Is it common to have a spinal fusion and still have unbearable pain?

No: If you have undergone a successful spinal fusion you should have attained at least 85% reduction on your symptoms intensity if your fusion is solid. Would recommend that you speak to your spinal surgeon so that reason for your pain can be identified and a proper treatment plan instituted to alleviate you of your pain.

Not common but does: Not all surgeries have a good outcome. The hardest ones to get a good outcome is a fusion for low back pain for multiple reasons. Sometimes, the surgery was not the right thing to do in the first place or the wrong type of fusion may have been done. Sometimes, a fusion does not fully heal. We sometimes do not identify all the pain generators when indicating fusion. Some patints are poor risks.