(1) Biomechanics-- Tissue Biomechanics Cont., Bones, Cartilage Flashcards Preview

Biomechanics > (1) Biomechanics-- Tissue Biomechanics Cont., Bones, Cartilage > Flashcards

Flashcards in (1) Biomechanics-- Tissue Biomechanics Cont., Bones, Cartilage Deck (55)
Loading flashcards...
1
Q

What is the ability to return to the original shape when the load is removed?

A

Elasticity

2
Q

What is the point at which the applied stress can lead to permanent deformation?

A

yield point

3
Q

What is the nonlinear response of material after the yield point, where some degree of deformation will persist after removal of the stress?

A

Plastic region

will NOT go back to normal shape

4
Q

What is the term for the property of materials to resist load that produce shear or tensile forces?

A

viscosity

5
Q

Describe what Viscous (plastic) stretch refers to.

A

the putty-like behavior–> the linear deformation produced by tensile stress remains even after the stress it removed

6
Q

What is Viscoelasticity?

A

When a material shoes BOTH properties of viscosity AND elasticity

7
Q

What are most biologic tissues, especially tendons and ligaments?
A. Elastic
B. Viscous
C. Viscoelasticity

A

C. Viscoelasticity

8
Q

What are the two things that affect the Viscoelasticity of a tissue?

A

rate of loading AND length of time

9
Q

What are the 3 time dependent loading characteristics Viscoelastic structures will show?

A
  1. Creep
  2. Relaxation
  3. Hysteresis

(creep and relaxation are more related)

10
Q

What is the term for what occurs to tissues due to the expulsion of water?

A

Creep

11
Q

What will occur with continued deformation over time when constantly loaded?

A

Creep

12
Q

What is the corresponding eventual decrease in stress that occurs as fluid is no longer exuded?

A

Relaxation

as force no longer goes through

13
Q

What is the term for the energy loss as heat exhibited by viscoelastic materials when they are subjected to loading and unloading cycles?

A

Hysteresis

Ex: need energy to go out of tendon before can jump again

14
Q

What is Hysteresis Energy a measure of?

A

how efficient the tissue is at letting the load out

15
Q

If we have a lower/decrease Hysteresis, what does this tell us about the tissues ability to absorb force?

A

it have a better ability to absorb force = good

16
Q

How will a longer load affect Hysteresis?

A

longer the load, the greater the hysteresis

17
Q

What type of Hysteresis will tendons and have? How does this relate to injury?

A

due to be compliant (pliable/ductile)–> tendons can absorb elastic energy more easily = tend to have a decrease Hysteresis

could be related to decrease injury risk

18
Q

What would we want to warm-up before we exercise?

A

tendons are Viscoelastic–> and an increase in temperature lessens the viscosity, improving the efficiency of the tendon’s response to stretch and recoil (less Hysteresis)

19
Q

Resistance Training will strength our muscles, but will stiffen the muscle-tendon complex, so what do we do?

A

must strike right balance b/w tendon pliability and sitffness

heavy weight training will increase stiffness

flexibility exercises will increase compliance

20
Q

Is low or high Hysteresis advantageous? Why?

A

Low hysteresis–> because hysteresis is dependent on the RATE of loading and unloading

21
Q

What may dynamic exercises be beneficial fro us, like plyometrics or ballistics?

A

they may increase pliability of muscle-tendon complex –> therefore decrease hysteresis and –> decrease injury risk

22
Q

Overall, what is the bottom line when it comes to Hysteresis?

A

no ONE answer–> rate of loading/unloading is important

23
Q

In general, who is most likely to get injured?

A
  • workout in cold
  • no warm up
  • only weight lift and no stretching
24
Q

What is the Toe Region? What occurs after this is “taken away”?

A

normal range of motion

little force required to remove the “crimping” or “slack” in the tissue

after this, tissue resists elongation much more strongly

25
Q

What occurs during the Micro-Failure region of a Stress/Strain graph?

A

after slack is taken out of the soft tissue–> still ELASTIC in this region–> small amount of damage to the tissue (Grade One Sprain)

26
Q

What point of the Stress/Strain graph contains a Grade One Sprain?

A

Micro-Failure region

aka sore muscles after a workout

27
Q

What occurs during the Macro-Failure region of the Stress/Strain graph?

A

the tissue undergoes PLASTIC deformation (Grade 2 sprain) and eventually tissue ruptures (Grade 3 sprain)

28
Q

When does a Grade Three Sprain occur?

A

when tissues ruptures (in Macro-Failure region)

29
Q

When does a Grade Two Sprain occur?

A

when the tissue undergoes PLASTIC deformation (Macro-Failure Region)

30
Q

What does bone consist of? What does it provide?

A

collagen, ground substance, and minerals– in a matrix—> provides strength and support

31
Q

Describe the metabolic activity of bone.

A

one of the most dynamic and metabolically active tissues in body and remains active throughout life

32
Q

Is bone highly vascular or not? What does this allow for?

A

highly vascular –> allows for excellent capacity for self-repair

33
Q

Compare the mechanical properties of cortical bone and trabecular bone.

A

Cortical bone = stiffer/brittle

Trabecular bone = tougher

34
Q

Describe Anisotropic and its relation to bone.

A

exhibits distinct mechanical properties when loaded along various axes b/c its structure differs in the transverse and longitudinal directions

when load bone longitudinally = toughest

35
Q

Out of longitudinal loads and transverse loads, which can cortical bone tolerate the better?

A

longitudinal loads > transverse loads

36
Q

Out of tension, shear, compression, list from greatest to least of what cortical bone can withstand greater stress.

A

compression > tension > shear

37
Q

What are the two ways that bone fractures can be produced in bone?

A
  1. single load that exceeds the ultimate strength of the bone
    OR
  2. repeated applications of a lower-magnitude load (fatigue and stress Fx)
38
Q

Can bone remodel?

A

yes! it have the ability to remodel– by altering its size, shape, and structure–> to meet the mechanical demands placed on it

39
Q

What is the term for bones ability to remodel by altering its size, shape, and structure to meet the mechanical demands placed on it?

A

Wolff’s Law

NOT a degenerative response

40
Q

How is load and demand placed on bone? What does this lead to?

A

muscle activity or gravity–> leading to bone deposition

41
Q

What happens to bone when it is not needed or there is disuse or aging?

A

bone is resorbed

42
Q

What is cartilage composed of and is it vascular or avascular?

A

collagen, chondrocytes, and ground substance

avascular

43
Q

What are the three types of cartilage?

A
  1. articular cartilage (our focus)
  2. hyaline cartilage
  3. fibrocartilage
44
Q

Why is cartilage unlike any man-made material?

A

with respect to its near frictionless properties

45
Q

What type of material describes articular cartilage? What two things is it subject to?

A

it is viscoelastic

creep and relaxation

46
Q

During joint articulation, what do the forces at the joint surface vary from?

A

almost 0 to greater than 10x body weight

47
Q

What normally allows cartilage to experience minimal wear under varied load?

A

synovial lubrication

48
Q

What are two types of wear that occur to articular cartilage?

A
  1. Interfacial water

2. Fatigue water

49
Q

What will cause interfacial wear on articular cartilage?

A

adhesion or abrasion

50
Q

What type of wear of articular cartilage is the interaction of bearing surfaces?

A

Interfacial wear

51
Q

What type of wear of articular cartilage is bearing deformation under load?

A

Fatigue wear

52
Q

What causes Fatigue wear of articular cartilage?

A

repetition or high loads over a relatively short period OR with repetition of low loads over an extended period

53
Q

Describe the ability for articular cartilage to repair and regenerate.

A

it has LIMITED ability

54
Q

What determines the magnitude of stress sustained by articular cartilage?

A
  1. Total load on the joint

2. How that load is distributed over the articular surface contact area

55
Q

What will play a primary role in tissue degeneration of articular cartilage?

A

any intense stress concentration