Non-inflammatory degenerative joint disease driven by progressive articular cartilage loss.
Also known as: OA, degenerative joint disease, DJD, osteoarthrosis
Overview
Chronic degenerative joint disease characterized by progressive loss of articular cartilage, subchondral bone remodeling, osteophyte formation, and mild synovitis. Most commonly affects weight-bearing joints (knee, hip), the hand DIP/PIP and first CMC joints, and the cervical and lumbar spine.
Epidemiology
Most prevalent form of arthritis worldwide. Prevalence rises sharply after age 50; women > men after menopause. Symptomatic knee OA affects ~10% of US adults over 60.
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Question 1MusculoskeletalMedium
A 68-year-old woman reports several months of right knee and bilateral hand pain that worsens with activity and improves with rest. Morning stiffness lasts about 10 minutes. Exam shows bony enlargement at the distal interphalangeal joints and crepitus of the right knee without warmth or effusion. Radiographs show asymmetric joint-space narrowing, marginal osteophytes, and subchondral sclerosis. Inflammatory markers are normal. Which of the following is the most appropriate first-line pharmacologic treatment?
AHydroxychloroquine
BOral duloxetine
COral prednisone
DTopical diclofenac
EGlucosamine sulfate
Reveal answer & full explanation
Correct answer: D — Topical diclofenac
AHydroxychloroquine
BOral duloxetine
COral prednisone
DTopical diclofenac✓
EGlucosamine sulfate
Why Topical diclofenac is correct
This presentation is osteoarthritis, a degenerative joint disease distinguished from inflammatory arthritis by activity-related pain, brief morning stiffness (under 30 minutes), bony rather than soft-tissue swelling, normal inflammatory markers, and the classic radiographic tetrad of asymmetric joint-space narrowing, osteophytes, subchondral sclerosis, and cysts
First-line pharmacotherapy per ACR/OARSI guidance is a topical NSAID such as diclofenac, favored for knee and hand OA because it provides analgesia with minimal systemic exposure
Oral NSAIDs and duloxetine are added when needed; intra-articular corticosteroids treat acute flares
Why the others are wrong
Oral duloxetine — conditionally recommended for knee osteoarthritis, but ACR places it after topical and oral NSAIDs rather than as initial therapy, and it has little role in hand OA
Glucosamine sulfate — ACR strongly recommends against glucosamine for hand, hip, and knee osteoarthritis because trials show no benefit over placebo
Oral prednisone — used for systemic inflammatory and autoimmune arthritis; systemic steroids are not indicated for osteoarthritis and carry unnecessary metabolic risk
Hydroxychloroquine — an antimalarial DMARD that can seem logical when DIP involvement suggests an inflammatory hand arthritis, but trials in hand osteoarthritis showed no benefit over placebo and ACR strongly recommends against it for hand, hip, and knee osteoarthritis
Additional high-yield points
The key misconception these distractors target is escalating to a systemic or unproven agent before trying the topical NSAID that guidelines place first
Question 2MusculoskeletalEasy
A 55-year-old male has bilateral knee osteoarthritis with moderate symptoms despite acetaminophen and physical therapy. He asks about intra-articular injections. Which of the following injections has the strongest evidence for symptomatic relief?
ACorticosteroid
BProlotherapy
CHyaluronic acid
DStem cell
EPlatelet-rich plasma
Reveal answer & full explanation
Correct answer: A — Corticosteroid
ACorticosteroid✓
BProlotherapy
CHyaluronic acid
DStem cell
EPlatelet-rich plasma
Why Corticosteroid is correct
Intra-articular (IA) corticosteroid injection for knee osteoarthritis (OA) has the strongest evidence: most studies support 4–8 weeks of pain relief.
Triamcinolone or methylprednisolone are commonly used agents.
American College of Rheumatology (ACR) guidelines (2019 and 2026 update): strongly recommend IA corticosteroids for knee and hip OA.
Why the others are wrong
Hyaluronic acid — viscosupplementation shows modest benefit in some studies; ACR 2019 conditionally recommends against it due to inconsistent evidence.
Platelet-rich plasma — not FDA-approved as a specific OA treatment; growing but inconsistent evidence base.
Stem cell — no FDA approval and insufficient evidence for knee OA.
Prolotherapy — dextrose prolotherapy is widely marketed and small trials suggest some benefit, but the evidence is limited and inconsistent, and the 2019 ACR guideline conditionally recommended against it for knee OA; it lacks the reproducible short-term pain relief shown with IA corticosteroids.
Additional high-yield points
Limitation of IA corticosteroids: triamcinolone injections every 3 months for 2 years caused greater cartilage volume loss than saline without better pain relief (McAlindon et al., JAMA 2017).
Most effective overall OA treatments: exercise, weight loss, topical NSAIDs, and oral nonsteroidal anti-inflammatory drugs (NSAIDs) (with GI protection).
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Imbalance between cartilage matrix synthesis and degradation, driven by matrix metalloproteinases and pro-inflammatory cytokines (IL-1, TNF). Cartilage softens, fibrillates, and erodes. The underlying subchondral bone responds with sclerosis, cyst formation, and marginal osteophytes. Low-grade synovial inflammation contributes to pain but is qualitatively different from autoimmune arthritis.
Clinical presentation
Symptoms
Insidious joint pain worse with activity and improved by rest
Brief morning stiffness (<30 minutes) and gel phenomenon after inactivity
Reduced range of motion, crepitus, functional limitation
Knee: medial joint-line pain, buckling, difficulty with stairs
Hip: groin pain referred to thigh or buttock, limp
Hand: pain and bony enlargement at DIP (Heberden) and PIP (Bouchard) nodes; first CMC squaring
Signs / physical exam
Bony enlargement, crepitus, tenderness at joint line
Cool joint without significant warmth or erythema
Restricted ROM, antalgic gait
Mild effusion possible but lacking the boggy synovitis of RA
Classic findings
Heberden nodes (DIP) and Bouchard nodes (PIP); squared first CMC joint; medial knee joint-line tenderness.
Avascular necrosis (hip) — Groin pain with restricted internal rotation; crescent sign on plain film; MRI sensitive
Bursitis / tendinopathy — Periarticular tenderness without true joint-line pain; preserved passive ROM
Diagnostic workup
Diagnostic criteria
ACR clinical criteria for knee OA: knee pain plus at least 3 of: age >50, stiffness <30 min, crepitus, bony tenderness, bony enlargement, no palpable warmth. Radiographic hallmarks (Kellgren-Lawrence): joint-space narrowing, subchondral sclerosis, subchondral cysts, marginal osteophytes.
Labs
Generally not required for diagnosis when classic clinical and radiographic features present
ESR, CRP, RF, anti-CCP, ANA only if inflammatory arthritis suspected (should be normal or negative in OA)
Arthrocentesis only when effusion present and inflammatory or septic process must be excluded — OA fluid is non-inflammatory (WBC <2000, clear/straw-colored)
Imaging
Weight-bearing plain radiographs of the affected joint — first-line
MRI reserved for atypical presentations, suspected meniscal or ligamentous injury, or possible avascular necrosis
Ultrasound can detect effusion and osteophytes but is not routinely needed
Periarticular osteopenia, marginal erosions, symmetric joint-space loss
Comparison of osteoarthritis vs rheumatoid arthritis — the highest-yield differentiation on PANCE.
Treatment
First-line
Patient education and self-management programs
Exercise: low-impact aerobic, strengthening (quadriceps for knee OA), aquatic therapy
Weight loss (5-10% body weight) for knee or hip OA in overweight patients; a GLP-1 receptor agonist may be added to diet and exercise in knee OA with obesity (ACR 2026, conditional)
Topical NSAIDs (diclofenac gel) — preferred initial pharmacotherapy for hand and knee OA
Acetaminophen up to 3 g/day (modest benefit, useful when NSAIDs contraindicated)
Oral NSAIDs — ibuprofen, naproxen, meloxicam (lowest effective dose, shortest duration; add PPI if GI risk)
Second-line / adjunct
Intra-articular corticosteroid injection (triamcinolone, methylprednisolone) — strongly recommended by ACR for knee and hip OA (ultrasound-guided for the hip), conditionally for hand OA; short-term relief for flares; limit to 3-4 per joint per year
Duloxetine — adjunct for chronic knee OA pain, particularly with comorbid depression or widespread pain
Topical capsaicin — conditional option for knee OA; ACR conditionally recommends against it for hand OA
Tramadol — limited role; reserve for patients who cannot tolerate NSAIDs and have failed other measures
Intra-articular hyaluronic acid — conditional, not recommended by 2019 ACR for knee or hip
Avoid chronic opioids — no long-term benefit and substantial harm
Joint deformity (varus knee, fixed flexion of hip)
Perioperative complications of arthroplasty: infection, DVT/PE, periprosthetic fracture
PANCE pearls
Morning stiffness <30 minutes and pain that worsens through the day with activity favor OA over RA.
First CMC squaring and Heberden/Bouchard nodes are pathognomonic for primary hand OA.
ACR strongly recommends AGAINST glucosamine, chondroitin (alone or combined), hydroxychloroquine, bisphosphonates, and TNF inhibitors for OA, and against PRP and stem cell injections for knee and hip OA. Methotrexate is conditionally recommended against for knee and hip OA but conditionally recommended for erosive hand OA (ACR 2026).
If a patient with presumed OA develops a hot, swollen joint, perform arthrocentesis — superimposed gout, pseudogout, or septic arthritis can occur.
References
ACR/AF 2019 — 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee (Kolasinski et al., Arthritis Care Res 2020)
OARSI 2019 — OARSI Guidelines for the Non-Surgical Management of Knee, Hip, and Polyarticular Osteoarthritis (Bannuru et al., Osteoarthritis Cartilage 2019)
AAOS 2021 — AAOS Clinical Practice Guideline: Management of Osteoarthritis of the Knee (Non-Arthroplasty), 3rd ed.
ACR 2026 — 2026 Update of the American College of Rheumatology Recommendations for the Management of Osteoarthritis of the Knee, Hip, and Hand (ACR guideline summary, approved by the ACR Board of Directors, September 8, 2026)
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