Osteoarthritis

Question 1

osteoarthritis

Answer 1

progressive degenerative changes in the shape, composition, and mechanical properties of joint tissues, especially the articular cartilage, leading to joint malfunction

Question 2

most common form of arthritis?

Answer 2

OA (75% of people)

Question 3

components of articular cartilage

Answer 3

matrix and chondrocytes

Question 4

composition of matrix

Answer 4

60-80% water.

Dry weight: 2/3 type 2 collagen and 1/3 proteoglycan

Question 5

collagen in matrix

Answer 5

type 2, provides tensile strength

Question 6

proteoglycan in matrix

Answer 6

negative charge, resists compression

Question 7

what happens when force is applied to a joint?

Answer 7

cartilage compresses and water is squeezed out. shock is absorbed. water then returns via the negative charges of the proteoglycans and cartilage reforms

Question 8

what is cartilage matrix lacking?

Answer 8

blood vessels and nerves.

Question 9

what lies between bone and cartilage in joint?

Answer 9

calcified cartilage

Question 10

synovium

Answer 10

2-3 cells thick, synoviocytes/blood vessels/lymphatics/nerves in posse bed of connective tissue

Question 11

synovial fluid

Answer 11

provides nutrition to chondrocytes, helps remove waste, primary role is lubrication via lubricin and hyaluronic acid

Question 12

main characteristic of OA

Answer 12

loss of cartilage and consequential functional abnormality

Question 13

inflammation in OA

Answer 13

chronic, low grade inflammation that is not a driver of the disease but aids in progress. synoviocytes release cytokines that activate proteases that chomp away at cartilage

Question 14

mechanical factors of OA

Answer 14

macrotrauma, microtrauma+time

Question 15

biochemical factors of OA

Answer 15

inflammation, proteases, imperfect repair

Question 16

who is more affected by OA

Answer 16

women!

Question 17

clinical manifestations of OA

Answer 17

decreased ROM, contractures, crepitus, osteophytes

Question 18

heberden’s node

Answer 18

osteophytes presenting on DIP

Question 19

bouchard’s node

Answer 19

osteophytes presenting on PIP

Question 20

what happens when there is abnormal loading on a joint?

Answer 20

decreased proteoglycan synthesis

Question 21

macroscopic changes indicative of OA

Answer 21

eburnation, fibrillations, cartilage thinning

Question 22

microscopic changes indicative of OA

Answer 22

clefts at surface, clustering of chrondrocyte clones, fewer chondrocytes overall

Question 23

composition changes indicative of OA

Answer 23

decreased: type 2 collagen, proteoglycans
increased: type 1 collagen, water content, glycated proteins (all leading to decreased stiffness and softening)

Question 24

why is cartilage poor at repair?

Answer 24

poor vascular supply, chondrocytes are immobile

Question 25

sclerosis

Answer 25

increase in bone density. in OA, commonly occurs at the subchondral bone

Question 26

early stage OA bone changes

Answer 26

subchondral bone thins because resorption outpaces formation

Question 27

late stage OA bone changes

Answer 27

calcified cartilage thickens, subchondral bone thickens (but is poorly mineralized and brittle), trabecular bone thins

Question 28

synovium pathology in OA

Answer 28

hyperplasia, macrophage/lymphocyte infiltrates, fibrosis, neoangiogenesis (VEGF)

Question 29

synovial fluid changes in OA

Answer 29

decreased concentrate of lubricants, decreased concentration and molecular weight of hyaluronic acid

Question 30

OA and obesity

Answer 30

8x risk, increased load and inflammation lead to OA in joints everywhere, weight loss improves symptoms