Osteoarthritis primarily affects the cartilage, even if the entire joint can ultimately be changed. Since cartilage is a part in all the joints in our body, any of our joints can be affected by osteoarthritis. The disease is the most common in the knees and hips, but can also develop in smaller joints, such as fingers and toes. The spine and neck can also be affected. Here, we dive deeper in what happens when specific joints are affected by osteoarthritis.