fail long bone growth - affect endochondral ossification - membranous ossification unchanged activation of FGFR3 - inhibit chondrocyte proliferation auto dom - full penetrance MCC dwarfism

MSK/Derm III Flashcards by Matt Stanton

muscle components

Z disc - actin attachment
M line - myosin attach
A band - all myosin
H band - myosin only
I band - myosin only

sarcomere - Z disc to Z disc

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smooth m contraction

nitric oxide - guanylate cyclase - increased cGMP

de-P myosin
relaxation

action potential - L-type Ca channel - increased Ca
-increased Ca/calmodulin complex > P of myosin

myosin-P bind actin and contraction occurs

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endochondral ossification

cartilage bone - replaced by osteoclasts/blasts - into woven bone

remodeled to lamellar bone

woven bone - after fx and with pagets

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membranous ossification

bones of calvarium and face

woven - without cartilage

later remodel to lamellar

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osteoblast

from mesenchymal stem cell in periosteum

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osteoclast

from monocyte/macrophage

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PTH action

low - anabolic - build bone

chronic high - catabolic - osteitis fibrosa cystica

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estrogen

inhibit apoptosis of osteoblasts
induce apoptosis osteoclasts

deficient - excess remodeling - osteoporosis

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achondroplasia

fail long bone growth

affect endochondral ossification
membranous ossification unchanged

activation of FGFR3 - inhibit chondrocyte proliferation

auto dom - full penetrance
MCC dwarfism

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primary osteoporosis

loss trabecular spongy bone and interconnections

with long term steroid use, anticonvulsant, antigcoag, thyroid replacement therapy

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DEXA scan

T score

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colles fx

distal radius

common with osteoporosis pt

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type I osteoporosis

more resorption bc of low estrogen

post-menopause

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type II osteoporosis

men and women >70yo

prophylaxis - Ca and vit D

tx - bisphosphonate, PTH analog, SERM

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denosumab

mAb - RANKL

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osteopetrosis

marble bone disease

failure resorption
-thick dense bones that fx

bone fills marrow space - pancytopenia

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mutation of osteopetrosis

carbonic anhydrase II
-impair osteoclast ability generate acidic environment for bone resportion

bone in bone appearnce

get nerve impingement

tx osteopetrosis

bone marrow transplant
-curative

bc osteoclasts from monocytes

osteomalacia and rickets

Vit D deficient

defective calcification of osteoid - soft bones

low vit D, low serum Ca, igh PTH, low serum P

hyperactive osteoblast - elevated ALP

osteitis deformans

paget disease of bone

increased osteoblast and osteoclast activity

serum Ca, PTH, P - normal
elevated ALP

mosaic pattern of woven and lamellar bone

pagets stages

1 - lytic - osteoclast
2 - mixed - osteoclast/osteoblast
3 - sclerotic - osteoblast
4 - quiescent - minimal clast/blast activity

osteonecrosis

avascular

often femoral head - insufficient medial circumflex femoral a

with alcoholism, sickle cell, storage problem, pancreatitis, trauma, idiopathic, caisson

lab values osteoporosis

normal except low bone mass

osteopetrosis labs

possible low Ca all else normal dense brittle bone low Ca if severe

paget disease of bone labs

high ALP abnormal mosaic bone pattern

osteomalacia/rickets labs

low Ca low P high ALP high PTH soft bones

primary hyperPTH labs

high Ca low P high ALP high PTH

secondary hyperPTH labs

low Ca high P high ALP high PTH compensation end stage renal disease - low P excretion and production of activated vit D

giant cell tumor

B9 in epiphysis aka osteoclastoma often around knee soap bubble o X-ray multinucleated giant cell

osteochondroma

B9 tumor -often in kids mature bone with cartilage cap

ostesarcoma

aka osteogenic sarcoma -2nd MC primary malignant bone tumor - after MM bimodal

risk fx osteosarcoma

``` paget bone infarct radiation Rb li fraumeni ```

location of osteosarcoma

metaphysis see onion skin periosteal rxn of bone

codman triangle

elevation of periosteum - with osteosarcoma also see sunbursy apttern spread - hematogenous

ewing sarcoma

malignant tumor - boys

prognosis of ewing sarcoma

often in young kid aggressive with early mets -responsive to chemo

tumor of epiphysis

giant cell

tumor of metaphysis

osteosarcoma | osteochondroma

tumor of diaphysis

ewing myeloma osteoid osteoma - night pain with central nidus fibrous dysplasia

t (11;22)

translpation fusion ESW-FLI 1 ewing sarcoma -11 + 22 = 33 partic ewing jersey #

CD99 +

ewing sarcoma