Hi Renee -- Spruce trees are moderately long lived, often surviving 100 to 250 years, depending on the species. I don’t know what type of spruce you have but given its relatively young age and current health issues suggest that the tree may benefit from any measures that can improve its health and resistance to disease. 

Stem girdling roots is unfortunately not uncommon although much of the literature talks about its prevention rather than its treatment, especially in mature trees. As in your case, not all trees with stem girdling roots die young or fail during windstorms. For those trees a root collar excavation whereby the tree’s root flare is exposed and girdling roots can then be removed, preferably back to a point where they will grow outward from the trunk, is a potential treatment. 

There are risks. Some roots may be too in-grown to remove and may result in greater damage to the tree if removal is attempted. There is also the risk of introducing new pathogens during the excavation process. However, if successful a root collar excavation could potentially help by reducing stress on your tree and improving the health of its root system, but the treatment is invasive and expensive.

I found a few resources that you might peruse as you make your decision. One is pdf
by a UMN Forestry Professor. This publication has tips for management after girdling is addressed. Colorado State University Extension does a nice job describing common root issues, including girdling. If still undecided, it may be worth consulting with a second arborist who is familiar with the specific needs of spruce trees and learn their recommendation for treatment. Good Luck!