What condition is characterized by a wearing down of joint cartilage?

Osteoarthritis is the condition characterized by the wearing down of joint cartilage. This degenerative joint disease occurs when the cartilage that cushions the ends of the bones in the joint gradually erodes, leading to pain, stiffness, and inflammation in the affected joint. Because cartilage allows for smooth movement of the joints, its degradation results in decreased mobility and increased discomfort.

In contrast, osteoporosis is primarily related to a reduction in bone density, which increases the risk of fractures but does not directly involve the degradation of cartilage. Osteology refers to the study of bones, and while it is related to the skeletal system, it does not specifically describe a condition affecting joint cartilage. Otorrhea is the medical term for ear discharge and is unrelated to joint issues. Therefore, the focus on joint cartilage makes osteoarthritis the correct answer.