I attended a workshop in June 2018 on this topic,  run by Alison Trewhela who designed the yoga course for this University of York/Arthritis UK project.  Participants reported improvements and a sense of empowerment, “knowing what to do” when experiencing either crisis back pain or ongoing back discomfort.  Less reliance on painkillers was also reported – again, very encouraging!

https://www.arthritisresearchuk.org/arthritis-information/arthritis-today-magazine/155-winter-2012/yoga-trial.aspx