Tissue Biomechanics

Question 1

What effect do mechanical forces have on tissues?

Answer 1

Important for:
Development (of tissue and damage/disease)
Maintenance
Remodeling

Question 2

What is the definition of tissue biomechanics?

Answer 2

Study of how different parts of the human body react to external forces

Question 3

What is the definition of tension?

Answer 3

When a structure is stretched longitudinally

Question 4

What is the definition of compression?

Answer 4

When a load produces forces that push the material together

Question 5

What is the definition of shear?

Answer 5

Forces acting parallel to each other in opposite directions

Question 6

What is the definition of torsion?

Answer 6

Forces twisting/rotating in opposite directions about the long axis

Question 7

What is the definition of bending?

Answer 7

Combination of tensile and compressive loads

Question 8

What kind of a force is tension?

Answer 8

Stretching or pulling force

Question 9

What are the tension elements of the body?

Answer 9

Soft tissues (fascia, muscles, ligaments, and connective tissue)

Question 10

When do tensile forces occur in the intervertebral disc?

Answer 10

During rotational movements

Question 11

What part of the intervertebral disc tends to bear the tensile loads?

Answer 11

Annular fibers

Question 12

What is the compressive force continually being transmitted to the vertebral bodies and intervertebral discs of the spine?

Answer 12

Gravity

Question 13

How does the structure deform during a shear injury?

Answer 13

Internally in an angular manner

Question 14

What type of bone is most at risk for a fracture?

Answer 14

Cancellous bone (ex. femoral condyles and tibial plateaus)

Question 15

What spinal structures are able to resist shear forces?

Answer 15

Facet joins and fibers of the annulus fibrosus

Question 16

What areas of the spine are at risk for damage by excessive rotational force (torsion)?

Answer 16

Facet joint
Pars interarticularis
Capsule
Annulus

Question 17

What kind of long bone fracture would be an example of a torsional load failure?

Answer 17

Spiral fracture

Question 18

Long bone fractures frequently occur through what mechanism?

Answer 18

Bending (combination of compression and tension)

Question 19

What are the three common tissue responses to mechanical loading?

Answer 19

Deformation
Growth and remodeling
Failure

Question 20

What is the definition of deformation?

Answer 20

Local shape change under the effect of applied forces

Question 21

What kind of deformation occurs when an object is subjected to external forces but is in static equilibrium?

Answer 21

Some local shape change within the object

Question 22

What four things does the extent of deformation depend on?

Answer 22

Material properties
Size and shape of object
Environmental factors (ex. heat or humidity)
Force

Question 23

What is the difference between the measurement of a stress or strain?

Answer 23

Stress - measure of the intensity of the force

Strain - measure of the degree of deformation

Question 24

What is the definition of “stress” in terms of deformation?

Answer 24

The external force acting to deform the material

Question 25

What is the definition of "strain" in terms of deformation?

Answer 25

Magnitude of deformation as a result of the applied stress/loading

Question 26

What determines the strength of a tissue?

Answer 26

The maximum stress a tissue can withstand without permanent deformation

Question 27

What kind of tissue strength is considered the level of stress at the yield point of a material beyond which permanent deformation will occur?

Answer 27

Yield strength

Question 28

What kind of tissue strength is considered the maximal stress that a material can withstand prior to the initiation of failure?

Answer 28

Ultimate strength

Question 29

What kind of tissue strength is considered the stress at which the material actually breaks or ruptures?

Answer 29

Failure strength

Question 30

What is the definition of ductility?

Answer 30

Force per unit area required to deform a material, represented by the steepness (slope) of the stress/strain curve

Question 31

What kind of tissues fail at low stress by can withstand a large strain (ductile/pliant or brittle/stiff)?

Answer 31

Ductile (pliant)

Question 32

What kind of tissues can withstand high stress but fail with relatively low strain (ductile/pliant or brittle/stiff)?

Answer 32

Brittle (stiff)

Question 33

How can the amount of "toughness" of a tissue be estimated?

Answer 33

Observing the total area under the stress/strain curve

Question 34

What is the definition of "toughness" when referring to tissue?

Answer 34

The total energy required to cause material failure

Question 35

What type of tissue, (bone, tendon, or ligament), is more brittle but very strong with low overall toughness?

Answer 35

Bone

Question 36

What type of tissue, (bone, tendon, or ligament), is moderate for both strength and ductility with high overall toughness?

Answer 36

Tendon

Question 37

What type of tissue, (bone, tendon, or ligament), is more pliant but has lower strength with moderate overall toughness?

Answer 37

Ligament

Question 38

What is the definition of elasticity?

Answer 38

Ability to return to the original shape when the load is removed

Question 39

What is the yield point of elasticity?

Answer 39

Point at which the applied stress can lead to permanent deformation

Question 40

In terms of elasticity, what is the nonlinear response of the material after the yield point?

Answer 40

Plastic region

Question 41

In terms of elasticity, once reaching the plastic region, will some degree of deformation persist after the removal of the stress?

Answer 41

Yes, some

Question 42

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

Answer 42

Viscosity

Question 43

Is the linear deformation produced by tensile stress alleviated even after the stress is removed?

Answer 43

No; it remains

Question 44

What is another name for viscous stretch?

Answer 44

Plastic (putty-like behavior)

Question 45

Are most soft tissues viscous or elastic?

Answer 45

BOTH (viscoelastic)

Question 46

What affects the viscoelastic property of a material?

Answer 46

Both the rate of loading and the length of time that it is subjected to a constant load

Question 47

What is the definition of creep?

Answer 47

Continued deformation over time when CONSTANTLY loaded

Question 48

What is the cause of the creep in tissues?

Answer 48

Expulsion of water

Question 49

What is the definition of relaxation in terms of viscoelastic tissue?

Answer 49

The corresponding eventual decrease in stress that will occur as fluid is no longer exuded

Question 50

What is the definition of hysteresis?

Answer 50

Energy loss exhibited by viscoelastic materials when they are subjected to loading and unloading cycles

Question 51

What effect does load size have on hysteresis?

Answer 51

Increased load = increased hysteresis

Question 52

What happens to hysteresis levels when a load is applied a second time?

Answer 52

Decreases (less capacity to absorb the shock energy)

Question 53

What is the "toe region" of a tissue?

Answer 53

Its normal range of motion

Question 54

When does micro-failure of a tissue occur?

Answer 54

After taking out the slack

Question 55

What kind of sprain is an example of a micro-failure?

Answer 55

Grade One

Question 56

At the micro-failure stage, is a tissue still elastic?

Answer 56

Yes

Question 57

What kind of stress is present when plastic deformation starts?

Answer 57

Yield stress

Question 58

What kind of sprain is known as a macro-failure where the tissue undergoes plastic deformation?

Answer 58

Grade Two

Question 59

What kind of sprain occurs when a tissue ruptures?

Answer 59

Grade Three