Cartilage biology and osteoarthritis

Question 1

What are the 5 layers of cartilage?

Answer 1

Superficial
Transitional/intermediate
Deep/radial
Calcified
Bone

Question 2

What is the visual line between the deep and calcified cartilage called?

Answer 2

Tide mark

Question 3

What is in the ECM of healthy cartilage?

Answer 3

Proteoglycan (aggrecan)
Type 2 collagen
water

Question 4

Why does aggrecan exert a negative swelling pressure?

Answer 4

Negatively charged so attracts water, which helps cartilage resist compression

Question 5

What is the only cell in articular cartilage?

Answer 5

Chondrocyte

Question 6

What percentage of cartilage do chondrocytes make up?

Answer 6

5%

Question 7

What is the role of chondrocytes in articular cartilage matrix?

Answer 7

Producer and degrader of cartilage matrix

Question 8

Are chondrocytes highly metabolically active?

Answer 8

Yes

Question 9

Do chondrocytes exist in a state of relative hyperoxia?

Answer 9

No- relative hypoxia

Question 10

When does cell division in chondrocytes stop?

Answer 10

After adolescence

Question 11

What structure are type 2 collagen chains?

Answer 11

Triple helix

Question 12

When does matrix loss occur?

Answer 12

When degradation outweighs anabolism

Question 13

What is needed to maintain cartilage thickness and turnover?

Answer 13

Mechanical load

Question 14

What patients have cartilage atrophy and why?

Answer 14

Stroke patients due to decrease weight baring (mechanical load)

Question 15

What are 3 pieces of evidence for mechanical factors in OA?

Answer 15

1. Paralyzed joints are usually protected from OA
2. Maligned joins get OA
3. Occupational examples of increased use e.g. coal miner’s back

Question 16

Describe the hypothesis for OA.

Answer 16

(Normal joint, abnormal load) or (abnormal joint, normal load)
Leads to mechanical tissue injury
Tissue damage/inadequate repair
Leads to symptomatic OA

Question 17

Can OA be diagnosed from clinical symptoms only?

Answer 17

Yes

Question 18

What are 4 clinical signs of OA?

Answer 18

1. Joint pain typically on activity
2. Stiffness, typically <30mins
3. Loss of function
4. Examination findings: crepitus, deformity, loss of range

Question 19

Is CRP in OA normal or abnormal?

Answer 19

Normal

Question 20

What are the crooked nodully fingers in OA called?

Answer 20

Heberden’s nodes

Question 21

At what stage in life does hand OA often occur in women?

Answer 21

Around menopause but may settle after 2-5 years

Question 22

What is a good surgical treatment for OA in base of thumb?

Answer 22

Trapeziectomy (removal of thumb bone)

Question 23

What is a syMOAD and what does it do?

Answer 23

Symptom modifying OA drug
Aim to treat pain and improve function

Question 24

What is a DMOAD and what does it aim to do?

Answer 24

Disease modifying OA drug
Slow/prevent early disease