Windyshores,
I'm not sure if the statistic includes vertebral fractures that weren't x-rayed at all.
MRI can miss fractures that are obscure, which is the way osteoporotic vertebral fractues begin. It's just those little spicules. Once they are evidenced on x-ray, you've already had loss of height. If a person plans on kyphoplasty, they can reduce the depth of crush. The same issue applies to hairline fractures in long bones, except that the hazard isn't crush but displacement.
With vertebral fractures early treatment means stopping permanent damage. Kyphoplasty can only partially restore height, though kyphoplasty has its own hazards.
The radiation issue is important.