Swan neck deformity seen iri ?
**Core Concept**
Swan neck deformity is a type of flexion contracture of the proximal interphalangeal (PIP) joint, characterized by hyperextension of the distal interphalangeal (DIP) joint and flexion of the PIP joint. This deformity is often associated with rheumatoid arthritis, but can also occur due to trauma, infection, or other joint diseases.
**Why the Correct Answer is Right**
The correct answer is related to rheumatoid arthritis, a chronic autoimmune disorder that causes inflammation and destruction of joints. In rheumatoid arthritis, the synovium of the PIP joint becomes inflamed, leading to synovial proliferation and eventual destruction of the joint cartilage and bone. As the disease progresses, the joint becomes flexed and the distal interphalangeal joint becomes hyperextended, resulting in a swan neck deformity.
**Why Each Wrong Option is Incorrect**
* **Option A:** While swan neck deformity can be seen in other conditions, it is not typically associated with osteoarthritis, which primarily affects the weight-bearing joints and is characterized by cartilage wear and tear.
* **Option B:** Traumatic injuries can cause flexion contractures, but they are not typically associated with the specific combination of hyperextension at the DIP joint and flexion at the PIP joint seen in swan neck deformity.
* **Option C:** Infection of the PIP joint (septic arthritis) can cause joint destruction and deformity, but it is not typically associated with the characteristic hyperextension of the DIP joint seen in swan neck deformity.
* **Option D:** While systemic lupus erythematosus (SLE) is an autoimmune disease that can affect multiple joints, it is not typically associated with the specific deformity of swan neck deformity.
**Clinical Pearl / High-Yield Fact**
In patients with rheumatoid arthritis, swan neck deformity is often seen in association with other deformities, such as boutonniere deformity (flexion of the PIP joint with extension of the DIP joint). Recognizing these deformities can help guide treatment and management of the underlying disease.
**Correct Answer: C. Rheumatoid arthritis**