Description:
Axial lumbosacral interbody fusion (LIF; also called presacral, transsacral, or paracoccygeal interbody fusion) is a minimally invasive technique designed to provide anterior access to the L4-S1 disc spaces for interbody fusion, while minimizing damage to muscular, ligamentous, neural, and vascular structures. It is performed under fluoroscopic guidance.

For individuals who have degenerative spine disease at the L4-S1 disc spaces who receive axial LIF, the evidence includes a comparative systematic review of case series and 1 retrospective comparative study. Relevant outcomes are symptoms, functional outcomes, quality of life, and treatment-related morbidity. The systematic review found that fusion rates were higher following transforaminal LIF than following axial LIF, although this difference decreased with use of bone morphogenetic protein or pedicle screws. The findings of this systematic review were limited by the lack of prospective comparative studies and differences in how fusion rates were determined. Studies suggest that complication rates may also be increased with 2-level axial LIF. Controlled trials with clinical outcome measures are needed to better define the benefits and risks of this procedure compared with treatment alternatives. The evidence is insufficient to determine the effects of the technology on health outcomes.

Background 
Interbody Fusion
Interbody fusion is a surgical procedure that fuses 2 adjacent vertebral bodies of the spine. Lumbar interbody fusion may be performed in patients with spinal stenosis and instability, spondylolisthesis, scoliosis, following a discectomy, or for adjacent-level disc disease.

Axial Lumbosacral Interbody Fusion
Axial lumbosacral interbody fusion (LIF; also called presacral, transsacral, or paracoccygeal interbody fusion) is a minimally invasive technique designed to provide anterior access to the L4-S1 disc spaces for interbody fusion while minimizing damage to muscular, ligamentous, neural, and vascular structures. It is performed under fluoroscopic guidance. 

An advantage of axial LIF is that it preserves the annulus and all paraspinous soft tissue structures. However, there is an increased need for fluoroscopy and an inability to address intracanal pathology or visualize the discectomy procedure directly. Complications of the axial approach may include perforation of the bowel and injury to blood vessels and/or nerves.

Regulatory Status
The U.S. Food and Drug Administration has cleared for marketing multiple anterior spinal intervertebral body fixation device systems through the 510(k) pathway (See Table 1). The systems are not intended to treat severe scoliosis, severe spondylolisthesis (grades 3 and 4), tumor, or trauma. The devices are also not meant for vertebral compression fractures or any other condition in which the mechanical integrity of the vertebral body is compromised. Their usage is limited to anterior supplemental fixation of the lumbar spine at the L5-S1 or L4-S1 disc spaces in conjunction with a legally marketed facet or pedicle screw systems. Food and Drug Administration product code: KWQ.

Table 1. Select Anterior Spinal Intervertebral Body Fixation Orthoses Cleared by FDA

Adapted from the Food and Drug Administration (2007, 2008).^2,3
FDA: Food and Drug Administration.

Policy:
Axial lumbosacral interbody fusion (axial LIF) is investigational and/or unproven and therefore NOT MEDICALLY NECESSARY.

Policy Guidelines
Please see the Codes table for details.

Benefit Application
BlueCard^®/National Account Issues
State or federal mandates (e.g., FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational, and, thus, these devices may be assessed only on the basis of their medical necessity.

Rationale
Evidence reviews assess the clinical evidence to determine whether the use of a technology improves the net health outcome. Broadly defined, health outcomes are length of life, quality of life, and ability to function, including benefits and harms. Every clinical condition has specific outcomes that are important to patients and to managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of a technology, 2 domains are examined: the relevance and the quality and credibility. To be relevant, studies must represent one or more intended clinical use of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. Randomized controlled trials are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Promotion of greater diversity and inclusion in clinical research of historically marginalized groups (e.g., people of color [African-American, Asian, Black, Latino and Native American]; LGBTQIA (lesbian, gay, bisexual, transgender, queer, intersex, asexual); women; and people with disabilities [physical and invisible]) allows policy populations to be more reflective of and findings more applicable to our diverse members. While we also strive to use inclusive language related to these groups in our policies, use of gender-specific nouns (e.g., women, men, sisters, etc.) will continue when reflective of language used in publications describing study populations.

Axial Lumbosacral Interbody Fusion
Clinical Context and Therapy Purpose
The purpose of axial lumbosacral interbody fusion in individuals who have L4-S1 disc space diseases is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The question addressed in this evidence review is: Does axial lumbosacral interbody fusion improve net health outcome in individuals who have L4-S1 disc space diseases?

The following PICO was used to select literature to inform this review.

Populations
The relevant population of interest are individuals who have degenerative spine disease at the L4-S1 disc spaces.

Interventions
The therapy being considered is axial lumbosacral interbody fusion (also called presacral, transsacral, or paracoccygeal interbody fusion). Axial lumbosacral interbody fusion is a minimally invasive technique designed to provide anterior access to the L4-S1 disc spaces for interbody fusion while minimizing damage to muscular, ligamentous, neural, and vascular structures.

The procedure for 1-level axial lumbosacral interbody fusion is as follows3,: Under fluoroscopic monitoring, a blunt guide pin introducer is passed through a 15- to 20-mm incision lateral to the coccyx and advanced along the midline of the anterior surface of the sacrum. A guide pin is introduced and tapped into the sacrum. A series of graduated dilators are advanced over the guide pin, and a dilator sheath attached to the last dilator is left in place to serve as a working channel for the passage of instruments. A cannulated drill is passed over the guide pin into the L5-S1 disc space to rest on the inferior endplate of L5. It is followed by cutters alternating with tissue extractors, and the nucleus pulposus is debulked under fluoroscopic guidance. Next, bone graft material is injected to fill the disc space. The threaded rod is placed over the guide pin and advanced through the sacrum into L5. The implant is designed to distract the vertebral bodies and restore disc and neural foramen height. The additional graft material is injected into the rod, where it enters into the disc space through holes in the axial rod. A rod plug is then inserted to fill the cannulation of the axial rod. Percutaneous placement of pedicle or facet screws may be used to provide supplemental fixation.

Comparators
The following practice is currently being used to treat degenerative spine disease: standard lumbosacral interbody fusion and conservative therapy.

Outcomes
The outcomes of interest are symptoms, functional outcomes, quality of life, and treatment-related morbidity. Follow-up was up to 24 months.

Study Selection Criteria
Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.
• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.
• To assess long-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.
• Studies with duplicative or overlapping populations were excluded.

Review of Evidence
Single-Level Axial Lumbosacral Interbody Fusion
The literature on axial lumbosacral interbody fusion includes a systematic review of case series and a retrospective comparison of axial lumbosacral interbody fusion with anterior lumbar interbody fusion. No prospective randomized controlled trials have been identified comparing outcomes of axial lumbosacral interbody fusion with other approaches to lumbosacral interbody fusion.

Systematic Reviews
Schroeder et al. (2016) reported on a systematic review of L5-S1 disc space fusion rates following axial lumbosacral interbody fusion compared with anterior lumbar interbody fusion or transforaminal lumbar interbody fusion.⁴ Reviewers included 42 articles (total N = 1,507 patients). There were 11 articles with 466 patients who underwent anterior lumbar interbody fusion, 21 articles with 432 patients who underwent transforaminal lumbar interbody fusion, and 11 articles with 609 patients who underwent axial lumbosacral interbody fusion. Overall fusion rates were 99.2% for transforaminal lumbar interbody fusion, 97.2% for anterior lumbar interbody fusion, and 90.5% for axial lumbosacral interbody fusion. Fusion rates for transforaminal lumbar interbody fusion were significantly higher than those for axial lumbosacral interbody fusion (p = 0.002). However, when either bone morphogenetic protein or bilateral pedicle screws were used with the procedures, the differences in fusion rates between transforaminal lumbar interbody fusion and axial lumbosacral interbody fusion were no longer statistically significant. The findings of this systematic review were limited by the lack of comparative studies and differences in how fusion rates were determined across studies.

Nonrandomized Comparative Studies
Whang et al. (2014) reported on a multicenter, retrospective comparison of axial lumbosacral interbody fusion with anterior lumbar interbody fusion of the L5-S1 disc space in 96 patients who had a minimum of 2 years of follow-up.⁵ Most procedures were performed for degenerative disc disease or spondylolisthesis and used bilateral pedicle screws. Various graft materials were used, including recombinant human bone morphogenetic protein-2 (in 29 axial lumbosacral interbody fusion and 11 anterior lumbar interbody fusion procedures). Fusion rates, assessed at 24 months by 2 independent evaluators and based on radiographs and multiplanar computed tomography images, were similar for the 2 procedures (85% for axial lumbosacral interbody fusion vs 79% for anterior lumbar interbody fusion; p > 0.05). The incidence of adverse events was also similar, with no cases of rectal perforation. Interpretation of this study is uncertain given its retrospective design, variability in procedures, the absence of validated clinical outcome measures, and lack of randomization.

Case Series
The largest case series included in the 2016 systematic review was a retrospective analysis by Tobler et al. (2011), which evaluated 156 patients from 4 clinical sites in the United States.⁶ Patients were selected if they underwent an L5 through S1 interbody fusion via the axial approach and had both presurgical and 2-year radiographic or clinical follow-up. The number of patients who underwent axial lumbosacral interbody fusion but were excluded from the analysis was not reported. The primary diagnosis was degenerative disc disease (61.5%), spondylolisthesis (21.8%), revision surgery (8.3%), herniated nucleus pulposus (8.3%), spinal stenosis (7.7%), or other (8.3%). Pain scores on a numeric rating scale improved from a mean of 7.7 to 2.7 (n = 155), while the Oswestry Disability Index scores improved from a mean of 36.6 preoperatively to 19.0 (n = 78) at 2-year follow-up. Clinical success rates, based on an improvement of at least 30%, were 86% (n = 127/147) for pain and 74% (n = 57/77) for the Oswestry Disability Index scores. The overall radiographic fusion rate at 2 years was 94% (145/155). No neural, urologic, or bowel injuries were reported in this study group. Study limitations included its retrospective analysis, lack of controls, and potential for selection bias because it only reported on patients who had 2 years of follow-up.

The second largest series included in the systematic review was that by Zeilstra et al. (2013), who retrospectively assessed 131 axial lumbosacral interbody fusion procedures (L5-S1) performed at their institution over a 6-year period.⁷ All patients had a minimum of 6 months (mean, 5 years) of unsuccessful nonsurgical management and had magnetic resonance imaging, radiography, provocative discography, and anesthetization of the disc. Magnetic resonance imaging of the sacrum and coccyx was performed to identify vascular anomalies, tumor, or surgical scarring that would preclude safe access through the presacral space. Percutaneous facet screw fixation was used in all patients beginning mid-2008. No intraoperative complications were reported. At a mean follow-up of 21 months (minimum, 1 year), back pain had decreased by 51% (change in visual analog scale score, 70 to 39), leg pain decreased by 42% (from 45 to 26), and back function scores (Oswestry Disability Index) improved by 50% compared with baseline. With clinical success defined as an improvement of 30% or more, 66% of patients met criteria for reduction in back and leg pain severity. Employment increased from 24% to 64% at follow-up. The fusion rate was 87.8%, with 9.2% indeterminate on radiograph and 3.1% showing pseudoarthrosis. There were 8 (6.1%) reoperations at the index level.

Gerszten et al. (2012) reported on a series of patients who had a minimum 2 year follow-up after axial lumbosacral interbody fusion with percutaneous posterior fixation with pedicle screws for the stabilization of grade 1 or 2 lumbosacral isthmic spondylolisthesis.⁸ There were no perioperative procedure-related complications. The spondylolisthesis grade in the 26 consecutive patients was significantly improved at follow-up, with 50% of patients showing a reduction of at least 1 grade. Axial pain severity was reduced (change in visual analog scale score, 8.1 to 2.8), and 81% of patients had excellent or good results based on Odom criteria. At 2 years post-treatment, all patients showed solid fusion.

Two-Level Axial Lumbosacral Interbody Fusion
Marchi et al. (2012) reported on prospective 2 year follow-up for 27 patients who underwent 2 level axial lumbosacral interbody fusion at the L4-5 and L5-S1 disc spaces.⁹ Average back pain decreased from a visual analog scale score of 8.08 to 4.04 and Oswestry Disability Index scores improved from 51.7 to 31.4. Although no intraoperative complications occurred, the authors reported malpositioned rods in 3 cases due to difficulty attaining an adequate route for the double-level access. In one of these cases, the rod migrated and perforated the bowel. Five (18.5%) patients underwent additional surgery for malpositioned rods, broken posterior screws, rod failure, or collapse of spine levels. Total complications observed at follow-up included screw breakage (14.8%), transsacral rod detachment (11.1%), radiolucency around the transsacral rod (52%), and disc collapse with cephalic rod migration (24%). A gain in disc height was observed 1 week after surgery, but, by the 24-month follow-up, the disc space was less than that of the preoperative state. Only 22% of levels had solid fusion at the 24-month radiologic evaluation, and only 2 patients had solid fusion at both levels.

Adverse Events
An industry-sponsored, 5 year, voluntary postmarketing surveillance study of 9,152 patients was reported by Gundanna et al. (2011).¹⁰ A single-level (L5-S1) fusion was performed in 8,034 (88%) patients, and a 2-level (L4-S1) fusion was performed in 1,118 (12%) patients. A predefined database was designed to record device- or procedure-related complaints through spontaneous reporting. Several procedures, including the presence of a TranS1 representative during every case, were implemented to encourage complication reporting. Complications recorded included bowel injury, superficial wound and systemic infections, transient intraoperative hypotension, migration, subsidence, presacral hematoma, sacral fracture, vascular injury, nerve injury, and ureter injury (pseudoarthrosis was not included). Follow-up ranged from 3 months to 5 years 3 months. Complications were reported in 120 (1.3%) patients at a median of 5 days (mean, 33 days; range, 0 – 511 days). Bowel injury was the most commonly reported complication (0.6%), followed by transient intraoperative hypotension (0.2%). All other complications had an incidence of 0.1% or lower. There were no significant differences in complication rates for single-level (1.3%) and 2-level (1.6%) fusion procedures. Although this study included a large number of patients, it relied on spontaneous reporting, which could underestimate the true incidence of complications.

Lindley et al. (2011) found high complication rates when retrospectively reviewing 68 patients who underwent axial lumbosacral interbody fusion between 2005 and 2009.¹¹ Patient diagnoses included degenerative disc disease, spondylolisthesis, spinal stenosis, degenerative lumbar scoliosis, spondylolysis, pseudoarthrosis, and recurrent disc herniation. Ten patients underwent 2-level axial lumbosacral interbody fusion (L4-S1), and 58 patients underwent a single-level axial lumbosacral interbody fusion (L5-S1). A total of 18 complications in 16 (23.5%) patients were identified at a mean 34-month follow-up (range, 17-61 months). Complications included pseudoarthrosis (8.8%), superficial infection (5.9%), sacral fracture (2.9%), pelvic hematoma (2.9%), failure of wound closure (1.5%), and rectal perforation (2.9%). Both patients with rectal perforation underwent emergency repair and had no long-term sequelae. Patients with nonunion underwent additional fusion surgery with an anterior or posterior approach. The 2 patients with sacral fractures had preexisting osteoporosis. Because of the potential complications, the authors recommended full bowel preparation and preoperative magnetic resonance imaging before an axial lumbosacral interbody fusion procedure to assess the size of the presacral space, to determine rectal adherence to the sacrum, to rule out vascular abnormalities, and to determine a proper trajectory.

The purpose of the following information is to provide reference material. Inclusion does not imply endorsement or alignment with the evidence review conclusions.

Clinical Input From Physician Specialty Societies and Academic Medical Centers
While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.

In response to requests, input was received from 2 specialty medical societies and 3 academic medical centers while this policy was under review in 2011. Input considered axial lumbosacral interbody fusion to be investigational.

Practice Guidelines and Position Statements
Guidelines or position statements will be considered for inclusion in Supplemental Information if they were issued by, or jointly by, a U.S. professional society, an international society with U.S. representation, or National Institute for Health and Care Excellence (NICE). Priority will be given to guidelines that are informed by a systematic review, include strength of evidence ratings, and include a description of management of conflict of interest.

North American Spine Society
In 2014, the North American Spine Society published guidelines on the treatment of degenerative spondylolisthesis.¹² The North American Spine Society gave a grade B recommendation for surgical decompression with fusion in patients with spinal stenosis and spondylolisthesis. The guidelines discussed posterolateral fusion, 360º fusion, and minimally invasive fusion; it did not address axial lumbosacral interbody fusion.

National Institute for Health and Care Excellence
In July 2018, the National Institute for Health and Care Excellence (NICE) provided evidence-based recommendations on transaxial interbody lumbosacral fusion for low back pain in adults.¹³ The recommendation, based on a literature review conducted in December 2017, states, "Evidence on the safety of transaxial interbody lumbosacral fusion for severe chronic low back pain shows that there are serious but well-recognized complications. Evidence on efficacy is adequate in quality and quantity. Therefore, this procedure may be used provided that standard arrangements are in place for clinical governance, consent and audit. This procedure should only be done by a surgeon with specific training in the procedure, who should carry out their initial procedures with an experienced mentor."

U.S. Preventive Services Task Force Recommendations
Not applicable

Ongoing and Unpublished Clinical Trials
A search of Clinicaltrials.gov in March 2023 did not identify any ongoing trials that would influence this review.

References  

1. U.S. Food and Drug Administration. Premarket Notification [510(K)] Summary. TranS1 AxiaLIF Fixation System. 2007; https://www.accessdata.fda.gov/cdrh_docs/pdf7/K073514.pdf. Accessed March 9, 2023.
2. U.S. Food and Drug Administration. Premarket Notification [510(K)] Summary. TranS1 AxiaLIF II System. 2008; https://www.accessdata.fda.gov/cdrh_docs/pdf7/K073643.pdf. Accessed March 10, 2023.
3. Shen FH, Samartzis D, Khanna AJ, et al. Minimally invasive techniques for lumbar interbody fusions. Orthop Clin North Am. Jul 2007; 38(3): 373-86; abstract vi. PMID 17629985
4. Schroeder GD, Kepler CK, Millhouse PW, et al. L5/S1 Fusion Rates in Degenerative Spine Surgery: A Systematic Review Comparing ALIF, TLIF, and Axial Interbody Arthrodesis. Clin Spine Surg. May 2016; 29(4): 150-5. PMID 26841206
5. Whang PG, Sasso RC, Patel VV, et al. Comparison of axial and anterior interbody fusions of the L5-S1 segment: a retrospective cohort analysis. J Spinal Disord Tech. Dec 2013; 26(8): 437-43. PMID 24196923
6. Tobler WD, Gerszten PC, Bradley WD, et al. Minimally invasive axial presacral L5-S1 interbody fusion: two-year clinical and radiographic outcomes. Spine (Phila Pa 1976). Sep 15 2011; 36(20): E1296-301. PMID 21494201
7. Zeilstra DJ, Miller LE, Block JE. Axial lumbar interbody fusion: a 6-year single-center experience. Clin Interv Aging. 2013; 8: 1063-9. PMID 23976846
8. Gerszten PC, Tobler W, Raley TJ, et al. Axial presacral lumbar interbody fusion and percutaneous posterior fixation for stabilization of lumbosacral isthmic spondylolisthesis. J Spinal Disord Tech. Apr 2012; 25(2): E36-40. PMID 21964453
9. Marchi L, Oliveira L, Coutinho E, et al. Results and complications after 2-level axial lumbar interbody fusion with a minimum 2-year follow-up. J Neurosurg Spine. Sep 2012; 17(3): 187-92. PMID 22803626
10. Gundanna MI, Miller LE, Block JE. Complications with axial presacral lumbar interbody fusion: A 5-year postmarketing surveillance experience. SAS J. 2011; 5(3): 90-4. PMID 25802673
11. Lindley EM, McCullough MA, Burger EL, et al. Complications of axial lumbar interbody fusion. J Neurosurg Spine. Sep 2011; 15(3): 273-9. PMID 21599448
12. North American Spine Society. Diagnosis and treatment of degenerative lumbar spondylolisthesis. 2nd Ed. 2014; https://www.spine.org/Documents/ResearchClinicalCare/Guidelines/Spondylolisthesis.pdf. 
13. National Institute for Health and Care Excellence (NICE). Transaxial interbody lumbosacral fusion for severe chronic low back pain IPG620 2018; https://www.nice.org.uk/guidance/ipg620 .

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies and accredited national guidelines.

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