Posterolateral Fusion (PLF) Versus Transforaminal Lumbar Interbody Fusion (TLIF) for Spondylolisthesis: a Systematic Review and Meta-analysis

Background Context: Lumbar fusion is an effective and durable treatment for symptomatic lumbar spondylolisthesis; however, the current literature provides insufficient evidence to recommend an optimal surgical fusion strategy.

Purpose: The present study aims to compare the clinical outcomes, fusion rates, blood loss, and operative times between open posterolateral lumbar fusion (PLF) alone and open transforaminal lumbar interbody fusion (TLIF) + posterolateral fusion for spondylolisthesis.

Study Design: This is a systematic literature review and meta-analysis of English language studies for the treatment of spondylolisthesis with PLF versus PLF + TLIF.

Patient Sample: Data were obtained from published randomized controlled trials (RCTs) and retrospective cohort studies.

Outcome Measures: Clinical outcomes included Oswestry Disability Index (ODI), back pain, leg pain, and health-related quality of life (HRQOL) scores. Fusion rate, operative time, blood loss, and infection rate were also assessed.

Methods: A literature search of three electronic databases was performed to identify investigations performed comparing PLF alone with PLF + TLIF for treatment of low-grade lumbar spondylolisthesis. The summary effect size was assessed from pooling observational studies for each of the outcome variables, with odds ratios (ORs) used for fusion and infection rate, mean difference used for improvement in ODI and leg pain as well as operative time and blood loss, and standardized mean difference used for improvement in back pain and HRQOL outcomes. Studies were weighed based on the inverse of the variance and heterogeneity. Heterogeneity was assessed using the I-an estimate of the error caused by between-study variation. Effect sizes from the meta-analysis were then compared with data from the RCTs to assess congruence in outcomes.

Results: The initial literature search yielded 282 unique, English language studies. Seven were determined to meet our inclusion criteria and were included in our qualitative analysis. Five observational studies were included in our quantitative meta-analysis. The pooled fusion success rates were 84.7% (100/118) in the PLF group and 94.3% (116/123) in the TLIF group. Compared with TLIF patients, PLF patients had significantly lower odds of achieving solid arthrodesis (OR 0.33, 95% confidence interval [CI] 0.13-0.82, p=.02; I=0%). With regard to improvement in back pain, the point estimate for the effect size was -0.27 (95% CI -0.43 to -0.10, p=.002; I=0%), in favor of the TLIF group. For ODI, the pooled estimate for the effect size was -3.73 (95% CI -7.09 to -0.38, p=.03; I=35%), significantly in favor of the TLIF group. Operative times were significantly shorter in the PLF group, with a summary effect size of -25.55 (95% CI -43.64 to -7.45, p<.01; I=54%). No significant difference was observed in leg pain, HRQOL improvement, blood loss, or infection rate. Our meta-analysis results were consistent with RCTs, in favor of TLIF for achieving radiographic fusion and greater improvement in ODI and back pain.

Conclusions: Our results demonstrate that for patients undergoing fusion for spondylolisthesis, TLIF is superior to PLF with regard to achieving radiographic fusion. However, current data only provide weak support, if any, favoring TLIF over PLF for clinical improvement in disability and back pain.