Etiology

• Obesity
• Excessive joint loading or overuse (mechanical stress)
• Age (> 55 years)
• Calcium pyrophosphate deposition disease > Chronic CPP crystal arthritis
• Family history
• History of joint injury (especially anterior cruciate ligament injury), trauma, and/or surgery

Differential diagnosis

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Characteristic	Osteoarthritis (OA)	Rheumatoid Arthritis (RA)
Age of onset	>50 years	30-50 years
Cause	”Wear and tear” or trauma causing cartilage deterioration	Autoimmune inflammatory reaction against synovium
Primary joints affected	Weight-bearing joints (hips, knees), DIP, CMC of thumb	PIP, MCP, ankle, elbow, wrist; spares DIP Atlantoaxial subluxation
Joint characteristics	Hard and bony	Soft, warm, and tender
Pain pattern	Worse during or after activity	Worse in the morning or with inactivity
Stiffness	<30 minutes in morning, worse with activity	>30 minutes in morning, worse with inactivity
Joint symmetry	Often asymmetric, reflecting use patterns	Typically symmetric, diffuse involvement
Lab findings	Normal rheumatoid factor, normal anti-CCP antibody, normal ESR and CRP	Positive rheumatoid factor, positive anti-CCP antibody, elevated ESR and CRP
Associated signs	Heberden’s nodes (DIP), Bouchard’s nodes (PIP)	Ulnar deviation, boutonniere deformity, swan-neck deformity
Systemic involvement	None	Potential pulmonary and cardiac disease
Gender predilection	None	2x more common in females
X-ray findings	Osteophytes, subchondral sclerosis, asymmetric joint space narrowing	Symmetric joint space loss, osteopenia, “apple coring” bone erosion
Exam findings	Effusion, tenderness	Effusion, tenderness, redness, warmth, synovitis

Treatment

Approach

Follow a stepwise approach to treatment: Start with nonpharmacological management, followed by pharmacological and/or surgical treatment if needed.

• Nonpharmacological management: e.g., exercise and weight loss
• Pharmacotherapy
  • First line: e.g., topical or oral NSAIDs
  • Second line: e.g., acetaminophen or intraarticular glucocorticoid injections
• Surgical management: e.g., complete or partial joint replacement (arthroplasty) using an endoprosthesis

Tip

Pharmacotherapy should only be used as a short-term treatment in symptomatic patients; long-term therapy is associated with many adverse effects.