cartilage and osteoarthritis

Question 1

what are some features of cartilage?

Answer 1

avascular, aneural, tissue with a low metabolic rate

Question 2

does cartilage heal quickly or slowly?

Answer 2

slowly because avascular

Question 3

what is cartilage designed to withstand?

Answer 3

rigorous loading without failure, to distribute loads, and to provide a low friction surface

Question 4

what is articular cartilage made of?

Answer 4

zones

Question 5

what does the tide mark mark?

Answer 5

the break between subchondral bone and calcified cartilage

Question 6

what happens with aging in articular cartilage?

Answer 6

we wear away cartilage from the top down so more subchondral bone will be laid down as we age

Question 7

what is the most unique AC material property as it relates to its mechanical beahvior?

Answer 7

fluid component

Question 8

water content __________ and PG content _______ with increased depth of tissue

Answer 8

decreases, increases

Question 9

why is it that the deeper we go in articular cartilage there is less water content?

Answer 9

because the pore size is smaller deeper

Question 10

is water compressable?

Answer 10

no it squishes out

Question 11

what is the solid component of articular cartilage?

Answer 11

porous, permeable matrix primarily of type 2 collagen and PG with an extremely low permeability coefficient (k)

Question 12

what is the significance of split lines with tensions?

Answer 12

surgeons use them so they can suture in certain directions to avoid scaring

Question 13

what materials display the same mechanical behavior despite the direction of forces?

Answer 13

isotropic (homogenous) ex) steel

Question 14

T/F material properties of articular cartilage differ with direction of motion?

Answer 14

True

Question 15

the solid component of articular cartilage is considered a _________ tissue?

Answer 15

anisotropic

Question 16

T/F, joint mobs/non thrust manipulations do lengthen adaptively shortened tissue

Answer 16

False

Question 17

the superficial fibers of AC are aligned _____ and the deeper fibers are aligned more ____

Answer 17

horizontally, vertical

Question 18

AC visco-elastic mechanical behavior;
- Stress is developed in ____ - ___ solid matrix
- frictional drag is generated by ____ ___ flow
- greater PG concentraion = _____ elastic response/rupture strength
- aging ____ degree of PG aggregation

Answer 18

collagen-PG
interstitial fluid
increased
reduces

Question 19

rate of creep is an indicator of tissue ______?

Answer 19

permeability

Question 20

______ pores result in ______ Permeability and high friction to flow

Answer 20

small, low

Question 21

what further reduces pore size?

Answer 21

compression

Question 22

a low rate of creep = a low ______?

Answer 22

permeability

Question 23

what is ideal mechanical behavior

Answer 23

we want high friction flow, low permeability, small pores, decreased creep rate

Question 24

aging: ______ aggregation, _______ GAG content, and ______ chains

Answer 24

decreased, decreased, shorter

Question 25

structural modifications may be linked to changes in what?

Answer 25

chondrocyte synthetic function

Question 26

during a biphasic creep response in compression a rapid initial exudation of fluid comes from?

Answer 26

articular surface

Question 27

what creates creep in a biphasic creep response in compression?

Answer 27

external compressive load

Question 28

what is creep resisted by in a biphasic creep response in compression?

Answer 28

stress developed in collagen PG solid matrix and frictional drag

Question 29

in a biphasic creep response in compression continued slower exudation until deformation equilibrium reached. external compressive load ultimately ______ stress developed in collagen-PG solid matrix alone

Answer 29

equals

Question 30

what does the friction coefficient deal with?

Answer 30

shear force, compression decreases shear force

Question 31

what does permeability coefficient go up with?

Answer 31

poor sizes

Question 32

does a low or high permeability coefficient take longer to reach equilibrium?

Answer 32

low

Question 33

during the biphasic stress-relaxation response stress is increased until what?

Answer 33

a given deformation is reached and then deformation/strain maintained

Question 34

during the biphasic stress-relaxation response stress decreases under constant strain until what?

Answer 34

equilibrium stress is reached

Question 35

in the biphasic stress-relaxation response what is fluid redistribution responsible for?

Answer 35

tissue stress relaxation

Question 36

in the biphasic stress-relaxation response what does rapid redistribution of load throughout tissue reduce?

Answer 36

peak stresses and thus contributes to articular cartilage's resilience

Question 37

we load tissues until deformation but stress decreases with time because why?

Answer 37

bc of fluid redistribution

Question 38

what re the 2 types of AC lubrication systems?

Answer 38

boundary and fluid

Question 39

what is the boundary AC lubrication system?

Answer 39

each load bearing surface is coated with lubrication (diarthrodial joints)= 2 surfaces do not touch one another

Question 40

when is the boundary AC lubrication system most effective?

Answer 40

at low loads

Question 41

what is the fluid AC lubrication system?

Answer 41

a film of fluid interposed between 2 joint surfaces

Question 42

what are examples of fluid AC lubrication systems?

Answer 42

hydrostatic, hydrodynamic, squeeze film, and elastohydrodynamic

Question 43

what are the three aberrant lubrication systems?

Answer 43

adhesive wear, abrasive wear, and fatigue wear

Question 44

what is adhesive wear?

Answer 44

osteochondritis dessicans complete or incomplete separation of a portion of cartilage and bone like post it notes

Question 45

what is abrasive wear?

Answer 45

joint mouse irritation like a stone in a shoe- annoyance

Question 46

what is fatigue wear?

Answer 46

PG washout, aging, DJD

Question 47

loss of PG matrix is caused by

Answer 47

prolonged immobilization, some anti-inflammatory drugs, trauma/sx, infection and/or as a normal component of aging

Question 48

T/F loss of PG matrix is permanent?

Answer 48

False it may be reversible dependent upon degree and duration

Question 49

what do NSAIDs do to PG content?

Answer 49

decrease it

Question 50

what occurs in the early stages of development of osteoarthritis?

Answer 50

fraying of collagen bundles in superficial layer

Question 51

why do we normally see rapid progression once fraying has begun in the development of osteoarthritis?

Answer 51

due to fiber orientation (the deeper layers are perpendicular so easier to knock down)

Question 52

T/F shear force is not optimal once you get rid of the superficial layer?

Answer 52

true

Question 53

what is chondromalacia?

Answer 53

softening of cartilage

Question 54

what layers does tissue degeneration in chondromalacia appear to begin in?

Answer 54

3 and 4

Question 55

T/F it is easy to to visualize tissue degeneration in chondromalacia early on?

Answer 55

no because it doesnt appear until layers 3 and 4. generally determined by palpation