Percutaneous Axial Lumbar Interbody Fusion (AxiaLIF) of the L5-S1 Segment: Initial Clinical and Radiographic Experience

Minimally Invasive Spine Surgery: An Overview

Spinal surgery is undergoing a major transformation toward a minimally invasive paradigm. This shift is being driven by multiple factors, including the need to address spinal problems in an older and sicker population, as well as changes in patient preferences and reimbursement patterns. Increasingly, minimally invasive surgical techniques are being used in place of traditional open approaches due to significant advancements and implementation of intraoperative imaging and navigation technologies. However, in some patients, due to specific anatomic or pathologic factors, minimally invasive techniques are not always possible. Numerous algorithms have been described, and additional efforts are underway to better optimize patient selection for minimally invasive spinal surgery (MISS) procedures in order to achieve optimal outcomes. Numerous unique MISS approaches and techniques have been described, and several have become fundamental. Investigators are evaluating combinations of MISS techniques to further enhance the surgical workflow, patient safety, and efficiency.

Biomechanical analysis of stand-alone lumbar interbody cages versus 360° constructs: an in vitro and finite element investigation

OBJECTIVE

Low fusion rates and cage subsidence are limitations of lumbar fixation with stand-alone interbody cages. Various approaches to interbody cage placement exist, yet the need for supplemental posterior fixation is not clear from clinical studies. Therefore, as prospective clinical studies are lacking, a comparison of segmental kinematics, cage properties, and load sharing on vertebral endplates is needed. This laboratory investigation evaluates the mechanical stability and biomechanical properties of various interbody fixation techniques by performing cadaveric and finite element (FE) modeling studies.

METHODS

An in vitro experiment using 7 fresh-frozen human cadavers was designed to test intact spines with 1) stand-alone lateral interbody cage constructs (lateral interbody fusion, LIF) and 2) LIF supplemented with posterior pedicle screw-rod fixation (360° constructs). FE and kinematic data were used to validate a ligamentous FE model of the lumbopelvic spine. The validated model was then used to evaluate the stability of stand-alone LIF, transforaminal lumbar interbody fusion (TLIF), and anterior lumbar interbody fusion (ALIF) cages with and without supplemental posterior fixation at the L4-5 level. The FE models of intact and instrumented cases were subjected to a 400-N compressive preload followed by an 8-Nm bending moment to simulate physiological flexion, extension, bending, and axial rotation. Segmental kinematics and load sharing at the inferior endplate were compared.

RESULTS

The FE kinematic predictions were consistent with cadaveric data. The range of motion (ROM) in LIF was significantly lower than intact spines for both stand-alone and 360° constructs. The calculated reduction in motion with respect to intact spines for stand-alone constructs ranged from 43% to 66% for TLIF, 67%-82% for LIF, and 69%-86% for ALIF in flexion, extension, lateral bending, and axial rotation. In flexion and extension, the maximum reduction in motion was 70% for ALIF versus 81% in LIF for stand-alone cases. When supplemented with posterior fixation, the corresponding reduction in ROM was 76%-87% for TLIF, 86%-91% for LIF, and 90%-92% for ALIF. The addition of posterior instrumentation resulted in a significant reduction in peak stress at the superior endplate of the inferior segment in all scenarios.

CONCLUSIONS

Stand-alone ALIF and LIF cages are most effective in providing stability in lateral bending and axial rotation and less so in flexion and extension. Supplemental posterior instrumentation improves stability for all interbody techniques. Comparative clinical data are needed to further define the indications for stand-alone cages in lumbar fusion surgery.

Paracoccygeal Transsacral Approach: A Rare Approach for Axial Lumbosacral Interbody Fusion

Lumbosacral interbody fusion is a mainstay of surgical treatment for degenerative spinal pathologies causing chronic pain and functional impairment. However, the optimal technique for this procedure remains controversial. Well-established open approaches, including anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF), have historically been the standard of practice. A recent paradigm shift in spinal surgery has led to the investigation of minimally invasive approaches to mitigate tissue damage without compromising outcomes. This extensive review aims to examine current clinical and biomechanical evidence on the paracoccygeal transsacral approach to an axial lumbosacral interbody fusion. Since this technique was first described in 2004, accumulating evidence suggests it results in high fusion rates, consistent improvements in pain and function, reduced perioperative morbidity, and low rates of complication. Although early clinical outcomes have been promising, there is a paucity of comparative data investigating outcomes of the paracoccygeal transsacral approach to traditional alternatives and other minimally invasive techniques. Here, we summarize current evidence and discuss pertinent topics for the spinal surgeon considering this novel approach, including indications, advantages, relevant anatomy, contraindications, and technical considerations.

Early Clinical Evaluation of Percutaneous Full-endoscopic Transforaminal Lumbar Interbody Fusion with Pedicle Screw Insertion for Treating Degenerative Lumbar Spinal Stenosis

Objective

To compare the clinical efficacy of percutaneous full‐endoscopic transforaminal lumbar interbody fusion (Endo‐TLIF) with percutaneous pedicle screws (PPSs) performed by using a visualization system with that of minimally invasive transforaminal lumbar interbody fusion (MIS‐TLIF) for the treatment of degenerative lumbar spinal stenosis (LSS).

Methods

From June 2017 to May 2018, the data of a total of 78 patients who met the selection criteria were retrospectively reviewed and were divided into the Endo‐TLIF group (40 cases) and the MIS‐TLIF group (38 cases) according to the surgical method used. The visual analog scale (VAS) and the Japanese Orthopaedic Association (JOA) scale were administered preoperatively and at the 1‐week, 3‐month, and 1–2‐year follow‐ups. The fusion rate and major complications, including revision, were also recorded.

Results

All the patients were followed up for 24 to 34 months, with an average follow‐up of 30.7 months. The intraoperative blood loss and length of hospital stay for the Endo‐TLIF group (60.56 ± 0.36 mL, 8.12 ± 0.92 days, respectively) were statistically significantly lower than those for the MIS‐TLIF group (65.47 ± 0.91 mL, 9.66 ± 1.34 days, respectively) (P < 0.05). The VAS and JOA scores of the patients in the two groups at postoperative 1 week, 3 months, 1 year, 2 years (Endo‐TLIF VAS: 4.16 ± 0.92, 3.72 ± 1.54, 1.32 ± 0.45, 1.29 ± 0.34; JOA:16.71 ± 0.99, 19.86 ± 0.24, 24.91 ± 0.97, 25.88 ± 0.52; MIS‐TLIF VAS: 4.17 ± 1.41, 2.98 ± 0.91, 1.54 ± 0.32, 1.33 ± 0.18; JOA: 16.67 ± 0.67, 19.58 ± 0.65, 25.33 ± 0.73, 25.69 ± 0.33) were statistically significantly improved from the preoperative scores (Endo‐TLIF: 8.45 ± 1.44, 14.36 ± 0.56; MIS‐TLIF: 8.11 ± 0.93, 14.45 ± 0.34, respectively) (P < 0.01). The VAS and JOA scores of the Endo‐TLIF group were statistically significantly better than those of the MIS‐TLIF group at 3 months and 1 year after surgery (P < 0.05). There were no statistically significant differences in the scores between the two groups at any of the other time points (P > 0.05). There was no significant difference in the intervertebral altitude between the two groups at the 3‐month (11.36 ± 0.23, 11.21 ± 0.42, respectively) or final follow‐up (10.88 ± 0.64, 10.81 ± 0.39, respectively) (P > 0.05). Dural tears, cerebrospinal fluid leakage, infection, and neurologic injury did not occur. Both groups showed good intervertebral fusion at the last follow‐up. The intervertebral fusion rate was 97.5% (39/40) in the Endo‐TLIF group and 94.7% (36/38) in the MIS‐TLIF group, with no statistically significant difference between the two groups (χ² = 0.118, P = 0.731). At the final follow‐up, the modified MacNab's criteria were 92.5% and 89.5% between the two groups.

Conclusion

Endo‐TLIF with percutaneous pedicle screws (PPS) performed by using a visualization system for lumbar degenerative disease may be regarded as an efficient alternative surgery for degenerative lumbar spinal stenosis. It is a safe and minimally invasive way to perform this surgery and has shown satisfactory clinical outcomes.

Transsacral interbody fixation versus transforaminal lumbar interbody fusion at the lumbosacral junction for long fusions in primary adult scoliosis

OBJECTIVE

Achieving fusion at the lumbosacral junction poses many technical challenges. No data exist in the literature comparing radiographic or clinical outcomes between the different surgical techniques of transsacral fixation (TSF) with rods and transforaminal lumbar interbody fusion (TLIF) in conjunction with iliac fixation. The purpose of this study was to compare the clinical outcomes and radiographic fusions of TSF to TLIF in patients with adult spinal deformity undergoing long fusions across the lumbosacral junction.

METHODS

Patients with primary adult spinal deformity who underwent long fusions from the thoracic spine across the lumbosacral junction with different approaches of interbody fusion at the L5-S1 level were reviewed. Patients were subdivided by approach (TSF vs TLIF). Fusion status at L5-S1 was evaluated by multiple radiographs and/or CT scans. Scoliotic curve changes were also evaluated preoperatively and at final follow-up. Clinical outcomes were assessed by Scoliosis Research Society Outcome Instrument 22 and Oswestry Disability Index scores.

RESULTS

A total of 36 patients were included in the analysis. There were 18 patients in the TSF group and 18 patients in the TLIF group. A mean of 14.00 levels were fused in the TSF group and 10.94 in the TLIF group (p = 0.01). Both groups demonstrated significant postoperative radiographic improvement in coronal parameters. The fusion rates for TSF and TLIF groups were 100% and 88.9%, respectively (p < 0.05). Eight patients in the TSF group had pelvic fixation with unilateral iliac screws, compared to 15 patients in the TLIF group (p = 0.015). No statistical differences in patients' reported outcomes were seen between groups.

CONCLUSIONS

Despite similar clinical and radiographic outcomes between both groups, TSF required fewer iliac screws to augment stability of the lumbosacral junction while achieving a higher rate of fusion. This study suggests that TSF may decrease potential instrument-related complications requiring revision while decreasing operating room time and implant-related costs.

[Minimally invasive spinal surgery: stages of development]

In recent decades, spinal surgery has changed significantly. The active use of modern knowledge of anatomy, various diagnostic modules, specialized surgical equipment and high-tech tools has made it possible to transform classical surgical techniques into a new area of spinal neurosurgery - minimally invasive spine surgery (MISS). Its main goals are to reduce damage to the skin and adjacent tissues, significantly reduce the level of pain, reduce the duration of inpatient treatment and fully restore functional status in the shortest possible time. This article reflects the main criteria for MISS compliance and types of surgical interventions, provides information on the advantages of minimally invasive surgical technologies and their possible disadvantages. Currently, the use of MISS is observed in all areas of vertebrology - for degenerative diseases, tumors, inflammatory and traumatic lesions of the spine. At the same time, minimizing surgical aggression while maximizing the achievement of goal becomes the main rule of modern spinal surgery.

Adjacent-segment disease following two-level axial lumbar interbody fusion

OBJECTIVE

While long-term studies have evaluated adjacent-segment disease (ASD) following posterior lumbar spine arthrodesis, no such studies have assessed the incidence and prevalence of ASD following axial lumbar interbody fusion (AxiaLIF). The aim of this study was to estimate the incidence of ASD following AxiaLIF.

METHODS

The authors retrospectively reviewed the medical records of 149 patients who underwent two-level index AxiaLIF and had at least 2 years of radiographic and clinical follow-up. ASD and pre- and postoperative lumbar lordosis were evaluated in each patient. ASD was defined as both radiographic and clinically significant disease at a level adjacent to a previous fusion requiring surgical intervention. The mean duration of follow-up was 6.01 years.

RESULTS

Twenty (13.4%) of the 149 patients developed ASD during the data collection period. Kaplan-Meier analysis predicted a disease-free ASD survival rate of 95.3% (95% CI 90.4%-97.7%) at 2 years and 89.1% (95% CI 82.8%-93.2%) at 5 years for two-level fusion. A laminectomy adjacent to a fusion site was associated with 5.1 times the relative risk of developing ASD. Furthermore, the ASD group had significantly greater loss of lordosis than the no-ASD group (p = 0.033).

CONCLUSIONS

Following two-level AxiaLIF, the rate of symptomatic ASD warranting either decompression or arthrodesis was found to be 4.7% at 2 years and 10.9% at 5 years. Adjacent-segment decompression and postoperative loss of lumbar lordosis predicted future development of ASD. To the authors' knowledge, this is the largest reported cohort of patients to undergo two-level AxiaLIF in the United States.

Clinical and Radiologic Fate of the Lumbosacral Junction After Anterior Lumbar Interbody Fusion Versus Axial Lumbar Interbody Fusion at the Bottom of a Long Construct in CMIS Treatment of Adult Spinal Deformity

Introduction:

Surgeons use numerous arthrodesis strategies for fusion of the lumbosacral junction including anterior lumbar interbody fusion (ALIF) and axial lumbar interbody fusion (AxiaLIF). The optimal L5-S1 fusion strategy remains inconclusive. The purpose of this study is to compare the fate of the lumbosacral junction in ALIF versus AxiaLIF patients in terms of clinical and radiographic outcomes.

Methods:

Adult spinal deformity patients, treated with CMIS techniques, with at least 2-year follow-up who underwent AxiaLIF or ALIF at the lumbosacral junction were included. Patients were separated into two groups: AxiaLIF (56 patients) and ALIF (38 patients). Outcome measures included segmental lordosis, sagittal vertical alignment, lumbar lordosis (LL), pelvic incidence–LL mismatch, and pseudarthrosis, major complication, and revision surgery rates.

Results:

The ALIF group achieved greater postoperative and delta segmental lordosis, higher delta sagittal vertical alignment, higher delta LL, and lower postoperative pelvic incidence–LL mismatch. The pseudarthrosis, major complication, and revision surgery rates were higher in the AxiaLIF group. Five cases of pseudarthrosis at L5-S1 were seen, all in the AxiaLIF group.

Discussion and Conclusion:

ALIF patients showed more favorable radiographic correction parameters and lower rates of pseudarthrosis, major complications, and revision surgeries. ALIF is the preferred strategy for L5-S1 arthrodesis at a bottom of a long construct.

Optimal axis for lumbosacral interbody fusion: Prospective finite element analysis and retrospective 3D-CT measurement

A feasible and optimal axis of biomechanical and anatomic significance in axial lumbosacral interbody fusion (AxiaLIF) was designed. Using the image dataset of an adult volunteer, two groups of finite element (FE) models of the AxiaLIF, lumbosacral anterior column fixation (ACF) models and middle column fixation (MCF) models with different bone graft fusion degrees, were prospectively established, and their biomechanical differences were comparatively predicted. In addition, 3D reconstruction was performed by retrospectively collecting CT data from pelvises in 60 adult cases. Their anatomic parameters relating to two groups of models were digitally measured and statistically compared. Numerical analysis revealed that the load and the maximum stress on the screw as well as the maximum stress difference between the screw and peripheral tissues in the MCF model were reduced compared with the ACF model. These indices of both models all decreased markedly in response to the increase in the disc fusion degree. Statistical analysis revealed that the effective fixed length of the sacrum in the MCF model was increased compared with the ACF model (P < 0.05). The surgical dissection distance of presacral vessels and nerves from the axis to sacrum of the MCF model was reduced compared with the ACF model (P < 0.05). The feasible and optimal axis of biomechanical and anatomic significance of the AxiaLIF is similar to the axis of the MCF model. Disc bone graft fusions plus axial screw fixations of middle column could strengthen the biomechanical stability of the AxiaLIF model. Clin. Anat. 32:337-347, 2019. © 2018 Wiley Periodicals, Inc.

Selective Anterior Lumbar Interbody Fusion for Low Back Pain Associated With Degenerative Disc Disease Versus Nonsurgical Management

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

To evaluate the long-term outcomes of selective one- to two-level anterior lumbar interbody fusions (ALIFs) in the lower lumbar spine versus continued nonsurgical management.

SUMMARY OF BACKGROUND DATA

Low back pain associated with lumbar intervertebral disc degeneration is common with substantial economic impact, yet treatment remains controversial. Surgical fusion has previously provided mixed results with limited durable improvement of pain and function.

METHODS

Seventy-five patients with one or two levels of symptomatic Pfirrmann grades 3 to 5 disc degeneration from L3-S1 were identified. All patients had failed at least 6 months of nonsurgical treatment. Forty-two patients underwent one- or two-level ALIFs; 33 continued multimodal nonsurgical care. Patients were evaluated radiographically and the visual analog pain scale (VAS), Oswestry Disability Index (ODI), EuroQol five dimensions (EQ-5D), and Patient-Reported Outcomes Measurement Information System scores for pain interference, pain intensity, and anxiety. As-treated analysis was performed to evaluate outcomes at a mean follow-up of 7.4 years (range: 2.5-12).

RESULTS

There were no differences in pretreatment demographics or nonsurgical therapy utilization between study arms. At final follow-up, the surgical arm demonstrated lower VAS, ODI, EQ-5D, and Patient-Reported Outcomes Measurement Information System pain intensity scores versus the nonsurgical arm. VAS and ODI scores improved 52.3% and 51.1% in the surgical arm, respectively, versus 15.8% and -0.8% in the nonsurgical arm. Single-level fusions demonstrated improved outcomes versus two-level fusions. The pseudarthrosis rate was 6.5%, with one patient undergoing reoperation. Asymptomatic adjacent segment degeneration was identified in 11.9% of patients.

CONCLUSION

Selective ALIF limited to one or two levels in the lower lumbar spine provided improved pain and function when compared with continued nonsurgical care. ALIF may be a safe and effective treatment for low back pain associated with disc degeneration in select patients who fail nonsurgical management.

LEVEL OF EVIDENCE

3.

Spinal Biologics in Minimally Invasive Lumbar Surgery

As the use of minimally invasive spine (MIS) fusion approaches continues to grow, increased scrutiny is being placed on its outcomes and efficacies against traditional open fusion surgeries. While there are many factors that contribute to the success of achieving spinal arthrodesis, selecting the optimal fusion biologic remains a top priority. With an ever-expanding market of bone graft substitutes, it is important to evaluate each of their use as it pertains to MIS techniques. This review will summarize the important characteristics and properties of various spinal biologics used in minimally invasive lumbar surgeries and compare their fusion rates via a systematic review of published literature.

Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine: A Biomechanical Study

OBJECTIVE

To evaluate stability of anterior transdiscal axial screw (ATAS) fixation for anterior instrumentation and to compare with standard anterior cervical decompression and fusion and plate (ACDFP) fixation in human subaxial cervical spine.

METHODS

Flexibility tests were conducted on 7 cadaveric specimens (C5-T1) in an intact and injured state and instrumented with ACDFP fixation, ATAS fixation, and ACDFP plus ATAS fixation at the C6-7 segment after section of the anterior and posterior longitudinal ligaments and discectomy. A pure moment of ±2.0 N-m was applied to the specimen in flexion-extension, lateral bending, and axial rotation. Range of motion (ROM) and neutral zone were calculated for the C6-7 segment.

RESULTS

ROM was reduced significantly compared with the intact or injured condition for 3 configurations under all motions. ATAS fixation resulted in similar ROM in C6-7 compared with ACDFP fixation in flexion (2.7° vs. 2.6°, P = 0.419), extension (2.7° vs. 2.1°, P = 0.152), and lateral bending (4.6° vs. 4.2°, P = 0.295) but larger ROM in axial rotation (6.1° vs. 5.3°, P = 0.014). When combined with an anterior plate, ATAS fixation reduced ROM to 1.2° in flexion, 1.1° in extension, 3.3° in lateral bending, and 3.8° in axial rotation, which were significantly smaller than ACDFP or ATAS fixation alone.

CONCLUSIONS

ATAS fixation is a biomechanically effective alternative or supplemental method of anterior fixation in subaxial cervical spine.

Radiographic and Clinical Outcome of Silicate-substituted Calcium Phosphate (Si-CaP) Ceramic Bone Graft in Spinal Fusion Procedures

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate the radiographic and clinical outcome of silicate-substituted calcium phosphate (Si-CaP), utilized as a graft substance in spinal fusion procedures.

SUMMARY OF BACKGROUND DATA

Specific properties of Si-CaP provide the graft with negative surface charge that can result in a positive effect on the osteoblast activity and neovascularization of the bone.

METHODS

This study included those patients who underwent spinal fusion procedures between 2007 and 2011 in which Si-CaP was used as the only bone graft substance. Fusion was evaluated on follow-up CT scans. Clinical outcome was assessed using Oswestry Disability Index, Neck Disability Index, and the visual analogue scale (VAS) for back, leg, neck, and arm pain.

RESULTS

A total of 234 patients (516 spinal fusion levels) were studied. Surgical procedures consisted of 57 transforaminal lumbar interbody fusion, 49 anterior cervical discectomy and fusion, 44 extreme lateral interbody fusion, 30 posterior cervical fusions, 19 thoracic fusion surgeries, 17 axial lumbar interbody fusions, 16 combined anterior and posterior cervical fusions, and 2 anterior lumbar interbody fusion. At a mean radiographic follow-up of 14.2±4.3 months, fusion was found to be present in 82.9% of patients and 86.8% of levels. The highest fusion rate was observed in the cervical region. At the latest clinical follow-up of 21.7±14.2 months, all clinical outcome parameters showed significant improvement. The Oswestry Disability Index improved from 45.6 to 13.3 points, Neck Disability Index from 40.6 to 29.3, VAS back from 6.1 to 3.5, VAS leg from 5.6 to 2.4, VAS neck from 4.7 to 2.7, and VAS arm from 4.1 to 1.7. Of 7 cases with secondary surgical procedure at the index level, the indication for surgery was nonunion in 3 patients.

CONCLUSIONS

Si-CaP is an effective bone graft substitute. At the latest follow-up, favorable radiographic and clinical outcome was observed in the majority of patients.

LEVEL OF EVIDENCE

Level-III.

Anatomic Study of Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine Injuries

Anterior transdiscal axial screw (ATAS) fixation is an alternative or supplement to the plate and screw constructs for the upper cervical spine injury. However, no existing literatures clarified the anatomic feasibility of this technique for subaxial cervical spine. Therefore, the objective of this study was to evaluate the anatomical feasibility and to establish guidelines for the use of the ATAS fixation for the subaxial cervical spine injury.Fifty normal cervical spines had radiographs to determine the proposed screw trajectory (the screw length and insertion angle) and the interbody graft-related parameters (the disc height and depth, and the distance between anterior vertebral margin and the screw) for all levels of the subaxial cervical spine. Following screw insertion in 8 preserved human cadaver specimens, surgical simulation and dissection verified the feasibility and safety of the ATAS fixation.Radiographic measurements showed the mean axial screw length and cephalic incline angle of all levels were 41.2 mm and 25.2°, respectively. The suitable depth of the interbody graft was >11.7 mm (the distance between anterior vertebral margin and the screw), but <17.1 mm (disc depth). Except the axial screw length, increase in all the measurements was seen with level up to C5-C6 segment. Simulated procedure in the preserved specimens demonstrated that ATAS fixation could be successfully performed at C2-C3, C3-C4, C4-C5, and C5-C6 levels, but impossible at C6-C7 due to the obstacle of the sternum. All screws were placed accurately. None of the screws penetrated into the spinal canal and caused fractures determined by dissecting the specimens.The anterior transdiscal axial screw fixation, as an alternative or supplementary instrumentation for subaxial cervical spine injuries, is feasible and safe with meticulous surgical planning.

L5/S1 Fusion Rates in Degenerative Spine Surgery: A Systematic Review Comparing ALIF, TLIF, and Axial Interbody Arthrodesis

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine the fusion rate of an anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF), and axial arthrodesis at the lumbosacral junction in adult patients undergoing surgery for 1- and 2-level degenerative spine conditions.

SUMMARY OF BACKGROUND DATA

An L5/S1 interbody fusion is a commonly performed procedure for pathology such as spondylolisthesis with stenosis; however, it is unclear if 1 technique leads to superior fusion rates.

MATERIALS AND METHODS

A systematic search of MEDLINE was conducted for literature published between January 1, 1992 and August 17, 2014. All peer-reviewed articles related to the fusion rate of L5/S1 for an ALIF, TLIF, or axial interbody fusion were included.

RESULTS

In total, 42 articles and 1507 patients were included in this systematic review. A difference in overall fusion rates was identified, with a rate of 99.2% (range, 96.4%-99.8%) for a TLIF, 97.2% (range, 91.0%-99.2%) for an ALIF, and 90.5% (range, 79.0%-97.0%) for an axial interbody fusion (P=0.005). In a paired analysis directly comparing fusion techniques, only the difference between a TLIF and an axial interbody fusion was significant. However, when only cases in which bilateral pedicle screws supported the interbody fusion, no statistical difference (P>0.05) between the 3 techniques was identified.

CONCLUSIONS

The current literature available to guide the treatment of L5/S1 pathology is poor, but the available data suggest that a high fusion rate can be expected with the use of an ALIF, TLIF, or axial interbody fusion. Any technique-dependent benefit in fusion rate can be eliminated with common surgical modifications such as the use of bilateral pedicle screws.

Thirty-Day Reoperation and Readmission Rates After Correction of Adult Spinal Deformity via Circumferential Minimally Invasive Surgery-Analysis of a 7-Year Experience

STUDY DESIGN

Single-center retrospective analysis of consecutive patients who have undergone circumferential minimally invasive surgery (cMIS) for correction of adult spinal deformity (ASD).

OBJECTIVES

To study the rates of reoperations and readmissions within the first 30 days following cMIS for correction of ASD.

BACKGROUND

Hospital readmission and reoperation rates have been emphasized as an important measure of quality and cost-effectiveness of care. However, there is little information about the readmission rates following cMIS correction of ASD.

METHODS

This is a retrospective cohort study of 214 consecutive patients with ASD who underwent correction using cMIS involving at least 2 levels. Major complications encountered during surgery or within 30 days following the index procedure that needed reoperation or readmission were recorded. The primary outcomes measured were early readmission, and early reoperation.

RESULTS

An average of 4 levels were fused. Nineteen complications were noted in the 30-day period following the index surgery, giving an early complication rate of 8.9%. Twelve of those complications occurred during the initial hospitalization and 7 complications occurred after the patient had been discharged home. Forty-seven percent of the complications occurred within the first 3 years of our experience, 37% in the next 2 years, and only 16% in the following 3 years. The 30-day readmission rate was 3.3%, which showed no statistically significant difference based on the number of levels fused.

CONCLUSIONS

Our study delivers significant evidence that efforts to reduce hospital readmissions for ASD patients should begin by concentrating on the postoperative complications. Although minimally invasive approaches will not eliminate all complications, they may have an effect on reducing the rate of major complications, most notably the rate of postoperative infection. This in turn can lead to a substantially lower readmission and reoperation rate as is reported in our study.

LEVEL OF EVIDENCE

Level IV, case series.

Axial interbody arthrodesis of the L5-S1 segment: a systematic review of the literature

OBJECT

The object of this study was to determine the fusion rate and safety profile of an axial interbody arthrodesis of the L5-S1 motion segment.

METHODS

A systematic search of MEDLINE was conducted for literature published between January 1, 2000, and August 17, 2014. All peer-reviewed articles related to the fusion rate of L5-S1 and the safety profile of an axial interbody arthrodesis were evaluated.

RESULTS

Seventy-four articles were identified, but only 15 (13 case series and 2 retrospective cohort studies) met the study inclusion criteria. The overall pseudarthrosis rate at L5-S1 was 6.9%, and the rate of all other complications was 12.9%. A total of 14.4% of patients required additional surgery, and the infection rate was 5.4%. Deformity studies reported a significantly increased rate of complications (46.3%), and prospectively collected data demonstrated significantly higher complication (36.8%) and revision (22.6%) rates. Lastly, studies with a conflict of interest reported lower complication rates (12.4%).

CONCLUSIONS

A systematic review of the literature indicates that an axial interbody fusion performed at the lumbosacral junction is associated with a high fusion rate (93.15%) and an acceptable complication rate (12.90%). However, these results are based mainly on retrospective case series by authors with a conflict of interest. The limited prospective data available indicate that the actual fusion rate may be lower and the complication rate may be higher than currently reported.

The axial transsacral approach to interbody fusion at L5-S1

Lumbosacral interbody fusion may be indicated to treat degenerative disc disease at L5-S1, instability or spondylolisthesis at that level, and severe neural foraminal stenosis resulting from loss of disc space height. In addition, L5-S1 interbody fusion may provide anterior support to a long posterior fusion construct and help offset the stresses experienced by the distal-most screws. There are 3 well-established techniques for L5-S1 interbody fusion: anterior lumbar interbody fusion, posterior lumbar interbody fusion, and transforaminal lumbar interbody fusion. Each of these has advantages and pitfalls. A more recently described axial transsacral technique, utilizing the presacral corridor, may represent a minimally invasive approach to obtaining lumbosacral interbody arthrodesis. Biomechanical studies demonstrate that the stiffness of the axial rod is comparable to existing fixation devices, suggesting that, biomechanically, it may be a good implant for obtaining lumbosacral interbody fusion. Clinical studies have demonstrated good early results with the use of the axial transsacral approach in obtaining lumbosacral interbody fusion for degenerative disc disease, spondylolisthesis, and below long posterior fusion constructs. The technique is exacting and complications can be major, including rectal perforation and fistula, loss of correction, and pseudarthrosis.

Mini posterior lumbar interbody fusion with presacral screw stabilization in early lumbosacral instability

BACKGROUND

Surgical options for the management of early lumbosacral spondylolisthesis and degenerative disc disease with instability vary from open lumbar interbody fusion with transpedicular fixation to a variety of minimal access fusion and fixation procedures. We have used a combination of micro discectomy and axial lumbosacral interbody fusion with presacral screw fixation to treat symptomatic patients with lumbosacral spondylolisthesis or lumbosacral degenerative disc disease, which needed surgical stabilization. This study describes the above technique along with analysis of results.

MATERIALS AND METHODS

Twelve patients with symptomatic lumbosacral (L5-S1) instability and degenerative lumbosacral disc disease were treated by micro discectomy and interbody fusion using presacral screw stabilization. Patients with history of bowel, bladder dysfunction and local anorectal diseases were excluded from this study. Postoperatively all patients were evaluated neurologically and radiologically for screw position, fusion and stability. Oswestry disability index was used to evaluate results.

RESULTS

We had nine females and three males with a mean age of 47.33 years (range 26-68 years). Postoperative assessment revealed three patients to have screw placed in anterior 1/4(th) of the 1(st) sacral body, in rest nine the screws were placed in the posterior 3/4(th) of sacral body. At 2 years followup, eight patients (67%) showed evidence of bridging trabeculae at bone graft site and none of the patients showed evidence of instability or implant failure.

CONCLUSION

Presacral screw fixation along with micro discectomy is an effective procedure to manage early symptomatic lumbosacral spondylolisthesis and degenerative disc disease with instability.

Segmental and global lordosis changes with two-level axial lumbar interbody fusion and posterior instrumentation

Background

Loss of lumbar lordosis has been reported after lumbar interbody fusion surgery and may portend poor clinical and radiographic outcome. The objective of this research was to measure changes in segmental and global lumbar lordosis in patients treated with presacral axial L4-S1 interbody fusion and posterior instrumentation and to determine if these changes influenced patient outcomes.

Methods

We performed a retrospective, multi-center review of prospectively collected data in 58 consecutive patients with disabling lumbar pain and radiculopathy unresponsive to nonsurgical treatment who underwent L4-S1 interbody fusion with the AxiaLIF two-level system (Baxano Surgical, Raleigh NC). Main outcomes included back pain severity, Oswestry Disability Index (ODI), Odom's outcome criteria, and fusion status using flexion and extension radiographs and computed tomography scans. Segmental (L4-S1) and global (L1-S1) lumbar lordosis measurements were made using standing lateral radiographs. All patients were followed for at least 24 months (mean: 29 months, range 24-56 months).

Results

There was no bowel injury, vascular injury, deep infection, neurologic complication or implant failure. Mean back pain severity improved from 7.8±1.7 at baseline to 3.3±2.6 at 2 years (p < 0.001). Mean ODI scores improved from 60±15% at baseline to 34±27% at 2 years (p < 0.001). At final follow-up, 83% of patients were rated as good or excellent using Odom's criteria. Interbody fusion was observed in 111 (96%) of 116 treated interspaces. Maintenance of lordosis, defined as a change in Cobb angle ≤ 5°, was identified in 84% of patients at L4-S1 and 81% of patients at L1-S1. Patients with loss or gain in segmental or global lordosis experienced similar 2-year outcomes versus those with less than a 5° change.

Conclusions/Clinical Relevance

Two-level axial interbody fusion supplemented with posterior fixation does not alter segmental or global lordosis in most patients. Patients with postoperative change in lordosis greater than 5° have similarly favorable long-term clinical outcomes and fusion rates compared to patients with less than 5° lordosis change.

Does minimally invasive transsacral fixation provide anterior column support in adult scoliosis?

BACKGROUND

Spinal fusion to the sacrum, especially in the setting of deformity and long constructs, is associated with high complication and pseudarthrosis rates. Transsacral discectomy, fusion, and fixation is a minimally invasive spine surgery technique that provides very rigid fixation. To date, this has been minimally studied in the setting of spinal deformity correction.

QUESTIONS/PURPOSES

We determined (1) the fusion rate of long-segment arthrodeses, (2) heath-related quality-of-life (HRQOL) outcomes (VAS pain score, Oswestry Disability Index [ODI], SF-36), and (3) the common complications and their frequency in adult patients with scoliosis undergoing transsacral fixation without supplemental pelvic fixation.

METHODS

Between April 2007 and May 2011, 92 patients had fusion of three or more segments extending to the sacrum for spinal deformity. Transsacral L5-S1 fusion without supplemental pelvic fixation was performed in 56 patients. Of these, 46 with complete data points and a minimum of 2 years of followup (mean, 48 months; range, 24-72 months; 18% of patients lost to followup) were included in this study. Nineteen of the 46 (41%) had fusions extending above the thoracolumbar junction, with one patient having fusion into the proximal thoracic spine (T3-S1). General indications for the use of transsacral fixation were situations where the fusion needed to be extended to the sacrum, such as spondylolisthesis, prior laminectomy, stenosis, oblique take-off, and disc degeneration at L5-S1. Contraindications included anatomic variations in the sacrum, vascular anomalies, prior intrapelvic surgery, and rectal fistulas or abscesses. Fusion rates were assessed by full-length radiographs and CT scanning. HRQOL data, including VAS pain score, ODI, and SF-36 scores, were assessed at all pre- and postoperative visits. Intraoperative and postoperative complications were noted.

RESULTS

Forty-one of 46 patients (89%) developed a solid fusion at L5-S1. There were significant improvements in all HRQOL parameters. Eight patients had complications related to the transsacral fusion, including five pseudarthroses and three superficial wound dehiscences. Three patients underwent revision surgery with iliac fixation. There were no bowel injuries, sacral hematomas, or sacral fractures.

CONCLUSIONS

Transsacral fixation/fusion may allow for safe lumbosacral fusion without iliac fixation in the setting of long-segment constructs in carefully selected patients. This study was retrospective and suffered from some loss to followup; future prospective trials are called for to compare this technique to other, more established approaches.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Alternative Surgical Strategy for AxiaLIF Pseudarthrosis: A Series of Three Case Reports

Study Design Retrospective case series.

Objective The objective of this study is to describe an alternative technique to attain interbody lumbar fusion in the event of pseudarthrosis after axial lumbar interbody fusion (AxiaLIF) and to assess its safety.

Methods Three patients who suffered from pseudarthrosis after AxiaLIF underwent revision surgery with a DEVEX cage (DePuy Synthes, Raynham, MA, United States) through an anterior approach. We report technical details as well as clinical and radiological results at 12 months follow-up.

Results Preoperative symptoms resolved in all cases. There were no perioperative complications. One patient had a deep venous thrombosis at postoperative day 9. A decrease in visual analog scale score for pain was observed, from 8.67 preoperatively to 2 postoperatively at final follow-up. Radiographic workup after 12 months showed no sign of implant failure or loosening, and fusion was obtained in all cases.

Conclusion Anterior fusion with a DEVEX cage in front of a TranS1 screw (TranS1 screw, Inc., Wilmington, North Carolina, United States) for AxiaLIF pseudarthrosis is safe and effective.

The use of percutaneous lumbar fixation screws for bilateral pedicle fractures with an associated dislocation of a lumbar disc prosthesis

Study Design. Case report. Objective. To identify a safe technique for salvage surgery following complications of total disc replacement. Summary of Background Data. Lumbar total disc replacement (TDR) is considered by some as the gold standard for discogenic back pain. Revision techniques for TDR and their complications are in their infancy. This case describes a successful method of fixation for this complex presentation. Methods and Results. A 48-year-old male with lumbar degenerative disc disease and no comorbidities. Approximately two weeks postoperatively for a TDR, the patient represented with acute severe back pain and the TDR polyethylene inlay was identified as dislocated anteriorly. Subsequent revision surgery failed immediately as the polyethylene inlay redislocated intraoperatively. Further radiology identified bilateral pedicle fractures, previously unseen on the plain films. The salvage fusion of L5/S1 reutilized the anterior approach with an interbody fusion cage and bone graft. The patient was then turned intraoperatively and redraped. The percutaneous pedicle screws were used to fix L5 to the sacral body via the paracoccygeal corridor. Conclusion. The robust locking screw in the percutaneous screw allowed a complete fixation of the pedicle fractures. At 3-year followup, the patient has an excellent result and has returned to playing golf.

Diagnostic criteria and treatment of discogenic pain: a systematic review of recent clinical literature

BACKGROUND CONTEXT

Pain innate to intervertebral disc, often referred to as discogenic pain, is suspected by some authors to be the major source of chronic low back and neck pain. Current management of suspected discogenic pain lacks standardized diagnosis, treatment, and terminology.

PURPOSE

In an attempt to determine whether patterns existed that may facilitate standardization of care, we sought to analyze the terminologies used and the various modes of diagnosis and treatment of suspected discogenic pain.

STUDY DESIGN

A systematic review of the recent literature.

METHODS

A Medline search was performed using the terms degenerative disc disease, discogenic pain, internal disc disruption while using the limits of human studies, English language, and clinical trials, for the last 10 years. The search led to a total of 149 distinct citations, of which 53 articles, where the intervertebral disc itself was considered the principal source of patient's pain and was the main target of the treatment, were retained for further analysis.

RESULTS

The results of this review confirm and help quantify the significant differences that existed in the terminology and all the areas of diagnosis and treatment of presumed discogenic pain.

CONCLUSIONS

Our findings show that suspected discogenic pain, despite its extensive affirmation in the literature and enormous resources regularly devoted to it, currently lacks clear diagnostic criteria and uniform treatment or terminology.

Rectal perforation after AxiaLIF instrumentation: case report and review of the literature

BACKGROUND CONTEXT

Bowel perforation is an uncommon complication of posterior spinal surgery. The AxiaLIF transsacral instrumentation system has been used for the treatment of L5-S1 spondylolisthesis and degenerative disc disease since its introduction in 2005 as a potentially less invasive alternative to traditional anterior or posterior interbody fusion.

PURPOSE

In this article, we report a case of a rectal perforation as a complication of placement of the AxiaLIF instrumentation system that was successfully treated without the removal of the device.

STUDY DESIGN

Case report.

METHODS

The patient presented with progressive back pain and sepsis 3 weeks after an L5-S1 fusion done with the AxiaLIF technique at an outside facility. The patient was managed with antibiotic therapy and a diverting ileostomy, without the removal of the AxiaLIF device.

RESULTS

Over the next year, she had symptoms indicative of nonunion of the operated level and breakdown at the adjacent level, which were confirmed with imaging. She underwent revision posterior spinal fusion without the removal of the AxiaLIF device. Eighteen months after the AxiaLIF device was placed, the patient continued to demonstrate no signs of infection recurrence.

CONCLUSIONS

Delayed presentation of rectal perforation with a subsequent anaerobic sepsis is a potential complication of the presacral approach to the L5-S1 disc space. Recognition and treatment with fecal diversion and long-term intravenous antibiotics is an alternative to device removal and sacral reconstruction.

Radiographic and clinical outcome after 1- and 2-level transsacral axial interbody fusion

Object

The paracoccygeal approach allows for instrumentation of L5/S1 and L4/5 by using a transsacral rod (AxiaLIF; TransS1, Inc.). The authors analyzed clinical and radiographic outcomes of 1- or 2-level AxiaLIF procedures with focus on durability of the construct.

Methods

This was a retrospective study of 38 consecutive patients who underwent either 1-level (32 patients) or 2-level (6 patients) AxiaLIF procedures at the authors' institution. The Oswestry Disability Index (minimum clinically important difference [MCID] ≥ 12) and visual analog scale ([VAS]; MCID ≥ 3) scores were collected. Disc height and Cobb angles were measured on pre- and postoperative radiographs. Bony fusion was determined on CT scans or flexion/extension radiographs.

Results

Implantation of a transsacral rod allowed for intraoperative distraction of the L5/S1 intervertebral space and resulted in increased segmental lordosis postoperatively. At a mean follow-up time of 26.2 ± 2.4 months, however, graft subsidence (1.9 mm) abolished partial correction of segmental lordosis. Moreover, subsidence of the construct reduced L5/S1 lordosis in patients with 1-level AxiaLIF by 3.2° and L4–S1 lordosis in patients with 2-level procedures by 10.1° compared with preoperative values (p < 0.01). Loss of segmental lordosis predicted failure to improve VAS scores for back pain in the patient cohort (p < 0.05). Overall, surgical intervention led to modest symptomatic improvement; only 26.3% of patients achieved an MCID of the Oswestry Disability Index and 50% of patients an MCID of the VAS score for back pain. At last follow-up, 71.9% of L5/S1 levels demonstrated bony fusion (1-level AxiaLIF 80.8%, 2-level AxiaLIF 33.3%; p < 0.05), whereas none of the L4/5 levels in 2-level AxiaLIF fused. Five constructs developed pseudarthrosis and required surgical revision.

Conclusions

The AxiaLIF procedure constitutes a minimally invasive technique for L5/S1 instrumentation, with low perioperative morbidity. However, the axial rod provides inadequate long-term anterior column support, which leads to subsidence and loss of segmental lordosis. Modification of the transsacral technique to allow for placement of a solid interposition graft may counteract subsidence of the construct.

Rectocutaneous fistula and nonunion after TranS1 axial lumbar interbody fusion L5–S1 fixation

The authors report a case of rectal injury, rectocutaneous fistula, and pseudarthrosis after a TranS1 axial lumbar interbody fusion (AxiaLIF) L5–S1 fixation. The TranS1 AxiaLIF procedure is a percutaneous minimally invasive approach to transsacral fusion of the L4–S1 vertebral levels. It is gaining popularity due to the ease of access to the sacrum through the presacral space, which is relatively free from intraabdominal and neurovascular structures.

This 35-year-old man had undergone the procedure for the treatment of degenerative disc disease. The patient subsequently presented with fever, syncope, and foul-smelling gas and bloody drainage from the surgical site. A CT fistulagram and flexible sigmoidoscopy showed evidence of rectocutaneous fistula, which was managed with intravenous antibiotic therapy and bowel rest with total parenteral nutrition. Subsequent studies performed 6 months postoperatively revealed evidence of pseudarthrosis. The patient's rectocutaneous fistula symptoms gradually subsided, but his preoperative back pain recurred prompting a revision of his L5–S1 spinal fusion.

Minimally invasive presacral retrieval of a failed AxiaLIF rod implant: technical note and illustrative cases

BACKGROUND CONTEXT

There are few reported cases of failed axial lumbar interbody fusion (AxiaLIF) in the existing neurosurgical literature, and an anecdotal case of open paramedian retroperitoneal approach to L5-S1 level for retrieval of AxiaLIF rod has been published.

PURPOSE

The object of this study is to illustrate a minimally invasive presacral rod retrieval technique in cases with failed AxiaLIF causing lumbosacral instability.

STUDY DESIGN/SETTING

Retrospective case series.

METHODS

A retrospective analysis of the initial 26 cases of AxiaLIF done at our institution was performed; two cases of failed AxiaLIF that required rod removal were identified for detailed study. Available literature on the minimally invasive presacral techniques for rod retrieval was researched, and the use of a novel rod retrieval device with an expanding hex tip is discussed.

RESULTS

Using a minimally invasive presacral approach through the previous surgical corridor, the authors were able to retrieve the AxiaLIF rod implant and then proceed with an alternative fusion technique. Both patients improved clinically and radiographically after revision. Removal of the presacral rod was not associated with vascular or bowel complications and required minimal operating room time with minimal blood loss.

CONCLUSIONS

To the authors' knowledge, this is the first report demonstrating the safety and efficacy of minimally invasive presacral approach for removal of AxiaLIF rods in patients with failed AxiaLIF. As the AxiaLIF procedure is rapidly gaining acceptance among spine surgeons, we can expect to see increasing numbers of failed procedures as well. Understanding options for revision strategies is important for surgeons considering the use of this technique.

The projection of nerve roots on the posterior aspect of spine from T11 to L5: a cadaver and radiological study

STUDY DESIGN

A cadaver and radiological study.

OBJECTIVE

To investigate the projection of nerve roots on the posterior aspect of the spine from T11 to L5.

SUMMARY OF BACKGROUND DATA

Understanding the projection of nerve roots on the posterior lamina will help to determine the decompressing areas of lamina and avoiding unnecessary bony resection. It can prevent segmental instability and postoperative scar formation. No studies regarding this subject are available.

METHODS

Fifteen formalin-preserved spine specimens were used for this study. After exposing the dural sac and bilateral nerve roots, small pieces of stainless steel wires were placed along the root sleeves from their points of origin, and then standard anteroposterior and lateral radiographs were taken. Parameters were measured directly on radiographs using the picture archiving communication system. Measurements included: (1) take-off angles of the nerve roots at the coronal (CA) and sagittal planes (SA); (2) distance from the origin of the root sleeve to the posterior midline (DM); (3) distance from the origin of the root sleeve to the superior (DS) and inferior margin (DI) of its corresponding lamina; and (4) distance between the origins of neighboring nerve roots (DR).

RESULTS

The CA statistically decreased from T11 (52.4° ± 3.13°) to L5 (25.8° ± 3.10°). An opposite variation tendency was observed in SA. The DS increased from 1.8 ± 0.32 mm for T11 to 5.84 ± 1.05 mm for L5. No consistent change was found at DI. The DR was largest at the L1-L2 interval (33.9 ± 1.40 mm) and it decreased progressively to L4-L5 (25.5 ± 2.40 mm). DM statistically increased from T11 (8.9 ± 1.51 mm) to L1 (10.9 ± 1.11 mm) and then progressively decreased until it reached a minimum at L5 (8.1 ± 0.83 mm).

CONCLUSION

The precise projection of nerve roots to the posterior aspect of spine and intraspinal take-off angles at the sagittal plane have been presented. Surgical interventions of the lumbar disc and nerve root may benefit from this quantitative anatomical study.

Results and complications after 2-level axial lumbar interbody fusion with a minimum 2-year follow-up

Object

Axial lumbar interbody fusion (AxiaLIF) is a minimally invasive presacral surgical technique that damages neither the anulus fibrosus nor the anterior or posterior longitudinal ligaments. The technique was initially designed and used for L5–S1 interbody fusions and recently was extended to 2-level fusions (L4–5 and L5–S1). Until now, only biomechanical and radiological studies have discussed the feasibility of this new indication, and no clinical study has been published. The purpose of this article is to report results and complications associated with 2-level presacral AxiaLIF with a minimum of 24 months of follow-up.

Methods

In this prospective, nonrandomized, single-center study, 27 patients underwent presacral AxiaLIF surgery at the L4–5 and L5–S1 levels. Clinical outcomes were assessed using the visual analog scale for back and leg symptoms and the Oswestry Disability Index. Radiographic parameters, such as disc height, segmental lordosis, and bone fusion, were analyzed using radiographs and CT scans. Complications and revision surgeries were recorded as needed. The minimum follow-up was 24 months (up to 72 months).

Results

There were no intraoperative complications. One major complication was observed: a patient developed septicemia that resolved after proper care. Clinical outcomes scores showed overall improvement in pain and physical function. During follow-up, the following complications were observed in the construct: screw breakage (14.8%), proximal/distal transsacral rod detachment (11.1%), radiolucency around the transsacral rod (52%), and cephalic rod migration (24%). Disc height gain was reported early after surgery, but at the 24-month follow-up the disc space was diminished in comparison with the preoperative status. Compared with preoperative values, the 24-month results showed loss of segmental lordosis. Only 22% of all treated levels were considered to have solid fusion at the 24-month radiological evaluation.

Conclusions

Patients undergoing presacral 2-level AxiaLIF experienced satisfactory short-term clinical outcomes; however, complications were commonly seen on imaging studies obtained 24 months postoperatively. Additional studies are required to better understand the 2-level indications for this technique.

Axial lumbosacral interbody fusion appears safe as a method to obtain lumbosacral arthrodesis distal to long fusion constructs

BACKGROUND

Current methods to achieve lumbosacral interbody fusion have been complicated by approach-related morbidity, nerve root or cauda equina injury, or difficulty in implanting a large lordotic graft posteriorly. There is little information in the literature evaluating the presacral axial approach to the lumbosacral disc space.

QUESTIONS/PURPOSES

What are the short-term clinical and radiographic outcomes in patients undergoing axial lumbosacral interbody fixation and fusion at the end of long fusion constructs using the AxiaLIF implant (Trans1 Inc., Wilmington, NC, USA)? Furthermore, what complications are associated with this procedure?

PATIENTS AND METHODS

We performed a retrospective evaluation of nine patients who underwent presacral axial lumbosacral interbody fixation and fusion at the end of long fusion constructs using the AxiaLIF implant. Preoperative diagnoses included adjacent segment degeneration below a long fusion construct for adult scoliosis and progressive sagittal plane deformity.

RESULTS

There were two pseudoarthroses, one at L4-5 and one at L5-S1. No major complications occurred. There were no significant differences in coronal or sagittal plane alignment at the time periods measured. There was no significant difference in implant position between immediate postoperative and final follow-up periods. There were significant postoperative improvements in Scoliosis Research Society-22 scores, specifically in the pain, self-image, and satisfaction with management domains.

CONCLUSIONS

The axial lumbosacral interbody fusion is a minimally invasive and safe method to obtain lumbosacral fixation and arthrodesis distal to a long fusion construct. Longer follow-up of larger numbers of patients are needed prior to recommending this procedure as a routine method to fuse L4-5 or L5-S1.

Axial lumbar interbody fusion (AxiaLIF) approach for adult scoliosis

BACKGROUND

AxiaLIF was initially advocated as a minimally invasive, presacral lumbar fusion approach. Its use has expanded in to adult scoliosis surgeries.

METHODS

Current literature about AxiaLIF for degenerative lumbar surgery and adult scoliosis surgery were reviewed. Anatomy, biomechanical properties, clinical results, and complications were summarized.

RESULTS

Anatomically, AxiaLIF is relatively safe even though traversing blood vessels, and the pelvic splanchnic nerve can be at risk. AxiaLIF can provide significant stiffness compared to the intact spine, but posterior supplementation is recommended. AxiaLIF in the long construct for adult scoliosis surgeries can protect the S1 screw as effectively as pelvic fixation. Successful clinical outcomes after AxiaLIF were reported in the degenerative lumbar spine, adult scoliosis, and spondylolisthesis. It can facilitate a high fusion rate up to 96 % without BMP. Complications include pseudarthrosis, rectal injury, transient nerve irritation, and intrapelvic hematoma.

CONCLUSION

AxiaLIF is a relatively safe procedure, and it provides good clinical results in both short constructs and long constructs for adult scoliosis surgery. For a safer procedure, surgeons should seek out prior colorectal surgical history and review preoperative imaging studies carefully.

The relevant anatomy of the approach for axial lumbar interbody fusion

STUDY DESIGN

Prospective trial.

OBJECTIVE

To perform a precise anatomical study of the presacral space and to examine the approach safety of AxiaLIF (axial lumbar interbody fusion) in an anatomical aspect.

SUMMARY OF BACKGROUND DATA

AxiaLIF is a novel, minimally invasive surgery. Though there were a few clinical reports on its safety, AxiaLIF is less used in current practice because of the unfamiliarity of surgeons with the regional anatomy of presacral space. METHODS.: Sixteen adult cadaveric pelvic specimens were divided along the median sagittal plane. The presacral fascial structures, the rectosacral fascia, and the pelvic splanchnic nerves were dissected and measured. In the simulated operation, a blunt guide pin was inserted bilaterally to determine the relation of the guide pin's path with important anatomic structures. Mean distances with 95% confidence intervals (CIs) were calculated.

RESULTS

The results showed that the fascial structures of the presacral space were divided into 5 layers, and the pelvic splanchnic nerves limited the dissection of the lower rectum, the mean length of which was 2.2 cm (1.9-2.5 cm). In the simulated operation, the mean minimum distance from the guide pin to the pelvic splanchnic nerves was 0.8 cm (0.4-1.2 cm), and the mean vertical distance to the S3-S4 junction was 1.5 cm (1.2-1.7 cm).

CONCLUSION

Our study suggests that the approach for AxiaLIF is risky and requires further modification. We should choose the accurate surgical plane when performing the presacral approach.

Description of a transosseous approach to the L5-S1 disc and 2 clinical case reports

BACKGROUND

The lumbosacral disc with the adjacent iliac crest and its relationships to neurologic, visceral, and vascular structures is difficult to approach with cannula-based retractor systems. Previous, less invasive approaches have been described to access this space. Anterior, presacral, and transforaminal approaches each have approach-related complications that have prevented their widespread adoption. A laterally based approach to this disc between the exiting L5 nerve root and traversing S1 nerve root would theoretically eliminate visceral and vascular complications but would necessarily course through the adjacent iliac crest. Our objective was to determine the feasibility of placing an interbody device into the L5-S1 disc space through a lateral transosseous approach.

METHODS

Six transosseous pathways were created from the iliac crest, laterally through the sacral ala, and entering the L5-S1 intervertebral disc space (3 cadavers). The positions of the portals in relation to the local anatomy were evaluated anatomically and with computed tomographic sagittal, coronal, and axial planes. We measured the lengths, heights, and widths of the pathways; distance between the L5 and S1 nerve roots; endplate diameters; and angles necessary to access the space. In addition, 2 clinical cases using the transosseous pathway are presented.

RESULTS

Computed tomographic scans and anatomic evaluations showed that there was an average 22-mm distance between the L5 and S1 nerve roots available to enter the L5-S1 disc space. The mean length of the pathway was 69 mm, and the mean height was 27 mm. The mean angle of the approach was 45° off the posterior-anterior axis, and there was a 25° upward angle from true lateral in the frontal plane.

CONCLUSIONS

A lateral, transosseous approach to the L5-S1 disc space for placing an interbody device is feasible. A closed cannula-based technique may offer reduced approach-related complications. Further studies will be required to determine the reproducibility and utility of this pathway.

Minimally invasive trans-sacral approach to L5-S1 interbody fusion: Preliminary results from 1 center and review of the literature

BACKGROUND

Lumbar interbody fusion has long been used for the treatment of painful degenerative spinal conditions. The anterior approach is not feasible in some patients, and the posterior approach is associated with a risk of neural complications and possibly muscle injury. A trans-sacral technique was developed that allows access to the L5-S1 disc space. The purposes of this study were to investigate the clinical outcome of trans-sacral interbody fusion in a consecutive series of patients from 1 center and to perform a comprehensive review of the literature on this procedure.

METHODS

A literature search using PubMed was performed to identify articles published on trans-sacral axial lumbar interbody fusion (AxiaLIF). Articles reviewed included biomechanical testing, feasibility of the technique, and clinical results. The data from our center were collected retrospectively from charts for the consecutive series, beginning with the first case, of all patients undergoing fusion using the AxiaLIF technique. In most cases, posterior instrumentation was also used. A total of 41 patients with at least 6 months' follow-up were included (mean follow-up, 22.2 months). The primary clinical outcome measures were visual analog scales separately assessing back and leg pain and the Oswestry Disability Index. Radiographic assessment of fusion was also performed.

RESULTS

In the group of 28 patients undergoing single-level AxiaLIF combined with posterior fusion, the visual analog scale scores assessing back and leg pain and mean Oswestry Disability Index scores improved significantly (P < .01). In the remaining 13 patients, back pain improved significantly with a trend for improvement in leg pain. Reoperation occurred in 19.5% of patients; in half of these, reoperation was not related to the anterior procedure.

CONCLUSIONS

A review of the literature found that the AxiaLIF technique was similar to other fusion techniques with respect to biomechanical properties and produced acceptable clinical outcomes, although results varied among studies.

CLINICAL RELEVANCE

The AxiaLIF approach allows access to the L5-S1 interspace without violating the annulus or longitudinal ligaments and with minimal risk to dorsal neural elements. It may be a viable alternative to other approaches to interbody fusion at the L5-S1 level. It is important that the patients be selected carefully and surgeons are familiar with the presacral anatomy and the surgical approach.

Revision strategies for AxiaLIF

Object

Paracoccygeal transsacral fixation is a novel percutaneous technique for arthrodesis of L5–S1 and L4–5 (Axial Lumbar Interbody Fusion [AxiaLIF]). There are no reports on feasible revision strategies. The goal of this paper is to analyze the surgical details of failed AxiaLIF constructs and to describe revision strategies.

Methods

The medical charts, operative records, and imaging studies of 5 patients with failed multisegment instrumentation using the AxiaLIF device were reviewed.

Results

AxiaLIF constructs were revised in 5 patients with a mean age of 58.4 years. All AxiaLIF devices were part of multisegment fusion constructs for revision surgery and were revised an average of 15 months after implantation. Two AxiaLIF devices were percutaneously retrieved; one because of excessive bone resorption around the AxiaLIF screw, and the other because of chronic hardware infection. In these 2 patients, the anterior column was subsequently stabilized via anterior lumbar interbody fusion. In the other 3 patients, the AxiaLIF device was left in situ. In 2 of these patients the anterior column was stabilized with bilateral L5–S1 posterior lumbar interbody fusion, and in the remaining patient with L4–5 instability the posterior instrumentation only was revised. Revision surgeries were well tolerated. One patient suffered from a wound dehiscence of the back wound.

Conclusions

AxiaLIF devices are safely retrieved using percutaneous technique. Both anterior and posterior revision strategies may be used to achieve anterior column fixation.

Complication management with minimally invasive spine procedures

Spine surgery as we know it has changed dramatically over the past 2 decades. More patients are undergoing minimally invasive procedures. Surgeons are becoming more comfortable with these procedures, and changes in technology have led to several new approaches and products to make surgery safer for patients and improve patient outcomes. As more patients undergo minimally invasive spine surgery, more long-term outcome and complications data have been collected. The authors describe the common complications associated with these minimally invasive surgical procedures and delineate management options for the spine surgeon.

Minimally invasive presacral approach for revision of an Axial Lumbar Interbody Fusion rod due to fall-related lumbosacral instability: a case report

INTRODUCTION

The purpose of this study was to describe procedural details of a minimally invasive presacral approach for revision of an L5-S1 Axial Lumbar Interbody Fusion rod.

CASE PRESENTATION

A 70-year-old Caucasian man presented to our facility with marked thoracolumbar scoliosis, osteoarthritic changes characterized by high-grade osteophytes, and significant intervertebral disc collapse and calcification. Our patient required crutches during ambulation and reported intractable axial and radicular pain. Multi-level reconstruction of L1-4 was accomplished with extreme lateral interbody fusion, although focal lumbosacral symptoms persisted due to disc space collapse at L5-S1.Lumbosacral interbody distraction and stabilization was achieved four weeks later with the Axial Lumbar Interbody Fusion System (TranS1 Inc., Wilmington, NC, USA) and rod implantation via an axial presacral approach.Despite symptom resolution following this procedure, our patient suffered a fall six weeks postoperatively with direct sacral impaction resulting in symptom recurrence and loss of L5-S1 distraction. Following seven months of unsuccessful conservative care, a revision of the Axial Lumbar Interbody Fusion rod was performed that utilized the same presacral approach and used a larger diameter implant. Minimal adhesions were encountered upon presacral re-entry. A precise operative trajectory to the base of the previously implanted rod was achieved using fluoroscopic guidance. Surgical removal of the implant was successful with minimal bone resection required. A larger diameter Axial Lumbar Interbody Fusion rod was then implanted and joint distraction was re-established. The radicular symptoms resolved following revision surgery and our patient was ambulating without assistance on post-operative day one. No adverse events were reported.

CONCLUSIONS

The Axial Lumbar Interbody Fusion distraction rod may be revised and replaced with a larger diameter rod using the same presacral approach.

Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series

INTRODUCTION

Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbosacral spondylolisthesis.

CASE PRESENTATION

Three patients who had L5-S1 grade 2 spondylolisthesis and who presented with axial pain and lumbar radiculopathy were treated with a minimally invasive surgical technique. The patients-a 51-year-old woman and two men (ages 46 and 50)-were Caucasian. Under fluoroscopic guidance, spondylolisthesis was reduced with a percutaneous pedicle screw system, resulting in interspace distraction. Then, an axial presacral approach with the AxiaLIF System (TranS1, Inc., Wilmington, NC, USA) was used to perform the discectomy and anterior fixation. Once the axial rod was engaged in the L5 vertebral body, further distraction of the spinal interspace was made possible by partially loosening the pedicle screw caps, advancing the AxiaLIF rod to its final position in the vertebrae, and retightening the screw caps. The operative time ranged from 173 to 323 minutes, and blood loss was minimal (50 mL). Indirect foraminal decompression and adequate fixation were achieved in all cases. All patients were ambulatory after surgery and reported relief from pain and resolution of radicular symptoms. No perioperative complications were reported, and patients were discharged in two to three days. Fusion was demonstrated radiographically in all patients at one-year follow-up.

CONCLUSIONS

Percutaneous pedicle screw reduction combined with axial presacral lumbar interbody fusion offers a promising and minimally invasive alternative for the management of lumbosacral spondylolisthesis.

Complications with axial presacral lumbar interbody fusion: A 5-year postmarketing surveillance experience

Background

Open and minimally invasive lumbar fusion procedures have inherent procedural risks, with posterior and transforaminal approaches resulting in significant soft-tissue injury and the anterior approach endangering organs and major blood vessels. An alternative lumbar fusion technique uses a small paracoccygeal incision and a presacral approach to the L5-S1 intervertebral space, which avoids critical structures and may result in a favorable safety profile versus open and other minimally invasive fusion techniques. The purpose of this study was to evaluate complications associated with axial interbody lumbar fusion procedures using the Axial Lumbar Interbody Fusion (AxiaLIF) System (TranS1, Wilmington, North Carolina) in the postmarketing period.

Methods

Between March 2005 and March 2010, 9,152 patients underwent interbody fusion with the AxiaLIF System through an axial presacral approach. A single-level L5-S1 fusion was performed in 8,034 patients (88%), and a 2-level (L4-S1) fusion was used in 1,118 (12%). A predefined database was designed to record device- or procedure-related complaints via spontaneous reporting. The complications that were 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.

Results

Complications were reported in 120 of 9,152 patients (1.3%). The most commonly reported complications were bowel injury (n = 59, 0.6%) and transient intraoperative hypotension (n = 20, 0.2%). The overall complication rate was similar between single-level (n = 102, 1.3%) and 2-level (n = 18, 1.6%) fusion procedures, with no significant differences noted for any single complication.

Conclusions

The 5-year postmarketing surveillance experience with the AxiaLIF System suggests that axial interbody lumbar fusion through the presacral approach is associated with a low incidence of complications. The overall complication rates observed in our evaluation compare favorably with those reported in trials of open and minimally invasive lumbar fusion surgery.

Complications of axial lumbar interbody fusion

OBJECT

Axial lumbar interbody fusion (AxiaLIF) is a novel minimally invasive approach for fusion of L4-5 and L5-S1. This technique uses the presacral space for percutaneous access to the anterior sacrum. The AxiaLIF procedure has the potential to decrease patient recovery time, length of hospital stay, and overall occurrence of surgical complications. It can be used alone or in combination with minimally invasive or traditional open fusion procedures. The purpose of this study was to evaluate complications of the AxiaLIF procedure at the authors' institutions.

METHODS

Patients who underwent AxiaLIF surgery between October 2005 and June 2009 at the authors' institutions were identified. The authors retrospectively reviewed these patients' charts, including operative reports and postoperative medical records, to determine what complications were encountered.

RESULTS

A total of 68 patients underwent AxiaLIF surgery, with an average follow-up time of 34 months. Sixteen patients (23.5%) experienced a total of 18 complications (26.5%); this group included 8 men and 8 women (mean age 52.1 years). These complications included pseudarthrosis (8.8%), superficial infection (5.9%), sacral fracture (2.9%), pelvic hematoma (2.9%), failure of wound closure (1.5%), transient nerve root irritation (1.5%), and rectal perforation (2.9%).

CONCLUSIONS

The complication rate associated with AxiaLIF in the present study was relatively low (26.5%). The most common complications were superficial infection and pseudarthrosis. There were 2 cases of rectal perforation associated with AxiaLIF; one case was found intraoperatively and the other presented 4 days postoperatively. Both patients underwent emergency repair by a general surgeon and had no long-term sequelae as a result of the rectal injuries. It is important for surgeons to be aware of the potential for these complications. Many of these complications can probably be avoided with proper patient selection and operative planning. Preoperative MR imaging, a detailed patient physical examination and history, full bowel preparation, and the use of live fluoroscopy can all help to prevent complications with AxiaLIF surgery.