Osteoarthritis primarily affects which joints?

Osteoarthritis primarily affects the distal interphalangeal (DIP) joints, which are the joints closest to the fingertips. This condition is characterized by the degeneration of cartilage and changes in the underlying bone. In osteoarthritis, the disease commonly targets weight-bearing joints and those with a high degree of use over time, which includes the DIP joints.

The reason DIP joints are particularly affected is linked to the mechanical stress they endure from daily activities such as gripping and fine motor tasks. In contrast, although other joints may also be affected by osteoarthritis, they are not as characteristically associated with this condition as the DIP joints are.

For instance, the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints are more commonly associated with rheumatoid arthritis than osteoarthritis. Similarly, the wrist and elbow joints, while they can be involved in osteoarthritis, do not show the same hallmark pattern. The shoulder and hip are larger joints that are also affected but not to the same specificity as the DIP joints when considering osteoarthritis. Thus, the specific targeting of the DIP joints makes them the primary joints affected in osteoarthritis.