guided growth

AKA

Diaphyseal Aclasis / Multiple Osteochondromas

Definition

Heritable skeletal dysplasia

Epidemiology

AD with variable penetrance (96%)

Malignant Transformation

Incidence of malignant transformation much higher 

- 10% overall

- 1 % / year

Chondrosarcoma (CS) > Osteosarcoma (OS)

Definition 

Disturbance of endochrondral ossification of epiphyses of tubular bones

- preservation of vertebrae (c.f. SED)

Characteristics

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

Definition

Dysproportionate dwarfism

- short limbs and normal trunk

- rhizomelic

DDx

- physeal dysplasia (SED, MED)

Aetiology

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

Goals

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

Definition

Rickets

- paediatric disorder characterised by deformity and growth retardation

- secondary to defective mineralisation of the growth plate

Osteomalacia

- adult disorder

- defective mineralisation of osteoid

Physiology

Generation of Vit D

Vitamin D3 ingested and absorbed

- activated by sunlight

Definition

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