The basic symptoms of arthritis are pain, swelling, and stiffness. The condition can affect any joint in the body, although it is most frequent in the knee. Knee arthritis can make it difficult to do numerous daily activities, such as walking or climbing stairs. Arthritis may also change the way other conditions affect your body. For example, knee arthritis may cause other problems with your hips or back. Knee arthritis can be classified according to what's causing the problem: osteoarthritis or rheumatoid arthritis. Osteoarthritis occurs when the protective cushioning lining of your joints wears away. This allows bone surfaces to rub together, causing pain and loss of function. It is the most common form of arthritis and affects individuals of all ages. Rheumatoid arthritis is a chronic disease that causes inflammation of the joints. It often starts in young adulthood and is more common in women. Like osteoarthritis, rheumatoid arthritis can cause pain, stiffness, and disability. However, with rheumatoid arthritis, these symptoms are usually present day-to-day rather than only at night or in response to movement. Diagnosing arthritis requires a medical history and physical examination by your doctor. Your doctor will ask you about your symptoms and conduct a complete physical exam of your joint area.