5.4: Injury and healing (part 1 of 2) Flashcards

1
Q

3 mechanisms of bone fracture

A

Trauma
Stress
Pathological

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2
Q

What 2 things are bones made up of

A

Cells
Matrix

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3
Q

How do bones develop in utero

A

Intramembranous (flat bones e.g. skill, clavicle, mandible) and
endochondral (long bones, ribs, vertebrae)
ossification

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4
Q

Process of Intramembranous ossification

A

Mesenchymal cells condensate, differentiate into osteoblasts and secrete osteoid
This traps osteoblasts which become osteocytes - collate and form ossification centre
Multiple ossification centres form and fuse, forming trabecular matrix and periosteum
Compact bone develops

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5
Q

Intramembranous ossification is

A

Bone development from fibrous membranes

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6
Q

Process of endochondral ossification

A

Bone collar formation
Cavitation
Periostea’s bud invasion
Diaphysis elongation
Epiphyseal ossification

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7
Q

Which bone formation takes a longer amount of time?

A

Endochondral ossification

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8
Q

Primary ossification centre of endochondral ossification

A

Diaphysis

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9
Q

What is the secondary ossification centre of endochondral ossification

A

Epiphysis

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10
Q

2 Different types of bone structure

A

Immature bone
Mature bone

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11
Q

Characteristics of immature bone

A

First bone that’s produced
Laid down in a woven manner - relatively weak
Mineralised and replaced by mature bone

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12
Q

Characteristics of mature bone

A

Mineralised woven bone
Lamellar structure - relatively strong

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13
Q

2 types of mature bone

A

Cortical
Cancellous

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14
Q

Characteristics of cortical bones

A

Compact - dense
Suitable for weight bearing

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15
Q

Characteristics of cancellous bone

A

Spongy - honeycomb structure
Not suitable for weight bearing

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16
Q

Organisation of cortical bone (compact)

A

Osteons found in compact bone, repeated structural units , around central Haversian canal which contains blood vessels, nerves and lymphatics

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17
Q

Structure of long bones

A

Diaphysis - long part of bone
Metaphysis- area that flares up
Physis- growth plate
Piphysis - distal or proximal part of bone

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18
Q

2 locations of Osteogenic cells

A

Marrow
Deep layers of periosteum

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19
Q

Where are osteoblasts found

A

Growth portions of bone :
Periosteum and endosteum

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20
Q

Where are osteoclasts formed

A

Bone surfaces and at sites of old, injured or unneeded bone

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21
Q

Where are osteocytes found

A

Entrapped in matrix

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22
Q

2 ways that bones can grow

A

Interstitial - increased length
Appositionsl -increased thickness and diameter

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23
Q

Where does Interstitial occur

A

In the physis

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24
Q

Where does appositional growth occur

A

Periosteum :
Osteoblasts add more and more bone cells

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25
Q

Role of bone in calcium homeostasis

A

Calcium hydroxyapatite- structural support
Calcium deposited and withdrawn during bone remodelling
Regulated by PTH and calcitriol
Calcitonin stimulates calcium uptake into bone
VitaminD helps body absorb and use calcium

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26
Q

Trauma causing bone to break

A

Low energy or high energy transfer

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27
Q

Stress fracture is

A

Abnormal stress on normal bone

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28
Q

A pathological fracture is

A

Normal stress on abnormal bone

29
Q

How do stress fractures occur

A

Repetitive applications of forces on bone, results in stress exertion on localised region, excess remodelling capacity, bone weakening persists, stress fractures

30
Q

When does a bone experience stress

A

When a force is loaded upon it , low levels of these forces cause bone to deform and place strain

31
Q

4 weigh bearing bones in body

A

Femur, tibia, metatarsals, navicular

32
Q

6 examples of conditions that can lead to a pathological/insufficiency fracture

A

Osteopenia and osteoporosis - Soft bone

Malignancy

Vitamin-D deficiency - Insufficient exposure to sunlight, reduced vitamin-D source → Osteomalacia + Ricket’s

Osteomyelitis

Osteogenesis Imperfecta - Collagen deficiency

Paget’s disease

33
Q

What causes osteopenia and osteoporosis?

A

Bone remodelling imbalance → Osteoclast activity greater than osteoblast activity

Leads to disrupted microarchitecture

34
Q

At what age do senile and postmenopausal osteoporosis occur?

A
  • Senile osteoporosis: >70Postmenopausal osteoporosis: Women 50-70

-

35
Q

Is osteoporosis more common in men or women

A

Women
4:1

36
Q

What fractures is osteoporosis associated with?

A

Fragility fractures - Hip, spine, wrist

Low energy trauma fractures

37
Q

What can secondary osteoporosis be caused by?

A

Hypogonadism - low oestrogen

Glucocorticoid excess - glucocorticoids inhibit insulin growth factor-1 which can directly or indirectly reduce osteoblast function

Alcoholism - increases PTH which leaches Ca2+ from the bone and excess alcohol can kill osteoblasts

38
Q

What is the T-score of a person with osteoporosis and osteopenia respectively?

A

Osteoporosis: Equal to or less than -2.5

Osteopenia: Between -1 and -2.5

39
Q

What does vitamin D facilitate

A

Calcium, magnesium and phosphate absorption

40
Q

What can inadequate calcium or phosphate lead to in bones

A

Defect on osteoid matrix mineralisation

41
Q

What can a Vitamin D deficiency cause in children and adults respectively?

A

Children - rickets
Adults - osteomalacia

42
Q

What type of inheritance pattern does congenital osteogenesis imperfecta (OI) display?

A

Autosomal dominant or recessive

43
Q

Explain the pathogenesis of congenital OI

A

Reduction in type I collagen secretion

Collagen is an ECM protein secreted by fibroblasts and osteoblasts and organised into insoluble fibres, comprising the ECM surrounding cells → Provides mechanical strength and rigidity to tissues and organs, especially to skeletal tissues: Bone cartilage, tendons and ligaments

44
Q

What 4 things does congenital OI affect

A

Bones
Hearing
Heart
Sight

45
Q

What is Paget’s disease

A

Excessive bone degradation and disorganised bone remodelling→ Deformity, pain, fracture or arthritis

May transform into malignant disease

46
Q

4 stages of Paget’s disease

A
  1. Osteoclastic activity (Increased bone resorption)
  2. Mixed osteoclastic-osteoblastic activity (Imbalance) results in disorganised bone remodelling, considering the osteoid scaffold is disrupted and diverted through osteoclastic activity → Deformities arises
  3. Osteoblastic activity
  4. Malignant degeneration
47
Q

4 primary bone cancers

A

Osteosarcoma

Chondrosarcoma

Ewing sarcoma

Lymphoma

48
Q

What is secondary bone cancer

A

Metastatic bone tumour from other tissues

49
Q

What are the types of secondary bone cancers that can lead to a pathological bone fracture?

A

Lytic - Bone eating; Kidney, thyroid, lung and breast

Blastic - Bone forming; Prostate and breast

50
Q

3 ways to describe fractures

A

Soft tissue integrity : open or closed (skin remains intact)
Bony fragments (greenstick- partial fracture in which one side of bone is broken, simple, multifrahmentory)
Movement (displaced/undisplaced)

51
Q

Process of fracture healing

A

1) Bleeding - release of cytokines causing inflammation
2) granulation - tissue deposited and blood vessel formation forms soft callus then forms a hard callus
3)bone remodelled through endochondral ossification

52
Q

What is wolffs law

A

Bone grows and remodels in response to the forces that are placed on it

53
Q

Outline the differences between primary and secondary bone healing

A

Primary: Intramembranous healing + Absolute stability

Mesenchymal stem cell goes to the bone cells in fracture to start replacing bone cells

Secondary: Endochondral healing involving responses in the periosteum and external soft tissues + Relative stability; Endochondral ossification → More callus

Mesenchymal stem cell goes to the chondral precursor to start producing new bone cells

54
Q

When do you see signs of healing visibly on an X-ray?

A

From 7-10 days

55
Q

What is the duration for each step in fracture/bone healing?

A

Inflammatory - Hours to days

Repair - Days to weeks

Remodelling - Months to years

56
Q

3 general principles of fracture management?

A

Reduce → Closed, open

Hold → Metal; no metal

Rehabilitate → Move, physiotherapy, use

57
Q

What is reduction in terms of fracture management

A

Involves restoring the anatomical alignment of a fracture or dislocation of derormed limbs

58
Q

What is skin traction

A

Wrap bandage around fracture and the add a weight to bring limb into natural alignment

59
Q

What is skeletal traction

A

Put a pin through bone and use a larger weight

60
Q

2 different types of hold

A

Fixation
Closed - plaster and traction

61
Q

4 methods to rehabilitate fractures

A

Use - Pain relief and strain

Move

Strengthen (Muscles)

Weight-bear

62
Q

2 examples of soft tissue injury

A

Tendinopathy:

Tendinitis - Inflammation of tendon associated from overuse (In additions to infection or rheumatic disease). Swelling + pain → reduced mobility of tendon and muscle.

Tendinosis - Caused by overuse of a tendon → Abnormal thickening.

Rupture

(Mainly ligaments/tendons tearing)

63
Q

List and explain ligament injury classifications

A

Grade I - Slight incomplete tear → No notable joint instability.

Grade II - Moderate/severe incomplete tear → Some joint instability. One ligament may be complete torn.

Grade III - Complete tear of 1+ ligaments → Obvious indication of stability of instability surgical requirement.

64
Q

How can we treat tendon or ligament tears?

A

Immobilise - Plaster OR boot/brace

Surgical repair - Suture

65
Q

Good effects of immobilisation on injured tissue

A

Less ligament laxity (lengthening)

66
Q

Bad effects of immobilisation on injured tissue

A

Less overall length of ligament repair scar

Protein degradation exceeds protein synthesis

Production of inferior tissue by blast cells

Resorption of bone at site of ligament insertion

Decreased tissue tensile strength (50% in 6-9 weeks)

67
Q

2 benefits of mobilisation on injured ligaments is tissue?

A

Ligament scars are wider, stronger and more elastic

Better alignment/quality of collagen

68
Q

2 factors affecting tissue healing

A

Mechanical environment - Movement and forces

Biological environment - Blood supply, immune function, infection, nutrition