Tissue Mechanics: Bone Flashcards Preview

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Flashcards in Tissue Mechanics: Bone Deck (31)
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1
Q

what are the 2 major components of bone?

A

organic matrix- 40%

inorganic matrix- 60%

2
Q

what are the constitutents of the organic matrix of bone?

A

type 1 collagen
proteoglycans
non-collagenous matrix proteins
amorphous ground substance

3
Q

what are the constitutents of the inorganic matrix of bone?

A

calcium hydroxyapatite

4
Q

what provides tensile strength to bone?

A

type 1 collagen

5
Q

what is the significance of cross-linking of collagen fibers?

A

cross-linking decreases solubility and increases the tensile strength

6
Q

what inhibits mineralization of bone?

A

proteoglycans

7
Q

what are proteoglycans composed of?

A

glycosaminoglycans

8
Q

what is the function of proteoglycans?

A

partially responsible for COMPRESSIVE strength of bone (but must of it comes from the inorganic matrix instead)

9
Q

give some examples of the non-collagenous matrix proteins.

A

osteocalcin
osteonectin
osteopontin

10
Q

which matrix protein is most abundant and responsible for regulating bone density?

A

osteocalcin

11
Q

what provides compressive strength of bone?

A

(inorganic matrix): calcium hydroxyapaptite

12
Q

what is responsible for the mineralization of bone?

A

inorganic matrix- calcium hydroxyapatite

13
Q

describe the structure of cortical vs. cancellous bone. which is more porous? which is stratified into osteons?

A

cortical bone- less porous; is stratified into layers of osteons
cancellous bone- more porous; no osteons

14
Q

what are the types of cortical bone?

A

lamellar bone & woven bone

15
Q

describe lamellar bone vs. woven bone, which is more dense? which is stronger? describe fiber arrangement

A

lamellar bone- fibers are parallel within each lamella; less dense but it stronger than woven bone
woven bone- fibers are randomly arranged; more dense but not as strong as lamellar bone

16
Q

describe some characteristics of compact bone (cortical)- in terms of turnover, Young’s modulus, and resistance to torsion/bending.

A
  • slow turnover
  • relatively high Young’s modulus (stiff)
  • higher resistance to torsion and bending than cancellous
17
Q

describe some characteristics of cancellous (trabecular) bone- in terms of turnover, YOung’s modulus, resistance, density.

A
  • less dense; more remodeling along lines of stress
  • much larger surface area
  • higher turnover
  • lower apparent modulus (more elastic)
  • more resistance to compressive forces
18
Q

what is Wolff’s law?

A

bone remodels in response to the stresses applied to it ; this remodeling occurs to keep strain (not stress) between certain limits

  • if strain is too high –> bones become thicker and denser
  • if strain is too low -> bones become less dense and may lead to osteoporosis
19
Q

what is metaphyseal modeling?

A

(reduces bone diameter during growth) by resorption of bone at the metaphysis and adding it to the ends of bones

20
Q

what is diaphyseal modeling?

A

(increases bone diameter)- addition of bone on the periosteum and resorption of bone at endosteum

21
Q

describe the stress-strain curve for bone.

A

bone has a non-linear elastic behavior with a moderate plastic region.

22
Q

bone mechanical characteristics vary according to:

A
  • geometry
  • load mode applied
  • direction of load
  • rate of loading
  • frequency of loading
23
Q

Compare cortical and cancellous bone for load:

A

cortical >cancellous

24
Q

Compare cortical and cancellous bone for deformation:

A

cancellous > cortical (easier for cancellous bone to be deformed)

25
Q

compare energy stored between cortical and cancellous bone.

A

cancellous bone> cortical

26
Q

what is the peak age range for Young’s modulus?

A

40-50 y/o

27
Q

what is the peak age for ultimate stress?

A

40-50 y/o

28
Q

how does energy to fail change with age?

A

energy to fail decreases

29
Q

how does strain change with age?

A

strain decreases

30
Q

how does tissue density change with age?

A

stays the same

31
Q

how does apparent density change with age?

A

amount of bone decreased