Answer: Osteoarthritis
Explanation: Osteoarthritis is a condition that normally occurs due to the wear and tear of the joints, and it mostly affects the elderly. It commonly affects weight-bearing joints such as the spine, hips, and knees. The disease causes the smooth lining of a joint—the articular cartilage—to crack and flake. As the cartilage deteriorates, the underlying bone becomes thickened and distorted. Because movement becomes painful, the muscles begin to decline from lack of use.
The symptoms of osteoarthritis are episodes of pain, swelling, and stiffness in the joint area, which sometimes results in knobby-looking joints.