Cartilage biology

Question 1

Healthy cartillage is made up of what components?

Answer 1

Proteoglycans, type II collagen and water.

Question 2

How do proteoglycans support healthy cartillage?

Answer 2

Exerts swelling, resists compression.

Question 3

How does type II collagen support healthy cartillage?

Answer 3

Provides structural support due to high tensile strength.

Question 4

Chondrocyte function

Answer 4

Producer and degrader of cartilage matrix.

Question 5

Chondrocyte properties

Answer 5

Metabolically active, adapted to low oxygen environment and no cell division after adolescence.

Question 6

What is aggrecan?

Answer 6

Proteoglycan.

Question 7

What glycosaminoglycan chains are present in aggrecan?

Answer 7

Hyaluronan, keratin sulfate and chondroitin sulfate.

Question 8

Function of glycosaminoglycan chains in aggrecan?

Answer 8

Highly negative charge. Attracts sodium and causes water to move in which results in swelling pressure that resists compression.

Question 9

What breaks down aggrecan?

Answer 9

Matrix metalloproteinases and aggrecanases.

Question 10

What is articular cartilage?

Answer 10

Hyaline cartilage found in joints.

Question 11

Intrinsic anabolic and anti-catabolic factors for articular cartilage in joints?

Answer 11

Tissue inhibitor of metalloproteinases. Growth factors.

Question 12

Extrinsic anabolic and anti-catabolic factors for articular cartilage in joints?

Answer 12

Hormones and drugs

Question 13

What maintains cartilage thickness?

Answer 13

Mechanical load.

Question 14

What does a loss of cartilage in the joints result in?

Answer 14

Osteoarthritis.

Question 15

What is the largest factor that affects load on joint?

Answer 15

Bodyweight.

Question 16

What are the molecular changes present during osteoarthritis?

Answer 16

Proteoglycan fragmented by aggrecanases. Collagen broken down by collagenases (MMP).

Question 17

What early changes in cartilage would be present in early osteoarthritis?

Answer 17

Loss of proteoglycan in superficial zone leads to fibrilation.

Question 18

What late changes in cartilage would be present in late osteoarthritis?

Answer 18

Fissuring deep into cartilage matrix, loss of cartilage thickness, formation of osteophytes and bone cysts. Synovial inflammation.

Question 19

What are osteophytes?

Answer 19

Bony lumps.

Question 20

What are bone cysts?

Answer 20

Fluid filled holes in bone.

Question 21

What is synovial inflammation?

Answer 21

Inflammation of synovial membrane.

Question 22

OA risk factors?

Answer 22

Age, obesity, joint injury, stickler syndrome.

Question 23

How would you diagnose OA?

Answer 23

Joint pain, joint stiffness and X ray for staging and treatment planning.

Question 24

Where does hand osteoarthritis occur?

Answer 24

Distal interphalangeal joint, proximal interphalangeal joint and trapeziometacarpal joint (base of thumb OA).

Question 25

How to manage OA?

Answer 25

Exercise, weight management, non steroidal anti inflammatory drug.

Question 26

OA treatment?

Answer 26

Total joint replacement. Trapeziectomy