Generally, it is recommended to do a fusion if the level has already had 3 herniations (HNP). The reason is scar generation, 4th recurrent HNP and the “battered root” syndrome.
These roots don’t like to be manipulated too many times as manipulation can cause root damage even without recurrent HNPs so the fewer surgeries to free the root, the better. We have figured that 3 decompressions should be the maximum number to prevent battered root.
A disc that has already spit 3 herniations out can easily herniate again. For the first three HNPs, it is noted that recurrence rate is about 10-20%. However, after the first three, the reherniation rate goes up possibly to 50%
Finally, every time the root is decompressed, there is scar that forms. This scar only multiplies with each subsequent surgery. Again, it seems like three is the magic number here too.
Then finally add severe left foraminal stenosis due to the loss of disc height and degeneration bone spurs that occur. This will not get better with a redo surgery but could get worse and become symptomatic. I would advise a decompression and fusion of this level.