Cartilage

Question 1

What is the role of articular cartilage?

Answer 1

• Transfers force between articulating bones
• Distributes forces in joints
• Allows relative movement between articular surfaces with minimal friction

Question 2

What are the characteristics of articular cartilage?

Answer 2

• Cells
• Intercellular matrix
• Avascular
• Aneural
• Synovial Fluid

Question 3

What percentage of the cartilage are cells and what do they contain?

Answer 3

5-10%

- contains chondrocytes

Question 4

What percentage of the cartilage are intercellular matrix and what do they contain?

Answer 4

90-95%

- water (65-80%) and structural macro molecules (20-35%)

Question 5

what are structural macro-molecules

Answer 5

• collagen (type ii)

- proteoglycan

Question 6

What is collagen?

Answer 6

• structural framework of cartilage, tendon and ligament
• tensile stiffness and strength
• Little resistance to compression
• Exploit tensile strength

Question 7

What are Proteoglycans?

Answer 7

- Visco-elastic properties 
(depends on load and rate)
- negative electro static charge
- attracted to water
-reacts to compressive

Question 8

What are the physical properties of cartilage?

Answer 8

Tensile
Compressive
Shear
Visco-Elastic

Question 9

Describe Tensile properties of cartilage

Answer 9

• These are determined by the arrangement of collagen

- Tensile strength is higher parallel to the surface than perpendicular

Question 10

Describe Compressive properties of cartilage

Answer 10

• Determined by proteoglycan content

- Compressive stiffness least at surface and greatest in the middle zones

Question 11

Describe Shear properties of cartilage

Answer 11

• provided by arrangement of collagen

Question 12

Describe Visco-Elasticity properties of cartilage

Answer 12

• associated with movement of water in the tissue
• The higher the pressure and compressive strains, the less permeable cartilage become
• Display ‘creep’

Question 13

What are essential to keep the cartilage healthy?

Answer 13

Mechanical loading and unloading of joints

• Influx of nutrient
• Efflux of waste products

Question 14

When does the remodelling process begin

Answer 14

When the cartilage is damaged

Question 15

What is the job of chondrocytes?

Answer 15

-synthesise new matrix components but fails to restore matrix to normal

Question 16

What is the failure of the cartilage due to?

Answer 16

• Acute
• -> Active forces
• -> Impact forces
• Chronic
• -> Interfacial wear caused by lack of lubrication in abnormal or degenerative joints.
• -> Fatigue wear - occurs when proteoglycan-collagen matrix is damaged by cyclic stressing.

Question 17

What are the menisci?

Answer 17

Fibrocartilage

• spacer and stabiliser
• shock absorber

Question 18

What are the basic physics of MRI?

Answer 18

• strong magnetic field aligns the protons in the body
• perpendicular magnetic field pulses at different frequencies
• different tissues of the body re-aligns at different speeds emitting different radio-frequencies

Question 19

What are the key features of an MRI?

Answer 19

• it is a 3D image of all structures of the body
• much greater contrast of different soft tissues than CT
• Lengthly imaging (40-60mins)
• expensive (350 per scan)
• no ionizing radiation

Question 20

What patients may not be able to have MRI

Answer 20

pacemaker
Stimulator implant
claustrophobia

Question 21

What is arthroscopy

Answer 21

Surgical technique for viewing inside patient joints

Question 22

what are characteristics of an osteoarthritic knee?

Answer 22

• degenerative condition of cartilage and underlying bone
• can occur at any joint on body
• occurs in 15% of 60+ experience
• caused by mechanical stress within sufficient repair

Question 23

How do you treat osteoarthritis

Answer 23

• Lifestyle modification
• pain medication
• joint replacement