Agree and disagree with Jeff and Joe. Inner-springs have stood the test of time and have long proven to be an effective support system, unlike all foam or memory foam which have not been tested over the long term. There's a reason why steel springs have stood the test of time -- because they work. In fact, inner springs are one of the only support systems that actually give the back real, proper support.

Having said that, not all spring systems are created equal.

How Back Support Works:

In order to get back support, something underneath must be "pushing up" along the body to support and prop the back into a natural alignment. This is the function of springs. They both adapt to heavier parts of the body and push up as well. However springs can cause pressure points without suitable padding, so it's good to have some comfort layers over it, such as memory foam or latex (memory foam is not a support layer, it's a comfort layer) to reduce those pressure points. Most of the luxury firm models from S&F will have a decent amount of comfort layers.

The combination of metal springs with certain types of comfort layers is a time tested, proven way to make a mattress both supportive and comfortable.

I've been recommending high quality innerspring mattresses to people who have had back surgeries for nearly 15 years. Considering your situation and the fact that you're about to have a lumbar fusion it's absolutely critical that you get real, correct support at night, and springs are far and away the best way to get that support. Another excellent alternative would be an all-latex mattress, but that's only because latex behaves a lot like springs do. Latex has a natural "spring" to it which pushes up along the body yet doesn't create as much pressure. The luxury firm models from S&F still have a decent amount of padding, so it should still be good on your side as well.

Generally a "firm" mattress is not good for a side sleeper but each sleeper is unique, however I would see the comfort exchange policy requirements. Since you are buying an expensive mattress make sure you find out their return policy if you are not happy with it. This may include buying a mattress encasement to keep your mattress clean. Be sure to go to a locally-owned store so you can deal right with the owner if their is a comfort issue. Since you have had several issues with your back their may not be any one solution to "fix" your back problems but I am sure you would like to get as comfortable as possible in the meantime. Good Luck

Jeff is right on, and I will go a step further by saying with fusions and back surgeries, I personally would recommend avoiding any kind of metal coil bed. Metal coils deflect energy, pushing back at you, causing subtle pressure. This action will likely cause pain in those sensitive areas. I would recommend looking for a non-toxic memory foam bed. That will provide the support you seek without the pressure.