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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
State a pathological defect in the hypertrophic zone
Rickets (children) Osteomalacia (adults)
26
Rickets
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
27
Osteomalacia
Epiphyseal plates have already fused and formed. Undermined by deficiency in calcium and phosphate.
28
Describe the pathological defect in the Hypertrophic zone
Insufficiency of calcium or phosphate for normal calcification
29
State a pathological defect in the Ossification (Metaphysis) zone
Osteomyelitis Osteogenesis imperfecta Scurvy
30
Describe the pathological defect in the Ossification (Metaphysis) zone
Bacterial infection - osteomyelitis Abnormality of osteoblasts and collagen synthesis - osteogenesis imperfecta Inadequate collagen turnover- scurvy
31
What does normal growth and development of bone require ?
Calcium Phosphorus Vitamins A, C and D Balance between growth hormone, thyroid and parathyroid hormones, oestrogen and androgens.
32
What results from abnormalities in bone growth and development factors ?
These can influence bone growth and so are likely to influence bone healing.
33
Importance of Vitamin C
Important for collagen synthesis and generation.
34
Proportion of types of bones
Cortical bone (80%) Trabecular bone (20%)
35
Location of cortical bones
Shafts of long bone
36
Location of trabecular bone
Ends of long bones, vertebral bodies, flat bones
37
Structure of cortical bones
Concentrically arranged lamellae - Haversian systems
38
Structure of Cancellous / Trabecular bone
Meshwork of trabeculae with intercommunicating spaces
39
Function of cortical bone
Mechanically strong
40
Function of trabecular bone
Metabolic
41
Features of cortical bone
Thick periosteum Slow turnover Slow blood supply
42
Features of trabecular bone
Thin periosteum Rapid turnover Rich blood supply
43
Fracture patterns of cortical bone
Direct or indirect violence may result in deficits at the fracture site leading to non-union
44
Fracture patterns of trabecular bone
Honeycomb structure falls, as the result of compression (e.g. a fall from height compacts the bone)
45
State the 2 features of mechanism of injury
Direction of Force Energy transfer
46
Direction of force
Direct v Angular Rotational Compression
47
Energy transfer
Cause Site
48
Periosteum
Covering of cells over the bony region
49
What does medical imaging of bones show ?
Sites and Bones involved Clues on soft tissue injury Clues on energy transfer: - wide displacement - comminuted - multiple fracture sites Pathological bone Paediatric bone
50
Fracture
A complete or incomplete break in a bone
51
Description of fractures
Site Open to surface Contaminated Associated soft-tissue injury Joint involvement Number of pieces Alignment Degree of separation
52
State some fracture patterns (7)
Transverse Linear Oblique non-displaced Oblique displaced Spiral Greenstick - more common in paediatric bone Comminuted
53
Transverse
Horizontal fracture
54
Linear
Vertical fracture
55
Oblique
Diagonal line
56
Spiral
Curves around the bone Torsion twisting action
57
Greenstick fracture
Paediatric bone - bone which is not fully mineralised and has the ability to bend and distend without necessarily fracturing it.
58
Comminuted fracture
Disintegration and Fracturing of bone - fragmented bone Gunshot wound straight to bone Energy transfer - crushing injury
59
Avulsion fracture
A fragment of bone is separated from the main mass. - often happens with large energy transfer
60
Buckled frature
a.k.a impacted fracture, torus fracture Ends are driven into each other Commonly seen in arm fractures in children
61
Compression or wedge fracture
Usually involves the vertebrae
62
Pathological Fracture
Caused by a disease that weakens the bone
63
Stress fracture
Hairline crack - likely seen in feet, toes
64
What things are associated with fractures ?
Dislocation Comminuted Compound Compartment syndrome Vascular / nerve injury Significant soft tissue injury Pathological bone
65
What does growth, remodelling and fracture repair depend on ?
Depends of the activity of cells of the periosteum.
66
Bone remodelling units
Consists of osteoblasts and osteoclasts Keeps adult bone mass relatively constant in the face of developmental, physiological and physical demands.
67
Healing capacity of bone
Bone has a remarkable capacity to heal well - unlike articular cartilage
68
What does bone healing following a fracture involve ?
Fracture healing depends on the activity of osteoblasts in the local periosteum.
69
How long does bone healing take ?
Takes 2-20 weeks depending on: - Severity and position of the fracture - Age of the patient
70
State the 3 major phases of fracture healing
Reactive phase Reparative phase Remodelling phase
71
Reactive phase
Fracture and Inflammatory response (haematoma) Fibroblasts in the periosteum proliferate to form granulation tissue around the fracture site.
72
Callus formation
Osteoblasts quickly form woven bone, to bridge the gap
72
Reparative phase
Callus formation Woven bone Lamellar bone
73
Woven bone
Woven bone is weak, as the collagen fires are arranged irregularly
74
Lamellar bone
Lamellar bone is laid down - collagen is organised in regular sheets to give strength and resilience.
75
Remodelling phase
Remodelling by osteoclasts to restore original bine shape
76
State the 2 types of treatment of bone fractures
Conservative Intervention
77
Conservative treatment
Simple fracture with low risk of non-union Dependent on natural healing process +/- immobilisation Rehabilitation
78
Intervention treatment
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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