Cartilage

Question 1

How is compressive force expressed?

Answer 1

kg/cm^3

Question 2

What is the compressive threshold for cartilage injury?

Answer 2

20-26 kg/cm^3

Question 3

Excessive unit loads on cartilage lead to…

Answer 3

damage of articular cartilage
(too much pressure can kill chondrocytes, can’t regenerate cartilage)

Question 4

What protects the joint cartilage from exceeding unit load?

Answer 4

• MC adjacent mm & tendons
• extra-articular ligaments
• joint & bone deformation (cartilage; bony curvatures)
• intra-articular structures (ligaments, menisci)

Question 5

Name 3 external support structures of a joint

Answer 5

• tendons
• ligaments
• muscles

Question 6

What are the 3 types of articular cartilage?

Answer 6

• hyaline cartilage
• fibrocartilage
• elastic cartilage

Question 7

What type of collagen is found in hyaline cartilage?

Answer 7

type 2 collagen

Question 8

What is fibrocartilage composed of?

Answer 8

type 1 collagen

Question 9

What is elastic cartilage composed of?

Answer 9

type 2 collagen + elastin

Question 10

What type of joints have hyaline cartilage?

Answer 10

synovial jts
rib cartilages

Question 11

Type 2 collagen resists ____ forces

Answer 11

compressive

Question 12

Type 1 collagen resists ____ forces

Answer 12

tensile

Question 13

What is the weakest type of cartilage?

Answer 13

hyaline

Question 14

What type of cartilage is susceptible to chondral fractures from tensile forces?

Answer 14

hyaline
(sideways forces eg. varus/valgus force on knee)

Question 15

What is an osteochondral fracture?

Answer 15

a break in cartilage and subarticular bone

Question 16

What type of cartilage resists tensile forces?

Answer 16

fibrocartilage

Question 17

What types of joints have fibrocartilage?

Answer 17

symphyseal jts & special cartilages

Question 18

Menisci are composed of what type of cartilage?

Answer 18

fibrocartilage

Question 19

The glenoid and acetabular labrums contain what type of cartilage?

Answer 19

fibrocartilage

Question 20

What type of cartilage is between the distal radioulnar joint and the carpals?

Answer 20

(triangular) fibrocartilage

Question 21

What is the strongest type of cartilage?

Answer 21

fibrocartilage

Question 22

What is the most flexible type of cartilage?

Answer 22

elastic

Question 23

Where is elastic cartilage found?

Answer 23

(not generally articular)
- pinna of ear
- eustacian tube
- epiglottis

Question 24

What type of cartilage helps to “clear” ears?

Answer 24

elastic

Question 25

What is hyaline cartilage composed of?

Answer 25

- chondrocytes - ECM

Question 26

What makes up the extracellular matric of hyaline cartilage?

Answer 26

- 70-80% water - 20-30% type 2 collagen & proteoglycans - trace amounts of lipids, phospholipids & lysozymes

Question 27

What gives the shock-absorbing capability of hyaline cartilage?

Answer 27

fluid (70-80% water)

Question 28

What draws water into hyaline cartilage?

Answer 28

proteoglycans are hydrophilic

Question 29

What proteoglycan is found in the nucleus of intervertebral discs that accounts for shock absorption?

Answer 29

chondroitin sulfate (strongly hydrophilic)

Question 30

What accounts for the decreased shock absorption of the intervertebral discs as we age?

Answer 30

chondroitin sulfate is converted to keratin sulfate which is less hydrophilic

Question 31

What are the functions of hyaline cartilage?

Answer 31

- shock absorption - lower coefficient of friction (near 0)

Question 32

Generally, hyaline cartilage should be no thicker than ____, because...

Answer 32

- 6mm - obtains nutrients via diffusion, needs to be thin

Question 33

Why would patients with Acromegaly have degenerative changes in their joints?

Answer 33

thickened cartilage reduces diffusion of nutrients

Question 34

How does healthy hyaline cartilage create a coefficient of friction near 0?

Answer 34

- smooth, glass-like surface - covered by synovial fluid (no ^heat)

Question 35

What happens to the coefficient of friction in degenerative arthritis?

Answer 35

increases (^friction, ^heat)