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Flashcards in Osteoarthritis Deck (30):
1

osteoarthritis

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

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most common form of arthritis?

OA (75% of people)

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components of articular cartilage

matrix and chondrocytes

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composition of matrix

60-80% water.
Dry weight: 2/3 type 2 collagen and 1/3 proteoglycan

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collagen in matrix

type 2, provides tensile strength

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proteoglycan in matrix

negative charge, resists compression

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what happens when force is applied to a joint?

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

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what is cartilage matrix lacking?

blood vessels and nerves.

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what lies between bone and cartilage in joint?

calcified cartilage

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synovium

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

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synovial fluid

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

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main characteristic of OA

loss of cartilage and consequential functional abnormality

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inflammation in OA

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

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mechanical factors of OA

macrotrauma, microtrauma+time

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biochemical factors of OA

inflammation, proteases, imperfect repair

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who is more affected by OA

women!

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clinical manifestations of OA

decreased ROM, contractures, crepitus, osteophytes

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heberden's node

osteophytes presenting on DIP

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bouchard's node

osteophytes presenting on PIP

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what happens when there is abnormal loading on a joint?

decreased proteoglycan synthesis

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macroscopic changes indicative of OA

eburnation, fibrillations, cartilage thinning

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microscopic changes indicative of OA

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

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composition changes indicative of OA

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

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why is cartilage poor at repair?

poor vascular supply, chondrocytes are immobile

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sclerosis

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

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early stage OA bone changes

subchondral bone thins because resorption outpaces formation

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late stage OA bone changes

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

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synovium pathology in OA

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

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synovial fluid changes in OA

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

30

OA and obesity

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