Joint involved in Rheumatoid ahritis are all except
**Core Concept**
Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by symmetrical polyarthritis, primarily affecting the small joints of the hands and feet. The disease process involves the formation of autoantibodies against the Fc region of IgG, leading to inflammation and joint destruction.
**Why the Correct Answer is Right**
The correct answer involves identifying the joint not typically involved in Rheumatoid arthritis. RA commonly affects the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the hands, as well as the metatarsophalangeal (MTP) joints of the feet. The disease process is thought to involve the activation of immune cells, such as T lymphocytes and macrophages, which release pro-inflammatory cytokines and enzymes, leading to joint inflammation and destruction. Key enzymes involved in this process include matrix metalloproteinases (MMPs) and cyclooxygenase-2 (COX-2).
**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable in this case. If you're unsure, please provide the actual options.
**Option B:** Not applicable in this case. If you're unsure, please provide the actual options.
**Option C:** Not applicable in this case. If you're unsure, please provide the actual options.
**Option D:** Not applicable in this case. If you're unsure, please provide the actual options.
**Clinical Pearl / High-Yield Fact**
The American College of Rheumatology (ACR) criteria for diagnosing Rheumatoid arthritis include the presence of morning stiffness lasting at least one hour, symmetrical joint involvement, and the presence of rheumatoid factor (RF) or anti-citrullinated protein antibody (anti-CCP). These criteria are useful for distinguishing RA from other forms of arthritis.
**Correct Answer:** Not applicable in this case. Please provide the actual options.