In a 60‑year‑old patient with hand pain, swelling of the proximal interphalangeal (PIP) joints, Heberden’s nodes, and stiffness that worsens with use, which finding most indicates osteoarthritis rather than rheumatoid arthritis?

Heberden's Nodes: The Pathognomonic Feature of Osteoarthritis

The presence of Heberden's nodes is the most indicative feature of osteoarthritis rather than rheumatoid arthritis in this patient. These bony nodules at the distal interphalangeal (DIP) joints are clinical hallmarks of hand osteoarthritis and are essentially absent in rheumatoid arthritis, which characteristically spares the DIP joints 1.

Key Distinguishing Features Supporting Osteoarthritis

Joint Distribution Pattern

• DIP joint involvement (Heberden's nodes) is pathognomonic for OA, as rheumatoid arthritis mainly targets MCPs, PIPs, and wrists while typically sparing the DIP joints 1
• The patient's PIP joint involvement (where Bouchard's nodes would develop) can occur in both conditions, but when combined with DIP involvement, strongly favors OA 1
• Heberden's and Bouchard's nodes associate strongly with underlying osteophytes (OR = 5.15,95% CI 4.37 to 6.08), representing bony enlargement rather than inflammatory synovitis 1, 2

Stiffness Pattern

• Stiffness that worsens with use is characteristic of OA, whereas RA typically causes prolonged morning stiffness (>30 minutes) that improves with activity 1
• OA presents with "pain on usage and only mild morning or inactivity stiffness," which matches this patient's presentation 1

Nature of Joint Swelling

• Bony enlargement (nodes) indicates OA, while soft tissue swelling suggests inflammatory arthritis like RA 3
• The nodes represent osteophyte formation and bony remodeling, not synovial inflammation 2

Clinical Diagnostic Confidence

In adults over 40 with Heberden's nodes, pain on usage, and characteristic joint distribution (DIPs, PIPs, thumb base), a confident clinical diagnosis of hand OA can be made without requiring radiographs or laboratory tests 1. The American College of Rheumatology criteria specify that hard tissue enlargement of at least 2 DIP joints is a key classification criterion for hand OA, with 92% sensitivity and 98% specificity 4.

Common Pitfall to Avoid

Do not be misled by the presence of swelling at PIP joints alone—the critical distinguishing feature is DIP joint involvement (Heberden's nodes), which occurs in OA but not in RA 1, 5. When MCP joints are predominantly involved with DIP sparing, consider RA instead 1, 5.