Ligaments | Tendons | Nerves

Question 1

What elements make up the structure of capsule, ligaments and tendons?

Answer 1

~20% cellular material

~80 Extra-cellular material (70% water, 30% solids: collagen, ground substance - proteoglycons, amino acids -, elastin

Question 2

Describe the role of type I and Type III collagen

Answer 2

Type I: resists tensile forces (stretching).

Type III: more elastic; increased recoil capacity

Question 3

Collagen is primarily type….

Answer 3

Type I: important for resisting tensile forces

Question 4

Collagen fibres and cells align in the direction of the force. What process is this called?

Answer 4

Reorientation

Question 5

Name Six types of loading

Answer 5

Compression
Tension
Shear
Torsion
Bending
Combined (tension + compression)

Question 6

What are 3 measurements of force?

Answer 6

1. Strain gauge (ligaments)
2. Instrom testing (compression/tensile)
3. Insitu muscle testing (change length)

Question 7

What are the biomechanical variables of interest (load:elongation graph)

Answer 7

Toe-in Region
(Stiffness)
Elastic Limit
Ultimate Load
Ultimate Elongation

Question 8

The tissue is at what point when it is stretched to the point of rupture?
(biomechanical variables of interest)

Answer 8

Ultimate Load

Question 9

Stiffness describes the relationship between a change in load and a change in elongation. T or F?
(biomechanical variables of interest)

Answer 9

True: it is represented by the linear region of the Load:Elongation curve and is experienced between the Toe Region and Elastic Limit

Question 10

What does the area under the load:elongation curve represent?
(biomechanical variables of interest)

Answer 10

Energy absorbed. When a muscle is unable to absorb sufficient energy, it’s risk of rupture will increase

Question 11

Describe the Toe-in Region

Answer 11

Observed at the start of stretch where there is little resistance to stretch.

Influencing factors include: fibre orientation, slippage of collagen fibres, injury

Fibres are slight crimped. As stretch increases, they straighten out as they transition from Toe-in region to elastic region

Tension (stretch) lengthens fibres, stretch tissue, cause collagen fibres to slip. This increases toe-in region.

Question 12

What structures prevent overstretching of sarcomeres during toe-in region?

Answer 12

Endomysium and perimysium: stretch to protect contractile elements from damage

Question 13

What at the toe-in region of damaged tissue?

Answer 13

There is little resistance when load is applied resulting in length without resistance. More movement will occur with less resistance, reducing the stability of the joint

Question 14

Describe Elasticity

Answer 14

the ability of a material to resume its original size once the force is removed

The return to normal position indicates no damage to tissue

Question 15

Describe Plasticity

Answer 15

Continued application of force lengthens tissue to a point of damage (collage fibrils may be torn). Once force is removed, tissue does not return to original length resulting in permanent deformation.

Question 16

Factors that influence the biomechanical parameters when tissue is stretched

Answer 16

Size and strength of ligaments and tendons
Ageing
Velocity of stretch
Intrinsic factors (within musculo-tendinous unit: contractile elements)

Question 17

_____ is important to the strength of the tissue

Answer 17

size

The larger the tissue, the greater the strength and energy capacity (how much it can absorb)
- has a higher ultimate load before rupture

Question 18

How does age effect ligaments

Answer 18

Stiffness decreases by ~30%

Ultimate load up to 3x lower in older people

Rupture site: mid-substance of tissues in older people, closer to insertion points in younger people

Question 19

Explain how tissues respond differently to fast and slow velocities of stretch and what damage is likely to occur.

Answer 19

Fast: higher load applied to tissue, demanding greater strength and resistance from tissues. This results in stiffness.

More likely to result in tearing; damage to mid-substance of tissue

Slow: lower force levels applied, allowing tissues to lengthen with less strain as they build their capacity for elongation/withstanding load/stretch. Used in recovery stage to reduce risk of further damage

More likely to result in avulsion (separation); damage at point of insertion

Question 20

What are the effects of immobilisation on ligaments?

Answer 20

Disorganisation of collage
Varied shape to fibroblasts
Changes in water and proteoglycan content

These lead to:

• change in size of ligament
• reduced strength
• increased compliance: less stiffness/resistance capacity

> > > weaker tissue

(Characteristic elements of ligament + biomechanics variables related to strength, stiffness, and energy absorption)

Question 21

Why might complete ruptures occur when low level forces (intensity) is applied?

Answer 21

When there are pre-existing degradation of the tissue, reducing its strength and point of ultimate load

Question 22

Why is immobilisation important when repairing tendons?

What other tissues may be impacted due to immobilisation?

Answer 22

It allows the ends of tendons to start healing; ideally to a similar length prior to injury

Other Tissues: ligaments around joint, intrinsic muscles may experience atrophy, changes in collagen, reduced strength etc. as a result

Question 23

Weight Bearing impacts the about of energy stored and therefore the _________ of the tissue

Answer 23

Elasticity.

The greater energy stored, the greater the capacity for tissues to recoil.

Question 24

Two steps to rebuild tendon function following immobilisation

Answer 24

1. reorganize collagen

2. remodel scar tissue

Question 25

What is creep?

Answer 25

change in length of tissue when load is applied and held constant.

Sliding of collagen occurs at fasicle/fibre level, and water is redistributed resulting in the gradual lengthening of the tissue.

Question 26

When does the greatest amount of change occur during creep?

Answer 26

In the first 5 minutes, sliding of collagen fibres and redistribution of fluid and proteoglycans is evident, before becoming gradual after 20 minutes

Question 27

____ creep occurs when the same loading level is applied repetitively i.e. on the achilles tendon during running

Answer 27

Cyclic

Question 28

Less force leads to less tension in tissues which leads to a reduced…….?

Answer 28

Risk of injury