Childrens Ortho Flashcards
A child’s skeleton has how many bones?
270
What does the physis describe?
The areas from which long bone growth occurs post-natally
How do flat bones develop in utero?
Intramembranous ossification
Mysenchymal cells -> bone
How do long bones develop in utero?
Endochondral ossification
Mesenchymal cells -> cartilage -> bones
Outline the process of intramembranous ossification
- Condensation of mesenchymal cells which differentiate into osteoblasts - Ossification centre forms
- Secreted osteoid traps osteoblasts which become osteocytes
- Immature woven trabecular matrix and periosteum form
- Compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
What bones are formed by intramembranous ossification?
Flat bones of skull, clavicle and mandible
Intramembranous ossification describes the bone development from what origin?
Fibrous membranes
What is the cell templates for intramembranous ossification?
Mesenchymal cells
What is endochondral ossification?
Development of long bone by replacing the hyaline cartilage precursor
Does endochondral or intramembranous ossification take longer?
Endochondral
What are primary ossification centres?
Sites of pre-natal bone growth through endochondral ossification from the central part of the bone
What are secondary ossification centres?
Occurs post-natal after the primary ossification centre and long bones often have several (the physis)
Outline the process of primary endochondral ossification
PRIMARY endochondral ossification1. Mesenchymal differentiation at the primary centre2. The cartilage model of the future bony skeleton forms3. Capillaries penetrate cartilage.> Calcification at the primary ossification centre - spongy bone forms> Perichondrium transforms into periosteum4. Cartilage and chondrocytes continue to grow at ends of the bone5. Secondary ossification centres develop with its own blood vessel and calcification at the proximal and distal end - calcification of the matrix6. Cartilage remains at epiphyseal (growth) plate and at joint surface as articular cartilage.
Outline the process of secondary ossification
ossification occurs at the physis
• basically interstitial growth
• proliferation of chondrocytes and the subsequent calcification of the extracellular matrix into immature bone that is then subsequently remodelled
What is the role of secondary ossification in children?
• physis is responsible for the skeletal growth of a child
• any congenital malfunction to this area or acquired insult - whether it is traumatic/infective or otherwise will therefore have a subsequent impact on growth of the child
What differences are there between child and adult skeleton?
Elasticity
Physis
Speed of healing
Remodelling
Are a child’s bones more or less elastic than an adults, why, and what affects does this have?
More elastic
Increased density of Haversian canals as bones are more metabolically active
Therefore can get: buckle fractures, plastic deformity, green stick fractures
When does physeal closure complete in boys vs girls
Boys 18-19
Girls 15-16
What affect can physeal injuries have on a child?
Can lead to growth arrest which can lead to deformity
The speed of healing and remodelling potential of bones is dependent on what?
Location and age of the patient
How are physical injuries categories?
Salter-Harris
Outline the Salter-Harris classification of physeal injuries (SALT)
1.Physeal separation
2.Fracture transverses physis and exits metaphysis (above)
3.Fracture transverses physis exits epiphysis (Lower)
4.Fracture passes Through epiphysis, physis, metaphysis
5.Crush injury to physis
Which Salter-Harris classification of physeal injury has to highest risk of growth arrest?
Crush injury to physis, increases from 1-5
Which type of Salter-Harris physeal injury is most common?
Type 2 - fracture transverses physis and exits metaphysis (above)
