The hip and psoas muscles, which, when inflamed, can cause significant stress on the back, will be targeted by this stance which will target those muscles.
In the same manner that you would perform a half butterfly, bend your right knee while seated and allow it to fall open to the side. This is the same as the half butterfly. You should reach forward and wrap your torso over your legs in a gentle manner.
Switch sides once you have taken three breaths. Instead of straining yourself into this pose, try to relax into it. This will allow you to achieve the most optimal release possible in your spine.