Paediatrics Part 2

Question 1

How are children’s bones different to adults bones?

Answer 1

• Children’s bones are different to adults
• Children’s bones also have the Physis and Periosteum
• This allows for growth, it is more flexible than the adult bone which has implications on injury and how you treat them

Question 2

Compare primary and secondary bone healing

Answer 2

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Question 3

When do the limbs begin to form and finish forming?

Answer 3

• Upper and lower limbs begin development in the 4th week of gestation
• Limbs are well differentiated by week 8

Question 4

What is limb bud development controlled by?

What causes the enlargement of the limb bud?

Answer 4

• Limb bud development appears to be controlled by fibroblast growth factor (FGF)
• Enlargement of the limb bud is due to interaction between the apical ectodermal ridge (AER) and mesodermal cells in the progress zone

Question 5

What are the stages of limb bud development

Answer 5

• Notochord expresses SHH (Sonic Hedgehog genes) which regulates limb bud formation
• Limb bud is a combination of lateral plate mesoderm and somatic mesoderm growing outward into ectoderm (AER)
• Mesenchyme condenses and chondrification occurs where mesoderm differentiates into chondrocytes

Question 6

What are the muscles derived from?

Answer 6

• Development of skeletal muscle
• Muscles of the head are derived from seven somitomeres (partially segmented spirals of mesenchymal cells derived from paraxial mesoderm
• Muscles of the axial skeleton, body walls and limbs are derived from somites (derived from paraxial somites)
• Somites extend from the occipital region to the tail bud. In humans there are 42-44 somite pairs

Question 7

How does the Groove of Ranvier and Perichondrial fibrous ring of La Croix cause Circumferential growth?

Answer 7

Groove of Ranvier
• During the first year of life, the zone spreads over the adjacent metaphysis to form a fibrous circumferential ring bridging from the epiphysis to the diaphysis
• This ring increases the mechanical strength of the physis and is responsible for appositonal bone growths
• Supplies chondrocytes to the periphery
Perichondrial fibrous ring of La Croix
• Dense fibrous tissue that is the primary limiting membrane that anchors and supports the physis through peripheral stability.

Question 8

Describe how embryonic long bone will form?

Answer 8

1. Endochondral bone formation occurs with a cartilage model:- chondrocytes produce cartilage which is absorbed by osteoclasts
2. osteoblasts lay down bone on cartilaginous framework(bone replaces cartilage, cartilage is not converted to bone) • This forms primary trabecular bone
3. Bone deposition occurs on metaphyseal side
4. Type X collagen associated with endochondral ossification

Question 9

What are the stages of embryonic long bone formation?

Answer 9

Steps of embryonic long bone formation:
• Vascularisation vascular buds invade the mesenchymal model
• Primary ossification centres form at 8 weeks osteoprogenitor cells migrate through vascular buds and differentiate into osteoblasts forming primary ossification centres
• Cartilage model forms through appositional (width) and interstitional (length) growth
• Marrow forms by resorption of central portion of cartilage by myeloid precursor cells that migrate in through vascular buds
• Secondary ossification centres form at bone ends and lead to epiphyseal ossification

Question 10

Where does the physis run from?

Answer 10

• Physeal zones are respectively from epiphysis to metaphysis

Question 11

Describe the contents of the physis

Answer 11

• Physeal zones are respectively from epiphysis to metaphysis
• The reserve zone (B)
o Stores lipids, glycogen, proteoglycan and aggregates for later growth
• The zone of proliferation (C)
o Proliferation of chondrocytes
• Hypertrophic zone (D)
o Chondrocyte maturation, hypertrophy chondrocyte calcification
o Type X collagen
• Primary spongiosa (E) metaphysis
• Secondary spongiosa metaphysis

Question 12

Describe the blood supply to the physis

Answer 12

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Question 13

What 4 factors affect potential for angular remodelling?

Answer 13

Factors affecting potential for angular remodelling

1. Skeletal age
2. Individual potential of a specific growth plate
3. Proximity to the joint
4. Orientation to the axis of the joint

Question 14

What is a buckle fracture?

Answer 14

• Buckle fracture are incomplete fractures of the shaft of a long bone that is characterised by bulging of the cortex.
• They result from trabecular compression due to an axial loading force along the long axis of the bone. They are usually seen in children, frequently involving the distal radial metaphysis.
• These are inherently stable and can be managed with a splint

Question 15

What is a greenstick fracture?

Answer 15

• Greenstick fractures resemble a supple green branch of a tree that breaks incompletely.
• Commonly diaphyseal in children under 10 years old.
• Incomplete fracture resulting from failure along tension (convex) side, therefore the fracture is inherently unstable and progressive deformation can be expected.
• Typically plastic deformation occurs along compression side
• Reduction and three-point moulding of a suitable cast are necessary

Question 16

What is plastic deformation?

Answer 16

Plastic deformation refers to the deformation of a bone, without fracture of its cortices, that persists once the deforming force has been removed. It is not a common condition but is seen more frequently in children than in adults.
• Diaphyseal injuries may not cause fracture, but may cause plastic deformation of the bone.
• This usually occurs in the very young and, unless the deformity is excessive, the bone will model over time.
•
• In this example, the ulna has a greenstick fracture, but the radius is plastically deformed

Question 17

Describe injuries to the physis

Answer 17

• Some displaced non-articular growth plate injuries can be sufficiently unstable after reduction to require operative management.
• The direction of displacement, in relation to the expected plane of modelling, may also determine the need for surgical reduction and stabilization.
• Physeal injuries are common in the paediatric population, accounting for approximately 30% of all bony injuries.
• Most fractures occur in ambulatory children and are especially common in the adolescent population.
• Those who participate in sporting activities have a higher incidence of injury. Overall, they are twice as prevalent in boys as girls.

Fracture doesn’t go through physis in children we can rely on growth and remodelling from the growth plate

Fracture through the physis -> intervention is needed -> normal growth -> might be some abnormalities

Question 18

What is the Salter harris classification?

Answer 18

The growth plate is shown in green. The mnemonic refers to the fracture line and its relationship to the growth plate. The metaphysis is the bone above the growth plate, and the epiphysis is the bone below.

1. Type I fractures disrupt the physis.
2. Type II fractures involve a break from the growth plate up into the metaphysis, with the periosteum usually remaining intact.
3. Type III fractures are intra-articular fractures through the epiphysis that extend across the physis.
4. Type IV fractures cross the epiphysis, physis, and metaphysis.
5. Type V fractures are compression injuries to the physis.

Question 19

What is open reduction internal fixation?

Answer 19

Is a surgery to fix severely broken bones.
It’s only used for serious fractures that can’t be treated with a cast or splint. These injuries are usually fractures that are displaced, unstable, or those that involve the joint.

“Open reduction” means a surgeon makes an incision to re-align the bone. “Internal fixation” means the bones are held together with hardware like metal pins, plates, rods, or screws. After the bone heals, this hardware isn’t removed.

Generally, ORIF is an urgent surgery. Your doctor might recommend ORIF if your bone:
• breaks in multiple places
• moves out of position
• sticks out through the skin

Question 20

What is SUFE?

Answer 20

With a SUFE, the growth plate at the top of the thigh bone is fractured, and the ball at the top of the bone slips out of position. The symptoms of SUFE seem like a pulled muscle or strain of the hip, thigh or knee. Treatment is usually an operation to insert metal screws that help keep the hip stable.

Question 21

What is left leg discrepancy?

Answer 21

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