There can be many causes of pain after failed back surgery.
Improper preoperative patient selection before back surgery. This is the most common cause of failed back surgery syndrome. Surgeons look for an anatomic lesion in the spine that they can correlate with a patients pain pattern. Some lesions are more reliable than others. For example, degenerative disc disease is less commonly correlated with patients back pain than leg pain from a disc herniation pinching a nerve root. There are other sources of pain that can mimic back pathology such as piriformis syndrome, sacroiliac joint dysfunction and hip pathology (such as hip osteoarthritis).
Recurrent disc herniation after spine surgery. This is another common cause of recurrent pain after a discectomy/microdiscectomy spine surgery. The typical clinical picture is one where the patient initially has substantial pain relief, followed by a sudden recurrence of leg pain. In contrast to symptomatic pain caused by scar tissue (epidural fibrosis), in which symptoms tend to appear gradually, the symptoms of recurrent disc herniation tend to occur acutely. In addition to clinical history and presentation, an MRI scan is also useful in distinguishing the two pathologies
Technical error during spine surgery. The spine surgeon must also consider technical error if there is continued pain after a discectomy or microdiscectomy or a laminectomy. For example, was a fragment of herniated disc material missed, or a piece of bone left adjacent to the nerve? In either case, the resulting compression of the nerve root could cause pain. Were the correct operative levels chosen during surgical planning? If not, an adjacent disc may be the true source of the pain. Again, postoperative imaging and clinical presentation will help answer these questions.
Treatment of pain persisting after surgery should be approached in a systematic way.
Diagnosing each pain generator and eliminating the pain generators can serve to restore function and eliminate pain and in order to do that, we can employ a number of different tools that are available to us. And those include a wide array of the tools. Now it can be manipulations, it could be physical therapy, at times injections, or at times if we need to things like spinal cord stimulation or implantable pumps that can supply a steady state of medication can be used to control the pain. By using all the tools that are available to us, we can really improve the patient's quality of life by doing two very important things: decreasing the pain and restoring function. That way, they can reintegrate back into life and not be limited by pain or by mobility.