Tissue mechanics

Question 1

Apects of tissue failure mechanics

Answer 1

• Magnitude
• Repetition
• Duration (Creep)
• Intervals bw load cycles
• Biological meterial
• direction of load

Question 2

how does repitition affect injury

Answer 2

Over time tissue tollerance will continue to diminish untill eventually somethiong u could always do hurts u

Question 3

What is Creep

Answer 3

a slow elongation of tissue due to being loaded at a constant force

Question 4

difference is you load something quick then slow

Answer 4

if you load something quick in the body, tollerance will momentarially go up because water doesnt have time to leave the system ( thus manipulation better than mobalization)

Question 5

Typical stress/ strain curve

Answer 5

1. elastic region
2. Yield point- point where the material starts to break but doesnt completely break (nonelastic region)
3. Failure point- the point at which the material breaks

Question 6

Collagen vs elastin stress strain curve

Answer 6

1. stiff, has steep slope, can withstand force w/o stretching
2. Can be stretched but will hit a wall and have a steep slope after

Question 7

easiest to break a bone w

Answer 7

shear force

Question 8

Wolffs law

Answer 8

bone will adapt and become stronger in the direction u load it

Question 9

in boot top fracture which side will break first

Answer 9

tension side

Question 10

failure mechanism in stress fracture and what inturupts it

Answer 10

tiny scratch will happen in the bone and if more force is applied stress begins to build arround the crack\
-haversion cannals and lacunea inturupt the growth

Question 11

How does trabeculae bone survive compression

Answer 11

Trabeculae will bend sideways under compression but sty strong due to horzintal cross ties
–if compression is >10% strain we get plastic deformation

Question 12

Collagen direction in skin, ligs and tendon

Answer 12

skin- haphazard pattern to handle forces from all dif firections

ligs- cross ties to also withstand joint play

Tendon- 100% collagen all orientated one direction

Question 13

Ligaments- what happens at low and high loading rates

Answer 13

low- avulsions likely

high- tear likely

Question 14

what increase in strength do you get w fascia attached

Answer 14

10%

Question 15

Why does streching increase the stiffness of fascia

Answer 15

after streching, water is drawn into the tissue which temporarily increases stiffness and matrix hydration

Question 16

In girls ACL laxity and injury is associated with which parts of their period

Answer 16

laxity- luteal

injury- follicular

Question 17

3 degrees of msucle strain

Answer 17

1- few muscle fibres tear, minor swelling + discomfort

2- greater damage to muscle and clear loss of function

3- cross sectional tear of muscle, complete loss of function

Question 18

3 phases of muscle injury

Answer 18

Destruction- necrosis of myofibres, formation of scar bridge, inflammation

Repair- Phagocytosis of necosis, regeneration of myofibres and capilarization

Remodeling- Maturation of regenerated myofibres, reorganization of scar tissue, recovery of muscle