Hi primasilva,
If you’ve not already done so, the first place to start is a great post about how to find the best mattress for you. Phoenix has documented 5 steps, which are important because the comfort of a mattress is something only you can assess. The link is here:
The health issues don’t specifically require a different approach, except that ensuring a mattress matches your PPP (described in the above link) will be more important than for someone who can sleep on anything.
One note, pain in hips and shoulders often is an indicator of insufficient pressure relief (one of the P’s in PPP). It can be caused where your comfort / top layer isn’t doing a sufficient job… It could certainly mean the upper comfort layers in your Serta have worn out/ softened to the point they aren’t pressure relieving enough for you.