Discuss changes in bone density in the late adulthood phase of life.

Answers will vary. Bones begin to lose density in middle adulthood, becoming more brittle and vulnerable to fracture. Bones in the spine, hip, thigh, and forearm lose the most density as we age. Osteoporosis is a disorder in which bones lose so much calcium that they become dangerously prone to breakage. Osteoporosis results in more than one million bone fractures a year in the United States, the most serious of which are hip fractures (that is, breaks in the thigh bone, just below the hip joint). Hip fractures often result in hospitalization, loss of mobility, and, in people in advanced late adulthood, even death from complications. Osteoporosis can shorten one's stature by inches and deform one's posture, causing the curvature in the spine known as "dowager's hump." Both men and women are at risk of osteoporosis, but it poses a greater threat to women. Men typically have a larger bone mass, which provides them with more protection against the disorder. Following the decline in bone density that women experience after menopause, women stand about twice the risk of hip fractures and about eight times the risk of spine fractures that men do. But older women who engage in walking as a form of regular exercise are less likely than their sedentary counterparts to suffer hip fractures.