Hi Mirta, welcome. Sorry about your situation. Can you tell us more about your spinal health? How long have you had these levels affected? Did you have trauma, such as a car accident? Have you had problems like arthritis? What diagnostics have you had?
If you are set on having a keeled design, which removes a lot of bone, it's important to get a bone density exam (like DEXA). Also, as a woman, you may be in a higher risk category for osteoporosis. If that's not enough, localized osteoporosis of the spine from undiagnosed diseases has been documented for some time now.
In case you've not seen this forum, you can find specifications from each of the manufacturers you mention:
Manufacturer Product Information - ADRSupport Community
And also, help us help you:
http://www.adrsupport.org/forums/f58...-health-11053/