Which mattress is best for builder and scoliosis sufferer?

Hi,My partner and I are looking to buy a new mattress but are unsure of what type would be best.Our combined weight is under 23st and we both suffer with back ache, I have scoliosis and my partner is a builder so suffers with every day back aches.We currently have a orthopaedic mattress but I don't find it's made my back ache any better and to be honest my partner complains more about his since we've had it.Any advice would be much appreciated.Thank you.