Which joints are typically affected in rheumatoid arthritis?

Rheumatoid arthritis is a systemic autoimmune disorder that predominantly affects the synovial joints. The condition is characterized by symmetrical polyarthritis, leading to inflammation and damage primarily in the metacarpophalangeal (MCP) joints and proximal interphalangeal (PIP) joints of the hands.

The reason that the MCP and PIP joints are specifically highlighted lies in the pattern of joint involvement typical in rheumatoid arthritis, which tends to spare the distal interphalangeal (DIP) joints of the fingers. This characteristic helps differentiate rheumatoid arthritis from other forms of arthritis, such as osteoarthritis or psoriatic arthritis, which may involve the DIP joints.

In summary, the classic involvement of the MCP and PIP joints is a key feature of rheumatoid arthritis due to its symmetrical polyarticular nature and the specific joints typically affected in this disease. This is what makes this answer correct regarding the joints commonly impacted by rheumatoid arthritis.