I have a temperpedic adjustable bed and have had it for years. You have to get the expensive one now if you want it to be firm enough. Back in 2005 when I bought my first one, they were solid temperpedic, now the cheaper ones have it in layers and they don't seem to work as well. But the best thing is the adjustable as I can accommodate whatever pain is highest and then switch if I need to do so.

Female 54 yrs old
HLA-B27 negative
Dx with AS 2011
Dx with Psoriatic Arthritis 2015
Family history of RA and Crohn's
Can't take Enbrel, Humira, or other drugs like that
Have problems with both Sacral Joints, pelvis, neck, back, shoulders, jaw, GI problems, ribs and heels
Had over 8 surgeries most with fusion/titanium
On low starch diet due to high CRP and other inflammatory