In old age, people often suffer from stiff and inflamed joints. What is this condition called? What are the possible reasons for these symptoms?

Explanation

### Step-by-Step Solution:

1. **Identify the Condition**: The condition characterized by stiff and inflamed joints in old age is known as **osteoarthritis**. It is important to note that while osteoporosis is related to bone density loss, osteoarthritis specifically refers to the degeneration of joint cartilage and underlying bone.

2. **Understand the Characteristics**: Osteoarthritis leads to symptoms such as joint stiffness, pain, and inflammation. The cartilage that cushions the joints wears down over time, causing bones to rub against each other, which results in stiffness and inflammation.

3. **Explore Possible Reasons**:
- **Age-Related Changes**: As people age, the cartilage can become less resilient and more prone to wear and tear.
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