Which statement best differentiates osteoarthritis from rheumatoid arthritis?

• A. OA is wear-and-tear and distal; RA is autoimmune and proximal.
• B. RA is wear-and-tear and distal; OA is autoimmune.
• C. OA is autoimmune and proximal; RA is wear-and-tear and distal.
• D. OA is autoimmune and distal; RA is wear-and-tear and proximal.

Answer: (A)

Distinguishing features are the cause and where the joints are typically affected. Osteoarthritis is a degenerative, wear-and-tear process that often involves distal joints in the hands (such as the DIP joints) and weight-bearing joints, with less prominent systemic inflammation. Rheumatoid arthritis, by contrast, is an autoimmune inflammatory disease that preferentially targets proximal joints, including the metacarpophalangeal and proximal interphalangeal joints, and it’s usually symmetric and associated with systemic features.

Therefore, describing osteoarthritis as wear-and-tear and distal, while rheumatoid arthritis is autoimmune and proximal, best reflects the common patterns seen clinically. The other statements mix up which disease is autoimmune or which joints are typically affected, which makes them less accurate representations.