**Core Concept**
Non-inflammatory arthritis refers to a group of joint disorders characterized by cartilage degeneration and bone-on-bone contact, often resulting in joint pain and stiffness. This category of arthritis is typically not associated with inflammation or autoimmune responses.

**Why the Correct Answer is Right**
Osteo-arthritis (OA) is a classic example of non-inflammatory arthritis. The disease process in OA involves the gradual loss of articular cartilage due to a combination of mechanical stress and biochemical changes. As cartilage degenerates, subchondral bone undergoes sclerosis and new bone formation, leading to joint deformity and pain. The underlying pathophysiology of OA involves the imbalance between the synthesis and degradation of cartilage matrix components, such as collagen and proteoglycans.

**Why Each Wrong Option is Incorrect**
**Option A:** Rheumatoid arthritis is a classic example of inflammatory arthritis, characterized by synovial inflammation, joint effusion, and systemic symptoms like fever and fatigue.

**Option B:** Reiter's syndrome, also known as reactive arthritis, is another form of inflammatory arthritis, typically triggered by a bacterial infection. It is characterized by the classic triad of conjunctivitis, urethritis, and arthritis.

**Option C:** Gonococcal arthritis is a type of septic arthritis, caused by Neisseria gonorrhoeae infection. It is characterized by joint inflammation, fever, and systemic symptoms, making it an inflammatory arthritis.

**Clinical Pearl / High-Yield Fact**
Osteo-arthritis is the most common type of arthritis, affecting millions of people worldwide. It often presents in older adults, with the knees, hips, and spine being the most commonly affected joints.

**✓ Correct Answer: D. Osteo-arthritis**