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Eq SX Musc Skel Exam > Osteoarthritis > Flashcards

Osteoarthritis Flashcards

1
Q

Health/function of joint depends on

A
  1. Anatomy (mechanics)
    - Energy efficient motion
    - Shock absorption
  2. Physiology (biology)
    - Balance of anabolic/catabolic proc
    - Regulation of inflammation
    - Response to dz and infection
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2
Q

Articular cartilage components (hyaline cartilage)

A
  1. Chondrocytes-1-2% total cartilage volume

2. Extracellular matrix-70% water, 30% dry weight

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3
Q

Extracellular matrix

A
  1. 70% water
  2. 30% dry weight
    - 50% collagen (mostly type II)
    - 35% proteoglycans
    - 10% glycoprotein
    - 5% mineral, lipids, other
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4
Q

Chondrocytes

A
  1. synthesize, organize, regulate composition of extracellular matrix
  2. Detect and respond to mechanical stimuli
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5
Q

Collagen fibrils

A
  1. 90-95% type II collagen
  2. Slow turnover
  3. Framework for organizatino of other matrix molecules/chondrocytes
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6
Q

Proteoglycans

A

Glycosaminoglycans (GAGs) attached to protein core

  1. Aggrecan
    - 85% proteoglycan content of ECM
    - Core protein interacts with hyaluronan
    - neg charged glycosaminoglycans
    - Condroitin sulfate
    - Keratin sulfate
    - Resists compressive forces (high density neg charge attracts water to separate molecules)
  2. Small proteoglycans
    - bind growth factors, regulate collagen synthesis
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7
Q

Cartilage nutrition

A

Nutrition and waste removal through synovial fluid

-applied load compresses cartilage squeezes things out

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8
Q

Collagen resists osmotic pressure exerted by proteoglycans resulting in

A

positive cartilage swelling pressure

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9
Q

Cartilage layers

A
  1. Superficial (tangential)
    - chondrocytes and collagen arranged parallel to joint surface
    - Most dense zone of collagen and cells
  2. Intermediate (transitional)
    - larger ovoid chondrocytes
    - collagen fibers oblique to surface
    - many branching fibers
  3. Deep (radiate)
    - largest chondrocytes arranged perpendicular to surface and arranged in columns
    - collagen fibers oriented perpendicular to surface
  4. Calcified cartilage
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10
Q

Two other important cartilage structures

A
  1. Tidemark
    - junction of calcified and noncalcified cartilage
  2. Subchondral bone
    - supports cartilage
    - determines shape and congruity of joint surface
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11
Q

Synovial membrane

A
  1. Subintimal layer

2. Intimal layer

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12
Q

Subintimal layer of synovial membrane

A
  • fibrous and fatty tissue

- abundant vascular and nerve supply

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13
Q

Intimal layer of synovial membrane

A
  • 1 to 4 synoviocytes thick, no basement membrane to allow passage of plasma and production synovial fluid
  • Type A synoviocytes-phagocytes
  • Type B synoviocytes-secrete protein
  • Type C synoviocytes-intermediary between A and B
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14
Q

Type B synoviocytes

A
  1. Synovial fluid components
    - hyaluronan, lubricin, collagen
  2. Inflammatory and catabolic cytokines
    - interleukins, prostaglandins, pro-matrix metalloproteinases
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15
Q

Synovial fluid

A
  1. Ultrafiltrate of plasma (low protein < 2 g/dL)
  2. Low cellularity (< 500 cells/uL) 90% monos
  3. Inflammation alters permeability
  4. Hyaluranon
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16
Q

Hyaluranon

A
  1. Large molecule
  2. Responsible for synovial fluid viscosity
  3. High affinity for water
  4. Molecules entangle, provides joint fluid viscosity
17
Q

Subchondral bone

A
  • Dense, like cortical bone in diaphysis of long bones
  • Haversian canals run parallel to joint surface
  • Supports cartilage
18
Q

Ligaments/tendons/muscle

A

Regulate range of motion and provide stability

19
Q

Joint capsule

A
  • Fibrous, poorly cellular
  • Composed of collagen, proteoglycan, noncollagenous proteins and water
  • Lined by synovial membrane
  • regulates range of motion and stabilizes
20
Q

Vascular supply

A
  • Substantial to synovial membrane

- None to cartilage

21
Q

Innervation

A
  1. Proprioceptive and nociceptive fibers
  2. Nerve fibers terminate in joint capsule, ligaments, menisci
  3. No ennervation in articular cartilage
22
Q

Matrix Metalloproteinases (MMPS)

A
  • Articular cartilage/extracellular matrix degradation

- Released in latent form, must be activated

23
Q

Aggrecanases

A

ADAMTS4 and ADAMTS5

-A Disintegrin And Metalloprotease with ThromboSpondin motifs

24
Q

Cytokines

A
  1. Soluble peptides produced by cells (endocrine/paracrine/autocrine fashion)
  2. Proinflammatory cytokines
    - IL-1a and b, TNF-a
  3. Proteoglycan synthesis inhibition
    - IL-1a and b stim production of MMPs by chondrocytes and synoviocytes
  4. Inhibited by IL-1 receptor antagonist protein (IRAP)
25
Q

Prostaglandins

A
  1. PGE2
  2. Causes proteoglycan depletion from cartilage matrix
    - softening of cartilage
  3. Enhances pain perception
  4. Production stimulated by IL-1
26
Q

Oxygen derived free radicals

A
  1. Produced by neutrophils and macrophages

2. Cleaves proteoglycan, collagen, and hyaluranon molecules

27
Q

Consequences of inflammatory mediator production

A
  1. biochemical damage to articular cartilage
  2. Accelerated degradation articular cartilage collagen and proteoglycan
  3. Inability of chondrocytes to replace collagen and proteoglycans
  4. Weakened articular cartilage can’t resist loading and shear stress
  5. Development gross cartilaginous lesions
  6. Wear particles causes continued damage and further mediator production
28
Q

Intrinsic mech cartilage repair

A
  1. inc metabolic activity of chondrocytes
  2. increased cell division
  3. synthesis proteoglycans and collagen
29
Q

Extrinsic mech cartilage repair

A
  1. Mesenchymal elements subchondral bone produce connective tissue
    - fibrocartilage, not type II collagen
30
Q

Matrix flow cartilage repair

A
  1. Cartilage produced at periphery of lesion
  2. Wave-like lips of cartilage migrate towards center of defect
  3. very limited movement
31
Q

Partial thickness lesions

A
  1. Calcified cartilage layer not breached
  2. Minimal to no inflammatory response
  3. some intrinsic repair
  4. pre-existing cartilage superior to repair cartilage
32
Q

Full thickness lesions

A
  1. Injury through to subchondral bone with exposure
  2. penetration of SC bone causes inflammatory repsonse
  3. formation of granulation tissue
  4. fibroblasts recruited and produce collagen
  5. fibrous tissue undergoes chondrification to produce fibrocartilage (inferior to type II)
33
Q

Osteochondral defect

A

Injury extends into or beyond subchondral bone

34
Q

Osteoarthritis definition

A

Chronic degeneration of joint tissues/articular cartilage, w/ irreversible changes to joint.

35
Q

OA occurs due to

A

cumulative effects of joint tissue over time, or single major trauma

36
Q

Altered mechanics of injury produce change in

A

biology (catabolism>anabolism) of joint which further degrades mechanical properties of joint.

37
Q

Tissue changes contributing to or resulting from OA

A
  1. Synovitis
  2. Capsulitis
  3. Ligamentous damage
  4. primary cartilage damage
38
Q

Diagnosis of OA

A
  1. PE
  2. Local anesthesia
  3. Rads
  4. U/S
  5. Nuclear Scintigraphy
  6. Computed tomography
  7. MRI
  8. Synovial fluid analysis
39
Q

Treatment of OA

A
  1. REST
  2. SX
    - arthroscopy
    - arthrodesis
    - facilitated ankylosis
  3. Medical therapy
    - NSAIDS
    - Corticosteroids
    - Dz modifiers
    - Biologics
    - Complementaries

Eq SX Musc Skel Exam (20 decks)

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