Pain and arthritis of distal interphalangeal joint is seen in –
The distal interphalangeal joint (DIP) is the joint closest to the fingertip. Common conditions affecting it include osteoarthritis and psoriatic arthritis. Osteoarthritis typically affects the DIP and proximal interphalangeal (PIP) joints, causing Heberden's nodes. Psoriatic arthritis can also involve the DIP, sometimes with a "sausage digit" or nail changes. Rheumatoid arthritis usually affects the PIP and metacarpophalangeal joints, not DIP. Gout and pseudogout are more common in the first MTP joint (big toe) and knee, respectively.
The correct answer here is likely osteoarthritis. The other options might include rheumatoid arthritis, gout, or psoriatic arthritis. Need to make sure why each incorrect option is wrong. For example, rheumatoid arthritis doesn't typically affect DIP. Gout and pseudogout have different predilection sites. Psoriatic arthritis can affect DIP but is less common than OA. So the core concept is the differential diagnosis for DIP joint pain, with OA being the most common.
**Core Concept**
The distal interphalangeal (DIP) joint is commonly involved in osteoarthritis (OA) and psoriatic arthritis. Osteoarthritis of the DIP joint is characterized by Heberden’s nodes, while psoriatic arthritis may present with dactylitis or nail dystrophy. Rheumatoid arthritis (RA) typically spares the DIP joint, focusing instead on the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints.
**Why the Correct Answer is Right**
Osteoarthritis (OA) is the most common cause of DIP joint arthritis. Degenerative changes in the articular cartilage lead to pain, stiffness, and bony enlargements (Heberden’s nodes). OA primarily affects weight-bearing joints and the distal and proximal interphalangeal joints of the hands. The pathophysiology involves cartilage breakdown, osteophyte formation, and subchondral bone sclerosis, which are hallmark features of OA in these joints.
**Why Each Wrong Option is Incorrect**
**Option A:** Rheumatoid arthritis (RA) predominantly affects PIP and MCP joints symmetrically, not DIP joints.
**Option B:** Gout typically involves the first metatarsophalangeal (MTP) joint ("podagra") and not the DIP.
**Option D:** Psoriatic arthritis can affect DIP joints but is less common than OA and is associated with skin/nail psoriasis, which is not mentioned here.
**Clinical Pearl / High-Yield Fact**
Remember **Heberden’s nodes** (DIP OA) and **Bouchard’s nodes** (PIP OA) as classic signs of hand osteoarthritis. DIP joint involvement in RA is rare, making OA the most likely diagnosis in the absence of systemic features.
**Correct Answer: C. Osteoarthritis**