Bone Structures

Getting closer to the source of osteoporosis.

Photography by ALAN BOYD, DONALD FAWCETT, RANDY KARDON, RICHARD KESSEL, and RON MILLER

Bones support and protect the body. They are also the body�s calcium banks; the calcium one needs is withdrawn from the bones, and the surplus is stored there. In the course of ten years, this recycling dissolves and rebuilds the entire skeleton. But as estrogen production declines with age, the body�s bone-building cells (osteoblasts) are stimulated less and less. The result is that aging bone gives up more calcium than it takes in, leaving bones fragile and susceptible to fracture. More than 200 million people around the world and 44 million in the United States have osteoporosis or the weakened bone condition that precedes the disease. It afflicts one in five U.S. women in their 60s and four in five in their 80s. This year, well over 1 million men and women will fracture a bone, substantially increasing their likelihood of dying or entering a nursing home. Meanwhile, health care costs top $14 billion.

Current therapies include bisphosphonate drugs, which stall the cells that shunt calcium from bone to blood, and the hormones estrogen and calcitonin, which encourage the cells that build bone. Potential therapies will make the bone-building cells more sensitive to estrogen, improve the effectiveness and dosing of bisphosphonates, and modulate calcium resorption with recombinant parathyroid hormone.The following images go closer and closer into the structures affected by this disease.

— Produced by Karen Mullarkey