9.3 Children's Orthopaedics Flashcards
How many bones does a child’s skeleton have?
270
Where does long bone growth occur postnatally?
the physis (growth plate)
What are the two types of ossification?
Intramembranous
Endochondral
What bones are formed from intramembranous ossification?
flat bones
What bones are formed from endochondral ossification?
long bones
What is the difference between intramembranous and endochondral ossification?
intramembranous:
mesenchymal cells –> bone
endochondral:
mesenchymal cells –> cartilage –> bone
What are the four stages of intramembranous ossification?
- In central ossification centers, differentiation of mesenchymal cells –> pre-osteoblasts, –> osteoblasts.
- osteoblasts synthesis and secrete osteoid. differentiation of osteoblasts –> osteoclasts
- cells become trabecular matrix and periosteum
- angiogenesis –> blood vessels incorporated and become red bone marrow. Compact bone develops superficial to cancellous bone
What two places does endochondral ossification occur?
primary and secondary ossification centers
What are the primary ossification centers?
Sites of prenatal bone growth at central part of the bone (through endochondral ossification)
What are the secondary ossification centers?
The physis
Long bones often have several and bone growth only occurs here postnatally, after the primary ossification centres.
What are the 5 stages of endochondral primary ossification?
- mesenchymal differentiation
- cartilage model of the future bony skeleton forms
- capillaries penetrate cartilage, calcification at primary ossification center - spongy bone forms, perichondrium transforms into periosteum
- cartilage and chondrocytes continue to grow at the end of the bone
- secondary ossification centers (the physis) develop
What are the two sides of the physis?
epiphyseal side and diaphyseal side
What happens at the epiphyseal side?
hyaline cartilage divides and grows to form hyaline cartilage matrix
What happens at the diaphyseal side?
cartilage calcifies and dies and then is replaced by bone
What are 4 ways that a children’s skeleton is different from an adults?
Elasticity
Physis
Speed of Healing
Remodeling
Why are childrens bones more elastic than an adults?
Increased density of haversian canals (microscopic tunnels)
Because of the increased elasticity in children’s bones, what are 3 types of fractures we see in children that we don’t usually see in adults.
Plastic deformity - bends before breaks
Buckle fracture - tarus like column
Greenstick - one cortex fractures but does not break other side
How does growth at the physis stop, when does this usually occur?
Growth stops gradually as the physis closes
Girls: 15-16
Boys: 18-19
Can be affected by parental height
What is the speed of healing and remodelling potential dependent on?
location and age of patient
younger children heal more quickly, different physis’ grows at different speed (knee more than hip etc.) but fractures near the physis heal more quickly
What is developmental dysplasia of the hip?
‘packaging’ disorder of the neonatal hip where the head of the femur is unstable or incongruous in relation to the acetabulum
What is required for normal development of the hip?
concentric and balanced forces through the hip
What is the difference between dysplasia and dislocation of hip?
on spectrum
dysplasia –> subluxation –> dislocation
dysplasia much more common than dislocation
What are the risk factors of developmental dysplasia of the hip?
female first born breech family history oligohydramnios - not enough fluid in amniotic sac native american/lapanders
How is developmental dysplasia of the hip screened and what do they check for?
usually picked up on baby check - screening in the UK
- range of motion
- usually limitation in hip abduction
- leg length discrepancy
How is developmental dysplasia of the hip investigated?
birth to 4 months: ultrasound
4 months +: x-ray
How is developmental dysplasia of the hip treated?
reducible hip and <6 months: pavlik harness
failed pavlik harness or 6-18 months: manipulation under anesthetic (MUA) and spica cast (this is because of secondary changes to the capsule and soft tissue)
What is congential talipes equinovarus?
club foot
What are the risk factors for congenital talipes equinovarus?
male
hawaiian
family history (there is a very large genetic component, 5% chance if siblings, familial cause in 25% of cases)
What gene is mutated in congenital talipes equinovarus?
PITX1 gene
How is clubfoot characterised?
congenital talipes equinovarus consists of four deformities (all four present) = CAVE Cavus Adductus of the foot Varus Equinous
What is the C in CAVE caused by ?
Cavus - high arch, tight intrinsic flexor hallucis longus, flexor digitorum longus