Healthy joints are vital to an active lifestyle; however, aging, obesity and overuse tend to increase joint deterioration. Two major factors determining the health of joints are the integrity of the bones making up the joint and the quality of joint articulation. A significant deficiency in either aspect can lead to the decision to replace the joint. Bone is primarily made up of the mineral calcium, and although bone is hard and strong, it is also considered a living tissue of the body. This means that bone is not static but is constantly being replenished and drawn upon by the body as a part of natural human physiology. For instance, calcium is drawn upon by the body for many cellular processes that are essential to life.