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Medicine Year 1 - Semester 2 - Part 2 > Bone Growth and Fractures > Flashcards

Bone Growth and Fractures Flashcards

1
Q

Where does bone growth start ?

A

Starts pre-brith in the primary ossification centre, at the centre of long bones.

Post-birth, development of secondary ossification centre in long bones- epiphysis.

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2
Q

Blood supply to bones

A

Starts with nutrient foramen - artery feeding blood supply to the centre of the bone.

Rich plexus and multiple routes of infiltration into the bone itself.

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3
Q

Issue with bone fracture and damage to long bone

A

The bit which is really avascular and poorly perfused is at the end where we articulate joints together.

The cartilage that lines joints is poorly vascularised, which creates problems.

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4
Q

Problem with poorly vascularised cartilage

A

Problems with:

  • Regenerating the tissue
  • Getting nutrients in the bone to allow damage repair
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5
Q

What is bone growth ?

A

Bone growth in long bones is a process of elongation, from the 2 types of ossification centres.

Eventually at some point growth plates will fuse, as puberty - no further elongation.

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6
Q

When does cessation of bone growth occur ?

A

Growth in height ceases at the end of puberty.

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7
Q

Describe cessation of bone growth

A

Sex steroids stimulate growth spurt but promote closure of epiphyseal plates.

Growth in length ceases, cell proliferation slows and plate thins.

Plate is invaded by blood vessels, epiphyseal and diaphyseal vessels unite.

May leave a line, visible on X-rays.

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8
Q

What bones have only 1 ossification centre ?

A

Carpals
Tarsals
Ear ossicles

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9
Q

State some bones that have 2+ ossification centres

A

Head of the humerus has 3

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10
Q

Describe the appearance of ossification centres

A

Appearance in age varies.

Allows estimation of skeletal vs chronological age

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11
Q

Describe the rate of growth of ossification centres

A

The rate of growth varies:
- from bone to bone
- within the same bone

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12
Q

State the zones of the epiphyseal plate

A

Resting zone (Quiescent)
Growth zone (Proliferation)
Hypertrophic zone
Calcification zone
Ossification zone (Osteogenic)

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13
Q

What happens in the resting zone ?

A

Contains to the chondrocytes that are going to proliferate and increase in number.

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14
Q

What happens in the growth zone ?

A

Cartilage cells undergo mitosis - expansion of cell number

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15
Q

What happens in the hypertrophic zone ?

A

Older cartilage cells enlarge - swelling and enlarging

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16
Q

What happens in the calcification zone ?

A

Matrix bones calcified; cartilage cells die; matrix begins deteriorating.

  • weak structure not well woven bone
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17
Q

What happens in the ossification zone ?

A

New bone formation is occurring.

  • eating away poorly woven, distributed framework by OSTEOCLASTS
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18
Q

Osteoclasts

A

Dissolving away the matrix

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19
Q

Osteoblasts

A

Laying down well formed, well constructed bone.

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20
Q

State a pathological defect in the Resting Zone

A

Diastrophic dysplasia - shortened trunk and limbs, height and stature

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21
Q

Describe the pathological defect in the Resting zone

A

Defective collagen synthesis/ processing of proteoglycans

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22
Q

State some pathological defects in the Growth zone

A

Achondroplasia
Malnutrition
Irradiation injury
Gigantism

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23
Q

Achondroplasia

A

Maintained trunk size, but shortened limbs

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24
Q

Describe the pathological defect in the Growth zone

A

Deficiency in cell proliferation and/or matrix synthesis - achondroplasia

increased cell proliferation - gigantism

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25
Q

State a pathological defect in the hypertrophic zone

A

Rickets (children)
Osteomalacia (adults)

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26
Q

Rickets

A

Children

Starts to impact the developing growth plates, leading to a problem in region associated with strength and rigidity.

Can lead bowing of bones / deformation

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27
Q

Osteomalacia

A

Epiphyseal plates have already fused and formed.

Undermined by deficiency in calcium and phosphate.

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28
Q

Describe the pathological defect in the Hypertrophic zone

A

Insufficiency of calcium or phosphate for normal calcification

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29
Q

State a pathological defect in the Ossification (Metaphysis) zone

A

Osteomyelitis
Osteogenesis imperfecta

Scurvy

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30
Q

Describe the pathological defect in the Ossification (Metaphysis) zone

A

Bacterial infection - osteomyelitis

Abnormality of osteoblasts and collagen synthesis - osteogenesis imperfecta

Inadequate collagen turnover- scurvy

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31
Q

What does normal growth and development of bone require ?

A

Calcium
Phosphorus
Vitamins A, C and D

Balance between growth hormone, thyroid and parathyroid hormones, oestrogen and androgens.

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32
Q

What results from abnormalities in bone growth and development factors ?

A

These can influence bone growth and so are likely to influence bone healing.

33
Q

Importance of Vitamin C

A

Important for collagen synthesis and generation.

34
Q

Proportion of types of bones

A

Cortical bone (80%)
Trabecular bone (20%)

35
Q

Location of cortical bones

A

Shafts of long bone

36
Q

Location of trabecular bone

A

Ends of long bones, vertebral bodies, flat bones

37
Q

Structure of cortical bones

A

Concentrically arranged lamellae - Haversian systems

38
Q

Structure of Cancellous / Trabecular bone

A

Meshwork of trabeculae with intercommunicating spaces

39
Q

Function of cortical bone

A

Mechanically strong

40
Q

Function of trabecular bone

A

Metabolic

41
Q

Features of cortical bone

A

Thick periosteum
Slow turnover
Slow blood supply

42
Q

Features of trabecular bone

A

Thin periosteum
Rapid turnover
Rich blood supply

43
Q

Fracture patterns of cortical bone

A

Direct or indirect violence may result in deficits at the fracture site leading to non-union

44
Q

Fracture patterns of trabecular bone

A

Honeycomb structure falls, as the result of compression (e.g. a fall from height compacts the bone)

45
Q

State the 2 features of mechanism of injury

A

Direction of Force
Energy transfer

46
Q

Direction of force

A

Direct v Angular
Rotational
Compression

47
Q

Energy transfer

A

Cause
Site

48
Q

Periosteum

A

Covering of cells over the bony region

49
Q

What does medical imaging of bones show ?

A

Sites and Bones involved
Clues on soft tissue injury

Clues on energy transfer:
- wide displacement
- comminuted
- multiple fracture sites

Pathological bone
Paediatric bone

50
Q

Fracture

A

A complete or incomplete break in a bone

51
Q

Description of fractures

A

Site
Open to surface
Contaminated
Associated soft-tissue injury

Joint involvement
Number of pieces
Alignment

Degree of separation

52
Q

State some fracture patterns (7)

A

Transverse
Linear

Oblique non-displaced
Oblique displaced

Spiral
Greenstick - more common in paediatric bone

Comminuted

53
Q

Transverse

A

Horizontal fracture

54
Q

Linear

A

Vertical fracture

55
Q

Oblique

A

Diagonal line

56
Q

Spiral

A

Curves around the bone

Torsion twisting action

57
Q

Greenstick fracture

A

Paediatric bone - bone which is not fully mineralised and has the ability to bend and distend without necessarily fracturing it.

58
Q

Comminuted fracture

A

Disintegration and Fracturing of bone
- fragmented bone

Gunshot wound straight to bone
Energy transfer - crushing injury

59
Q

Avulsion fracture

A

A fragment of bone is separated from the main mass.

  • often happens with large energy transfer
60
Q

Buckled frature

A

a.k.a impacted fracture, torus fracture

Ends are driven into each other

Commonly seen in arm fractures in children

61
Q

Compression or wedge fracture

A

Usually involves the vertebrae

62
Q

Pathological Fracture

A

Caused by a disease that weakens the bone

63
Q

Stress fracture

A

Hairline crack
- likely seen in feet, toes

64
Q

What things are associated with fractures ?

A

Dislocation
Comminuted

Compound
Compartment syndrome

Vascular / nerve injury
Significant soft tissue injury

Pathological bone

65
Q

What does growth, remodelling and fracture repair depend on ?

A

Depends of the activity of cells of the periosteum.

66
Q

Bone remodelling units

A

Consists of osteoblasts and osteoclasts

Keeps adult bone mass relatively constant in the face of developmental, physiological and physical demands.

67
Q

Healing capacity of bone

A

Bone has a remarkable capacity to heal well - unlike articular cartilage

68
Q

What does bone healing following a fracture involve ?

A

Fracture healing depends on the activity of osteoblasts in the local periosteum.

69
Q

How long does bone healing take ?

A

Takes 2-20 weeks depending on:

  • Severity and position of the fracture
  • Age of the patient
70
Q

State the 3 major phases of fracture healing

A

Reactive phase
Reparative phase
Remodelling phase

71
Q

Reactive phase

A

Fracture and Inflammatory response (haematoma)

Fibroblasts in the periosteum proliferate to form granulation tissue around the fracture site.

72
Q

Callus formation

A

Osteoblasts quickly form woven bone, to bridge the gap

72
Q

Reparative phase

A

Callus formation
Woven bone
Lamellar bone

73
Q

Woven bone

A

Woven bone is weak, as the collagen fires are arranged irregularly

74
Q

Lamellar bone

A

Lamellar bone is laid down - collagen is organised in regular sheets to give strength and resilience.

75
Q

Remodelling phase

A

Remodelling by osteoclasts to restore original bine shape

76
Q

State the 2 types of treatment of bone fractures

A

Conservative
Intervention

77
Q

Conservative treatment

A

Simple fracture with low risk of non-union

Dependent on natural healing process

+/- immobilisation

Rehabilitation

78
Q

Intervention treatment

A

Fractures with limb threat or risk of non-union

Augment natural healing with replacement or strengthening

+/- immobilisation

Rehabilitation

Medicine Year 1 - Semester 2 - Part 2 (53 decks)

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