201 L6

Question 1

Name the Types of mechanical loads.

Answer 1

Tension
Compression
Shear
Torsion
Bending

Question 2

What mechanical loads affect cartilage?

Answer 2

Mainly compression

Also shear

Question 3

What mechanical loads affect bone?

Answer 3

Tension and compression in equal amounts

Question 4

What mechanical loads does articular cartilage experience?

Answer 4

Main = Compression
Less = Tension and shear at surface

Question 5

What form of cartilage is articular cartilage?

Answer 5

Hyaline cartilage

Question 6

Where is articular cartilage found?

Answer 6

On the ends of bones between joints.

Question 7

What is the function of articular cartilage?

Answer 7

Limits the amount of shear stress and friction

Provides a coating for the underlying bone

Question 8

What is the function of cartilage with respect to load bearing?

Answer 8

Cartilage spreads the load

Question 9

What happens to cartilage when it meets the blood supply?

Answer 9

It dies

Question 10

Name the zones in articular cartilage?

Answer 10

Articular surface
Superficial zone
Middle zone
Deep zone
Calcified zone
Subchondral bone
Bone

Question 11

In the ———- zone the ——– fibres are ——– to the ——– surface providing a smooth surface to minimise —— stress.

Answer 11

In the superficial zone the collagen fibres are parallel to the articular surface providing a smooth surface
to minimise shear stress.

Question 12

In the ———- zone the ——– fibres go in — ——–. This makes this zone the ——— load bearing zone.

Answer 12

In the middle zone the collagen fibres go in 3 dimensions. This makes the zone the most load bearing zone.

Question 13

In the ——– zone the ———– fibres are ———— to the surface. Here the fibres cross the ——- into the ——- zone and plug into the ——–.

Answer 13

In the deep zone the collagen fibres are perpendicular to the surface. Here the fibres cross the tidemark into the calcified zone and plug into the bone.

Question 14

Loading cycle of articular cartilage:

1. In recently ———— cartilage ——— charges on the repeating ——— units attract ——— ions into the ———- from the ——– space. This ————- the —— concentration in the ——–.
2. The —— in ionic concentration creates an —— gradient which draws ——- into the ——-. The cartilage begins to ——– with the influx of ———.
3. As the cartilage swells the ——– is placed under increasing ——. Eventually the ———- force = the ——— force, and the cartilage stops swelling. This is known as the ——— ———–.
4. When a —— is introduced the ——– ions and ——– are squeezed ——- of the cartilage and back into the —– space and ——— fluid.
5. The loss of ——- reduces the ——— of the cartilage, which is called ——–. This pushes the ——– charges closer together. Eventually the ———— load will be supported by the —— component and the repulsive ——– charges. The cartilage will stop ——— when it is ——– equilibrium

Answer 14

1. In recently unloaded cartilage negative charges on the repeating dissacharide units attract + ions into the cartilage from the joint space. This increases the ionic concentration in the matrix.
2. The increase in ionic concentration creates an osmotic gradient which draws water into the matrix. The cartilage begins to swell with the influx of water.
3. As the cartilage swells the collagen is placed under increasing tension. Eventually the swelling force = the tension force, and the cartilage stops swelling. This is known as the unloaded equilibrium.
4. When a load is introduced the + ions and water are squeezed out of the cartilage and back into the joint space and synovial fluid.
5. The loss of water reduces the volume of the cartilage, which is called creep. This pushes the negative charges closer together. Eventually the compressive load will be supported by the solid component and the repulsive negative charges. The cartilage will stop swelling when it is loaded equilibrium.

Question 15

What collagen fibres are in articular cartilage?

Answer 15

Type 2

Question 16

If the articular cartilage loses its ability of —– and the strength of the —— network it will start of wear away.

Answer 16

If the articular cartilage loses its ability of hydration and the strength of the collagen network it will start of wear away.

Question 17

The quicker you —- the cartilage the quicker the —– comes out.

This refers to ———-

Answer 17

The quicker you load the cartilage the quicker the water comes out.

This refers to viscoelastic

Question 18

When the load is first introduced to the articular cartilage what component supports the load first and why?

Answer 18

Fluid component can’t escape immediately takes a bit of time so when the load is first introduced the fluid component is what actually supports the load first

Question 19

What tissues does Osteoarthritis affect?

Answer 19

All the tissues of the joints:
Cartilage
Bone
Muscle
Ligaments

Question 20

What body parts are commonly affected by osteoarthritis?

Answer 20

Knee, hands and hips

Question 21

Osteoarthritis typically occurs ——- in life, usually after age ——, although may start ——– in the case of joint ——-.

Answer 21

Osteoarthritis typically occurs later in life, usually after age 50, although may start earlier in the case of joint injury.

Other than joint replacement surgery there is no cure

Question 22

What is the causation of primary and secondary osteoarthritis?

Answer 22

Primary = unknown
secondary = injury

Question 23

What are some risk factors of osteoarthritis?

Answer 23

Age
obesity
genetics

Question 24

What happens to ECM and chondrocytes in osteoarthritis?

Answer 24

Fibrillation of collagen network at zone 1

Breakdown of collagen network, swelling of tissue due to increased water presence

Loss of proteoglycans results in fissure cracks

Cells divide forming clusters of cells, there is futile repair and secretion of matrix

The zones wear away resulting in osteophytes - bony knobs at joint margins.

Question 25

What are present in joint food?

Answer 25

Glucosamine

chondroitin sulphate

Question 26

What does glucosamine and

chondroitin sulphate achieve in joint food?

Answer 26

Anti inflammatory property - may help with the pain, but does not repair the cartilage