I do not have an inversion table yet, but my Chiropractor recommended I get one when my legs become stronger. He feels it is good therapy for the whole spine and can prevent the recurrence of problems. I will have to save to buy one though. I suggest you talk with her doctors and therapists before buying one, but it might prove to be of help.

I own and use a Hang-Ups inversion table and also, a Bounce Back fitness chair.
I would recommend them for anyone who does not have the opportunity to move as much as they would like to. Both products are especially good in moving the lymph through the system.

The inversion table would require help to use if your wife's mobility is limited. I do use the bonuce back chair more because it is easy to get in and out of, although certainly there are benefits of both which are desireable. The inversion table stretches the back and over time you can regain inches lost from compression. It takes time to work up to but as a therapy I consider it time well spent.

A knee injury makes the Bounce Back chair more appealing since I am unable to use our outside trampoline without reinjuring the knee and so the chair does not limit my use of it, weather-wise either and because it sits in front of the television I find myself using it more and for longer periods of time. Sort of a modern version of the old-timers Rocking Chairs which also moved the lymph and kept them healthier.

I've added some urls you may find of interest.

rebounding therapy in a chair
http://www.bonuce backfitnesschair.com/

benefits of inversion
http://www.energycenter.com/grav_f/benefits.html

frequently asked questions about inverting
http://www.energycenter.com/grav_f/freq_ask_quest.html#14

be happy, be well,
Zoe