differential diagnosis

Pes Planus

Definition

 

No good definition

- flexible flat foot

- medial longitudinal arch of foot in weight-bearing is in contact with ground or closer to ground than 'normal'

 

Epidemiology

 

Common

- almost always bilateral

- strong familial tendency

 

Aetiology

 

Physiological

 

All infants have flat feet

Calcaneovalgus

Definition

 

Condition present at birth

- ankle dorsiflexed & in valgus

- foot abducted

 

Epidemiology

 

1 in 1000 births

 

Aetiology

 

Probably result of intrauterine positioning

- packaging defect

 

Associations

 

Oligohydramnios

DDH

 

Blount's Disease

DefinitionBlounts

 

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 

Synovial Sarcoma

Epidemiology

 

4th most common STS

- 10-35% of STS

 

Peak age 3rd-4th decade

- rare in children

 

Pathology

 

Cellular characteristics suggest tumour arises from primitive synovial cells

- rarely actually occurs within joint

 

Characteristic

 

Occasionally metastasis to lymph nodes (5-7%) 

- like Epitheloid Sarcoma 

Ewing Sarcoma

Principles

 

Treatment algorithm similar to OS

 

Overall prognosis similar to OS

- 70% long term survival

 

Definition

 

A malignant neoplasm composed of small round cells of uncertain histogenesis

 

Genetics

 

Recent data suggests it is of neuroepithelial derivation

- ? neuroectodermal cells

Aneurysmal Bone Cyst

Definition

 

Expansile pseudotumor of reactive hemorrhagic tissue arising in bone

- characterised by blood filled spaces separated by fibrous tissue

 

Types

 

Primary 50%

- arise de novo 

 

Secondary 50%

- in association with other tumours 

- probably secondary to haemorrhage into 1° tumour

- GCT / chondroblastoma / osteoblastoma / osteosarcoma

Septic Arthritis

Definition

 

Joint inflammation secondary pyogenic organism

 

Epidemiology

 

All age groups

 

Usually children

- 50% < age 3

 

M= F

 

Any joint

- Infants = Hip

- Children = Knee

- Adults = Large Joints

 

IVDU - SCJ & SIJ

 

Pathogenesis

 

Two Routes