Hi @mom2five,
Please see my post above to @callalloo one day ago. It gives information about the Whole Body Vibration Plate Exerciser I bought. However, based on Margaret Martin's review of high intensity vibration vs. low, I've stopped using it and feel fortunate that I did not experience any serious injury. Once I read her article, it was easy to discontinue the whole body vibration, although I really liked it. Here is the link to the article:

If you are interested in building bone density, I encourage you to look at Dr. Loren Fishman's work at http://www.sciataca.org and his "Twelve Poses vs. Osteoporosis" which increases bone density and has not caused any injuries to study participants. I do the Twelve Poses everyday now and substitue 15 -20 minutes on a stepper to compensate for loss of the vibration plate.

Whatever you decide, I wish you the best.