It is very common to have some initial improvement from a TLIF decompression and fusion but have symptoms “show up” 6-8 months after surgery due to pseudoarthrosis. (“My symptoms improved at about 8 months post the TLIF and i started ramping up my activity at that point. Unfortunately shortly after doing so many of my pain and nerve sx became more noticeable and have continued to get worse and worse. I started pushing my surgeon’s office for imaging and they discovered i am not fused)”.
Generally, if you have local back pain (central pain-not unilateral) some time after fusion is unsuccessful, this pain is generated by the spine itself (the non-united bone fragments press together). Unilateral pain at the L5- S1 level can be either pseudoarthrosis or nerve related. Pain in the SI joint or buttocks on one side more likely is nerve irritation.
How would you characterize your pain in percentage lower back to leg and how does it change with activity?