Exercise and Arthritis Your bones hang out in a large amount of joints. Knee joints. Hip joints. The joints in your fingers and the joints in your toes. Wherever bones meet, there is also cartilage, a rubbery, protective layer that makes sure your joints bend smoothly and painlessly. But even cartilage can’t do this tremendous job alone. A thin membrane called the’synovium’ provides liquid that lubricates the moving parts of the joint.
