Tissue Mechanics: Cartilage Flashcards Preview

Biomechanics > Tissue Mechanics: Cartilage > Flashcards

Flashcards in Tissue Mechanics: Cartilage Deck (24)
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1
Q

Where is articular (hyaline) cartilage found?

A

joints, growth plates

2
Q

Where is fibrocartilage found?

A

IV disks, mandibular condyles, meniscus

3
Q

Where is elastic cartilage found?

A

epiglottis, eustachian tube

4
Q

does cartilage function as a shock absorber?

A

NO

5
Q

what is teh function of cartilage?

A
  • supports/transmits loads across mobile surfaces
  • distributes joint loads over a wider area (stress reduction)
  • stabilize and guide joint motion
  • lines the ends of bones (prevents wear)
  • lubrication reduces friction coefficient
6
Q

describe the composition of hyaline cartilage

A

water (58-78%)
chondrocytes (1%)
proteoglycans

7
Q

where is most of the water in cartilage found?

A

middle zone

8
Q

describe the orientation fo cartilage in its different layers.

A

superficial layer: parallel
middle layer: oblique
deep zone: perpendicular

9
Q

describe the proteoglycan content in cartialge

A

increases from surface till the middle zone and diminishes towards the deep zone
(so there is the most proteoglycan in the middle)

10
Q

the proteoglycan + collagen network limits flow of water in/out of the tissue

A

true

11
Q

what provides cartilage with its tensile strength?

A

type 2 collagen

12
Q

tissues with high proteoglycan content exhibit what properties?

A
  • high water content
  • low hydraulic permeability
  • highly resists compressive stress
  • damage to proteoglycans will result in increased water mobility and impaired mechanical function
13
Q

what happens to cartilage under tension?

A

-collagen fibers stretch along the axis of loading

14
Q

what does tensile modulus (stiffness) depend on?

A
  • type/amount of collagen cross-linking
  • density of collagen fibers
  • orientation of collagen fibers
  • tensile modulus is FLOW INDEPENDENT
15
Q

tensile modulus varies 5-25 MPa depending on what?

A
  • location of joint surface
  • depth of specimen
  • orientation of specimen relative to joint surface
16
Q

what happens to cartilage under compressive force?

A

permeability decreases

17
Q

what is the response of cartilage to shear force?

A

stretching & deformation of the solid matrix. Deformation but

  • no change in volume
  • no pressure gradient
  • no fluid flow thru the matrix
18
Q

for a 2-4mm human or bovine articular cartilage, how long does it take to reach creep equilibrium?

A

4-16 hours

19
Q

the higher the rate of loading results in what effect on cartilage?

A

more stress/more resistance

20
Q

what effect does OA have on cartilage metabolism?

A

imbalance of cartilage metabolism (anabolism/catabolism is disrupted)

21
Q

what effect does OA have on cartilage tensile and compressive stiffness?

A

both decrease

*fracture stress also decreases

22
Q

what does decreased tensile and compressive stiffness manifest as histologically and microscopically?

A

disorganized ECM (disrupted collagen and GAG network)

23
Q

what happens to hydraulic permeability with OA?

A

increases

24
Q

what are some predisposing factors to OA?

A

Immobilization, joint instability, overuse, trauma, injury, or obesity