Decompression or Fusion

Hello, I am new to this forum, but have been active in the TKR for a long time. While moving last year I suffered a back injury that appeared to be herniated disc. Before this though I had had years of back pain and finally went to a surgeon. At that time he suggested a disc replacement. I started the PT/Injection process in the Phoenix area then moved back to San Diego to finish this. I have been to one surgeon who said a fusion is needed of S1-L2?? Then to another who said he would do a "spinal decompression without fusion". I have never heard of this and was wondering if anyone has experience with this. Hopefully I am posting in the right place for this.... Thanks in advance.