Osteoarthritis

Question 1

What is osteoarthritis?

Answer 1

Joint failure/pathologic changes in all joint structures with hyaline articular cartilage loss, thickening/sclerosis of bony plates, outgrowth of osteophytes at joint margins, articular capsule stretching, mild synovitis, and weakness in muscles bridging joints

Question 2

What are systemic risk factors for OA?

Answer 2

Older age, female sex, genetic factors, excess body weight, certain occupations, elite athletic activity

Question 3

What are local risk factors for OA?

Answer 3

Major injury, meniscectomy, developmental abnormalities, varus alignment, meniscal tear/meniscal extrusion

Question 4

What are occupational risk factors for OA?

Answer 4

Knee - heavy lifting, mining
Hip - farming
Elbow - jackhammer operator
Hand - cotton mill

Question 5

What is the natural history of OA?

Answer 5

Some joints will not progress, others will have phases of compensation (remodeling) and decompensation (more insult than repair)

Question 6

What are the constituents of healthy cartilage type II?

Answer 6

• type II cartilage collagen fibrils
• aggrecan
• ECM proteins
• chondrocytes

Question 7

What is the function of aggrecans?

Answer 7

Proteoglycans that link with hyaluronic acid and retain water to give cartilage compressive stiffness

Question 8

What is the function of chondrocytes?

Answer 8

Cartilage cells that synthesize elements of the matrix, produce cytokines/growth factors/enzymes

Question 9

What are the main proteinases involved in cartilage destruction of OA?

Answer 9

Matrix metalloproteinases

Question 10

What controls the function of MMPs?

Answer 10

TIMPs (tissue inhibitors of MMPs)

Question 11

What are the stages of cartilage pathology in OA?

Answer 11

surface fibrillation and irregularity –> full-thickness defect to the bone –> cartilage damage/loss to bare bone

Question 12

What pathological changes occur in bones in OA?

Answer 12

Thickening/stiffening of subchondral plate and osteocyte formation in joint margins

Question 13

What pathological changes occur in the synovium in OA?

Answer 13

Can become edematous and inflamed (but not as much as inflammatory joint pains)

Question 14

What pathological changes occur int he joint capsule in OA?

Answer 14

Edema, later fibrosis

Question 15

What is phase 1 of OA?

Answer 15

• edema of ECM
• microcracks on cartilage
• focal loss of chondrocytes, alternating with areas of proliferation

Question 16

What is phase 2 of OA?

Answer 16

• microcracks deepen
• vertical clefts form in cartilage
• clusters of chondrocytes appear around these clefts and at surface

Question 17

What is phase 3 of OA?

Answer 17

• fissures cause cartilage fragments to break off (osteocartilaginous loose bodies)
• subchondral bone uncovered
• subchondral cysts
• mild synovitis
• subchondral bone sclerosis

Question 18

What sites are commonly affected by primary OA?

Answer 18

Hands (DIP, PIP, first CMC)
Cervical and lumbar spine
Feet (especially 1st MTP big toe)
Knees (medial or lateral tibiofemoral compartment not both)
Hips
C and L spine

Question 19

What joint involvement pattern is suggestive of generalized OA?

Answer 19

Hands + at least one large joint

Question 20

What are Heberden’s nodes?

Answer 20

Enlarged DIP joints, common in generalized OA

Question 21

What are symptoms of early OA?

Answer 21

aching pain that increases with joint use and is relieved by rest

Question 22

What are symptoms of advanced OA?

Answer 22

aching pain at rest and with use, night pains, sleep interference worsens pain

Question 23

What are key physical exam findings of OA?

Answer 23

• bony enlargements at joints
• limited motion
• crepitus (crackling)
• malalignment
• mild inflammation, warmth, and effusion

Question 24

What are bouchard’s nodes?

Answer 24

Swelling at the proximal interphalangeal (PIP) joints

Question 25

What are the common synovial fluid findings of OA?

Answer 25

non-inflammatory fluid, low turbidity, low WBC, may have pseudogout crystals

Question 26

What are radiographic findings associated with OA?

Answer 26

- focal joint space narrowing, often asymmetric - marginal and central osteophytes - subchondral sclerosis and cysts - osteochondral bodies - bony attrition

Question 27

Which imaging modality is most useful for evaluation of OA?

Answer 27

X-rays, MRIs are mostly used in research and do not demonstrate findings that would alter management

Question 28

What factors are associated with progression of knee OA?

Answer 28

Excess body weight, varus alignment (bow-legged), valgus alignment (knock-knee), meniscal damage

Question 29

What are the non-pharmacologic treatments of OA?

Answer 29

- education on coping strategies and self-efficacy - physical and occupational therapy - weight loss

Question 30

What are systemic pharmacologic treatments of OA?

Answer 30

- non-narcotic analgesics (acetaminophen) - anti-inflammatories (NSAIDs, COX-2 inhibitors) - narcotic analgesics

Question 31

What are local pharmacologic treatments of OA?

Answer 31

- intra-articular injections - corticosteroids - hyaluronic acid (low evidence)

Question 32

What are disease-modifying pharmacologics for OA?

Answer 32

There aren't any