Osteo-articular Pathology Flashcards Preview

Human Disease > Osteo-articular Pathology > Flashcards

Flashcards in Osteo-articular Pathology Deck (159):
1

Name developmental osteo-articular disorders (x3)

- Osteogenesis imperfecta
- achondroplasia
- osteopetrosis

2

Name systemic / generalised osteo-articular disorders (x5)

- infections - osteomyelitis
- osteoporosis
- rickets / osteomalacia
- hyperparathyroidism (skeletal effects)
- Paget's disease

3

Name neoplastic osteo-articular disorders (x4)

- bone forming tumours
- cartilage tumours
- fibrous tumours
- tumours of uncertain histogenesis

4

Name joint osteo-articular diseases (x2)

- osteoarthritis
- rheumatoid arthritis

5

What is the outer section of bone called?

Cortex
- compact bone

6

What is the inner section of bone called?

Medulla
- cancellous bone
- spongy
- trabeculae

7

What is in the trabeculae?

Bone marrow

8

What does bone marrow do?

makes RBC / WBC

9

What are the functions of bone? (x4)

- support
- protect organs
- host and protect bone marrow
- supplies calcium and phosphate

10

Describe intramembranous ossification

1. ossification centre in fibrous connective tissue membrane
- mesenchymal cells differentiate into osteoblasts
2. Bone matrix (osteoid) is secreted within fibrous mem
- osteoblasts secrete osteoid
- osteoid is mineralised / calcified within a few days = bone matrix
- trapped osteoblasts become osteocytes
3. Woven bone and periosteum form
- osteoid laid down between embryonic blood vessels - random network = trabeculae
- vascularised mesenchyme condenses on external surface of woven bone to become periosteum
4. bone collar of compact bone forms and red marrow appears
- trabeculae thicken just deep to periosteum = woven bone collar - later replaced by mature lamellar bone
- spongy bone remains internally and its vascular tissue becomes red bone marrow

11

What bones are created by intracmembranous ossification?

Flat bones
- skull (not occipital bone)
- part of mandible / maxilla
- part of clavicles

12

How long does is take for ostoid to become calcified once secreted from osteoblasts?

a few days

13

What bones are created by endochondrial ossification?

long bones

14

How are bone created by endochondrial ossification?

- Mesenchymal cells form hyaline cartilage
- bone collar forms on sides of long bone
- Blood vessels enter central ossification centre (cartilage can't survive if O2 present, so bone forms) from periosteal bud
- spongy bone formed
- medullary cavity forms
- secondary ossification centres form
- epiphyseal blood vessels enter secondary ossification centres
- ossification of the epiphyses
- hyaline cartilage remains on epiphyseal plate and articular cartilage

15

What is a periosteal bud?

Blood vessels from the periosteum which enter the centre of ossification in endochondrial ossification

16

What is the medullary cavity?

aka marrow cavity
- central part of bone where marrow stored

17

What are the following:
- diaphysis
- epiphysis
- epiphyseal

diaphysis
- bone between epiphyseal plates (middle part)
epiphysis
- bone above eiphyseal plates (top / bottom)
epiphyseal
- plate of cartilage

18

Describe the growth plate in bone

aka epiphyseal plate
- well ordered columns of chondrocytes
- chondrocytes release matrix (proteoglycans, water, collagen)
- hypertrophy of chondrocytes are they get closer to zone of bone formation - reduced proteoglycan release, increased alkaline phosphatase - therefore increased calcification
- then they become calcified
- then converted to bone

19

What happens if bone does not calcify in growth plate?

bone does not grow

20

Where does alkaline phosphatase come from and what does it do in bone formation?

from chondrocytes in growth plates
causes calcification of hypertrophy chondrocytes to form bone

21

Name condition associated with short limbs

achondroplasia

22

What are physical symptoms of achondroplasia?

- short limbs
- trident hands
- smaller occipital bone / contracted base of skull

Normal - trunk/thorax

23

What are trident hands?

- fingers all similar length
- fingers splay at 1st joint

24

What type of bone formation is faulty in achondroplasia?

endochondrial ossification

25

how many births have achondroplasia?

1 in 30,000 live births

26

What % of achondroplasia is
- hereditary
- sporadic

hereditary = 25%
- autosomal dominant trait

Sporadic = 75%
- new mutations

27

Name long bones

humerus, ulna, radius
femur, fibula, tibia

28

How is cartilage different in long bones in achondroplasia|

epiphyseal plates don't develop normally
cartiage at end of long bones is enlarged

29

What happens in achondroplasia endochondrial ossification?

- disrupted columns of chondrocytes
- chondrocytes fail to hypertrophy
- defective calcification
- bone not formed

30

Which gene is responsible for achondroplasia and what is the type of mutation?
What does this gene do?

Fibroblast growth factor receptor 3 (FGFR3)
- point mutation
- in achondroplasia, FGFR3 is always active, so chondrocytes aren't switched on for hypertrophy

31

What are three conditions caused by faulty FGFR3?

- achondroplasia (dwarfism)
- craniosynostosis (abnormal scalp/sutures)
- lethal dwarism (foetus doesn't grow)

32

What is osteogenesis imperfecta?

aka brittle bones
- defective connective tissue
- abnormal synthesis of type 1 collagen

33

What % of ORGANIC matter of bone is made of collagen?

90%

34

What makes up 90% of organic matter of bone?

Collagen

35

What mutations cause osteogensis imperfecta?

point mutations of many genes.
mainly - COL1A1 and COL1A2

36

how many types of osteogensis imperfecta are there?

8
mild - severe

37

What determines the severity of osteogenesis imperfecta?

- number of point mutations
- type of point mutations (amino acid substitution at point mutation)

38

What is the pattern of inheritance for osteogensis imperfecta?

autosomal dominant or recessive

39

What is the organic matrix in bone?

collagen / osteoid

40

What is the inorganic matrix in bone?

Calcium

41

What are symptoms of mild osteogenesis imperfecta?

- delicate bones
- early osteoporosis

42

What are symptoms of severe osteogenesis imperfecta?

- can be lethal perinatally (just before / after birth)
- foetus can get fractures

Adults
- abnormal bone structure
- defective mineralisation

43

What are bones like in adults with osteogenesis imperfecta?

thin cortex = weak, bendy
epiphyseal cartilage is fine, so normal length bones

44

What other symptoms can be present in osteogenesis imperfecta? (none bone related)

blue/grey eyes
- sclera is thin, so choroidal veins below show through

Dentogenesis imperfecta
- irregular dentine formation (NB enamel = no collagen)
- blue /grey hue
- in type III and IV osteogenesis imperfecta?

- loose joints for slender weak tendons
- poor muscle tone
- early loss of hearing in some children (middle ear bones)
- protrusion of the eyes

45

What type of osteogenesis imperfecta gets dentogenesis imperfecta?

types Ib, III and IV

46

What is the most common type of osteogenesis imperfecta?

type I

47

What are symptoms of osteogenesis imperfecta type I?

- fragile bones (fracture, slight spinal curvature)
- loose joints for slender weak tendons
- poor muscle tone
- blue-grey sclera in eye (choroidal veins below show through)
- early loss of hearing in some children (middle ear bones)
- protrusion of the eyes
- type 1A = no dentogenesis imperfecta
- type IB = dentogenesis imperfecta
- reduced life exp (risk fatal bone fracture)

48

Why does life exp reduce in osteogenesis imperfecta?

risk of fatal bone fracture

49

Which type 1 osteogenesis imperfecta is associated with dentogenesis imperfecta?

Type IB (not type 1A)

NB type III and IV collagen issues are also linked to dentogenesis imperfecta

50

What is disorder with v dense bone?

osteopetrosis

51

What is osteopetrosis?

osteoclast defect
bone formation > resorption
become become denser
reduced medullary cavity / space for marrow
reduced haemoposesis, inc WBC
increased risk infection

52

What is inhertiance pattern of osteopetrosis?
How common is it?

inherited
rare

53

What is haemoposesis?

Formation of blood cells in bone marrow

54

What does xray of osteopetrosis look like?

dense, bright white bone
can't see medulla

55

with thick bone of osteopetrosis, is there an increase or decrease in risk of fracture?

increase

56

How many men / women get osteoporosis?

1 in 3 women (over 50)
1 in 10 men (over 50)
get fractures from osteoporosis

57

How many hip fractures are caused by osteoporosis each year?

70,000

58

How many wrist fractures are caused by osteoporosis each year?

50,000

59

How many spinal fractures are caused by osteoporosis each year?

40,000

60

What is most common fracture associated with osteoporosis?

hip (70,000 / year) - neck of femur fractures

then wrist (50,000) - radius in wrist - Colles fracture
then spine (40,000) - vertebral crush

61

How much does osteoporosis cost the NHS each year?

£1.7billion!

62

Define osteoporosis

reduced bone mass / density
- thinner cortex
- increased trabeculae spaces

63

What is main cause of osteoporosis?

post-menopause

64

What are other causes of osteoporosis?

Disuse
- prolonged bed rest
- paralysis
- weightlessness (space travel)
Diet
- Vit D, vit C, calcium, protein deficiency
- anorexia
Drugs
- heparin
- ethanol (poor diet)
- steroids - reduces bone mass
Endocrine
- adrenal failure
- testicular / ovarian failure

65

Name of form of protection against osteoporosis?

exercise

66

What is a Colles fracture?

fracture of radius in wrist, common in osteoporosis

67

What part of hip is likely to fracture?

neck of femur

68

How does spine fracture in osteoporosis?

vertebral crush

69

How do steroids cause osteoporosis?

reduces bone mass

70

What factors affect bone density?

- ethnicity
- age
- gender

71

What age is max bone density reached? and until what age is this level maintained?

18yrs
to 25yrs

72

What age does bone density deteriorate?

30+yrs

73

What is max bone density? (g/cm2)

1 - 1.1g/cm2

74

What is bone density for someone with osteopenia?

0.7 - 0.9g/cm2

75

What is bone density of someone with osteoporosis?

76

At what age is the decreasing bone density levels most critical?

30-70yrs
- early menopause / fast density losers = increased risk

77

How many times faster can some individuals lose bone density?

10x faster

78

What is the adult version of rickets?

osteomalacia

79

What is rickets?

inadequate bone mineralisation of existing organic bone matrix in growing bones
- lack of vit D

80

What is osteomalacia?

inadequate bone mineralisation of existing organic bone matrix in adult bones

81

What is most common cause of rickets / osteomalacia?

lack of vit D

82

What is high risk profile for rickets?

- lack of vit D / sunlight / use of sunscreen
- lack of calcium
- poor background

83

What are symptoms of rickets?

mechanical weakness in long bones in LOWER limbs
bending / deformed lower limb long bones

84

What are causes of rickets / osteomalacia?

Intrinsic Vit D
- lack in diet
- poor absorption
- metabolism of vit D
- lack of sunlight

Kidney disease
- chronic kidney disease
- renal tubular disorders

Inborn errors metabolism
- familial hypophosphataemia
- hypophosphatasia

85

What bone disease does familial hypophosphataemia and hypophosphatasis cause and why?

Rickets / osteomalacia
- reduced phosphate in body
- therefore reduced alkaline phosphatase
- therefore deficient chondrocytes and osteoblasts
- therefore reduced bone mineralisation
- causes rickets

86

What happens to the epiphyseal plate in rickets?

- chondrocytes become disorganised / lines lost
- fibrous proliferation
- no calcification

87

How is vit D activated in body?

- skin
- liver (Vit D hydroxlyated)
- kidney (Vit D hydroxylated again)

88

What does vit D do?

promotes calcium absorption from gut and kidney
- therefore increases calcium for bones

89

What happens to bones if lack of vit D?

cartilage forms (osteoid) instead of bone
- bendy, deformed, easily fractured

90

What bones are affected by osteomalacia?

- adults
- sites with active turnover
- structural weakness here

91

What type of fractures are common in osteomalacia?

Looser's zones
- micro-fractures at sites with active bone turnover

92

What are micro-fractures at sites with active bone turnover called?

Looser's zones
- seen on xray
eg hip, neck of femur

93

What are other names for hyperparathyroidism?

Osteitis fibrosa cystica
von Recklinghausen's disease

94

What is von Recklinghausen's disease?

hyperparathyroidism

95

What is Osteitis fibrosa cystica?

hyperparathyroidism

96

What does parathyroid hormone regulate?

Blood calcium and phosphate levels

97

What is primary hyperparathyroidism?

Issue with 1-4 parathyroids
eg tumour - adenoma / carcinoma
excess PTH produced

98

What is an adenoma?

benign cancer from glandular cells in epithelial tissue

99

What is a carcinoma?

cancer from epithelial cells

100

What is secondary hyperparathyroidism?

response to hypocalcemia
- due to vit D deficiency
- chronic renal disease

101

How is hyperparathyroidism diagnosed?

blood test - raised plasma calcium

102

What happens to PTH release if blood calcium high?

reduces

103

What happens to PTH release if blood calcium low?

increases

104

Do most patients with hyperparathyroidism have bone disease symptoms?

no, only a small number

105

What happens if hyperparathroidism is mistaken for bone disease?

issues will continue in other bone areas until hyperparathyroidism is diagnosed and treated

106

What is Paget's disease?

Excessive breakdown and formation of bone
with disorganised remodelling
irregular scalloped edges
multiple reversal lines

Chronic condition
usually localised (one / few bones)
usually asymptomatic
increase of serum alkaline phosphatase

107

What happens to bone in excessive osteoblasts activity in Paget's disease?

- excessive bone formation
- increase bone deformity
- reduced joint movt

108

What happens to bone in excessive osteoclast activity in Paget's disease?

- excessive resorption
- risk of fracture
- pain

109

Is Paget's disease symmetrical or unsymmetrical?

unsymmetrical
- can occur anywhere

110

what is associated with Paget's disease?

parasytic infection

111

What can Paget's disease lead to? (another disease)
Who is most at risk of this?

osteocarcinoma (malignant)
- young people

112

What disease can cause the scalp to enlarge?

Paget's disease

113

What changes in blood serum in Paget's disease?

increase in serum alkaline phosphatase

114

What age is most susceptible to Paget's disease?

middle age

NB younger ppl more likely to progress to osteocarcinoma

115

What happens if bones of the skull are affected by Paget's disease?

middle ear bones = loss of hearing
skull = uneven thickness, extensive sclerosis and enlargement

116

Which bone disease can cause loss of hearing and why?

Paget's disease
- middle ear bones have excessive resorption / formation

117

Is fibrous dysplasia genetic or non-genetic?

genetic
- specific mutations

118

What is fibrous dysplasia?

intramedullary fibro-osseous lesion

119

Who is affected by fibrous dysplasia?

all ethnic groups
adults and children
men and women
- men = skull and ribs
- women = long bones

120

Which bone disease has wonky eyes and lips?! (forming a > sign!)

fibrous dysplasia

121

Name and describe the two forms of fibrous dysplasia

Monostotic - only one bone involved
- skull - 35%
- femur/tibia - 33%
- ribs - 20%

Polyostotic - many bones affected
- femur / pelvis / tibia - >60% of cases
- one extremity or one side of body
- earlier onset cf monostotic
- associated with
- McCune-Albright syndrome (endocrine abnormalities and skin pigmentation)
- Mazabraud syndrome (intramuscular myxomas)

122

Which form of fibrous dysplasia has the later onset?

monostotic fibrous dysplasia

123

What bone disease is associated with McCune-Albright syndrome?

polyostotic fibrous dysplasia

McCune-Albright syndrome (endocrine abnormalities and skin pigmentation)

124

What bone disease is associated with Mazabraud syndrome?

polyostotic fibrous dysplasia

Mazabraud syndrome (intramuscular myxomas)

125

What is most common area for surgery for people with fibrous dysplasia?

gnathic (jaw) surgery

126

What is a lytic lesion?
Which bone disease is it associated with?

radiolucent area on xray of bone, suggesting it's been destroyed
- bone expands and looks like 'ground glass'
- can be solid or partly cystic

Found in fibrous dysplasia

127

Where does a lytic lesion in bone spread to?

- remains in the bone - expands the bone
- does NOT cause a periostial reaction or enter soft tissue

128

What is a periosteal reaction?

Formation of new bone by the periosteum
Usually due to trauma / bone healing

129

What are the symptoms of fibrous dysplasia?

- usually asymptomatic
- pain
- risk of fracture

130

What % of tumours are bone tumours?
Incidence rate?

1% (ie rare)
1000 new cases per year

131

What % of bone tumours are osteosarcoma?
Incidence rate?

15%
150 new cases per year

132

Name a type of bone tumour

osteosarcoma

133

What age get osteosarcoma?

under 30yrs
Mainly 12-25yrs

134

Is osteosarcoma usually benign or malignant?

benign
(malignant = rare)

135

What is a classic sign of osteosarcoma?

periosteal reaction (ie new bone formation)
- 'sunburst' on xray
- ie perpendicular ossifications from osseous matrix streams from bone
- can have skip metastases (to other bone / lung)

136

Where does high grade intramedullary osteosarcoma occur most often in the body?

>50% in knees
- distal femur (32%)
- proximal tibia (15%)

137

Where does osteosarcoma occur in the bone?

>90% in metaphyseal (contains epiphyseal plate)

138

Where is osteosarcoma unlikely to occur in the body?

ribs
vertebrae
peripheral limbs
head and neck

139

What are the three types of osteosarcoma and what % for each?

high grade intramedullary osteosarcoma - 80%
periosteal osteosarcoma - 2%
parosteal - 5%

140

What other bone disease is linked to osteosarcoma?

osteoporosis

141

What is visible by bone in osteosarcoma?

woven bone
cartilage

142

What is high grade intramedullary osteosarcoma?

tumour starts in medulla of bone and progresses towards metaphysis at one end
- v. aggressive
- both bone destruction (moth eaten) and formation on xrays
- bone can completely disappear

143

What is the treatment for high grade intramedullary osteosarcoma?

Chemotherapy and resection.

144

What is treatment for parosteal osteosarcoma?

'sharp bite' - remove tumour on the surface of the bone and part of cortex.
- no chemotherapy
- no full resection

145

What is parosteal osteosarcoma?

bone tumour on surface of the bone
low grade malignancy

146

Where is the new bone formation most easily seen in high grade intramedullary osteosarcoma on xrays?

subperiosteal / above cortex

147

What is Codman's triangle?

Visible on xrays in high grade intramedullary osteosarcoma
- area where periosteum is detached from cortex (acute angled triangle)

148

What does high grade intramedullary osteosarcoma look like histologically?

osteoblasts
- disorganised
- pleomorphic (cells change size/shape)
- nuclear hyperchromatism

Osteoid / bone
- disorganised

149

What is osteoarthritis?

disorder of synovial joints
- cartilage degeneration / articular cartilage breakdown
- secondary changes in neighbouring bone

reduced capillaries in joint, therefore reduced cartilage (needs nutrients from external blood vessels), subchondral bone exposed, osteophytes created to replace cartilage

Not a single disease, but a common response to physiologic and metabolic conditions

150

Which part of long bone isn't vascularised?

cartilage

151

What are osteophytess?

new bone formation at joint to replace lost cartilage
- reduced joint movt

152

Where does osteoarthritis occur?

anywhere
- esp knees / femur (hip) / hands / first metatarsophalangeal joint

153

What are the two types of osteoarthritis?

Primary osteoarthritis
- generalised or erosive
- unknown aetiology

Secondary osteoarthritis
- joints previous damaged (eg gout, rheumatoid arthritis)

154

What are three main symptoms of osteoarthritis?

- pain
- stiffness in morning (improves throughout day)
- joint may 'gel' with immobility

155

Who is likely to get osteoarthritis?

50+yrs
obese

156

What can cause articular cartilage breakdown in the jaw in osteoarthritis? (x4)

- parafunction
- poor occlusion
- trauma
- genetics

157

What are symptoms of articular cartilage breakdown in the jaw in osteoarthritis? (x4)

- crepitation (crackling sound)
- pain around the ear
- limited movt
- bite shifting

158

What happens to the joint space in osteoarthritis?

Joint space narrows
- subchondrial sclerosis
- subchondrial cyst formation
- osteophytes

159

What happens when joint space is reduced?

reduced movt