Thank you for your question to HCM.
The symptoms you have described, in the setting of previous spine surgery can arise from nonunion
of the bones or new stenosis. New stenosis above and below the level of previous surgery can be detected by MRI
. Nonunion of the bones which were supposed to fuse can lead to recurrent stenosis at the same level.
Standing Xrays while bending forward and backward are needed to detect this nonunion. MRI interpretation in this area is sometimes confusing as a result of artefact from the metal. A study called CT myelogram which is a CT scan
along with an injection of a dye in spine can confirm nonunion as well as show this stenosis. You can discuss this possibility with your surgeon.
Hope this is helpful. Wish you the best.