## **Core Concept**
Heberden's arthropathy, also known as osteoarthritis (OA), primarily affects the joints, causing degeneration of the articular cartilage and underlying bone. This condition is characterized by the formation of Heberden's nodes and Bouchard's nodes, which are bony enlargements of the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints, respectively.

## **Why the Correct Answer is Right**
The correct answer, , indicates that Heberden's arthropathy mainly affects the distal interphalangeal (DIP) joints. This is because OA tends to affect weight-bearing joints and joints with high mobility, such as the DIP and PIP joints in the hands. The DIP joints are particularly prone to developing Heberden's nodes, which are a hallmark of OA.

## **Why Each Wrong Option is Incorrect**
* **Option A:** - This option is incorrect because, although OA can affect any joint, the question specifically asks about Heberden's arthropathy, which is most commonly associated with the DIP joints, not the metacarpophalangeal (MCP) joints.
* **Option B:** - This option is incorrect because, while the PIP joints (where Bouchard's nodes occur) are also affected in OA, Heberden's nodes specifically refer to the DIP joints.
* **Option D:** - This option is incorrect because Heberden's arthropathy primarily affects the small joints of the hands, not the wrist joint.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that Heberden's nodes (affecting DIP joints) and Bouchard's nodes (affecting PIP joints) are diagnostic hallmarks of osteoarthritis. The presence of these nodes can help differentiate OA from other forms of arthritis.

## **Correct Answer:** . DIP joints.