Sadly, very few surgeons will tell a spine surgery patient the real odds for success, or they will project a success rate that is far higher than reality. The success rate for spine surgery today is a little over 60%. Compared to other types of surgery, that success rate is deplorable.
On the physician's side, there are many reasons why a patient will continue to experience both pain and radiculopathy long after surgery and possibly for a lifetime. Almost all spine surgeries, including discectomies, result in some nerve damage. In some patients, it never heals. Nerves also heal at a notoriously slow rate. It can take a year or more for some damaged nerves to heal. Some of my nerve damage was caused by my disc herniations. But some of it (and it is permanent) was the result of a surgery.
Another culprit is fibrosis (a.k.a. scar tissue). Surgery creates scar tissue. It always creates scarring. Individuals produce scar tissue at their own unique rate. In some cases, the patient will live the rest of her or his life with no pain from it. But many of us experience serious and lasting pain from fibrosis. Technically, it can be surgically removed. But such procedures border upon ethical constraints because at least as much is likely to grow back, if not more.
Osteoarthritis is another result to spine surgery - even a discectomy. Whenever a joint is damaged, including those in the spine, the body's immune system with rush in to attack what it interprets as invading cells. The more damage to your spine, the more arthritic you are likely to become. This too depends upon the individual and genetic predispositions. In my family, rheumatoid and osteoarthritis is very prevalent. So it came as no surprise to me that my spine was riddled with arthritic damage before I turned 40.
To leave you with a bright thought, I'll conclude with one more type of post-spine-surgery pain - inflammation. Sometimes after spine surgery, your nerve roots are inflamed, rather than damaged. Again, like damage, spinal nerve root inflammation can take many months to dissipate. Let's hope that this is the culprit in your case.
One of the best things you can do now is to enroll in a comprehensive pain management program - one that focuses as much on mind-body treatments (biofeedback, Yoga, systematic relaxation, meditation, etc.) as on injections and medications. You can also try TENS, acupuncture, physical therapy, kinesiotherapy, etc.). I can reduce my pain by about 20% with biofeedback alone. If all of these fail and you continue to experience unrelenting pain and dysfunction, you can try the spinal cord stimulator or the intrathecal infusion pump.
There are still options if your condition does not improve. Good luck.