A systematic review of anterior lumbar interbody fusion (ALIF) versus posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), posterolateral lumbar fusion (PLF)

Lumbar spondylosis, a prevalent condition causing significant back pain, radiculopathy, and reduced quality of life, frequently necessitates lumbar fusion surgery. The number of elective lumbar fusions has dramatically increased over the past two decades, primarily due to patients presenting with spondylolisthesis. Several surgical techniques exist, including ALIF, PLIF, TLIF, and PLF, each with its own set of advantages and disadvantages. ALIF offers benefits like complete disc excision, restoration of disc height and lordosis, direct and indirect neural decompression, and avoidance of posterior ligamentous structure damage. However, it carries risks of vascular and visceral injury. Posterior approaches, while avoiding some of ALIF's risks, may involve more extensive muscle dissection. Stand-alone ALIF, when appropriately indicated, avoids the need for additional posterior surgery, potentially reducing recovery time, blood loss, and cost. The lack of consensus on the optimal technique for patients with degenerative disc disease (DDD) or spondylolisthesis, combined with previous studies often including complex populations or aggregating different anterior and posterior fusion approaches, necessitates a focused comparison of stand-alone ALIF with various posterior techniques. This study aims to address this gap in knowledge by performing a comprehensive systematic review and meta-analysis, evaluating stand-alone ALIF in the context of DDD and spondylolisthesis against PLIF, TLIF, and PLF.

The introduction briefly mentions previous studies, highlighting their limitations: inclusion of complex populations (spinal deformity, long constructs, prior fusion, advanced morbidities), aggregation of different fusion approaches, and a lack of focus on stand-alone ALIF. These shortcomings underscore the need for a more focused review. The paper’s methods section elaborates on the search strategy for identifying relevant studies, which included a comprehensive search of MEDLINE, EMBASE, and the Cochrane Register of Trials, supplemented by grey literature searches. This suggests a robust attempt to capture relevant literature to address the study limitations identified.

This systematic review and meta-analysis aimed to compare stand-alone ALIF with posterior lumbar spinal fusion (PLIF, TLIF, PLF) in adult patients experiencing back or leg pain despite at least 6 weeks of non-operative management. The search encompassed MEDLINE, EMBASE, and the Cochrane Register of Trials from inception to February 2022, with no language restrictions. The search strategy adhered to PRISMA-S guidelines. Three reviewers independently screened titles and abstracts; discrepancies were resolved through discussion. Two reviewers extracted data, assessed study quality using the Cochrane Back Review Group's Risk of Bias criteria, and analyzed the data using Review Manager (RevMan). The analysis incorporated methods to estimate means and standard deviations from studies reporting medians or ranges. The meta-analysis used a random-effects model to account for study heterogeneity. Inclusion criteria specified randomized controlled trials (RCTs), cohort studies, and case series, while excluding case reports, studies with uninstrumented posterior fusion, long constructs, kyphosis/scoliosis, or circumferential fusion. A total of 16,435 records were initially identified, and after the screening process, 21 studies involving 3686 patients met inclusion criteria. The studies represented various countries. The risk of bias assessment considered factors such as randomization, blinding, attrition, reporting of baseline prognostic risk factors, and selection bias. Data analysis involved calculating relative risk and 95% confidence intervals for dichotomous data and mean differences and 95% confidence intervals for continuous data. Heterogeneity was assessed using the chi-squared test and I² statistic.

The meta-analysis revealed that stand-alone ALIF demonstrated significantly shorter surgical time and less blood loss compared to TLIF/PLIF. The difference in blood loss between ALIF and PLF was not statistically significant. ALIF also resulted in significantly shorter hospital stays compared to TLIF, but not PLIF or PLF. Fusion rates were similar across all techniques. Patient-reported outcome measures (PROMs) showed mixed results. While VAS and ODI scores for back pain at one year did not significantly differ between ALIF and PLIF/TLIF, significant differences emerged at two years when comparing ALIF and PLF, favoring ALIF in both VAS back pain and ODI scores. Interestingly, two-year VAS leg pain scores favored PLF over ALIF. JOAS scores for back pain favored ALIF over PLF at both one and two years. The incidence of adverse events was comparable across all approaches. Specifically, comparing ALIF to TLIF showed significantly shorter surgical time and lower blood loss, as well as shorter hospital stays. In the comparison of ALIF to PLIF, both surgical time and blood loss were significantly shorter for ALIF. The comparison of ALIF versus PLF demonstrated non-significant differences in surgical time and blood loss, although the results concerning surgical time showed a trend towards significance (p=0.08). Overall, fusion rates were similar across all comparisons.

The findings support the hypothesis that stand-alone ALIF offers advantages in terms of reduced surgical time, blood loss, and hospital stay compared to posterior approaches, particularly TLIF. The reduction in these perioperative parameters translates into potential cost savings and resource optimization within healthcare systems. While the fusion rates were comparable, which aligns with existing literature reporting a wide range of fusion rates for single-level surgeries, the inconsistent methods and timing of fusion assessment limit robust comparisons. The equivocal nature of some PROMs highlights the complexity of surgical and patient factors influencing outcomes. The significant differences in back pain PROMs (VAS, ODI, JOAS) favoring ALIF over PLF suggest a potential advantage of ALIF in specific patient subgroups or disease types. The similar adverse event rates across approaches suggest that the choice of surgical technique might not significantly impact the risk of complications, at least in the short term. The study's limitations, such as the preponderance of non-randomized studies and potential confounding variables (comorbidities, patient selection bias), should be considered when interpreting the results. Future studies employing robust methodology and extended follow-up periods are crucial to clarify long-term effects on PROMs and the development of adjacent segment disease.

This systematic review demonstrated that stand-alone ALIF offers advantages over PLIF/TLIF approaches concerning shorter operative time, reduced blood loss, and decreased hospital length of stay. While PROMs showed equivocal results when comparing ALIF with PLIF/TLIF, ALIF showed better outcomes for back pain compared to PLF. Adverse event rates were similar. The study highlights the need for future high-quality, randomized controlled trials adhering to CONSORT and STROBE guidelines to provide stronger evidence for clinical decision-making regarding lumbar fusion techniques.

The study's major limitation stems from the predominance of non-randomized studies, increasing the risk of confounding factors influencing both surgical outcomes and PROMs. Patient selection bias, due to surgeon preference or other clinical factors, is a concern. The limited data available for PROMs and the lack of longer-term follow-up restrict the assessment of long-term impacts and adjacent segment disease rates. Variations in surgical techniques, implant types, and diagnostic sub-types across the included studies contribute to the heterogeneity observed in the results. The heterogeneity in reporting methods also limits the ability to draw definitive conclusions regarding some aspects of the comparison between surgical techniques.