Feature of osteoarthritis is –
**Core Concept**
Osteoarthritis (OA) is a degenerative joint disease characterized by the breakdown and eventual loss of cartilage in the joints. This leads to the formation of bony spurs, inflammation, and pain.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of OA, which involves the loss of cartilage and the formation of bony spurs. This occurs due to the imbalance between the production and degradation of cartilage, leading to its eventual loss. The subchondral bone undergoes sclerosis, and the joint space narrows due to cartilage loss.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a feature of osteoarthritis. While inflammation is a component of osteoarthritis, it is not a defining characteristic.
**Option B:** This option is incorrect because osteoarthritis is not primarily caused by an autoimmune response. While some autoimmune diseases can cause joint inflammation, OA is a degenerative joint disease.
**Option C:** This option is not a feature of osteoarthritis. While some joint diseases, such as rheumatoid arthritis, can cause joint deformity, OA typically does not.
**Clinical Pearl / High-Yield Fact**
A key feature of osteoarthritis is the presence of Heberden's nodes, which are bony spurs that form on the distal interphalangeal joints. These are a classic sign of OA and can be used to diagnose the condition.
**Correct Answer: C. Joint deformity is not a feature of osteoarthritis.**