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MSK 2 > Bones, Joints, Soft Tissue > Flashcards

Bones, Joints, Soft Tissue Flashcards

1
Q

What is syndactyly or craniosynostosis?

A

abnormal fusion of bones

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2
Q

Define dysplasia

A

mutations in genes controlling development or remodeling–> disorganization of bone/cartilage that is not premalignant

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3
Q

What defect causes abnormal differentiation in osteoblasts and chondrocytes?

A

homeobox proteins

HOXD13: brachydactyly

RUNX2: cleidrocranial dysplasia w/ wormian bones

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4
Q

What is the most common skeletal dysplasia and major cause of dwarfism?

A

achondroplasia

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5
Q

Define achondroplasia, genes involved, and sx

A

AD FGFR3 gain of fxn

defect in endochondral ossification so long bones are short–> short extremities with normal trunk length

enlarged head with bulging forehead, depression root of nose

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6
Q

Are there changes in longevity, intelligence or reproductivity in achondroplasia?

A

no- all normal

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7
Q

What is the most common lethal form of dwarfism?

A

thanatophoric dysplasia

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8
Q

Describe thantophoric dysplasia

A

different FGFR3 GOF than achondroplasia

diminished proliferation of chondrocytes and disorganization in zone of proliferation

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9
Q

What do people with thantophoric dysplasia look like?

A

micromelic shortening of limbs

frontal bossing

macrocephaly

small chest cavity–> respiratory insufficiency

bell-shaped abdomen

die at or soon after birth

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10
Q

What is LPR5 receptor implicated in?

A

osteoporosis or petrosis, depending on defect

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11
Q

What do mutations in RANKL cause?

A

decreased or absent osteoclasts

on blasts, activate clast proliferation and activity normally

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12
Q

What is the most common inherited disorder of connective tissue?

A

osteogenesis imperfecta

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13
Q

What type of collagen is implicated in osteogenesis imperfecta?

A

type 1

found in bone, some joints, eyes, ears, skin, teeth

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14
Q

What aspects of type 1 collagen is mutated in osteogenesis imperfecta?

A

a1 and 2 chains

no triple helix formation

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15
Q

What happens in osteogenesis imperfecta?

A

decreased synthesis of normal collaged–> skeletal abnormalities

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16
Q

What is the best way to tell between potential abuse and osteogenesis imperfecta?

A

bone pathology

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17
Q

What is the worse type of osteogenesis imperfecta?

A

type 2

no triple helix–> fatal in utero

extraordinary bone fragility with multiple intrauterine fractures

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18
Q

What is the best and most common type of osteogenesis imperfecta?

A

type 1- AD

normal life span, childhood fractures decrease in frequency following puberty

19
Q

Describe type 1 osteogenesis imperfecta

A

collagen structure is normal, but decreased amount

fractures before puberty

normal life span and stature

loose joints (increased mobility) and low muscle tone

blue, purple or gray sclera (normally whites of eyes)

triangular face

spinal curvature tendency

bone deformity is absent or minimal

brittle teeth

hearing loss in 20s-30s

20
Q

Describe type 2 osteogenesis imperfecta

A

most severe

collagen improperly formed

lethal at or shortly after birth d/t resp problems (small chest cavity)

numerous fractures and severe bone deformity

small stature with underdeveloped lungs

21
Q

Compare types 3 and 4 osteogenesis imperfecta

A

1 best, 2 worst

both have improperly formed collagen

4- intermediate
sclera white

shorter than average

3- intermediate to bad
fractures at birth, shows healed fx before birth

blue sclera

loose joints, low muscle tone

22
Q

What is Albers-Schonberg disease?

A

osteopetrosis

aka marble bone disease

23
Q

What is the pathogenesis of osteopetrosis?

A

deficiency in carbonic anhydrase 2

  • -> clasts need acid, so can’t break down bone
  • -> kidneys can’t get rid of acid, so renal tubular acidosis

mutation in CLCN7 (proton pump on clasts)

24
Q

What do bones in osteopetrosis look like?

A

lack medullary cavity (blasts make bone that grows into it–> anemia)

Erlenmeyer flask look d/t bulbous ends of long bones

neural foramina small, compress nerves

25
Q

Describe type 1 osteopetrosis

A

severe infantile form

AR (mediterranean, arab)

cranial nerve deficits
–> optic atrophy, deafness, facial paralysis (increased bone puts pressure on nerves)

postpartum mortality d/t:
–> fractures, anemia, hydrocephaly

26
Q

Describe type 2 osteopetrosis

A

mild AD in adolescence or adulthood

repeat fractures

mild CN deficits and anemia

27
Q

Describe mucopolysaccharidoses

A

lysosomal storage diseases caused by - in enzymes that degrade dermatan sulfate, heparan sulfate and keratan sulfate (acid hydrolase enzymes)

hunter and hurler syndromes

28
Q

Describe presentation of patients with mucopollysaccharidoses

A

chondrocytes normally degrade ECM mucopolysaccharides, but since there is more of them they accumulate and kill chondrocytes–> defect in articular cartilage
–> problems at growth plate

short stature
chest wall abn
malformed bones

29
Q

What is the difference between osteopenia and osteoporosis?

A

osteopenia

    • decreased bone mass
    • “lesser version of porosis”
    • 1-2.5 SD below the mean

osteoporosis
~~osteopenia severe enough to increase risk of fracture
~~ at least 2.5 SD below the bean during peak bone mass in young adults

30
Q

What signifies/ is a hallmark of osteoporosis?

A

atraumatic or vertebral compression fractures

31
Q

What are the most common forms of osteoporosis?

A

senile and postmenopausal

32
Q

What is the path behind senile osteoporosis?

A

low turnover variant

decreased proliferation and biosynthesis

decreased response to growth factors

33
Q

Why does decreased physical activity lead to osteoporosis?

A

Mechanical forces stimulate normal bone remodeling

bone loss in immobility, paralysis, astronauts in zero gravity

resistance exercises better

34
Q

Describe the defective nutrition in adolescent girls that leads to osteoporosis

A

insufficient calcium intake during period of rapid growth restricts peak bone mass

also increased PTH and decreased vitamin D

35
Q

What is the path behind postmenopausal osteoporosis?

A

accelerated bone loss

estrogen deficiency promotes resorption and formation, but resorption more

high turnover variant

36
Q

What medicine used in cancer treatment increases risk for osteoporosis?

A

tamoxifen used for breast cancer chemo adjunct

37
Q

Is osteoporosis normal bone?

A

YES, just less of it

38
Q

What does bone look like in senile osteoporosis?

A

cortex thinned by subperiosteal and endosteal resorption

haversian system widened

39
Q

What does bone look like in postmenopausal osteoporosis?

A

bones have increased surface area d/t increased osteoclast activity

trabeculae are perforated, THINNED, lose interconnections–> microfractures and vertebral collapse

40
Q

How to diagnose osteoporosis?

A

DEXA scan
(bone mineral density test)

blood test to check for secondary causes (renal/hepatic failure, hyperthyroid)

41
Q

Genetic/environmental associations with osteoporosis

A

Caucasian, light colored hair and eyes

not enough calcium in teen years–>guaranteed

too much phosphorus (soda)

smoking

42
Q

Prevention/treatment of osteoporosis

A

exercise, calcium, vitamin D

bisphosphonates (decrease clast activity)

hormone therapy (be careful of DVT and stroke)

denosumab (anti-RANKL)

43
Q

Clinical course of osteoporosis

A

thoracic and lumbar vertebral fractures
–> PE and pneumonia

loss of height d/t lumbar lordosis and thoracic kyphoscoliosis

MSK 2 (4 decks)

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