The important part of ANY chair for back conditions is, unsurprisingly, the back rest which needs to give proper support and be properly shaped - to ensure that your back keeps it's S-shape.
I have had back problems for years (including two ops) but have an "ordinary" recliner which has a firm, well-shaped back. Some people equate a soft chair with comfort, but (for problem backs) it's usually firmness you require.
You can make an unsuitably soft backrest better with the use of firm, well-placed cushions or the use of something like The Backfriend.
I wouldn't spend a fortune on "special" chairs.