People who receive spinal fusions most often have degenerative spinal disease. The fusion is done to stabilize the spine, keeping it from deteriorating further. However, because manmade material can break, or the condition of the spine can change over time, sometimes the materials break or they cannot hold on to the bones any longer.
If you are experiencing new back pain or the pain you had before the surgery appears to be returning, you should visit your surgeon to be evaluated. He or she should be able to tell through a physical examination and x-rays if there are any problems with the hardware used for the fusion.