy
2. Unequal leg lengths
- goal with paralysis / equinus foot
- aim 1-2 cm short for clearance
3. Level Pelvis
- should use blocks to estimate functional correction
4. Vertical LS Spine
- vertical spine more important than level pelvis
Rickets
- paediatric disorder characterised by deformity and growth retardation
- secondary to defective mineralisation of the growth plate
Osteomalacia
- adult disorder
- defective mineralisation of osteoid
Generation of Vit D
Vitamin D3 ingested and absorbed
- activated by sunlight
Progressive varus deformity of knees
- secondary to abnormality of medial upper tibial physis
- localised varus & internal rotation deformity
Infantile form
- onset 1-3 years / bilateral
Adolescent form