As a Pilates Instructor and also as someone who has had a lower back problem most of my adult life from a dance injury. I have to bring into thuis conversation a modified Pilates programme.
In the UK and many other countries we work with a referral programme with Physical therapists (physiotherapists) and after we get very specific directions from our medical friends we design a very specific individual session for our clients.
Now this is not a traditional classical Pilates session but a modified and very adapted personal session using the 1999 research of Carolyn Richardson, Paul Hodges , Julie Hides and their published work which is standard training work in this area.
Please check it out: Therapeutic Exercise for Lumbopelvic Stabilization: A Motor Control Approach for the Treatment and Prevention of Low Back Pain.
I have found this very successful with many clients and have helped many of them return to active programmes using this type of programming.
But this must be in a partnership with a qualified medical professional who guides us with specific information for making the correct programme.