Outcomes of Primary vs. Revision TLIF Following Decompression Alone in Degenerative Spondylolisthesis: A Retrospective Propensity Score Matched Study.
Background: 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.
Objective: 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.
Methods: Retrospective cohort study. Methods: Patients with grade 1 spondylolisthesis at L4-L5 or L5-S1 who underwent TLIF between 2018-2023 and had complete 1Y clinical follow-up and 6-month(6M) patient reported outcomes(PROs) were included. Methods: PROs (ODI, PROMIS, SF-12, VAS Pain) and Clinical (Readmission and Reoperation at six-week(6W), 6M, and 1Y). Methods: 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.
Results: 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=0.480), translation in flexion/extension (p=0.778), ADH(p=0.578), PDH(p=0.991), facet diastasis (p=0.132), facet cysts (p=0.550), or angular change across L3-S1. Preoperatively, PROs were comparable across all domains. At one-year postop, no differences were observed in back pain (p=0.430), leg pain (p=0.346), SF-12 PCS(p=0.976), MCS(p=0.737), PROMIS Score (p=0.063), or ODI(p=0.362). 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=0.062). At one year postop, there were no differences in back pain (2.62 vs. 2.10, p=0.414), leg pain (2.15 vs. 1.48, p=0.270), SF-12 PCS (43.02 vs. 43.38, p=0.888), SF-12 MCS (51.31 vs. 52.80, p=0.553), PROMIS Score (45.69 vs. 44.81, p=0.630), and ODI (18.66 vs. 15.26, p=0.375). 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% vs. 100.0%, respectively, from 6M to 1Y.
Conclusions: 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.