What are the differences in clinical and surgical outcomes between lumbar spine fusion approaches?—a narrative review

Introduction

Background and rationale

Lumbar interbody fusion (LIF) is an established surgery to treat lumbar spine instability, deformity, and dysfunction. In general, LIF involves removing the intervertebral disc and placing an implant (spacer, cage, or structural graft) to induce osteogenesis and eventual fusion of two or more vertebrae to alleviate symptoms. While originally described as a posterior based approach [posterior LIF (PLIF)], other techniques to access the disc space have been developed including anterior (ALIF), transforaminal (TLIF), direct lateral (DLIF or LLIF), and oblique LIFs (OLIF) (1). However, despite this variety, there is inconclusive evidence supporting the clinical superiority of one approach over the others, each having their own advantages and disadvantages. This ambiguity remains a controversial topic as spine surgeons continue to debate which approach is most appropriate for their patients and specific aims. Factors to be considered when choosing an approach can include postoperative pain, fusion rate, patient-reported outcomes, subsidence, infection, deep vein thrombosis (DVT)/vascular injury rate, achievable lordosis, operational time, length of stay (LOS) in the hospital, and blood loss.

Objective

The present study aims to review the current literature regarding these factors and surgical approaches to identify a preferred approach based on the most recent studies. To our knowledge, this is the first narrative review article comparing these five lumbar fusion surgeries regarding these specific surgical and clinical outcomes, providing a comprehensive and up-to-date summary of the most recent literature. We present this article in accordance with the Narrative Review reporting checklist (available at https://amj.amegroups.com/article/view/10.21037/amj-23-142/rc).

Methods

We performed a non-systematic literature search of the PubMed database in June 2023 to select peer-reviewed scientific articles published between 2005 and 2023 (Table 1). The inclusion criteria were studies published in English and reporting outcomes following lumbar interbody fusion surgery (including PLIF, ALIF, TLIF, LLIF, OLIF). Specific outcomes included in the search were pain, patient-reported outcomes, fusion, subsidence, infection, DVT/vascular injury, lordosis correction, surgical time, LOS in the hospital, and blood loss. Applying the inclusion and search criteria resulted in 1,011 studies. The titles and abstracts of these studies were then reviewed by all authors and were selected for full review if they compared two or more of the lumbar fusion approaches regarding the above outcomes. References of key papers were also reviewed for potential studies to include in our review. The final selection and inclusion of the articles was approved by consensus of the four senior authors, all of whom are fellowship-trained orthopedic spine surgeons.

Comparison of outcomes between fusion techniques

Overview of LIF approaches

ALIF

ALIF involves accessing the lumbar spine through an abdominal incision, with the patient supine, and continuing through a retroperitoneal approach to access the anterior spine. The ventral visualization allows for detailed endplate preparation and interbody dimensional preference. Given the vascular anatomy overlying the anterior spine, this approach is generally restricted to the more caudal levels of the lumbar spine, L4–L5 and L5–S1, although can be used in specific circumstances in more cephalad levels (1). The addition of posterior fixation following anterior interbody stabilization is generally percutaneous or minimally invasive surgery (MIS), leaving the posterior spinal and paraspinal anatomy minimally disturbed. Common pitfalls are the anatomical hurdles of the peritoneum, retroperitoneal structures, and associated vasculature (1). Having a vascular surgeon perform this approach to the spine has been argued to lessen the risk of damaging these structures, yet this may not be entirely accurate. While a meta-analysis by Phan et al. did find that the use of an access surgeon was associated with lower rates of neurologic and peritoneal injuries, they were also found to have higher rates of arterial injuries (1.16% with access surgeon vs. 0.44% without), retrograde ejaculation (0.96 with vs. 0.41% without), and ileus (2.26% with vs. 1.93% without) (2).

DLIF/LLIF

This approach starts with the patient in a lateral decubitus or prone position, with an incision along the flank. To reach the spine, a myotomy is performed through the psoas major muscle, with tubular retraction placed for direct lateral visualization. While this can be performed at most lumbar levels, the iliac crest routinely prevents this from being done at L5–S1. Other common limitations include damage to the lumbar plexus, injury to vascular structures, and limited view of the vertebrae (3).

OLIF/anterior to psoas (OLIF/ATP)

This approach is generally described with a patient in the lateral decubitus position. OLIF allows an approach anterior to the iliac crest, kidney, and psoas muscle and a lateral visualization to the aorta/inferior vena cava. This approach is primarily used in conjunction with MIS techniques, thus limiting its visualization compared to other open approaches (4). Molinares et al. recommends using a magnetic resonance imaging (MRI) to preoperatively identify if the OLIF approach allows for sufficient visualization and space necessary for surgeon preferred interbody dimensions (5). This suggestion also can help preoperatively evaluate each patient’s variable vascular anatomy. Li et al. establish the importance of preoperative visual tools, perioperative muscle flexion, and relaxation manipulation to aid in accessibility (6). Davis et al. also argue that when considering OLIF, the retroperitoneal work area is better visualized from the left side (7). The primary anatomic concern with this approach is the sympathetic chain and its relation to the anterior longitudinal ligament (ALL) and the anterior third of the psoas muscle (6). However, in their retrospective chart review of 812 patients, Mehren et al. found neurologic injuries following OLIF to be exceedingly rare, at rate of 0.37% (8).

PLIF

While lying prone, a longitudinal midline incision is made along the patient’s spine, exposing the spinous processes, lamina, and facet joints. The disc space is then accessed through a removal of portions of or the entire lamina. However, given this direct posterior trajectory, this approach requires retraction of the thecal sac and nerve roots, placing them at risk for iatrogenic injury. Other limitations include complications associated with paraspinal dissection, prolonged muscle retraction, and limited space for the interbody implant (9).

TLIF

This approach is a slight variation of the PLIF, in which the surgeon accesses the disc space posteriorly through the neuroforamen. A facetectomy is performed, providing direct decompression of the exiting nerve root as well as giving the surgeon additional visualization and greater access to the disc space. Similar to the PLIF, its main disadvantages are those associated with prolonged paraspinal muscle dissection and retraction, although this more lateral approach affords less midline thecal manipulation (1). However, through MIS surgical techniques, the TLIF can be performed with minimal paraspinal muscular dissection while still achieving adequate neural decompression (10).

Comparison of surgical and clinical outcomes

Fusion rate

The fusion rate refers to the percentage of patients who achieve successful spinal fusion following LIF surgery, primarily determined by radiographs and clinical evaluation. As one of the primary goals of this surgery, determining the fusion rate allows surgeons to assess the success of the LIF in achieving the desired outcome. Comparing the respective fusion rates of the different LIF approaches has been extensively investigated but continues to have an unclear answer as to which has the highest rate (1).

Kim et al. retrospectively reviewed records for patients who underwent either ALIF or TLIF for low-grade spondylolisthesis at L4–L5 or L5–S1, and they found no differences in rates of radiographic fusion 94% for ALIF and 88% for TLIF (11). Two systematic reviews and meta-analyses also comparing radiographic fusion rates found no significant difference in fusion rates between ALIF and TLIF (88.6% vs. 91.9%, P=0.23), or between ALIF and OLIF (93.66% vs. 90.83%) (12,13). In a 2017 meta-analysis comparing ALIF, PLIF, TLIF, and LLIF, Teng et al. found that all four approaches had similar fusion rates, with relative rates of fusions ranging from 0.98 to 1.10 (14).

The rate of successful fusion is less related to the approach a surgeon utilized and is more dependent on patient selection, graft material, and quality of vertebral endplate preparation. While certain approaches allow for a more direct visualization of the endplates, adequate endplate preparation is achievable through all approaches (14). Overall, these results do not favor the use of any particular approach over another in achieving bony fusion.

Interbody subsidence

Subsidence is the postoperative migration of an implant/interbody into the body of the vertebrae, causing a decrease in the achieved operative intervertebral height. This can lead to decreased disc height restoration and, if significant enough, may lead to the recurrence of initial symptoms leading to further intervention. Interbody devices that extend circumferentially to the cortical bone of the epiphyseal ring and rely less on the cancellous portion have shown to provide better support, load distribution, and less subsidence (11). This is likely due to the peripheral cortical bone being less porous with a higher bone mineral density than central cancellous bone.

In a 2022 systematic review evaluating interbody subsidence following LIF, interbodies placed through the ALIF approach had the lowest reported median subsidence occurrence (12.8%) of the five surgical approaches (15). This low rate of subsidence was attributed to the increased access to and visualization of the intervertebral disc space afforded by the anterior approach. By covering a larger surface area of the endplate, the implant is able to distribute the load over a greater area as well engage more of the peripheral cortical bone. Alternate approaches do not provide as much visualization and space needed for this optimal implant insertion. While the lateral and posterior approaches have their respective advantages and indications, they are more frequently associated with higher subsidence rates than ALIF due to these factors (11).

However, interbody subsidence is multifactorial, with patient pathology, anatomy, bone quality, surgeon expertise, technique, use as stand-alone implants or with posterior instrumentation, implant design, cage material, bone quality, and patient’s overall health all serving as contributing factors. In addition, the literature is unclear as to whether subsidence leads to adverse clinical outcomes as long as the neuroforaminal decompression remains sufficient (15-17). In fact, one study found that subsidence may help with fusion rates, with associated mechanical stress from subsidence being theorized to induce osteogenesis in the adjacent vertebrae bodies (18).

Lordosis correction

Lordosis is the natural curvature of the spine and is typical in the cervical and lumbar regions. The standard range of lumbar lordosis is between 40–70°, and both too much or too little lordosis, either iatrogenic or congenital, has been associated with increased back pain and poor functional outcomes (19). Restoration of lordosis to typical anatomical ranges serves as a useful metric for sagittal correction and offers further data for comparison of these LIF approaches.

The majority of studies comparing sagittal correction following LIF surgery has been between ALIF and TLIF, with most showing superior lordosis correction with ALIF. In several retrospective cohort studies, the focal L4–S1 lordosis correction following ALIF ranged from +5.6° to +7.9°, while lordosis correction following TLIF ranged from −1.7° to +2.1° (20-24). In addition, Dorward et al. found ALIFs conferred greater regional lordotic correction from L3–S1 than TLIFs, with a gain of 6.9° compared to −2.6° (20). Lightsey et al. also demonstrated that the lordosis obtained from ALIF was more sustainable than that following TLIF, with much of the immediate postoperative lordosis maintained greater than a year out from surgery (25). However, while ALIFs were more successful in correcting sagittal deformities, TLIFs were found to generate more coronal correction, correcting up to 22.4° in lumbar and 10.3° in lumbosacral curves (20).

The literature on lordosis correction following LLIF has been mixed. In their retrospective radiographic analysis, Watkins et al. found that LLIFs provided greater lordotic correction than TLIFs (2.2° for LLIF and 0.8° for TLIF), but not as much as ALIFs (4.5°) (22). In their retrospective cohort study, Malham et al. also found ALIFs generated nearly twice as much lordosis correction compared to LLIFs (6° for ALIF vs. 3° for LLIF) (26). However, Acosta et al. found that the two approaches provide similar corrections (2.8° for ALIF vs. 2.9° for LLIF) (27).

This superiority in sagittal correction following ALIFs has been attributed to the direct exposure and visualization of the anterior intervertebral disc space and expansile discectomy. By directly accessing the anterior disc space, surgeons are able to place larger, more lordotic cages compared to the other approaches. In addition, resection of the anterior longitudinal ligament has been shown to generate greater segmental mobility and contributing to increased lordotic correction (28).

Blood loss

Blood loss can be associated with higher rates of complications, operation time, reoperation rate, prolonged recovery time, and postoperative morbidity (29). For these reasons, establishing a preferred method when blood loss is a top consideration is important in surgical planning.

In general, several studies have found the anterior-based approaches (ALIF, OLIF, LLIF) to have significantly less blood loss compared to posterior-based approaches (PLIF, TLIF). Two retrospective cohort studies demonstrated that blood loss following ALIF was significantly lower than TLIF when looking at long-construct deformity surgeries (1,281 vs. 2,011 mL) (20) and single level fusions (188.9 vs. 387.1 mL) (21). A 2023 meta-analysis further supports this, while also showing that ALIFs also had decreased blood loss compared to PLIFs, with a mean difference of 186.61 mL (30). In their National Surgical Quality Improvement Program (NSQIP) database study, Shillingford et al. found that the anterior and lateral approaches required significantly less transfusion volume than those patients undergoing posterior/transforaminal approaches (7.6% vs. 9.6%, P=0.005) (31). Another retrospective cohort study showed that both LLIF and OLIF had lower volumes blood loss compared to MIS-TLIF (49 mL for LLIF vs. 48 mL for OLIF vs. 200 mL for MIS-TLIF) (32).

Lower blood loss with anterior-based approaches is likely due to avoiding the dissection of paraspinal musculature and bony resection (laminectomy and facetectomy) required for open posterior-based approaches. Instead, these techniques approach the spine through the abdominal musculature, a comparatively less vascularized dissection plane with less muscle bulk, resulting in lower levels of blood loss. While these approaches require surgeons to frequently encounter large vascular structures, including the abdominal aorta, common iliac arteries and veins, and inferior vena cava, injury to these structures is uncommon whether performed with or without an access surgeon (2,33).

When comparing the individual anterior-based approaches, several small retrospective studies support LLIFs as having lower blood loss than ALIFs. Goodnough et al. found significantly less estimated blood loss in LLIF than in ALIF patients, with approximately 150 mL less following LLIF. However, the authors do cite a small sample size (54 ALIF vs. 21 LLIF) as a limitation of their study (34). In a similar study, Xu et al. retrospectively reviewed 8 ALIFs vs. 16 LLIFs performed at their institution and found that LLIFs had, on average, 61 mL less of blood loss (35).

Among the posterior-based approaches, several studies have shown that blood loss following TLIF has been found to be lower than PLIF, with differences ranging from 44 to 192 mL (30,36-38). While both approaches involve dissection of the posterior paraspinal musculature, the dissection required for a TLIF is comparatively limited with less muscular retraction and bony resection, as this approach is unilateral by design (37).

Vascular injury/DVT

The lumbar spine is closely situated to major blood vessels, and inadvertent injury can occur during the surgical approach, vertebral preparation, or placement of instrumentation. Vascular injury can lead to excessive bleeding, hematoma formation, or damage to the blood vessel integrity. Vascular injuries are considered serious complications that require immediate attention and may necessitate additional surgical intervention to repair or control bleeding (2). Surgeons must take precautions to minimize the risk of this complication during LIF surgery, including careful evaluation of preoperative imaging, meticulous surgical technique, and close attention to anatomical structures during the procedure.

The anterior-based approaches, including ALIF, LLIF, and OLIF, offer improved visualization of the disc space, but require mobilization of the peritoneum and great vessels in the abdomen. This procedure often utilizes vascular surgeons to perform the anterior retroperitoneal exposure of the lumbar spine (ARES). ALIF carries the highest possibility of vascular injuries due to the anatomical proximity of the abdominal aorta and common iliac arteries and veins. This risk further increases with more cephalad fusions relative to L4–L5 as the need to retract more vasculature increases (33).

Rates of vascular injury during ARES have widely varied within the literature. In their review of 447 ARES, Chiriano et al. reported 95 vascular injuries (21.3%) that required direct repair (39). However, Mobbs et al. reported a lower 6.6% rate of vascular injury in their retrospective review of 227 ARESs (33). In both of these studies, injuries most commonly occurred at the level of L4–L5, with the left common iliac vein and the inferior vena cava being the most frequently injured vessels. It is commonly believed that having a vascular surgeon perform the anterior approach to the spine may mitigate the risk of damaging these vessels. However, a 2017 meta-analysis by Phan et al. found that the rate of arterial injuries was 2.26 times greater when performed by an access surgeon (1.16%) compared to the spine surgeon (1.16%) (2).

DVT is the formation of a blood clot in a deep vein, commonly in the lower extremities. During LIF surgery, patients may be at an increased risk of developing DVT due to factors such as prolonged immobility, surgical trauma, and the use of anesthesia. The formation of blood clots can impede blood flow and may lead to serious complications if the clot travels to the lungs, causing a pulmonary embolism (40). Three large database studies found that patients undergoing ALIF/LLIF have higher rates of developing lower extremity DVTs than those undergoing a TLIF/PLIF with odds ratios (ORs) ranging from 1.16 to 2.03 (31,41,42). This increased risk with anterior-based approaches was attributed to the mobilization of the large abdominal vessels. Such manipulation and prolonged retraction increase the risk for causing endothelial damage and creating turbulent blood flow, resulting in clot formation (42).

Infection

The risk of infection in LIF surgery can arise from various sources, including the surgical site, adjacent tissues, or systemic factors. Surgical site infections (SSIs) can occur due to contamination during the procedure or patient-related factors, such as compromised immune system or diabetes. SSIs following LIF results in increased patient morbidity and medical resource utilization (43).

When comparing rates of SSIs between anterior and posterior-based approaches, there are conflicting conclusions. McCluskey et al. reviewed a database of over 112,000 patients and found that those undergoing single-level ALIF/LLIF had lower odds of developing an SSI than those undergoing TLIF/PLIF at both 30 (OR =0.88) and 90 days (OR =0.91) postoperatively (41). However, another study by Shillingford et al. analyzing the NSQIP database of single-level interbody fusion and found no difference in either rates of superficial (1% for ALIF/LLIF vs. 1.1% for TLIF/PLIF) or deep infections (0.4 for ALIF/LLIF vs. 0.6 for TLIF/PLIF) between the groups of approaches (31). A 2014 meta-analysis found SSI rates to be similar between PLIF and TLIF procedures [OR 1.70, 95% confidence interval (CI): 0.55–5.22] (44).

However, the risk for SSI remains largely complex, with factors other than the selected approach playing contributing roles. In a retrospective study analyzing 2,715 cases of posterior lumbar spine surgery, Liu et al. identified several independent risk factors for SSIs following lumbar spine surgery, which included: multiple fusion segments, increased surgical time and estimated blood loss, decreased postoperative hemoglobin, and prolonged wound drainage (45). The researchers also found that low perioperative serum albumin and calcium and high serum glucose levels were all independently associated with increased risk for SSI, as these markers act as surrogates for a patient’s overall nutritional and metabolic health.

Surgical time

Prolonged surgical times can predispose patients to adverse events such as infection, hematoma formation, venous thromboembolism (VTE), increased bleeding, and even necrosis (46,47). Therefore, decreased surgical time can minimize undue risk towards the patient and is thus an important factor to weigh when comparing these various approaches. However, it is important to emphasize that surgical timing is a complex metric influenced by many factors, including surgical pathology, patient anatomy, and surgeon expertise.

While there is currently no consensus as to which LIF approach is operatively the quickest, the posterior-based TLIFs and PLIFs have the most evidence substantiating their time efficiency over ALIFs. In their retrospective matched cohort study, Dorward et al. found that traditional open TLIFs had substantially less operative time than ALIFs when used in long-segment, deformity correcting constructs (481 vs. 595 min, P<0.001) (20). This is further supported by a meta-analysis that showed both traditional open TLIF and PLIF were found to be operatively shorter than stand-alone ALIF by an average of 25 min (48). While this study found no differences in operative times between the two posterior-based approaches, another 2017 meta-analysis of nine studies found TLIFs to be about 20 min quicker than PLIFs (36). When comparing the anterior-based approaches, one study of 28 patients found LLIF to be nearly 1.5 hours faster than MIS ALIF with percutaneous pedicle fixation, although the authors cite their small sample size as a potential limitation (35).

Several explanations have been proposed justifying why posterior-based approaches may be more time efficient. As a workhorse and staple of spine surgery, it is a common approach with which spine surgeons are very familiar and comfortable performing. In addition, both approaches allow for potential 360° fusion to be performed through a single incision without the need for multiple dissections or patient repositioning (1).

On the other hand, there was considerable variability reported in the literature regarding the precise technique used in an ALIF. In one study, ALIF was broadly generalized from several various subapproaches under the umbrella term of “ALIF”, to include traditional open, MIS, stand-alone, and with supplemental posterior pedicle screw instrumentation (48). This could account for the vast increases and variability in reported operative times for this approach. In fact, one retrospective cohort study found the operative time of stand-alone ALIFs to be significantly shorter than PLIF/TLIF approaches (49). To add further variability, some of the studies regarding ALIFs were meta-analysis, which did not explicitly detail whether or not an access surgeon was used for the approach (36,48).

Hospital LOS

Postoperative hospital LOS is an important outcome measure following surgery as it serves as an indicator for resource management and consumption. From a practical perspective, surgeons must select the procedure that is most appropriate for their patient while also being judicial and economical in their usage of healthcare resources (50). Despite the importance of this postoperative metric, there is no consensus among the current literature as to which LIF approach routinely confers the most favorable, shortest length of hospital stay.

There exists a plethora of studies within the current literature with conflicting conclusions regarding postoperative LOS following LIF. In a database study of over 900,000 LIF operations, patients who underwent a posterior/transforaminal approach were shown to have a significantly shorter LOS than an anterior approach (4.55 vs. 5.10 days, P=0.001) (51). In the same study, patients who underwent a combined anterior and posterior approach stayed in the hospital for the longest time (5.96 days). Another database study showed significantly longer LOS following PLIF/TLIF compared to ALIF/LLIF (3.6±4.3 vs. 3.4±4.2 days, P<0.05), though these findings were not clinically significant (31). However, in this study, posterior approaches were more commonly done in the setting of spine trauma while anterior/lateral approaches were more common with degenerative conditions, adding a further confounder to their analysis.

Conversely, a meta-analysis by Rathbone et al. found stand-alone ALIFs to have shorter LOS than TLIFs by 0.71 days but were similar LOS to PLIF (30). In a smaller retrospective study of 102 patients, researchers found no significant difference in LOS in TLIF vs PLIF (5.76±1.60 days for TLIF vs. 7.50±2.30 days for PLIF) (52). Yingsakmongkol et al. found in their retrospective cohort study that LLIF and OLIF had shorter LOS than TLIF (3.6 and 3.7 days, respectively, vs. 4.3 days for TLIF) but had similar LOS when compared to each other (32). Given this variance within the literature, comparing postoperative LOS following a LIF remains unclear as there is no conclusive evidence supporting one LIF approach as having the shortest hospital stay.

Among this debate of hospital LOS, Adogwa et al. challenged the notion that prolonged postoperative stays are associated with worse clinical outcomes and complications (53). In their retrospective study of over 23,000 cases of LIF, they found no correlation between prolonged LOS and postoperative complications or baseline comorbidities. In fact, they reasoned that this variation in LOS is less frequently due to preoperative baseline illness and more attributed to differences in practice style and surgeon preference.

Patient-reported outcomes

Measuring pain intensity and functional ability as reported by patients provides an objective assessment of these qualities and their impacts on the patient’s quality of life. These measures can determine both the need and effectiveness of a surgical intervention and are therefore useful tools in comparing their success (12). Multiple, verified patient-reported outcomes scales exist to capture these patient experiences, including the Oswestry disability index (ODI), visual analog scale (VAS), Scoliosis Research Society (SRS), and the Japanese Orthopaedic Association Score (JOAS). ODI and VAS were the two most commonly reported outcome scores assessing patient function and pain, respectively, following LIF surgery.

Overall, there is evidence that all LIF approaches improve patient-reported outcomes compared to preoperative assessments (48). However, the literature remains inconclusive as to which LIF approach, if any, improves patient-reported outcomes substantially more than the others.

There is some evidence that TLIFs provide a slight advantage in improving functional scores over the other approaches, but the supporting literature for this is mixed. In their retrospective matched cohort study of 363 patients comparing MIS-TLIF, LLIF, and OLIF, Yingsakmongkol et al. found improved ODI scores following MIS-TLIF compared to LLIF one year after surgery (−53.4 for MIS-TLIF vs. −49.65 for LLIF), but no differences in VAS between the three approaches (−8.1 for MIS-TLIF vs. −7.47 for LLIF vs. −8.86 for OLIF) (32). These results are similar to a 2016 meta-analysis comparing MIS-TLIF and LLIFs, where Keorochana et al. found that MIS-TLIFs trended toward having better VAS and ODI scores, but this was not statistically significant (12).

In a meta-analysis comparing TLIFs and PLIFs, de Kunder et al. found that ODI scores were slightly better following TLIF (mean difference of −3.46), but both had similar improvements in VAS scores (mean VAS difference of −0.05, 95% CI: −0.18 to 0.09) (36). However, a separate meta-analysis by Zhang et al., found that ODI and Japanese Orthopaedic Association (JOA) scores were equivalent between the two approaches (OR 0.81, 95% CI: 0.42 to 1.57, P=0.54) (44).

In a retrospective study comparing MIS-TLIFs and MIS-ALIFs for treating isthmic spondylolisthesis, Kim et al. found ODI scores were significantly improved in the MIS-TLIF group compared to the MIS-ALIF group when performed at L4–L5 (21.5±18.5 for TLIF vs. 11.1±12.3 for ALIF, P=0.01), due to ease of access to the disc space at this particular level (11). However, there was no difference in ODI scores when performed at L5–S1 or in VAS scores between the groups. A separate matched study compared these approaches when used in long deformity-correcting constructs and found no difference in ODI score improvements (38.4 for ALIF vs. 40.6 for TLIF, P=0.53). While there was a larger improvement in SRS scores following ALIF, these patients began with a much lower score preoperatively (44.4 to 70.7 for ALIF vs. 58.6 to 70.6 for TLIF, P=0.004) (20).

Further comparison of ALIFs with the other anterior-based approaches have also yielded inconclusive results. A 2023 meta-analysis of 36 studies comparing MIS-ALIF and OLIF found no differences in ODI or VAS scores (13). Similarly, Xu et al. compared these outcomes between MIS-ALIFs and LLIFs and found similar improvements in both ODI (21.0 for MIS-ALIF vs. 19.8 for LLIF) and VAS (3.8 vs. 3.9) scores (35). When comparing OLIF and LLIF, a 2019 meta-analysis found that both functional and pain measures were slightly more improved following OLIF procedure over LLIF (−3.25 vs. − 2.18 for ODI; −3.06 vs. −1.76 for VAS, respectively) (54). This difference in complications was likely related to psoas muscle injuries seen in the LLIF group.

Despite this lack of consensus regarding patient-reported outcomes, a common theme discussed among the various studies was the importance of surgeon preference and experience, proper surgical indication, restoration of anatomic parameters, and minimizing the damage to the patient’s natural anatomy when considering the most optimal approach. If such conditions were adequately satisfied, patients experienced significant improvement in pain and functional scores, regardless of the approach selected.

Discussion

The current body of scientific literature does not uniformly demonstrate any significant difference in fusion rates, infection rates, postoperative hospital lengths of stay, or patient-reported outcomes between the different LIF approaches. However, there is emerging evidence to suggest that anterior-based approaches (ALIF, LLIF, OLIF) can achieve higher lordosis correction, have lower levels of blood loss, and decreased rates of interbody subsidence compared to posterior-based approaches (PLIF, TLIF). Conversely, anterior approaches also have higher rates of DVT and vascular injuries, due to their anatomic proximity to and mobilization of large abdominal vessels. Posterior-based approaches may also have shorter surgical times due to less extensive dissection and surgeon familiarity with the approach.

A limitation in performing this literature review is that while this study hopes to compare all five approaches, the majority of studies published about lumbar interbody fusion compare only two or three techniques, while very few articles evaluate all five approaches. While this is understandable from a practical standpoint in conducting the studies, it limits the conclusions that can be drawn when directly comparing outcomes from the different approaches. We did find that many studies broadly grouped the different approaches as “anterior-based” or “posterior-based” approaches, as delineated by their relation to the transverse process, with anterior options including ALIF, OLIF, and LLIF, and posterior options including PLIF and TLIF (30,31,41,42). This was also done both for ease of statistical analysis as well as procedural coding limitations of the electronic medical records. Moreover, it is reasonable to assume that approaches with similar anatomic dissection planes would have similar outcomes and complications, all other things being equal. However, this grouping loses the technical nuances of each of the various approaches, further restricting the ability to compare them individually.

Another consideration of this study is that we limited our literature review to focus primarily on the surgical approach used to achieve lumbar interbody fusion. We specifically did not include in our review other technical aspects of the LIF surgery, such as cage type, graft material, or levels fused, which we understand all play important roles in the clinical and surgical outcomes of the procedure. However, by not including these technical variables, we hope to provide a more focused discussion on the advantages/disadvantages of the approaches themselves.

Similarly, we did not filter our literature based on surgical indication. LIFs can be performed for a wide range of pathology, including degenerative spondylolisthesis, isthmic spondylolisthesis, trauma, and deformity, making it one of the most commonly performed procedures in spine surgery. We understand that indication for the surgery plays a large role in surgical outcomes and this wide inclusion may limit direct objective comparisons between the approaches. However, we also feel this allows us to draw broad, generalizable conclusions based solely on the approach used to help surgeons identify which approach is most suitable for their specific patient situation.

And lastly, much like any review, the strength of our study is limited by the strength of the studies we include, many of which were small retrospective studies. As such, the analyses and conclusions drawn from these studies may be underpowered or limited by selection bias. This may contribute to the lack of scientific consensus when it comes to the various outcomes we investigated (such as fusion rates, patient-reported outcomes, and infection rates). It also highlights the need for larger, high quality prospective studies to further elucidate any differences in surgical and clinical outcomes between these individual techniques.

Conclusions

The current literature shows no significant difference in fusion rates, infection rates, hospital lengths of stay, or patient-reported outcomes between the different approaches. There is evidence to suggest that anterior-based approaches (ALIF, LLIF, OLIF) can achieve higher lordosis correction, have lower levels of blood loss, and decreased rates of interbody subsidence compared to posterior-based approaches (PLIF, TLIF), while posterior approaches may be surgically quicker. Anterior approaches also had higher rates of DVT and vascular injuries. Ultimately however, larger, more high-quality prospective studies are needed to further elucidate any differences in surgical and clinical outcomes between these individual techniques.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editors (Mark Lambrechts and Brian Karamian) for the series “Degenerative Spine Disease” published in AME Medical Journal. The article has undergone external peer review.

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://amj.amegroups.com/article/view/10.21037/amj-23-142/rc

Peer Review File: https://amj.amegroups.com/article/view/10.21037/amj-23-142/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://amj.amegroups.com/article/view/10.21037/amj-23-142/coif). The series “Degenerative Spine Disease” was commissioned by the editorial office without any funding or sponsorship. The authors have no other conflicts of interest to declare.

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