thanks for writing to us.
You have valid question. If we operate at particular level then we expect no stenosis at that level. As you said there was marked stenosis then it may be due to disc in the front and posterior spinal structures on the back. Anterior pressure was removed and there may be posterior pressure still remaining. Anyway you need to talk to your doctor about it and you can not go on taking morphine
for such a long period as it is always symptomatic treatment and it never change the pathology.
I would suggest to discuss with your doctor and consider definitive treatment option rather than taking pain medicine. Thanks.