40 years patient having arthritis of PIP and DIP along with carpometacarpal joint of thumb and sparing of wrist and metacarpophalangeal joint, most likely diagnosis is
**Core Concept**
The question is testing the clinical presentation of a specific type of arthritis that affects the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, as well as the carpometacarpal joint of the thumb, while sparing the wrist and metacarpophalangeal (MCP) joints. This pattern of joint involvement is characteristic of a particular rheumatological condition.
**Why the Correct Answer is Right**
The correct answer is based on the clinical presentation of osteoarthritis (OA). OA is a degenerative joint disease that affects the cartilage, leading to joint pain and stiffness. The PIP and DIP joints, as well as the carpometacarpal joint of the thumb, are commonly affected in OA due to their high degree of mobility and stress. The sparing of the wrist and MCP joints is also consistent with OA, as these joints are less prone to degenerative changes.
**Why Each Wrong Option is Incorrect**
* **Option A:** Rheumatoid arthritis (RA) typically affects the MCP and PIP joints symmetrically, making it less likely in this case.
* **Option B:** Psoriatic arthritis (PsA) can affect the DIP joints, but it often involves the MCP and PIP joints as well, and may also cause skin and nail lesions.
* **Option D:** Gout typically presents with acute, monoarticular joint inflammation, often affecting the base of the big toe, and is less likely to affect multiple joints simultaneously.
**Clinical Pearl / High-Yield Fact**
Osteoarthritis is the most common type of arthritis, affecting over 30 million people in the United States alone. It is a degenerative joint disease that can be treated with a variety of modalities, including physical therapy, medications, and surgery.
**Correct Answer:** C. Osteoarthritis.