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Birth and Early Years > Bone Growth > Flashcards

Bone Growth Flashcards

1
Q

Describe the state of the ossification centres in a long bone at birth.

A
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2
Q

When does bone growth stop?

Describe the mechanism by which bone stops growing.

A
  • Growth in height ceases at the end of puberty.
  • Sex steroids stimulate a growth spurt but promote closure of the epiphyseal plates.
  • Growth in length ceases, cell proliferation slows and the plate thins.
  • The plate is invaded by blood vessels, epiphyseal and diaphyseal vessels unite.
  • May leave a visible line on X-rays.
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3
Q

Give examples of bones with only one ossification centre.

A
  • Carpals
  • Tarsals
  • Ear ossicles
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4
Q

How many ossification centres does the head of the humerus have?

A

3

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5
Q

Name each of the zones of this epiphyseal plate.

A
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6
Q

What is the function of the resting zone of the epiphyseal plate?

Give an example of a disease which can affect this zone.

A
  • Function = matrix production.
  • Diastrophic dysplasia causes defective collagen synthesis / processing of proteoglycans.
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7
Q

What is the function of the growth zone of the epiphyseal plate?

Give an example of a disease which can affect this zone.

A
  • Function = cell proliferation.
  • Achondroplasia, malnutrition or irradiation injury would all cause deficiency in cell proliferation and / or matrix synthesis.
  • Gigantism would cause increased cell proliferation.
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8
Q

What is the function of the hypertrophic zone of the epiphyseal plate?

Give an example of a disease which can affect this zone.

A
  • Function = calcification of the matrix.
  • Rickets would cause insufficiency of calcium or phosphate for normal calcification.
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9
Q

What is the function of the metaphysis zone of the epiphyseal plate?

Give an example of a disease which can affect this zone.

A
  • Functions = bone formation and vascularisation.
  • Osteomyelitis could be caused by a bacterial infection.
  • Osteogenesis imperfecta is an abnormality of osteoblasts and collagen synthesis.
  • Scurvy causes inadequate collagen turnover.
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10
Q

Describe the effects of achondroplasia on the epiphyseal growth plate.

A
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11
Q

Describe the effects of rickets on the epiphyseal growth plate.

A
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12
Q

What are the substances required for normal bone growth?

A
  • Calcium
  • Phosphorus
  • Vitamins A, C and D
  • Balance between growth hormone, thyroid and parathyroid hormones, oestrogen and androgens.
  • Abnormalities of these can affect bone growth; also effects on fracture healing.
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13
Q

What are the different mechanisms of injury in a fracture?

A
  • Direction of force:
    • ​Direct vs angular
    • Rotational
    • Compression
  • Energy transfer
    • ​Cause
    • Site
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14
Q

How do you describe a fracture?

A
  • Site
  • Open to surface
  • Contaminated
  • Associated soft tissue injury
  • Joint involvement
  • Number of pieces
  • Alignment
  • Degree of separation
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15
Q

What is the definition of a fracture?

A

A complete or incomplete break in a bone

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16
Q

Which type of fracture pattern is depicted?

A

Transverse

17
Q

Which type of fracture pattern is depicted?

A

Linear

18
Q

Which type of fracture pattern is depicted?

A

Oblique non-displaced

19
Q

Which type of fracture pattern is depicted?

A

Oblique displaced

20
Q

Which type of fracture pattern is depicted?

A

Spiral

21
Q

Which type of fracture pattern is depicted?

A

Greenstick

22
Q

Which type of fracture pattern is depicted?

A

Comminuted

23
Q

What is an avulsion fracture?

A

A fragment of bone is separated from the main mass.

24
Q

What is a buckled fracture?

A
  • AKA impacted fracture; torus fracture.
  • Ends are drived into each other.
  • Commonly seen in arm fractures in children.
25
Q

What is a pathologic fracture?

A

A fracture caused by a disease that weakens the bones.

26
Q

What is a stress fracture?

A

A hairline crack in a bone.

27
Q

How does bone heal after a fracture?

A
  • Depends on the activity of the cells of the periosteum.
  • ‘Bone remodelling units’:
    • Consists of osteoclasts and osteoblasts
    • Keep adult bone mass relatively constant in the face of developmental, physiological and physical demands.
  • Bone has a remarkable capacity to heal well, unlike articular cartilage.
  • Fracture healing depends on the activity of osteoblasts in the local periosteum.
  • Takes 2-20 weks for healing, depending on:
    • Severity of fracture
    • Age of patient
28
Q

There are 3 major phses of fracture healing.

Describe the 1st phase.

A
  • Reactive phase
  • Fracture and inflammatory phase (haematoma).
  • Fibroblasts in the periosteum proliferate to form granulation tissue around the fracture site.
29
Q

There are 3 major phses of fracture healing.

Describe the 2nd phase.

A
  • Reparative phase
    • ​Callus formation - osteoblasts quickly form woven bone, to bridge the gap.
    • Woven bone is weak as the collagen fibres are arranged irregularly.
    • Lamellar bone is laid down - collagen is organised in regular sheets to give strength and resilience.
30
Q

There are 3 major phses of fracture healing.

Describe the 3rd phase.

A
  • Remodelling phase
  • Remodelling by osteoclasts to restore original bone shape.
31
Q

Describe non-union fractures.

What are the risk factors for non-union fractures?

A
  • Complete cessation of reparative processes of bone healing.
    • Overall risk est. 1.9-4.9%
    • Tibial risk reported as high as 23%
    • Atrophic - inadequate biological factors.
    • Hypertrophic - excessive callus formation outwith the fracture site.
32
Q

What is the conservative treatment for fractures?

A
  • Indicated in simple fractures with low risk of non-union.
  • Dependent on natural healing process.
  • +/- immobilisation
  • Rehabilitation
33
Q

What are the indications for intervention in fracture treatment?

A
  • Fractures with limb threat or risk of non-union.
  • Augment natural healing with replacement or strengthening.
  • +/- immobilisation
  • Rehabilitation
34
Q

What are the types of osteoconductive scaffolding which can be used in the treatment of fractures?

A
  • Autologous bone graft
    • Often from iliac crests
  • Allografts
    • Cadaveric
  • Synthetic
    • Hydroxyapatite
    • Collagen
35
Q

What are the other treatments with the potential to help heal fractures?

A
  • Inducing mechanical strain
    • Shockwaves and low-intensity ultrasound
  • Growth factors and pharmacological interventions:
    • Parathyroid hormone
    • Bone morphogenic proteins
    • Anti-sclerostin abs
    • Statins
    • Dasatinib

Birth and Early Years (31 decks)

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