Failed back surgery syndrome (also called FBSS, or failed back syndrome) is a misnomer, as it is not actually a syndrome – it is a very generalized term that is often used to describe the condition of patients who have not had a successful result with back surgery or spine surgery and have experienced continued pain after surgery. There is no equivalent term for failed back surgery syndrome in any other type of surgery (e.g. there is no failed cardiac surgery syndrome, failed knee surgery syndrome, etc.).There are many reasons that a back surgery may or may not work, and even with the best surgeon and for the best indications, spine surgery is no more than 95% predictive of a successful result.
Reasons for Failed Back Surgery and Pain after Surgery

Spine surgery is basically able to accomplish only two things:

Decompress a nerve root that is pinched, or
Stabilize a painful joint.

Unfortunately, back surgery or spine surgery cannot literally cut out a patient’s pain. It is only able to change anatomy, and an anatomical lesion (injury) that is a probable cause of back pain must be identified prior to rather than after back surgery or spine surgery.