There are over 100 different types of arthritis, each with its own causes and treatments. The more familiar types of arthritis include osteoarthritis, rheumatoid arthritis, psoriatic arthritis, lupus, and gout. The most common type of arthritis is osteoarthritis, which affects 21 million people over the age of 45. This type of arthritis tends to affect women more than men.

Osteoarthritis is best thought of as a wearing of the cartilage surface that covers the ends of your bones. When that surface wears down it becomes pitted and rough. Your joints are made up of two bones that rub their cartilage surfaces against each other when you move. If these surfaces are rough, as is the case with osteoarthritis, it becomes painful (see image).

Arthritis Diagnosis

Osteoarthritis is typically diagnosed based on your complete medical history, including a description of your symptoms and a physical exam. Imaging techniques — such as X-rays or Magnetic Resonance Imaging (MRI) — are sometimes used to show the condition of the joints. If other types of arthritis are suspected, lab tests on blood, urine, and/or joint fluid may be helpful in determining the type of arthritis. These tests also can help rule out other diseases as the cause of your symptoms.