OA

Question 1

Front

Answer 1

Back

Question 2

Define osteoarthritis (OA).

Answer 2

Degenerative joint disease characterised by progressive loss of articular cartilage, subchondral bone remodelling, osteophyte formation, and synovial inflammation leading to pain and functional limitation.

Question 3

Which joints are most commonly affected in OA?

Answer 3

Weight-bearing joints (knees, hips, spine), hands (DIP, PIP, 1st CMC), and feet (1st MTP). MCP joints are spared.

Question 4

Pathophysiology of OA?

Answer 4

Mechanical stress + biochemical degradation → chondrocyte injury → ↑ matrix metalloproteinases (MMPs), ↓ type II collagen synthesis → cartilage loss + bone sclerosis + osteophytes.

Question 5

List modifiable and non-modifiable risk factors for OA.

Answer 5

Modifiable: obesity, joint injury, occupational stress. Non-modifiable: age, female sex, genetics, congenital malalignment.

Question 6

Describe radiographic features of OA.

Answer 6

Joint space narrowing (asymmetric), osteophyte formation, subchondral sclerosis, subchondral cysts. No periarticular osteopenia (cf. RA).

Question 7

Clinical features of OA.

Answer 7

Pain worse with activity, relieved by rest; morning stiffness <30 min; bony swelling; crepitus; restricted ROM; Heberden (DIP) and Bouchard (PIP) nodes.

Question 8

Differentiate OA from rheumatoid arthritis (RA).

Answer 8

OA: asymmetric, non-inflammatory, <30 min stiffness, DIP involved, negative RF/CCP. RA: symmetric, inflammatory, >60 min stiffness, MCP/PIP involved.

Question 9

Role of MRI in OA.

Answer 9

Not routinely required. Used for differential diagnosis (AVN, meniscal tear, stress fracture) or early OA detection before radiographic changes.

Question 10

Initial management of OA.

Answer 10

Education, weight loss, exercise (quad strengthening, aerobic), physiotherapy, simple analgesia (paracetamol), topical NSAIDs, heat/cold therapy.

Question 11

Second-line pharmacologic therapy.

Answer 11

Oral NSAIDs ± PPI cover, intra-articular corticosteroids for flare, duloxetine (chronic pain), topical capsaicin. Avoid opioids long-term.

Question 12

Surgical indications in OA.

Answer 12

Severe pain/disability despite maximal therapy, significant functional limitation, radiographic evidence of joint destruction.

Question 13

Describe the role of joint replacement in OA.

Answer 13

Total joint arthroplasty relieves pain and restores function. Most effective for end-stage knee and hip OA; lifespan ~15–20 years.

Question 14

Which pharmacologic agents are NOT recommended for OA?

Answer 14

Glucosamine/chondroitin (no consistent evidence), hyaluronic acid injections (minimal benefit), systemic steroids (no role).

Question 15

What is erosive OA?

Answer 15

Inflammatory subset of hand OA affecting DIP/PIP joints with central erosions (‘gull-wing’ deformities). Middle-aged women; may respond to hydroxychloroquine.

Question 16

Biochemical findings in OA.

Answer 16

Normal inflammatory markers (ESR, CRP). Synovial fluid: non-inflammatory (WCC <2000/mm³).

Question 17

OA vs CPPD (pseudogout) overlap.

Answer 17

CPPD can mimic OA but often involves atypical joints (MCP, wrist). Radiograph: chondrocalcinosis. Synovial fluid: rhomboid, weakly positive birefringent crystals.

Question 18

Explain knee OA subtypes.

Answer 18

Medial compartment → varus deformity; Lateral → valgus deformity; Patellofemoral → anterior knee pain, worse on stairs.

Question 19

Practice-changing evidence for exercise therapy in OA.

Answer 19

2023 Cochrane review: structured exercise (≥12 weeks) improves pain/function equivalent to oral NSAIDs; cornerstone of long-term management.

Question 20

Australian PBS nuance for OA pharmacotherapy.

Answer 20

No PBS subsidy for duloxetine unless major depressive disorder; intra-articular corticosteroids PBS-listed for large joints; biologics not indicated.

Question 21

Key exam pearls.

Answer 21

Morning stiffness <30 min; asymmetrical; absence of systemic symptoms; no synovitis; DIP involvement; bony-hard swellings; x-ray features mnemonic: LOSS (Loss of space, Osteophytes, Sclerosis, Subchondral cysts).