**Core Concept**
Osteoarthritis (OA) is a degenerative joint disease characterized by progressive wear and tear of joint cartilage, leading to bone-on-bone contact and joint pain. The disease primarily affects weight-bearing joints, such as the knees, hips, and spine.

**Why the Correct Answer is Right**
The correct answer is based on the fact that the temporomandibular joint (TMJ) is the only joint in the body that is not typically affected by osteoarthritis. This is because the TMJ is a synovial joint that is primarily involved in the movement of the jaw, and it has a unique structure that makes it less susceptible to the degenerative changes associated with OA. The TMJ's cartilage is thicker and more resilient than that found in other joints, and it has a different type of synovial fluid that helps to reduce friction and wear.

**Why Each Wrong Option is Incorrect**
* **Option A:** The knee joint is a common site for osteoarthritis, particularly in individuals who have a history of trauma or repetitive stress injuries.
* **Option B:** The cervical spine is another area where osteoarthritis can occur, often leading to neck pain and stiffness.
* **Option C:** The hip joint is also frequently affected by osteoarthritis, particularly in individuals who have a history of hip dysplasia or previous hip injuries.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that osteoarthritis can affect any joint, but it's more common in weight-bearing joints and joints that are subject to repetitive stress or trauma.

**Correct Answer:** D. Temporomandibular joint