SM 225a - Osteoarthritis Flashcards

1
Q

What are the risk factors for developing osteoarthritis?

A
  • Older age
  • Female gender
  • Genetic factors
  • Excess body weight (knee)
  • Certain occupations
  • Elite athletic activity
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2
Q

What laboratory studies can help to diagnose osteoarthritis?

A

Synovial fluid analysis

  • Would reveal non-inflammatory characteristics
    • <2000 WBCs
    • Clear fluid
    • may show CPPD crystals
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3
Q

Does severe inflammation make a diagnosis of osteoarthritis more or less likely?

A

Less likely

May see mild inflammation in osteoarthritis, but moderate to sever inflammation raises suspicion for other conditions (septic arthritis, crystal process, or both)

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4
Q

What are the characteristics of generalized osteoarthritis?

A
  • Affects the hands and at least 1 large joint
  • Familial predisposition
  • More common in women
  • Onset in middle age
  • Polyarticular finger interphalangeal joints affected
  • Symptoms persist for years, but settle down
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5
Q

What is the role of type II collagen in cartilagee?

A

Provides tensile strength

The tight weave of these fibrils contains aggrecan moleules

  • Aggrecan = proteoglycan + hyaluronic acid
    • Serves to retain water to give cartilage compressive stiffness
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6
Q

What is the of MRI in the management of osteoarthritis?

A

Small role in patient care; only used in specific situations

  • Arthroscopy under consideration
  • Possible avascular necrosis
  • Unusual pattern or course
    • Ex: rapidly progressive
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7
Q

Which cells phagocytize released (degraded) cartilage fragments?

What are the consequences?

A

Synovial cells

  • This can lead ot synovial inflammation due to the release of matrix metaloproteinases (MMPs) and cytokines
  • This leads to further alterations in the ECM and active chondrocytes
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8
Q

Which phase of osteoarthritis is characterized by:

  • Edema of the extracellular matrix
  • Microcracks appear on the cartilage surface
  • Focal loss of chondrocytes
    • Alternate with areas of proliferation
A

Phase 1

  • Phase 2
    • ​Deeper microcracks; vertical clefts form
    • Clusters of chondrocytes appear around the clefts and at the surface
  • Phase 3
    • ​Fissures -> cartilage fragments break off
      • ​Create osteocartilaginous loose bodies
    • Subchondral bone is exposed
    • Subchondral cysts form
    • Mild synovitis
    • Subchondral bone sclerosis
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9
Q

What are the protective measures in normal joints that protect against osteoarthritis?

A
  • The joint capsule and ligaments prevent excessive motion
    • Mechanoreceptors provide feedback if these restraints are stressed
  • Muscles and tendons decelerate the joint before impact occurs to distribute the load
  • Synovial fluid reduces the friction between cartilage surfaces
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10
Q

What are the key physical exam findings of osteoarthritis?

A
  • Bony enlargement
  • Limited motion (flexion and extension)
  • Crepitus
  • Malalignment
  • Mild inflammation
    • If severe, consider infection or crystal process
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11
Q

In osteoarthritis, which structures of the joint show pathologic changes?

A

All joint structures

  • Hyaline articular cartilage
  • Subchondral bony plate
  • Bone
  • Muscles

This leads to joint failure

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12
Q

What is the role of aggrecan in healthy cartilage?

A

Aggrecan = proteoglycan macromolecules + hyaluronic acid

  • Electrostatic repulsion of negative charges and retained water give cartilage its compressive stiffness
  • Aggrecan is contained in tightly woven type II collagen fibrils
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13
Q

What pharmacologic treatments are used to manage osteoarthritis?

A
  • Non-narcotic analgesic
    • Acetaminophen
  • Anti-inflammatory
    • NSAID
    • Selective COX-2 inhibitor
  • Local
    • Intra-articular
    • Corticosteroid
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14
Q

What changes occur in cartilage as a result of osteoarthritis?

A
  • Aggrecan is gradually depleted
    • Aggrecan = proteoglycan + hyaluronic acid; helps the joint resist compressive forces
  • Tighly woven collagen matrix unfurls; type II collagen is lost
  • Water content in cartilage increases initially
    • Proteoglycans are lost, so water replaces
  • Cartilage is vulneraple without the compressive stiffness usually maintained by aggrecan
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15
Q

When should you consider secondary osteoarthritis vs. primary arthritis?

A

Likely secondary if it is in a site that is not commonly affected by primary

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16
Q

What are the treatment goals for osteoarthritis?

A
  • Relieve symptoms
  • Maintain or improve function
  • Limit disability
  • Avoid drug toxicity
  • Modify disease course
    • Via lifestyle modification

There are no disease-modifying agents for OA

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17
Q

Which phase of osteoarthritis is characterized by:

  • ​Fissures -> cartilage fragments break off
    • ​Create osteocartilaginous loose bodies
  • Subchondral bone is exposed
  • Subchondral cysts form
  • Mild synovitis
  • Subchondral bone sclerosis
A

Phase 3

  • Phase 1
    • Edema of the extracellular matrix
    • Microcracks appear on the cartilage surface
    • Focal loss of chondrocytes
      • Alternate with areas of proliferation
  • Phase 2
    • Deeper microcracks; vertical clefts form
    • Clusters of chondrocytes appear around the clefts and at the surface
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18
Q

What are the major constituents of healthy joint cartilage?

A
  • Thin rim of tissue at the ends of opposing bones
  • Compressible stiffness = impact-absorption
  • Made from:
    • Collagen Type II Fibrils
    • Aggrecan
    • ECM proteins
    • Chondrocytes
19
Q

Describe the pathologic changes that occur in osteoarthritis

  • Cartilage:
  • Bone:
  • Synovium:
  • Capusule:
A
  • Cartilage:
    • Initial surface fibrillation and irregularity
    • -> Full thickness defect extending to the bone
    • -> Bare bone
  • Bone:
    • Thickening and stiffness of the subchondral plate
    • Osteophytes form at joint margins
  • Synovium:
    • May become edematous and inflamed
  • Capusule:
    • Edema
    • Eventually fibrosis
20
Q

Which imaging method is most valuable for assessing the prognosis of osteoarthritis

A

X-ray

MRI is usually only used for research or in special circumstances

21
Q

What are the characteristics of osteoarthritis?

A
  • Hyaline articular cartilage loss that is initially focal
  • Thickening and sclerosis of subchondral bony plates
  • Ougrowth of osteophytes at joint margins
  • Articular capsule stretching
  • Mild synovitis
  • Weakness of the muscles bridging the joint
22
Q

People with arthritis in the hip will most likely experience pain in which areas?

Which movements will be difficult for these patients?

A

Groin, deep posterolateral

Pain/difficulty getting in and out of the car, putting on shoes and socks

23
Q

Is there an increased risk in developing osteoarthritis physical activity?

A
  • Recreational activity: no increased risk
  • Non-elite athletics: no increaesd risk
  • Elite athletics: increaed risk
24
Q

What are TIMPs?

What happens if the TIMP levels in a joint are low?

A

TIMP = tissue inhibitors of MMPs

If TIMP levels in a joint are low, MMPs will run rampant; cartilage will be degraded

25
Q

What is the role of surgical therapy in the management of osteoarthritis?

A
  • Advanced osteoarthritis
    • Total joint replacement is effective
  • Mild/moderate osteoarthritis (if no response to conservative therapy)
    • Arthroscopy may fix mechanical symptoms (locking), but may not improve outcome
    • Role of surgery is less clear
26
Q

Describe the pathologic changes that occur in phase 3 of osteoarthritis

A
  • ​Fissures -> cartilage fragments break off
    • ​Create osteocartilaginous loose bodies
  • Subchondral bone is exposed
  • Subchondral cysts form
  • Mild synovitis
  • Subchondral bone sclerosis
27
Q

Describe the pathologic changes that occur in phase 2 of osteoarthritis

A
  • Deeper microcracks; vertical clefts form
  • Clusters of chondrocytes appear around the clefts and at the surface
28
Q

Which part of the foot is most commonly affected by osteoarthritis?

A

1st MTP joint

29
Q

What symptoms would make you suspicious for osteoarthritis?

A
  • Aching
  • If early:
    • Pain increases with use and is relieved by rest
  • If advanced:
    • Pain at rest and with use
    • Night pain, not easily relieved
    • Interrupted sleep = increased pain experience
  • Morning stiffness (lasts <30 min)
  • Stiffness after inactivity
  • Mild swelling
    • Less pronounced, less persistent than RA

Note: the correlation between damage and pain is strong with hip OA and weak with hand OA

30
Q

What features help you distinguish osteoarthritis from other types of arthritis?

A

Osteoarthritis is…

  • Gradual onset
  • Usually only one or a few joints affected at a time
  • Progression is slow
  • Strong association with older age
    • Men > 40
    • Women perimenopausal or older
31
Q

What is the role of intra-articular hyaluronic acid in the treatment of osteoarthritis?

A

Data is contradictory - no clear indication

32
Q

Which phase of osteoarthritis is characterized by:

  • Deeper microcracks; vertical clefts form
  • Clusters of chondrocytes appear around the clefts and at the surface
A

Phase 2

  • Phase 1
    • Edema of the extracellular matrix
    • Microcracks appear on the cartilage surface
    • Focal loss of chondrocytes
      • Alternate with areas of proliferation
  • Phase 3
    • ​Fissures -> cartilage fragments break off
      • ​Create osteocartilaginous loose bodies
    • Subchondral bone is exposed
    • Subchondral cysts form
    • Mild synovitis
    • Subchondral bone sclerosis
33
Q

Why does incidence of osteoarthritis increase with age?

A

Age-related decline in…

  • Neuromuscular joint protective mechanism
  • Biomechanical properties of cartilage matrix
  • Ability to rebound from injury
  • Regenerative potential of joint tissue
34
Q

What factors are associated with progression of knee osteoarthritis?

A
  • Excess body weight
  • Varus or valgus alignment
  • Meniscal damage
35
Q

What is the essential element of the pathophysiology of osteoarthritis?

A

Hyaline articular cartilage loss that is initialy focal

36
Q

Osteoarthritis results from attempts of the joint components to produce new tissue.

What pathologic changes are seen as a result?

A
  • Osteophytes (new bone)
  • Synovial hyperplasia
  • Capsular thickening
  • Initial increase in chondrocyte number and activity
37
Q

What defines generalized osteoarthritis?

A

Osteoarthritis in the hands and at least 1 large joint

38
Q

What enzymes are involved in cartilage degradation?

Where do they come from?

A

Matrix metaloproteinases (MMPs)

Released by chondrocytes and synoviocytes in response to cytokines (IL-1, TNF-alpha)

39
Q

What occurs in phase 1 of osteoarthritis?

A
  • Edema of the extracellular matrix
  • Microcracks appear on the cartilage surface
  • Focal loss of chondrocytes
    • Alternate with areas of proliferation
40
Q

What are the radiographic findings of osteoarthritis?

A
  • Focal joint space narrowing
  • Marginal and central osteophytes
  • Subchondral sclerosis and cysts
  • Osteochondral bodies
  • Bony attrition
41
Q

What non-pharmacologic treatments are recommended for patients with osteoarthritis?

A
  • Patient education
    • Self management programs
    • Social support
  • Pysical + Occupational therapy
    • Preserve range of motion, strength, aerobic capacity
    • Assistive devices
    • Improve amulation and ADLs
  • Weight loss (if overweight)
42
Q

What is the difference between functional impairment and disability?

A
  • Functional impairment
    • Impaired performance of discrete actions
  • Disability
    • Limitation of performance of socially defined tasks expected of an individual (ex: cooking, shopping)
43
Q

Which sites are most commonly affected by primary osteoarthritis?

A
  • Hands
    • DIP, PIP, Base fo thumb
    • MCPs usually spared?
  • Cervical and lubar spine
  • Feet
  • Knees
  • Hips
  • 1st MTP joint
44
Q

How does physical activity affect your cartilage and bone health?

A

Physical activity is good!

Regular loading is required to maintain cartilage and bone health.

Excess loading or joint immobilization may lead to fibrillation/thinning of cartilage