I don't think memory foam is appropriate for your wife because it is still too soft and she would sink in and boost the pain. I think you should have a look at an extra firm type of mattress (http://www.urbanmattress.com/mattres...a/pegasus-firm its properties might help you). These mattresses give substantial support and pressure on muscles and eliminate back pains. However, do not expect the mattress to be magical, your wife needs exercise and proper medication in order to totally get rid of the pain. Hope she gets well soon