In rheumatoid arthritis, which joint is NOT typically involved?

• A. PIP
• B. Cervical spine
• C. Wrist
• D. DIP

Answer: (D)

Rheumatoid arthritis is driven by autoimmune inflammation of the synovium, leading to chronic synovitis and pannus formation that erodes cartilage and bone at joints with abundant synovial tissue. Because of this, the small joints most commonly affected are the metacarpophalangeal and proximal interphalangeal joints, along with the wrists. The cervical spine can also be involved due to inflammatory changes around the synovial-lined facets, particularly at the atlantoaxial joint, which carries a risk of instability.

The distal interphalangeal joints are typically spared in rheumatoid arthritis. Those joints are more characteristic of osteoarthritis, where wear-and-tear–related changes predominate. Therefore, the DIP joints are not typical targets of RA, making them the exception among the joints listed.