— -- Question: How does osteoarthritis differ from rheumatoid arthritis?
Answer: Osteoarthritis and rheumatoid arthritis are two very different diseases. Osteoarthritis is a condition primarily of the cartilage of the joint, with reactive changes in the bone and the soft tissues. Whereas rheumatoid arthritis is a primarily inflammatory disease of the soft tissues around the joint, the sack around the joint, called the synovium. This becomes so inflamed that it actually causes secondary damage to the joint. Now the differences are that osteoarthritis can involve knees and hips and fingers. And when it involves fingers, it primarily involves this row of joints, the distal joints, and sometimes the proximal joints. In contrast, rheumatoid arthritis, you almost always involves the wrists and this row of joints. So that the distribution of type of arthritis is different in the two conditions.