Spondylothesis

A woman interested in beginning yoga has reservation due to a condition her doctors have labeled, spondylothesis. I searched yoga forums and structural yoga therapy to find nothing solid. When you have time, would you please advise as to what types of postures she can do/should avoid?
She feels numbness in her legs when she moves the wrong way, and I have a sense she is VERY cautious. I am eager to have her in class, but not at the expense of her spine or my livelihood…

Indeed for student with this condition asanas are best dynamic not static. So a gentle Viniyoga format is the best approach. I would recommend some practices in my book, rolling bridge, extending into cobra and locust, in general backbends are good as long as she feels extension.
Twists same they need to be extended and not held. Into the pose and out with breath rhythm. You can find this concept explained in my joint freeing series that is the best method to use for deep spinal problems in general.
namaste