Five-year follow-up after minimally invasive transforaminal lumbar interbody fusion versus decompression alone for grade 1 spondylolisthesis: are there any differences in outcomes?

OBJECTIVE The Spinal Laminectomy Versus Instrumented Pedicle Screw trial reported the superiority of fusion compared to laminectomy alone for patients with grade 1 degenerative spondylolisthesis. However, it remains unclear if the advantages of fusion extend to using minimally invasive surgical (MIS) techniques. This study compared 60-month outcomes following minimally invasive transforaminal lumbar interbody fusion (TLIF) versus decompression for grade 1 spondylolisthesis. METHODS The authors analyzed patients who underwent single-segment MIS TLIF or MIS tubular decompression for grade 1 degenerative lumbar spondylolisthesis from the prospective Quality Outcomes Database’s 12 highest enrolling sites (SpineCORe team). Uni- and multivariable analyses compared outcomes including the Oswestry Disability Index (ODI), numeric rating scale (NRS) for back pain (NRS-BP), NRS for leg pain (NRS-LP), EuroQol-5D (EQ-5D), North American Spine Society (NASS) satisfaction score, and cumulative related reoperation rate. RESULTS Of 608 total patients, 143 underwent MIS TLIF (n = 72, 50.3%) or MIS decompression (n = 71, 49.7%). The overall study cohort’s 60-month follow-up rate was 86.8%. The MIS TLIF cohort was significantly younger (mean 62.1 ± 10.6 vs 72.3 ± 9.7 years), had lower rates of diabetes (9.7% vs 22.5%), higher rates of private insurance utilization (65.3% vs 26.8%), was more likely to be employed preoperatively (54.2% vs 23.9%), and had higher baseline NRS-BP scores (mean 6.9 ± 2.6 vs 5.6 ± 3.2, p < 0.05). Otherwise, the cohorts were similar in baseline characteristics. Sixty months postoperatively, both cohorts had significant mean improvements in ODI, NRS-LP, NRS-BP, and EQ-5D scores compared to their respective baselines (p < 0.05). MIS TLIF had a significantly lower reoperation rate (2.8% vs 15.5%, p = 0.008). The minimal clinically important difference rates for the ODI, NRS-LP, NRS-BP, and EQ-5D were equivalent (p > 0.05). MIS TLIF demonstrated significantly larger reductions in NRS-BP scores (−4.0 ± 3.5 vs −2.2 ± 3.4) and higher rates of satisfaction (NASS score 1 or 2 = 87.7% vs 74.5%; p < 0.05) but similar absolute 60-month ODI, NRS-LP, NRS-BP, and EQ-5D scores (p > 0.05). On multivariable analyses, fusion significantly reduced the odds of reoperation (OR 0.07, 95% CI 0.008–0.39; p = 0.006), but fusion status was neither a significant predictor of ODI, NRS-LP, NRS-BP, or EQ-5D scores, nor NASS satisfaction scores. CONCLUSIONS Regardless of the surgical approach, a dorsal-based MIS technique was associated with clinical benefits in patients with grade 1 spondylolisthesis. These 60-month results demonstrate that MIS TLIF and MIS decompression are associated with similar patient-reported outcomes. However, MIS TLIF is associated with significantly fewer reoperations.