Following open spine surgery, whether it is a fusion, discectomy or laminectomy patients can experience chronic pain in the back and or the arms or legs. These syndromes are often due to identifiable causes but are termed by surgeons and the medical community to be failed back surgery syndrome (FBSS). Nearly all open back surgeries include one form of fusion. The true test of whether an open back surgery is successful is not to measure the success of the fusion process but the actual reduction of pain. For single level fusions, the percentage obtaining significant pain relief is 40-80% while with three levels, this drops to approximately 15%.

Some of the most common causes of failed open back surgery are: 

Residual foraminal stenosis due to inadequate exploration of the nerve root during open.
Residual spinal stenosis due to failure to appreciate the spinal anatomy during surgery. 
Painful disc disease due to residual pain emanating from the discs which still retain motion.
Spinal instability due to removal of too much of the central disc or removal of too many supporting ligaments.