pediatric

Definition

Osteonecrosis of the navicular

Epidemiology

Present at age 4-6 years

- same as Perthes disease

M:F 5:1

Bilateral in 20%

Aetiology

Repetitive trauma to maturing ossific nucleus

Definition

Fracture / plastic malformation of proximal ulna with dislocation of radial head

Xray

Radio-capitellar line disrupted

Ossification

Distal tibia

- appears by 2 years

- closed at maturity

- asymmetrical closure

- central initially, then posteromedial to anterolateral

- accounts for Tillaux and Triplanar fractures

Distal fibula

- appears by 2 years

- closes 2 years after distal tibia

Medial Malleolar Extension

- begins age 7

- closes age 10

Meyers & McKeever classification

Type I:   Undisplaced avulsion fracture

Type II:  Anterior portion displaced & hinged

Type IIIA:   Displaced

Type IIIB:   Displaced & Rotated

DDx

Leukemia 

Neuroblastoma 

Wilm's    

Last two usually occur in < 5 year age group

Bone scan is method of choice for screening for metastasis

Leukemia

Epidemiology

Most common form of cancer in children 30%

- ALL 5 x AML

- 3 : 100 000