there are basically two kind of surgery done for chronic disc problems i.e. only decompression -when the leg pain is more than back pain
and decompression with fusion when backpain is equal or more significant than leg pain
Any chronic disc problem should treated with surgery only when all option of conservative management are exhausted i.e.
taken lot of analgesics continuously for more than 6 weeks , exhausted with physiotherapy
It is true that other disc are at increased risk but it takes quite a long time for the other discs to degenerate.
fusion is more of concern only in young age and obese