Outcomes of primary versus revision TLIF following decompression alone in degenerative spondylolisthesis: a retrospective propensity score matched study.

Abstract

Degenerative grade 1 spondylolisthesis is associated with lumbar instability, typically addressed with decompression and fusion to prevent iatrogenic instability. The SLIP trial indicated that decompression-only patients benefit significantly from early reoperation for instability. Yet, it's unclear how these revision patients' outcomes compare to those undergoing primary fusion. To evaluate whether outcomes were inferior among patients receiving revision transforaminal lumbar interbody fusion (TLIF) after prior decompression in the setting of degenerative, grade 1 spondylolisthesis when compared to those undergoing primary TLIF for grade 1 spondylolisthesis. Retrospective cohort study. Patients with grade 1 spondylolisthesis at L4-L5 or L5-S1 who underwent TLIF between 2018 and 2023 and had complete 1Y clinical follow-up and 6-month (6M) patient reported outcomes(PROs) were included. PROs (ODI, PROMIS, SF-12, VAS Pain) and Clinical (Readmission and Reoperation at 6-week [6W], 6M, and 1Y). No predictors for missing data were identified. Comparisons were made between primary fusion patients and those with prior decompression now undergoing revision TLIF. Bias was minimized via 2:1 propensity score matching (PSM) for age, comorbidities (CCI), slip percentage, slip translation, angular change, anterior and posterior disc height (ADH and PDH respectively), facet diastasis and cysts, and facet orientation-termed spondylolisthesis characteristics. Unmatched PROs and clinical outcomes were analyzed with a mixed-effects (ME) model and chi-Squared test, while matched PROs and clinical outcomes employed an ME model and conditional logistic regression. About 285 patients (55.4% female, mean age 60.80±0.73, CCI of 2.10±0.09, and 35.1% current/former smokers) were included. Spondylolisthesis slip was 13.11%±0.99% with mean translation in flexion/extension of 1.60±0.19 mm. Compared to revision patients (N=42, 14.7%), primary fusion patients (N=243, 85.3%) were younger (59.70±0.77 vs. 67.20±1.76) and had a lower prevalence of active smoking (2.48% vs. 11.90%), but showed no differences in slip percentage (p=.480), translation in flexion/extension (p=.778), ADH (p=.578), PDH (p=.991), facet diastasis (p=.132), facet cysts (p=.550), or angular change across L3-S1. Preoperatively, PROs were comparable across all domains. At 1-year postop, no differences were observed in back pain (p=.430), leg pain (p=.346), SF-12 PCS (p=.976), MCS (p=.737), PROMIS Score (p=.063), or ODI (p=.362). The PSM cohort, matched for age, CCI, and spondylolisthesis characteristics, showed standardized differences of less than 0.10 for all demographics, baseline PROs, and spondylolisthesis characteristics, aside angular change at L5-S1 (3.05 vs. 7.08, p=.062). At 1 year postop, there were no differences in back pain (2.62 vs. 2.10, p=.414), leg pain (2.15 vs. 1.48, p=.270), SF-12 PCS (43.02 vs. 43.38, p=.888), SF-12 MCS (51.31 vs. 52.80, p=.553), PROMIS Score (45.69 vs. 44.81, p=.630), and ODI (18.66 vs. 15.26, p=.375). Finally, no significant differences were found in early (6W) or long-term (6M to 1Y) complications, with 98.1% primary and 90.5% revision patients complication-free at 6W, and 93.6% versus 100.0%, respectively, from 6M to 1Y. Following decompression alone for grade 1 spondylolisthesis, patients having revision TLIF after decompression exhibit patient-reported and clinical outcomes similar to those undergoing primary TLIF.