The bone in your hip is living tissue and is continuously being absorbed into your body and then replaced. When bone is no longer replaced as quickly as it is absorbed, the density or mass of the bone is reduced—resulting in porous bone, or osteoporosis. Osteoporosis causes the bone to become progressively weaker, increasing the risk that it may break. Bones begin to weaken with age, particularly among women. It's estimated that osteoporosis affects more than 20 million postmenopausal women in America. With osteoporosis, your chances of breaking a bone in a fall increase dramatically.