Long-term Durability of Minimal Invasive Posterior Transforaminal Lumbar Interbody Fusion A Clinical and Radiographic Follow-up

Background Context: Both open and minimally invasive lumbar fusion surgeries (MIS) are used to treat patients with symptomatic degenerative spinal pathologies. Open lumbar fusion surgery studies have reported excellent short-term safety and long-term clinical outcomes. MIS has shown excellent safety and short-term clinical success, but there is very little information on its long-term clinical durability. Purpose: The purpose of this study was to document the long-term clinical durability and safety of patients treated with minimally invasive surgery-transforaminal lumbar interbody fusion (MIS TLIF). Secondary purposes were to evaluate the clinical outcomes of patients receiving fusion in 2 sequential lumbar disc segments (2-level) as compared with a single-level lumbar disc segment (1-level), and as an aside, to determine whether or not there were any differences in clinical outcomes in patients treated over the age of 60 years as compared with those under 60 years. Study Design: This study was a retrospective review of prospective collected outcomes data. Patient Sample: One hundred sixty-nine consecutive patients, with either isolated single-level or 2-level lumbar intervertebral segment pain manifested by back pain alone or back pain with leg pain associated with a primary diagnosis of degenerative spondylolisthesis, central herniated disc, central stenosis, Foraminal-lateral herniation of disc, Foraminal/lateral stenosis, or isolated degenerative disc or joint disease. Outcomes Measures: Hospital stay time postoperative, return to work time, Oswestry Disability Index (ODI), visual analog pain scores (VAS), pain medicine (narcotic) use, fusion status, and reoperation rate. Methods: Patients treated with 1or 2-level MIS TLIF were evaluated based on clinical outcomes, reoperation rates, and fusion status out to an average of 49 months postoperative (range, 36 to 60 mo). Effect of the number of levels fused, patient age, and worker compensation status on outcome was also assessed. Results: Average surgery time was 183 minutes, with no difference between older and younger patients. Hospital stay averaged 15 hours with a median return to work time of 8 weeks. Return to work for patients working before surgery was 97%. ODI improved 36% at the first follow-up and was improved 41% at 49 months postoperative (P < 0.001). Eighty-six percent of patients reached a 20% clinical improvement in ODI at the last follow-up. Every primary diagnostic group increased significantly over time (P< 0.001). VAS pain scores improved in a similar pattern as ODI (P< 0.001). Patients with 2-level fusions improved comparably in both ODI and VAS scores as 1-level fusion patients. Worker compensation patients improved in both ODI and pain scores, although a little less than nonworkers compensation patients. Neither smoking, nor obesity status impacted clinical outcomes. Narcotic use for spine related pain went from 100% to 31% 6 months postoperative. Fusion rates were 96% at the 1-year follow-up. When reviewing surgical revisions as a consequence of surgical technique, and omitting unanticipated adverse events, 99% of patients maintained a successful fusion at their last average follow-up. Conclusions: The results of this study support the long-term clinical effectiveness of MIS TLIF for varying diagnoses. These results suggest that those undergoing a 1-level or 2-level lumbar fusion improve equally, and that older patients do well with MIS surgery long term. Reoperation rates were acceptable, with excellent surgical durability at 49 months. The benefit of decompression was not assessed in this study, and future studies should assess its impact long term.