A Sleep Number which is adjustable in firmness.

I used to sell mattresses. I believe a mattress with inner springs is best as opposed to a new memory foam mattress. Get one with the highest number of springs and the thickest gauge wire. You want the springs to give solid support.

The type of padding is for personal preference. If she wants soft padding, that’s completely fine as long as it’s on top of extra firm coils.

I hope she gets comfort from it.

If possible, check out Stearns & Foster mattresses. I also recommend Sealy.

What @Hawaii_Jake said. Go with inner spring mattress that is firm, then top it with whatever your sister prefers. My back hates the fact we replaced our old spring mattress with a firm latex mattress last year.

I had a memory foam mattress and after about a year it was permanently formed into my body shape. Meaning if you moved around in the bed, you would roll back into the valley created by your body. So you pretty much have to sleep in the same position forever.
I hurt my back also and went with a sleep number bed. I went to the store and they had me lay on the bed and measured my pressure points to come up with a good sleep number specifically for me. I’ve changed it over time, depending on my back situation. I do highly recommend it.

For me, in general a firm mattress seems to make a huge difference – some soft ones will end up with my back hurting a lot after one night.

Let her devide, because this is a very personal choice dependent on her issues.
Make sure she tries adjustable beds; those that raise the head and/or legs.

I’d go for pocket sprung where the individual springs are contained in their own little pockets (I’m assuming this is what @Hawaii_Jake is taking about but different countries have different weird names for the same thing). The pockets stop springs moving into each other when you lie on it making the mattress firmer. Generally speaking higher doing count indicates better quality but be aware that some companies may ‘cheat’ by making a double layer of springs which increases the spring count but doesn’t necessarily improve the quality.
Also make sure the mattress is double sided as it will last longer. ‘No turn’ is marketing guff for we halved the cost to us and doubled the price we charge.

Is it impossible for her to try out the mattresses herself? Guessing for someone else sounds risky.

I’d go with individual springs also and you can always add a great mattress cover with cushion in it if the bed is a little too firm for her.

Oh, make sure the bed isn’t too high off the ground. I don’t know how tall she is, but thicker mattresses are common these days. If it’s more than 12” thick you can look into getting a smaller box spring. The smaller box springs are 8” instead of 12” thick I think.

When a mattress is high off the ground I need to hike my leg up to get in it and it can pull my back.

Unless it’s some sort of platform bed without a box spring.

Lastly, have you thought about getting a hospital bed that she can adjust her position? The doctor might be able to order one.

^Good points about height of bed. When my back was out, I slept in my spare room that had a twin bed that’s close to the floor so I could roll out easier.

The firmest innerspring mattress you can find…..check for high number of springs and the gauge. If it seems too hard at first, put a 2” memory foam pad on it. If back pains begins to come back, try removing the pad.

@filmfann, this needs to be done before she gets out of the hospital, unfortunately.

I would ask her physican what is required for her condition.