Arthritis of the left thumb is really starting to bother me, and I`m wondering if fellow sufferers can give me any idea of what neck will put the least strain on the thumb joint at the base of the thumb. I wasn't`t so aware of it on my WAL fretless but it`s an issue on a new Hohner B fretted bass I bought. Maybe because I fitted Rotosound 77 Jazz flats, which have too much tension I think. The nut is 40.5mm. Should I be playing a thin neck like an Ibby SR at 38mm? Or is it also a radius question = I don`t think flat is good here, maybe needs 9ins or so like a jazz neck.... Surely lower tension strings = which for example? I`m even wondering if I should go short or medium scale instead of 34ins All ideas welcome here = It`s a problem.