How long ago? This depends on how long it has been since the fusion surgery. Normal postoperative pain may last for weeks or months. Continued, severe pain many months or years after fusion surgery may indicate several possible problems, such as failure of the bones to fuse, recurrent nerve compression or a new problem at another level of the spine. This should be evaluated with x-rays, a ct scan or an mri.
Pseudoarthrosis. Wrong levels done if not preoperatively confirmed with discogram normal post op muscle painif done from posterior approach normal back muscles are hard to beat see pain specialist consider spinal cord stimulator see surgeon to rule out correctable cause of pain then see pain specialist surgical treatment of back ache has a significant failure rate it is a art not a science.