This article should be available to everyone. I am not sure if you have to register with pubmed to see it, but it's the first I've seen that actually randomly assigned people to either get fusion or rehabilitation and then followed people for 4 years!
Outcome was no significant difference in pain or disability after 4 years between the two groups. 25% of those who started in the rehab group went on to get surgery, but 25% of those in the surgical group went on to get a second surgery so even that was no benefit.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938881/?tool=pubmed
Details are in the extended report.