Msk: Vascular Bone Disease

Front 1

why does bone have such an extensive blood supply

Back 1

because of the dynamic nature of bone with constant reorganization and remodeling; the vasc provides nutrition and access to bone forming elements in the marrow, and it provides access to the mineral supply of bone for the rest of the body

Front 2

what are the 4 sources of blood supply to the long bones

Back 2

nutrient artery, periosteal vessels, metaphyseal vessels and epiphyseal vessels

Front 3

compare the blood pressures in the diaphysis, epiphysis, metaphysis and systemic BP

Back 3

systemic BP>diaphysis>metaphysis>epiphysis

Front 4

T/F: when the systemic BP increases (or decreases), the the pressure within the marrow always increases (or decreases)

Back 4

FALSE- in general it does, but with injection of epi, the pressure in the marrow falls (due to vasoconstriction of the nutrient artery) and with shock the pressure rises (due to compression of periosteum veins)

Front 5

what is the function of the periosteal vessels

Back 5

supply the outer 1/3 of the cortex- impt for circumfrential growth in kids and pathologic states in adutlts (fractures or infx)

Front 6

what does the nutrient artery supply

Back 6

marrow substances, haversian systems of the inner 2/3 of the cortex and they participate in endochondral ossification in kids (they terminate at the metaphyseal side of the epiphyseal plate)

Front 7

what is the function of the metaphyseal veins

Back 7

permit egress of blood from the marrow cavity

Front 8

what happens to the vessels with closure of the epiphyseal growth plate

Back 8

anastomoses btwn epiphyseal vessels, metaphyseal vessels, and terminal branches of nutrient artery (except in the femoral head)

Front 9

why are cuboid bones (carpals and tarsals) and epiphyses (secondary ossification centers) at risk for necrosis

Back 9

because a large portion of their surface area is covered by articular cartilage through which vessels can't penetrate-->blood supply enters thru very tight spaces and there is limited collateral circulation

Front 10

what is the pathogenesis of the early focus of hematogenous osteomyelitis that occurs in a growing kid

Back 10

there is extensive branching of the nutrient artery toward the metaphyseal side of the growth plate and with the contributions of the metaphyseal vessles there is almost one arteriole per column of chondrocytes, then when the vessel reaches the last chondrocyte in the column it does an abrupt 180 and links up with a venule-->this slowing of circulation permits the lodge and proliferation of bacteria

Front 11

bone death is recognized histologically by the disappearance of ___

Back 11

bone death is recognized histologically by the disappearance of OSTEOCYTES FROM THEIR LACUNAE

Front 12

why does infarcted bone appear denser than normal bone on xray

Back 12

1) the infarcted bone retains its density but the surrounding living bone becomes osteoporotic due to hyperemia from an attempt to revascularize the infarcted bone
2) the collapse of the dead bone into a smaller area
3) osteoclast resorption, new bone formation and revascularization create a mottled density

Front 13

does disruption of the terminal vessels of the nutrient artery in growing bone affect endochondral ossification, growth of the cartilage plate or both

Back 13

endochondral ossification

Front 14

Disruption of the nutrient artery in growing bone can result in what

Back 14

necrosis of a variable portion of the marrow and of the inner two thirds of the cortex

Front 15

does coritcal death occur in adult bone

Back 15

no because collateral circulation is sufficient

Front 16

When metaphyseal bone infarcts present with pain, ___ or ___ should be suspected

Back 16

malignant degeneration or secondary infection

Front 17

blood supply to the epiphyseal region is very similar to ___ bones

Back 17

cuboid bones (hence they develop similar pathologies)

Front 18

vascular insults to growing bone are termed ___

Back 18

osteochondrosis

Front 19

vascular insults to mature bone are termed ___

Back 19

osteonecrosis

Front 20

what is osteochondrosis

Back 20

a degenerative change in the ossification center of the epiphysis that continues on to avascular necrosis

Front 21

Common vascular osteochondroses include: Perthes (femoral head), Kohler (talar navicular), Frieberg (2nd metatarsal head).

Back 21

Common vascular osteochondroses include: Perthes (femoral head), Kohler (talar navicular), Frieberg (2nd metatarsal head).

Front 22

where does perthes vascular osteochondrsis occur

Back 22

femoral head

Front 23

where does kohler vascular osteochondrosis occur

Back 23

talar navicular

Front 24

where does friebery vascualr osteochondrosis occur

Back 24

2nd metatarsal head

Front 25

what is the pathophys of osteochondrosis and what does it result it

Back 25

obliteration of epiphyseal blood supply-->necrosis of epiphysis and deprives deeper growth plate cartilage cells of nutrition-->longitudinal growth ceseases-->permanent closure of growth plate if collateral circ is not restored

Front 26

what bones are at risk of osteonecrosis

Back 26

femoral head, talus, lunate, and scaphoid

Front 27

what are the common features of the bones that are at risk for osteonecrosis

Back 27

a surface area mostly covered with cartilage with limited and vulnerable vascular access

Front 28

the head of the femur receives most of its blood supply from which artery

Back 28

medial femoral circumflex (vessels of ligamentum teres supply a little bit after age 6)

Front 29

T/F: the nutrient artery of the femur contributes signficantly to the head of the femur

Back 29

false- sends branches to the metaphysis but not much to the head

Front 30

what is Legg-Calvé-Perthes disease

Back 30

avascular necrosis of the femoral head for no apparent reason (proposed mech is unrecog trauma), usually occurs in males age 5-10 years

Front 31

txt for Legg-Calvé-Perthes disease

Back 31

keep the hip abducted and internally rotated so the weight is transmitted from the acetabulum to a wide area of femoral head to prevent bone collapse

Front 32

causes of femoral head osteonecrosis

Back 32

idiopathic, steroids, etoh abuse, fractures, sickle cell anemia, the bends (caisson dz), gaucher dz, and several CT dz's (also high pressure from fluid or pus in jt space can cut off circulation)

Front 33

what are the 2 categories of osteonecrosis etiologies

Back 33

arterial compromise or high inraosseus pressures

Front 34

what are the txt options of osteonecrosis of femoral head

Back 34

drilling a hole to relieve pressure, bone grafting to prevent collapse, hip replacement in late stages

Front 35

what is paget's dz

Back 35

high bone turnover with inc osteoblast and osteoclast activity-->mosaic pattern of bone

Front 36

in paget's dz, there is a(n) ___ (increase/decrease) in blood flow to effected bones causing a __(Increase/decrease) in cardiac output

Back 36

increase in blood flow, increase in CO

Front 37

what abnl lab values are seen in paget's

Back 37

high alkaline phosphate

Front 38

how do pts with paget's present

Back 38

bone pain and often arthritis in adjacent jts

Front 39

T/F: fractures and other causes of increased blood flow are associated with an overgrowth of the affected bone in kids

Back 39

TRUE- inc in blood flow stimulates longitudinal growth

Front 40

in adults, degenerative arthritis is associated with increased or decreased vascularity of end bones

Back 40

increased

Front 41

T/F: infarcted bone in the nutrient artery distribution may be asymptomatic

Back 41

true