Osteoarthritis

Chronic degenerative joint disease caused by wear-and-tear cartilage loss, resulting in bone spurs (*osteophytes*) and gradual joint destruction.

• OA is the most common form of arthritis and a leading cause of chronic joint pain and disability in older adults. Med students must recognize it and distinguish it from inflammatory arthritides (like RA) on exams and in practice.

• Typically mid-older patients (≥50) with weight-bearing joint pain (knees, hips, spine) or hand OA (DIP Heberden nodes, PIP Bouchard nodes). Pain worsens with activity (especially later in the day) and improves with rest.
• Morning stiffness is brief (usually <30 minutes) – joints "gel" after inactivity but loosen up quickly (unlike RA's prolonged stiffness). Patients may report crepitus (a crackling joint sound) and joint stiffness after rest.
• Exam: bony joint enlargements (e.g. Heberden nodes at DIP joints), limited range of motion, and crepitus on movement. Knees often have a cool effusion; varus or valgus deformity can develop in advanced knee OA.
• Labs are typically normal (OA is non-inflammatory). Radiographs show joint space narrowing, osteophytes, subchondral sclerosis, and subchondral cysts.

1. Differentiate OA from rheumatoid arthritis: OA pain is mechanical (worse with use), with minimal morning stiffness and DIP involvement; RA is inflammatory (better with use) with prolonged stiffness and spares DIPs.
2. Confirm suspected OA with a weight-bearing X-ray of the joint, which reveals characteristic changes (asymmetric cartilage loss, osteophytes, etc.). Synovial fluid in OA is non-inflammatory (WBC < 2000/mm³).
3. Assess red flags (fever, redness, rapid onset, unusual age) that suggest alternative diagnoses (infection, crystal arthritis, inflammatory disease) instead of OA.
4. Initial management is conservative for all OA patients: exercise (e.g. physical therapy to strengthen muscles around the joint) and weight loss if overweight. These lifestyle measures can significantly reduce pain and improve function.

1. Non-pharmacologic: First-line is exercise (low-impact, plus muscle strengthening) and weight loss. Physical therapy and assistive devices (braces, canes) can help offload joints.
2. Analgesics: Begin with acetaminophen for mild pain (safe but modest effect). NSAIDs (topical for hand/knee or oral if needed) provide stronger relief but use lowest effective dose and monitor for GI, renal, CV side effects. Topical capsaicin may help in hand OA; duloxetine is an option for chronic OA pain in some patients.
3. Injections: Intra-articular corticosteroid injections can give short-term relief for painful flares (especially in knee/hip OA). Limit frequency (e.g. ~3–4 per year per joint). Viscosupplementation with hyaluronic acid injections is used in knee OA, though evidence for benefit is limited.
4. Surgery: Joint replacement (total hip or knee arthroplasty) is highly effective for end-stage OA with severe pain and functional limitation. Consider orthopedic referral when conservative measures no longer maintain quality of life.

• X-ray LOSS mnemonic for OA: Loss of joint space, Osteophytes, Subchondral sclerosis, Subchondral cysts.
• Heberden nodes (bony bumps at DIP joints) and Bouchard nodes (PIP) are classic for OA (absent in RA).
• Think "wear and tear": OA risk is increased by age, obesity, and prior joint injury – joints that have endured a lifetime of stress.

• Joint is red, hot, or swollen or patient has fever/chills → not typical for OA; evaluate for septic arthritis or crystal arthritis (urgent intervention needed).
• Extended morning stiffness (>1 hour), rapid joint destruction, or systemic symptoms (fatigue, weight loss) → consider an inflammatory arthritis (like RA) or other pathology, not simple OA.

1. Chronic joint pain in older adult (especially knee, hip, hands) → suspect osteoarthritis.
2. Evaluate for atypical features: if inflammation signs or unusual presentation, investigate for other diagnoses; otherwise proceed with OA management.
3. Obtain X-rays of affected joints to confirm OA changes (joint space narrowing, osteophytes) and exclude alternative diagnoses.
4. Begin conservative management for OA: patient education, exercise program, weight loss, and topical/oral analgesics as needed.
5. If pain persists and significantly limits function despite conservative therapy → escalate care (consider corticosteroid injections, and if severe, refer for possible joint replacement).

• Overweight 60‑year‑old woman with chronic knee pain that worsens throughout the day and brief morning stiffness → osteoarthritis (degenerative knee arthritis).
• Older patient with hard bony enlargements at DIP and PIP joints (Heberden and Bouchard nodes), hand pain worse with use, and <30 min stiffness → hand OA.