children's orthopaedics Flashcards
What are differences between children’s skeleton and adult skeleton?
- Child’s skeleton has more bones (270) & is in continuous change.
- Have growth plates (physis) where growth occurs post-natally.
Where is physis? How many?
Most bones have 2 physis (one at proximal end and one at distal end)
What do flat bones develop by?
Intramembranous ossification (flat bones - cranium, clavicle)
What do long bones develop by?
Endochondral ossification
What is the process of intramembranous ossification?
- Condensation of mesenchymal cells that differentiate into osteoblasts (ossification centre forms).
- They secrete osteoid that traps osteoblasts which become osteocytes.
- Osteocytes collectively create woven trabecular matrix & immature periosteum.
- Angiogenesis with blood vessels incorportated between woven bone & trabecular bone form future bone marrow.
- Immature woven bone remodelled & replaced by mature lamellar bone
What is the process of endochondral ossification pre-natally? Where does bone growth happen prenatally?
- Pre-natally at primary ossification centres (centre of bone).
- Mesenchymal differentiation, develop cartilage model of future bone, angiogenesis with capillaries penetrating cartilage.
- Calcification at primary centres forms spongy bone, perichondrium transforms into periosteum.
- Spongy bone forms up shaft & cartilage and chondrocytes form at ends of bones.
- Secondary ossification centres develop at ends of bones with own blood supply & begin to calcify the uncalcified matrix into spongy bone.
What is the process of endochondral ossification post-natally? Where does it happen?
- At physis.
- Physis has different zones with different roles of growth in long bones.
- At epiphyseal side, hyaline cartilage active & dividing to form hyaline cartilage matrix.
- At diaphyseal side cartilage calcifies and dies and is replaced by bone.
Why are children’s bones more elastic? What does this result in?
more elastic due to increased density of haversian canals.
- Results in plastic deformity so bone can bend more before it breaks giving different fracture patterns.
1. buckle fracture (it can buckle on itself forming tarus like column.
2. greenstick fracture - one side snaps and other side buckles
When does physis close? What does this depend on?
Growth stops when physis closes.
- Depends on puberty, menarche, parental height, genetics.
- In girls closes at 15-16, boys 18-19.
What are physeal injuries characterised by and what can they lead to?
By salter-harris.
-They can lead to growth arrest, which can lead to deformity if only 1 part of physis injured
What does the speed and remodelling of bone depend on in a child?
- Depends on location & age of patient. Y
- ounger child heals more quickly because growing more quickly.
- Rate at different physis differs (eg upper limb, knee).
- Ones with more growth have faster healing and remodelling potential.
- Kids can tolerate large amounts of angulation/deformity because healing very quickly
What is developmental dysplasia of the hip? Why does it develop and when? What does normal development of the hip rely on?
- Group of disorders of neonatal hip where head of femur is unstable or incongruous in relation to acetabulum.
- Happens in utero because of way child sits.
- Normal development of hip relies on concentric reduction & balanced forces (needs to sit within acetabulum, if sits outside both hip & acetabulum wont develop properly)
What are the different types of developmental dysplasia of the hip and what do they lead to?
- dysplasia: mild - hip within socket but not centrally placed.
- sublaxation - more severe, hip in shallow socket so pops in and out.
- dislocation - hip develops outside of socket so acetabulum develops as very shallow cup because of lack of forces
Who is developmental dyspasia of the hip more common in?
More common in females, first born, breech position, FH, oligohydramnios (not enough fluid in amniotic sac), more common in native american & laplanders because swaddling of hip once born. Rare in BA/asian.
What examinations should be done for a baby with developmental dyspasia + age ? How is it usually picked up?
- Picked up on baby check screening in UK.
- Examinations: examine ROM of hip (usually limited hip abduction), leg length (galeazzi).
- Barlow & ortalani tests (not in 3 months or older because not sensitive)
What investigations should be done to a child with developmetnal dysplasia of the hip?
- ultrasound from birth to 4 months, after 4 months x-ray. Before 6-weeks needs to be age-adjusted.
- Measures acetabular dysplasia & position of hip
