Arthritis is a condition that is caused by the wearing down of the cartilage between joints. Some of the major joints that are affected are the knees, hips, back, neck, and hands/wrist. Arthritis can be painful and can cause the affected areas to not function properly. Arthritis in one area can cause arthritis or other problems in a different joint. For instance, if you have arthritis in your left knee, you may compensate for this by putting more pressure on your right side, leading to right hip problems.