3-5 Men and women differ in risk of spinal fracture. Men are at increased risk for all types of bone fractures until approximately 45 years of age, an effect probably due to the higher overall trauma rate in men during this time.

However, after age 45, women are at increased risk for spinal fracture, most likely due to age-related increases in osteoporosis, a disease characterized by decreased bone density. S. Kudlacek and colleagues† wanted to investigate the relationship between gender and bone density in a group of older adults who have had a vertebral bone fracture. Their data are presented in Table 3-7. Are there differences in vertebral bone density between similarly aged men and women who have had a vertebral bone fracture?