Paediatric Orthopaedics

Question 1

Osteogenesis imperfecta

Answer 1

An inherited end disorder also known as brittle bone disease - a defect of the maturation and organisation of type 1 collagen (most of the organic composition of bone)

Autosomal dominant:

• childhood fragility fractures, short stature with multiple deformities, blue sclerae and loss of hearing

Autosomal recessive (more rare):

• either fatal in the perinatal period or associated. W spinal deformity

Bones tend to be thin (gracile) with thin corticies and osteopenic. Mild cases may have relatively normal x-rays with history of low level fractures
-> fractures tend to heal but poor quality callus => treat with splint age, traction or surgical stabilisation

Question 2

Skeletal dysplasia

Answer 2

Medical term for short stature (dwarfism no longer used) and is due to a genetic error (hereditary or sporadic mutation) resulting in abnormal development of bone and connective tissue.

Proportionate: limbs and spine proportionately short
Disproportionate: limbs disproportionally shorter than or longer than spine)

Most common and recognised: Achondroplasia = autosomal dominant, disproportionately small limbs with a prominent forehead and widened nose, joints are lax and mental development is normal

Question 3

Causes of connective tissue disorders (name 4)

Answer 3

1. Generalised (familial) joint laxity - “double-jointed” aka hypermobility = more prone to soft tissue injuries e.g. ankle sprains or recurrent dislocations
2. Marfans syndrome - mutation of the fibril in gene => tall stature with disproportionately long limbs and ligamentous laxity
3. Ehlers-Danlos syndrome - autosomal dominant => abnormal elastin and collagen formation, profound hypermobility, vascular fragility, easy bruising, joint instability and scoliosis
4. Down syndrome - Trisomy 21 => short stature, joint laxity with possible recurrent dislocation (esp. patella)

Question 4

What is the usual mode of inheritance for Muscualr dystrophies and give 2 examples

Answer 4

Rare X-linked disorders (only affecting boys) resulting on progressive muscle weakness and wasting

• Duchenne muscular dystrophy - unfortunately death in early 20s
• Beckers muscular dystrophy (milder than DMD and may survive to their 30s or 40s)