Comparison of patient outcomes of anterior and posterior lumbar interbody fusions: A retrospective national database analysis

Cole Veliky; Paul Michael Alvarez; Hania Shahzad; Diego Martinez; Elizabeth Yu; Varun K. Singh

doi:10.1016/j.jor.2024.10.014

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doi:

10.1016/j.jor.2024.10.014

Comparison of patient outcomes of anterior and posterior lumbar interbody fusions: A retrospective national database analysis

Cole Veliky^a, Paul Michael Alvarez^b, Hania Shahzad^b, Diego Martinez^c, Elizabeth Yu^b, Varun K. Singh^b

a The Ohio State University College of Medicine, USA

b Department of Orthopedics, The Ohio State University, Wexner Medical Center, USA

c Cooper Medical School of Rowan University, USA

∗Corresponding author: Varun K. Singh. Varun.Singh@osumc.edu

Received: 2024-9-12, Accepted: 2024-10-9, Published: 2024-10-10

The Authors

Disclaimer:
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.

Abstract

Lumbar interbody fusions are used to treat degenerative lumbar disease unresponsive to conservative treatment. This procedure may be divided into anterior lumbar interbody fusion (ALIF), and posterior lumbar interbody fusion (PLIF/TLIF). Despite their widespread use, comparative research on their outcomes remains limited.

The PearlDiver Database was utilized to identify patients undergoing single and multi-level ALIF and PLIF/TLIF between 2010 and 2022. We examined demographic data, comorbidities, and reoperation rates at 90 days, 1 year, and 2 years. Complications were assessed using multivariable regression to adjust for confounders.

The study included multi-level anterior interbody fusions (N = 569, mean age 59.8, 59 % female), multi-level posterior interbody fusions (N = 43,651, mean age 57.9, 60 % female), single-level anterior interbody fusions (N = 3,547, mean age 55.3, 61 % female) and single-level posterior interbody fusions (N = 25,792, mean age 56.9, 62 % female). Multi-level posterior interbody fusion patients had a lower prevalence of HTN (OR .77, P < .05), ischemic heart disease (OR .73, P < .05), CDK (OR .77, P < .05), postoperatively more DVTs (OR 1.44, P < .05), a lower incidence of respiratory failure (OR .57, P < .05), and a higher 90-day, 1-year, and 2-year all-cause reoperation rate (7.3 %) compared to multi-level anterior interbody fusion patients (3.7 %). Single-level posterior interbody fusion patients had more HTN (OR 1.1, P < .05), less ischemic heart disease (OR .89, P < .05), obesity (OR .92, P < .05), and postoperatively a higher incidence of DVT (OR 1.34, P < .05) but lower 90-day, 1-year, and 2-year all-cause reoperation rates.

This study confirms that posterior interbody fusions are more common than anterior procedures, though the latter is increasing. Reoperation rates are higher for multi-level posterior and single-level anterior fusions. Both anterior and posterior approaches show similar complication profiles, though specific risks, such as postoperative DVT, vary. These findings emphasize the need for ongoing research and consideration of individual patient factors when choosing an interbody fusion technique.

Keywords

Epidemiology

ALIF

PLIF

Database Study

Complications

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1 Introduction

Lumbar interbody fusion (LIF) procedures are integral to the surgical management of degenerative spinal diseases, aiming to alleviate pain, correct deformity, restore intervertebral height, and stabilize spinal segments. These procedures, by achieving solid arthrodesis, can significantly improve patient outcomes, enhancing quality of life and reduce the need for further interventions. Over time, surgical techniques for LIF have evolved, with the choice of approach often determined by the specific clinical scenario, surgeon expertise, and patient factors. The anterior lumbar interbody fusion (ALIF) and posterior lumbar interbody fusion (PLIF/TLIF) approaches are among the most commonly employed techniques. Despite their widespread use, there is ongoing debate regarding the optimal approach, as each method offers distinct advantages and potential drawbacks.

The anterior approach (ALIF) involves accessing the lumbar spine through a retroperitoneal corridor, which allows for direct visualization of the intervertebral disc space without the need to manipulate the spinal canal or neural elements.¹ ALIF provides unrestricted access to the anterior column; this technique facilitates the precise placement of larger interbody fusion devices and has been associated with reduced intraoperative blood loss, shorter surgical durations, and lower rates of postoperative pain in comparison to posterior interbody fusion techniques.¹ The anterior approach also protects posterior bony structures, posterior spinal nerves, and furthermore, by avoiding disruption of the posterior spinal musculature, ALIF may reduce the risk of postoperative complications such as muscle atrophy and chronic pain syndromes.²

In contrast, the posterior options, including posterior lumbar interbody fusions (PLIFs) and transforaminal lumbar interbody fusions (TLIFs), provide direct access to the disc space via a posterior or posterolateral route, involve traversing the spinal canal or foramen for access to the disc and interbody space (PLIF/TLIF).¹ These techniques allow for the placement of interbody grafts while simultaneously decompressing the neural elements, a critical advantage in cases where spinal stenosis or nerve root compression is a concern. However, the need to retract or manipulate the dural sac and nerve roots in PLIF/TLIF can increase the risk of neurological complications, including dural tears, nerve root injury, and postoperative radiculopathy.

Historically, PLIF/TLIF have been associated with reduced mortality rates, a lowered risk of adverse postoperative outcomes,³ and surgeons were simply more familiar with the procedure, and thus the posterior approach to the lumbar spine was the preferred method for interbody fusion procedures. However, anterior approaches are gaining popularity due to their more recent proven effectiveness and low morbidity and mortality rates, given that the surgeon masters the technique and vascular risks are well-managed.⁴ Recent literature offers a mixed perspective on the relative efficacy and safety of ALIF versus PLIF/TLIF.⁵ Moreover, most comparative studies to date have focused on single-level procedures³,⁶,⁷ with limited data available on multi-level fusions, which may carry different risk profiles and technical challenges. Additionally, many studies have not extended their follow-up beyond 90 days³,⁶,⁷ leaving a gap in understanding the long-term outcomes of these procedures. Additionally, these studies are now older and this study can more accurately show current trends and outcomes of contemporary spine surgery.

In light of these considerations, this study aims to provide a comprehensive analysis of the demographics, comorbidities, outcomes, and reoperation rates among patients who underwent single and multi-level anterior interbody fusions in comparison to those who underwent posterior interbody fusion procedures. By utilizing a large national database and examining long-term follow-up data, this study seeks to clarify the relative benefits and risks of these approaches, ultimately contributing to the ongoing discourse on the optimal surgical management of degenerative lumbar disease.

2 Methods

A retrospective cohort study was performed using the PearlDiver Database of Medicare records. This analysis encompassed patients who underwent lumbar interbody fusions, including anterior lumbar interbody fusion (ALIF) and posterior lumbar interbody fusion (PLIF/TLIF), at both single and multiple levels from 2010 to 2022. The specific Current Procedural Terminology (CPT®) codes used were CPT-22558 and CPT-22586 for single and multi-level ALIF, and CPT-22630 and CPT-22632 for single and multi-level PLIF/TLIF procedures.

Patients with metastatic cancer, spinal infections, and traumatic injuries were excluded to concentrate on elective surgical cases. Demographic information such as age, gender, Elixhauser comorbidity index (ECI) score, as well as insurance details, were extracted for analysis. Common comorbidities such as peripheral vascular disease (PVD), hypertension (HTN), ischemic heart disease (IHD), obesity, diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), coronary artery disease (CAD), chronic kidney disease (CKD), and tobacco use were evaluated using chi-square tests to determine the differences between groups.

Complications were classified into wound-related (e.g., wound infection, seroma), device-related (e.g., hardware breakage), and medical complications (e.g., deep vein thrombosis [DVT], pulmonary embolism [PE]). The study assessed complications and reoperation rates at 90 days, 1 year, and 2 years postoperatively. Multivariate regression models were employed to reveal associations while adjusting for confounding factors such as age, ECI score, and comorbidities. The analysis aimed to identify associations between surgical approach and outcomes while controlling for potential biases and variations in patient demographics.

3 Results

A total of 73,559 patient records were analyzed, ecompassing patients undergoing multi-level anterior interbody fusion (569 patients, mean age 59.8, 59 % female), multi-level posterior interbody fusion (43,651 patients, mean age 57.9, 60 % female), single-level anterior interbody fusion (3547 patients, mean age 55.3, 61 % female) and single-level posterior interbody fusions (25,792 patients, mean age 56.9, 62 % female). The demographic characteristics revealed that patients undergoing multi-level anterior procedures were statistically significantly older (59.8 years) vs. those undergoing multi-level posterior procedures (57.9 years) and patient undergoing single-level anterior interbody fusions were statistically significantly younger (55.3 years) than those undergoing single-level posterior interbody fusions (56.9 years); these age differences are unlikely to be clinically significant in practice.

In terms of comorbidities, multi-level PLIF/TLIF patients had a lower prevalence of HTN (OR .77, P < .05), ischemic heart disease (OR .73, P < .05) and CKD (OR .77, P < .05). However, they had a higher incidence of postoperative DVTs (OR 1.44, P < .05), a lower incidence of respiratory failure (OR .57, P < .05). The reoperation rates were notably much higher at 90-days, 1-year, and 2-years (7.3 %) compared to patients undergoing multi-level anterior interbody fusion (3.7 %). Single-level posterior interbody fusion patients had more HTN (OR 1.1, P < .05), less ischemic heart disease (OR .89, P < .05) and obesity (OR .92, P < .05), and postoperatively had a higher incidence of DVT (OR 1.34, P < .05) but a lower 90-day, 1-year (both 1.6 % compared to .7 %), and 2-year (1.6 % compared to 1.3 %) all-cause reoperation rate. Both anterior and posterior procedures at any number of levels were performed predominately on women.

4 Discussion

4.1

4.1 Contemporary utilization

The analysis underscores a predominant use of posterior interbody fusion over the anterior fusion, with a ratio of approximately 9:1 for multi-level procedures (43,651 compared to 569) and 7:1 for single-level procedures (25,792 compared to 3547). Despite this, the trend towards the increased use of ALIF is evident, as recent data shows a notable rise in ALIF utilization compared to the slower increase in posterior techniques compared to data published in 2017,⁶ where Medicare records spanning from 2005 to 2012 showed a proportion of nearly 15:1 of PLIF/TLIF procedures (162,906) compared to ALIF procedures (10,895). A recently published study by Singh et al., in 2020 reported that between 2012 and 2019, while the overall number of lumbar interbody fusion procedures increased, there was a more significant rise in ALIFs compared to posterior techniques (592.81 % vs 44.96 %).⁸

Several factors contribute to this shift. ALIF provides several clinical advantages, such as reduced postoperative pain and shorter inpatient stays due to the avoidance of paraspinal muscle dissection⁵; the thickness of paravertebral muscles has been found to be associated with complications in PLIF,⁹ thus ALIF may be better suited for younger, more muscular individuals. However, ALIF's technical complexity and risk of vascular complications may influence its adoption.¹⁰ Conversely, the PLIF/TLIF techniques are well established with extensive surgical experience, which may account for their continued preference despite the growing popularity of ALIF.

The PLIF/TLIF approach carries a higher risk of neurological complications, primarily due to the potential for retraction on the thecal sac and nerve roots. Existing reports suggest postoperative neurological deficits in the range of 9.0 %–24.64 %.¹¹ This elevated risk of neurological complications associated with the PLIF technique may influence surgeons to opt for the ALIF approach as a safer and more preferable choice.

4.2

4.2 Complications and outcomes

This study's findings regarding DVT incidence in posterior interbody fusions conflicts with reports of increased rates of anterior interbody fusion DVT's compared to posterior⁷,¹²,¹³,¹⁴. This may be attributed to more exposure and manipulation of vasculature,¹⁵ which is theorized to increase thromboembolic risks. Alternatively, the increasing proficiency of surgeons with ALIF techniques may mitigate these risks over time. As for the increased incidence of respiratory failure in the multi-level anterior approach, it is well documented that this is a risk of the procedure in the cervical spine¹⁶,¹⁷, but it a lesser known complication from procedures in the lumbar spine, although it has been reportedly associated with multi-level anterior spinal lumbar interbody fusions over single-level or posterior procedures,¹⁸ as well as anterior and posterior thoraco-lumbar interbody fusions.¹⁹ This suggests a need for careful postoperative monitoring in multi-level lumbar cases.

4.3

4.3 Reoperations

Reoperation rates varied significantly between procedures. The higher reoperation rate observed in multi-level posterior procedures may be influenced by the complexity and higher morbidity associated with these cases. Additionally, in the anterior approach, stabilizing structures such as the anterior longitudinal ligament (ALL) and posterior longitudinal ligament (PLL) are removed, increasing the likelihood of immediate cage migration postoperatively, which may necessitate reoperation.⁵ Endplate damage during ALIF cage insertion is linked to cage migration as well,²⁰ which is again more likely to occur when the surgeon is less experience in the procedure. A meta-analysis by Zhang et al. (2017) found no significant difference in the reoperation rate between anterior and posterior techniques,⁵ but this study's focus on single-level procedures may not fully capture the complexities of multi-level fusions. It should be noted however that in this study, the single-level anterior approach had more early complications that nearly equated by 2 years, highlighting the importance of extending to beyond 90-day complications.

4.4

4.4 Limitations

This study's retrospective nature and reliance on database records introduce limitations, including potential biases and inaccuracies in coding. The lack of access to original patient data restricts validation and correction of source information. Concurrent procedures and variations in surgical techniques across studies may also affect generalizability. Furthermore, the study's timeframe may exclude long-term complications and evolving trends in interbody fusion procedures. Confounding factors not accounted for could impact the interpretation of reoperation rates and outcomes.

Despite these limitations, this study provides valuable insights into the comparative outcomes of anterior and posterior interbody fusion techniques using a large dataset. The inclusion of both single-level and multi-level procedures, along with extended follow-up to two years, enhances the robustness of the findings. This study contributes to the understanding of contemporary trends and outcomes in lumbar interbody fusion, offering a comprehensive evaluation of both approaches' safety and efficacy.

However, this study stands out for its comprehensive approach, delving into various lumbar interbody fusion techniques, utilizing a large dataset from an insurance claims database, ensuring robust statistical power and greater generalizability. This study is unique in analyzing single-level and multi-level procedures, while most studies to date that compare anterior and posterior spinal interbody fusions focus exclusively on single-level procedures. Additionally, this study is robust in including complications out to two years postoperatively, while most studies have not analyzed beyond 90 days. This study is also important simply due to its recency in analyzing anterior approaches, which is becoming more common-place and thus more familiar to surgeons, which should impact its complication profile.

5 Conclusion

This study confirms that posterior interbody fusions are more commonly performed than anterior procedures, though the latter is increasingly utilized. Reoperation rates are higher for multi-level posterior and single-level anterior fusions, with women more frequently undergoing these procedures. Both anterior and posterior approaches show similar overall complication profiles, though specific risks, such as postoperative DVT, vary. These findings emphasize the need for ongoing research and consideration of individual patient factors when choosing between anterior and posterior lumbar interbody fusion techniques.

CRediT authorship contribution statement

Cole Veliky: Methodology, Investigation, Data curation, Writing – original draft, Writing – review & editing. Paul Michael Alvarez: Conceptualization, Methodology, Investigation, Writing – original draft, Writing – review & editing. Hania Shahzad: Conceptualization, Methodology, Formal analysis, Data curation, Writing – original draft, Writing – review & editing. Diego Martinez: Writing – review & editing. Elizabeth Yu: Conceptualization, Supervision, Validation. Varun K. Singh: Conceptualization, Validation, Supervision.

Disclosures

The authors report no conflicts of interest in relation to this work.

Consent

No consent was needed for this study.

Ethical statement

No ethical approval was needed for this study.

Funding source

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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