Failed back syndrome (FBS) is a condition that can occur following surgery to correct back pain. Although the surgery may be successful in relieving pain, some patients end up with new or recurrent pain in the surgical area. FBS is a complex problem, and the exact cause is often difficult to determine. However, possible contributing factors include scar tissue formation, nerve irritation, and muscle spasms. Treatment for FBS often includes a combination of pain medication, physical therapy, and counseling. In some cases, additional surgery may be necessary. With proper treatment, most people with FBS are able to find relief from their pain and live normal, active lives.