LECTURE 4 DISEASE OF BONE Flashcards

1
Q

what is CT good for?

A

imagine bone, soft tissue & blood vessels at the same time- pinpoints injuries with bony structures

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2
Q

what is MRI good for?

A

imaging soft tissue & showing tissue difference between normal & abnormal

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3
Q

what is good at seeing cortex of bone?

A

most easily visualised on plain radiographs, MRI of little value in evaluating cortex

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4
Q

what is good at seeing circumference & internal matrix of bone?

A

CT and MRI

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5
Q

what are 95% of bone radiographs obtained for?

A

evaluating trauma, arthrities, degenerative conditions or metastases

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6
Q

what is x-ray good for showing?

A

assessing imaging but not showing any soft tissue injuries

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7
Q

how can bone lesions be diagnosed?

A

mostly based on history

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8
Q

what are the 2 types of bone disease?

A

increase & decrease bone density

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9
Q

what is increased bone density known as?

A

sclerosis

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10
Q

what are the main diseases of sclerosis?

A

metastatic tumours (diffuse or focal sclerosis), avascular necrosis of bone (focal) , paget disease (focal)

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11
Q

what is the most common type of increased bone density?

A

metastatic tumours (diffuse or focal sclerosis

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12
Q

what are the characteristics of sclerotic diseases?

A

increase radio opacity (looks whiter) & loss of visibile structure

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13
Q

what is avascular necrosis of bone?

A

lack of blood supply to bone- when it dies it collapses & increases in bone density, bone mineral becomes concentrated e.g. scaphoid, head of femur- detected with MRI

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14
Q

what is an example of diffuse metastatic tumours?

A

metastatic carcinoma (cancer that start is tissue cells) of prostate due to uncontrolled osteoblast activity- travelling cancer

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15
Q

what can focal sclerotic lesions affect?

A

cortex & medullary cavity- specific regions

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16
Q

what occurs in the cortex due to focal sclerotic lesions?

A

produce periosteal new bone formation (periosteal reaction) causing thickening of cortex- periosteum is lifted off surface of bone and new bone grows down (sunburst reaction)

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17
Q

what occurs in medulla due to focal sclerotic lesions?

A

punctuate, amorphous sclerotic lesions surrounded by normal medullary cavity- see holes in medullary cavity (looks white due to more bone mineral)

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18
Q

what are metastatic bone tumours more common than?

A

primary bone tumours

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19
Q

what is a metastic tumour?

A

a tumour that has moved from the site where it originally developed e.g. growing in bone but started

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20
Q

what can metastatic tumours be?

A

both osteoblastic, osteolytic & combination of both

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21
Q

what are examples of osteoblastic tumours?

A

prostate carcinoma (most common), breast carinoma (can be osteolytic), renal cell carcinoma, thyroid carcinoma

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22
Q

what is a malignant tumour?

A

have the ability to metastasise- leave point of growth & spread out to distance sites e.g. start is prostate & travels to bone

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23
Q

what is an osteoblastic tumour?

A

create more bone, more white

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24
Q

what is osteolytic tumor?

A

break down of bone

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25
Q

what is paget disease?

A

chronic disease of bone, seen in older men- varyin digress of increased bone resorption & increased bone formation

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26
Q

what diseases occur due to lack of bone density?

A

osteoporosis, hyperparathyroidism, rickets, osteomalacia

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27
Q

what will the bones look like with decreased bone density?

A

overall increase in lucency (not as white, more grey), loss of trabeculae, accentuatio of normal cortico-medullary junction (as cancellous bone degrades)- vertebral body cmpression- pathological fracture (occurs where u have bone disease)

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28
Q

what does the cortex and medulla look like with decreased bone density?

A

cortex is thinner, medulla is more lucent

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29
Q

what is osteoporosis?

A

systemic (impacts all bones) skeletal disorder, characterised by low bone mineral density

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30
Q

what are the 2 types of osteoporosis?

A

postmenopaual due to increased bone resorption caused by osteoclastic activity (estrogen inhibits osteoclasts to break down bone) & age related (senile) bone loss aroung 45-55 due to loss of total bone mass

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31
Q

what are the risks factors of osteoporosis?

A

exogenous steroid administration, cushings disease, estrogen deficiency, inadequate physical activity, alcoholism

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32
Q

what pathological fractures does osteoporosis predisposes one to?

A

femoral neck, distal radius (colles’ fractures), compression fractures of vertebral bodies

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33
Q

what are risk factors for vertebral and femoral neck fractures?

A

increases dramatically as BMD levels decrease to less than 1 g/cm2- & can be estimated

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34
Q

are conventional radiographs good to diagnose osteoporosis?

A

not really, 50% of bone mass must be lost before it is recognised on conventional radiographs

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35
Q

what are the signs of osteoporosis in x-rays?

A

overall lucency on bone, thinning of cortex, decrease of trabeculae

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36
Q

what is the most accurate scan to diagnose osteoporosis?

A

DEXA scans are most accurate as it measure bone mineral density- measures than compared to mean average

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37
Q

what is normal bone mineral density?

A

being within 1 standard deviation of yound adult mean

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38
Q

what is osteopenia bone mineral density?

A

being 1 to 2.5 deviations away from young adult mean

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39
Q

what is osteoporosis bone mineral density?

A

more than 2.5 SD away from young adult mean

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40
Q

what is hyperparathyroidism caused by?

A

excessive secretion of parathyroid hormone

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41
Q

what is the role of parathyroid hormone?

A

stimulates osteoclastic activity- regulates calcium levels in blood by regulating osteoclasts- low calcium, more parathyhoid hormone and breaks down bone to stabilise calcium levels

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42
Q

what are the 3 forms of hyperparathyroidism?

A

primary, secondary, tertiary

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43
Q

what is primary hyperparathyroidism?

A

caused by a single adenoma/tumour (80% to 90& of patients- most common)- hypercalcaemia (too much calcium in blood)

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44
Q

what is secondary hyperparathyroidism?

A

caused by calcium & phosphorous imbalances- chronic renal disease

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45
Q

what is tertiary hyperparathyroidism?

A

occurs in patients with long standing secondry hyperparathyroidism- autonomous hypersecretion

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46
Q

what is rickets caused by?

A

disroders afecting vitamin D ingestion, absorption or activation- failure of osteoid to calcify especially at sites of maximal growth in childrens

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47
Q

what population does rickets appear in?

A

children whose growth plates have not closed

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48
Q

what is osteomalacia?

A

failure to calcify the osteoid matric of bone in adults, commonly due to renal disease- similar to rickets but in adults- makes bone matrix but doesnt calcify

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49
Q

what is the imaging hallmark of osteomalacia?

A

pseudofracture (looser line)- occurs at multiple sites at the same time & is associated with nonunion

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50
Q

where are common location of pseudofractures?

A

medial femoral neck and shaft, pubic and ischial rami, metatarsals, and calcaneus.

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51
Q

how does focal loss of bone density occur?

A

produced by focal infiltration of bone by cells other than osteocytes

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52
Q

what are the main diseases of focal loss of bone density?

A

metastatic disease (osteolytic), multiple myeloma, osteomyelitis

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53
Q

what are the common forms of osteolytic metastatic disease?

A

lung cancer, breast cancer, lymphoma, carcinoid tumours

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54
Q

what occurs in osteolytic metastatic disease?

A

produces focal destruction of medullary cavity often expanding & destroying cortex

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55
Q

how much reduction in bone mass must occur to observed osteolytic metastatic disease?

A

50% reduction in bone moss in medullary cavity to be noticeable

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56
Q

how can we diagnose osteolytic metastatic disease?

A

through MRI- when onl cortex is involved its easier to visualise on plain radiographs

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57
Q

where are osteolytic metastatic disease uncommon?

A

distal to elbow or the knee- if present here, they are usually widespread & due to lung or breast cancer

58
Q

what is the best way to observe skeletal metastases?

A

radionuclide bone scane

59
Q

what is the most common primary malignancy of bone in adults?

A

multiple myeloma- originates in the bone

60
Q

where can multiple myeloma be?

A

solitary (in spine or pelvis) or disseminated (multiple, lytic lesions throughout axial & proximal appendicular skeleton)- at greater risk of developing fractures e.g. osteoporosis- can impact skull

61
Q

what is the most common early manisfestations of multiple myeloma?

A

diffuse & usually severe osteoporosis

62
Q

how can multiple myeloma be detected?

A

via plain radiographs

63
Q

what is osteomyelitis?

A

focal detruction of bone by bacterial infection (blood borne- haematogenous)- lots of inflammation, destruction of bone

64
Q

where does osteomyelitis occur in adults & children?

A

adults (occurs in joint space causing osteomyelitis & septic arthritis/infection of joints )- children (at the metaphysis- growth plates where blood supply is good but slow)

65
Q

what are the signs of osteomyelitis in plain radiographs?

A

focal cortical bone destruction, periosteal new bone formation, soft tissue swelling & focal osteoporosis

66
Q

how is osteomyelitis diagnosed?

A

MRI & nuclear medicine for early diagnosis as changes occur slowly- holes in skin where pus can escape

67
Q

what are the characteristics of primary tumours?

A

most are benign, in young patients they are benign, in older patient most are malignant- male predominance- originate in bone- less common than metastatic

68
Q

what do we need to know when diagnosing primary tumours?

A

bone involved, specific site involved (cortex or medulla, epiphysis, diaphysis or metaphysis), tumour margin & contour

69
Q

what are the characteristics of a benign primary tumour?

A

localised & well defined- don’t invade structures but grows by expansion (compress structures) vs malignant that throws out roots

70
Q

what are the characteristics of a malignant tumour?

A

invasive, ill defined

71
Q

what is osteosarcoma?

A

uncontrolled growth of cells- formation of new bone at a rapid rate- occurs in metaphyses of long bone e.g. distal femur- affects under 20 over 60- bone tunour from bone- periosteum lifts off with new bone growing underneath

72
Q

how does osteosarcoma appear on radiographs?

A

moth eaten sunburst appearance due to be rapidly growing & invasive

73
Q

what is chondrosarcoma?

A

cancer that forms in CT surroundnig the bone- in the metaphysis & diaphysis of long bone e.g. medullary cavity of femur, humerus & pelvis- gives a lucent defect to bone- middle age & older

74
Q

what is fibrosarcoma?

A

cancer that effects the fibroblast cells (creates fibrous tissue e.g. tendons)

75
Q

where does fibrosarcoma occur?

A

in metaphysis of femur & tibia- lucent lesios with cortical destruction- middle age

76
Q

what is a fracture?

A

disruption in continuity of all or part of cortex of a bone

77
Q

what is a complete fracture?

A

if cortex is broken on both sides of bone

78
Q

what is an incomplete fracture?

A

if only part of cortex is fractured

79
Q

where do incomplete fractures tend to occur?

A

in soft bones- children or adults with osteomalacia or paget disease

80
Q

what is a greenstick fracture?

A

incomplete fracture seen in children- tends to tear

81
Q

what is a torus fracture?

A

incomplete fracture with bulging of the cortex- result from trabeculae compression

82
Q

what are the signs of a fracture in radiograohs?

A

fracture lines are more lucent than other lines, tend to be straighter & more acutely angled than naturally occurring lines, edges tend to be jagged & rough

83
Q

what can fractures be confused with?

A

sesamoids, accessory ossicles, old ungealed fracture fragments

84
Q

how can you tell difference between sesamoids & fractures?

A

sesamoids are usually found on both sides & occur at anatomically predicted site e.g. under tendon

85
Q

how can you tell difference between accessory ossicle & fractures?

A

usually found on both sides & anatomically predictable sites- sites that do not fuse with parent bone

86
Q

how can you tell difference between old fractures & fractures?

A

white line completely surrounds fragment & edges are usually smooth- might not even see a fracture if there is no visible fracture line (takes a while to develop)

87
Q

what is a simple fracture?

A

2 fragments

88
Q

what is a comminuted fracture?

A

more than 2 fractures

89
Q

what is a segmental comminuted fracture?

A

portion of shaft is isolated

90
Q

what is a butterfly comminuated fracture?

A

central fragment has a triangular shape

91
Q

what directions can fractures occur in?

A

transverse, oblique, spiral

92
Q

what is a transverse fracture and how does it occur?

A

fracture line is perpendicular to long axis of bone- caused by a force directed perpendicular to shaft

93
Q

what is an oblique fracture & how does it occur?

A

fracture line is diagonal to long axis of bone- caused by a force applied along same direction as long axis

94
Q

what is a spiral fracture & how does it occur?

A

caused by a twisting force- start at one side & comes out the other

95
Q

what does displacement about a fracture describe?

A

amount by which the distal fragment is offset, front to back and side to side, from the proximal fragment

96
Q

what does angulation about a fracture describe?

A

· the degree to which the distal fragment is deviated from its normal position.

97
Q

what does shortening about a fracture describe?

A

how much overlap there is of the ends of the fracture fragments (how much shorter the bone is than its normal length)

98
Q

what does distraction about a fracture describe?

A

distance the bone fragments are separated from each other (how much longer the bone is than its normal length)

99
Q

what does rotation about a fracture describe?

A

the orientation of the joint at one end of the fractured bone relative to the orientation of the joint at the other end of the same bone.

100
Q

what is a closed fracture?

A

no communication between the fracture and the external environment

101
Q

what is a compound fracture?

A

there is communication between the fracture and the external environment

102
Q

what are special types of fracture?

A

avulsion, epiphyseal, stress

103
Q

what are avulsion fractures?

A

fracture fragment (avulsed fragment) is pulled from its parent bone by contraction of a tendon or ligament- any age, can be due to exercise, anatomically predicatable locations

104
Q

what are epiphyseal fractures?

A

occurs in epiphyseal plate- 30% of childhood fractures

105
Q

what are the classifications of epiphyseal fractures?

A

types i & ii (both heal well), type III (develop arthritic changes or asymmetric growth late fusion), type IV & V (develop early fusion with angular deformities & shortenings)- helps determine treatment & outcomes

106
Q

what are stress fractures?

A

occur as a result of numerous microfractures due to repeated forces before remodelling has occured- appear normal

107
Q

how are stress fractures diagnosed?

A

only after periosteal new bone formation occurs- radionuclide bone scans are useful

108
Q

where are stress fractures commonly found?

A

proximal femur, proxinal tibia calcaneous & 2nd, 3rd metatarsals

109
Q

what are the stages of fracture healing?

A

haematoma formation, procallus, callus, formation of normal bone with replacement of woven bone, remodelling of periosteal & endosteal surfaces

110
Q

what is haematoma formation?

A

occurs with vessel damage- fibrin forms initial framework for healing

111
Q

what is the procallus stage?

A

fibroblasts, osteoblasts & capillaries move into the wound to produce granulation tissue

112
Q

what is the callus stage?

A

osteoblasts deposit disorganised clumps of primitive bone matrix called woven bone (the callus)

113
Q

what is the final stages of fracture healing?

A

formation of normal bone with replacement of woven bone & remodelling of periosteal & endosteal surfaces

114
Q

what are the factors affecting fracture repair?

A

local blood supply, type of fracture, fixation, age, concurrent infection, disease, nutritional status

115
Q

how may type of fracture affect repair?

A

spiral & oblique repair faster than transverse- communited fractures have avascular fragments which may become sequestrated (necrotic tissue)

116
Q

how may fixation affect fracture repair?

A

better fixation gives faster healing- movement may lead to non-union- IM pins may disrupt blood suppy

117
Q

what are signs that a fracture is healed?

A

continuity of cortex, calcified complete bridging callus, no visible fracture line- takes 6 weeks with adequate fixation

118
Q

what are complications in fracture repair?

A

delayed union, non union, malunion

119
Q

what is delayed union is fracture repair?

A

failure of bone to unite within expected period of time, healing will eventually occur though- due to motion, infection, old patient, pathological fracture

120
Q

what is nonunion is fracture repair?

A

cessation of bone healing due to motion, avascularity, infection

121
Q

what are signs of nonunion in fracture repair?

A

smooth sclerotic edges with no callus, sealed medullary cavity, pseudoarthrosis

122
Q

what is malunion in fracture repair?

A

union of a fracture with angulatory or rotatory deformity caused by improper reduction, rotation or collapse during healing

123
Q

what are pathologic fractures?

A

fractures that occur in bone with a preexisting abnormality- occur with little force

124
Q

what occurs in pathological fractures?

A

bone surrounding the fracture will demonstrate abnormal density or architecture with delayed healing- cannot predict if fracture will occur in diseased bone

125
Q

what are dislocation?

A

bones that formed the joint are no longer in correct contact

126
Q

what are subluxations?

A

bones that formed the joint are in partial contact.

127
Q

what is arthritis?

A

affects joint & bones on either side of joint & caused joint space narrowing

128
Q

how is arthritis diagnose?

A

conventional radiography (osseous abnormalities & but can’t see soft tissue change)- also MRI to see soft tissue changes

129
Q

what are the types of arthritis?

A

hypertrophic, erosive, infectious

130
Q

what is hypertrophic arthritis?

A

causes bone formation at site of involved joint- main bone has subchondral sclerosis e.g. osteoarthrities

131
Q

what is erosive arthrities?

A

causes marginal, irregularly shaped lytic lesions in or around joint surfaces called erosions- underlying inflammation e.g. rheumatoid arthrities

132
Q

what is infectious arthritis?

A

causes joint swelling, osteopaenia & destruction of articular cortex e.g. septic arthrities

133
Q

what is osteoarthritis?

A

wear & tear causes degeneration of articular cartilage- mostly weightbearing joints e.g. hips, knees, hands

134
Q

how do we diagnose osteoarthritis?

A

marginal osteophyte formation (bony protrusion at end of bone), subchondral sclerosis, subchondral cysts, narrowing of joint space

135
Q

what is subchondral sclerosis?

A

bone thickening when protection of cartilage is removed

136
Q

how does secondary osteoarthritis occur?

A

due to trauma & damages the articular cartilage

137
Q

what is erosive arthrities associated with?

A

inflammation & synovial proliferation (pannus formation)

138
Q

how do we diagnose erosive arthritis?

A

lytic lesions in or near joint, articular cartilage & underlying cartilage called erosions

139
Q

what is rheumatoid arthritis?

A

form of erosive- bilateral & symmetrical, hereditary autoimmune disease, appears at a young age

140
Q

what is the diagnoses of RA?

A

via convential radiographs= soft tissue swelling, osteoporosis, deformities, changes to spine, hands and wrist joints

141
Q

what is gout?

A

when calcium urate crystal deposit in joint leading to inflammation- bone changes appear 5 to 7 years after sign- monoarticular- common in maes

142
Q

what is infectious arthritis caused by?

A

haematogenous spread (blood borne), penetrating wound, extension from osteomyelitis adjacent to joint