MIS lateral spine surgery: a systematic literature review of complications, outcomes, and economics

Sequential Depth Stimulation Within the Psoas Offers No Benefit for Localization of the Lumbar Plexus During Lateral Lumbar Fusion Surgery

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

In this study we aim to assess the difference in triggered EMG readings throughout different depths in the psoas muscle during the lateral approach to the lumbar spine and their effect on surgeon decision making.

METHODS

Three surgeons, practicing at different institutions, assessed triggered EMG readings during the trans psoas approach at the level of the disc and 5,10 and 15 millimeters into the psoas muscle with sequential dilators. Measurement of distance into the psoas muscle was done with a specially designed instrument. Results of anterior and posterior directed stimulation as well as the delta value between these were recorded and underwent statistical analysis. Patients who had partial readings were excluded from the study.

RESULTS

A total of 40 levels in 35 patients were included in the study. There was no significant difference found between means of anterior or posterior threshold readings along the different distance groups. A significant difference was found (P = .024) in the mean difference between the distance groups with a decrease in the difference between anterior and posterior threshold values found as the distance from the disc space increased. None of the surgeons reported a decision to abort the fusion of a spinal level.

CONCLUSIONS

In the trans-psoas approach to the lumbar spine, the assessment of the location of the femoral nerve using directional neuromonitoring when advancing in the psoas muscle shows no clear benefit as opposed to stimulating solely when adjacent to the disc space.

Transpsoas Approaches to the Lumbar Spine: Lateral and Prone

The lateral transpsoas approach has become fundamental to minimally invasive spine surgery. The large interbody grafts that can be placed through this approach allow for robust arthrodesis of the anterior column, indirect decompression, and restoration of lordosis without disrupting the posterior musculature or ligamentous structures. The lateral decubitus position has traditionally been used for this approach but the prone position has gained popularity because it can reduce operating times for patients who also require posterior pedicle screw fixation. The transpsoas approach can be effectively performed in either position but surgeons should know the nuances that distinguish them.

Simultaneous Single-Position Lateral Lumbar Interbody Fusion Surgery and Unilateral Percutaneous Pedicle Screw Fixation for Spondylolisthesis

OBJECTIVE

To evaluate the clinical and radiological efficacy of a combine of lateral single screw-rod and unilateral percutaneous pedicle screw fixation (LSUP) for lateral lumbar interbody fusion (LLIF) in the treatment of spondylolisthesis.

METHODS

Sixty-two consecutive patients with lumbar spondylolisthesis who underwent minimally invasive (MIS)-TLIF with bilateral pedicle screw (BPS) or LLIF-LSUP were retrospectively studied. Segmental lordosis angle (SLA), lumbar lordosis angle (LLA), disc height (DH), slipping percentage, the cross-sectional areas (CSA) of the thecal sac, screw placement accuracy, fusion rate and foraminal height (FH) were used to evaluate radiographic changes postoperatively. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy.

RESULTS

Patients who underwent LLIF-LSUP showed shorter operating time, less length of hospital stay and lower blood loss than MIS-TLIF. No statistical difference was found between the 2 groups in screw placement accuracy, overall complications, VAS, and ODI. Compared with MIS-TLIF-BPS, LLIF-LSUP had a significant improvement in sagittal parameters including DH, FH, LLA, and SLA. The CSA of MIS-TLIF-BPS was significantly increased than that of LLIF-LSUP. The fusion rate of LLIF-LSUP was significantly higher than that of MIS-TLIF-BPS at the follow-up of 3 months postoperatively, but there was no statistical difference between the 2 groups at the follow-up of 6 months, 9 months, and 12 months.

CONCLUSION

The overall clinical outcomes and complications of LLIF-LSUP were comparable to that of MIS-TLIF-BPS in this series. Compared with MIS-TLIF-BPS, LLIF-LSUP for lumbar spondylolisthesis represents a significantly shorter operating time, hospital stay and lower blood loss, and demonstrates better radiological outcomes to maintain lumbar lordosis, and reveal an overwhelming superiority in the early fusion rate.

Long-Term Durability of Stand-Alone Lateral Lumbar Interbody Fusion

BACKGROUND

The long-term durability of stand-alone lateral lumbar interbody fusion (LLIF) remains unknown.

OBJECTIVE

To evaluate whether early patient-reported outcome measures after stand-alone LLIF are sustained on long-term follow-up.

METHODS

One hundred and twenty-six patients who underwent stand-alone LLIF between 2009 and 2017 were included in this study. Patient-reported outcome measures included the Oswestry Disability Index (ODI), EuroQOL-5D (EQ-5D), and visual analog score (VAS) scores. Durable outcomes were defined as scores showing a significant improvement between preoperative and 6-week scores without demonstrating any significant decline at future time points. A repeated measures analysis was conducted using generalized estimating equations (model) to assess the outcome across different postoperative time points, including 6 weeks, 1 year, 2 years, and 5 years.

RESULTS

ODI scores showed durable improvement at 5-year follow-up, with scores improving from 46.9 to 38.5 ( P = .001). Improvements in EQ-5D showed similar durability up to 5 years, improving from 0.48 to 0.65 ( P = .03). VAS scores also demonstrated significant improvements postoperatively that were durable at 2-year follow-up, improving from 7.0 to 4.6 ( P < .0001).

CONCLUSION

Patients undergoing stand-alone LLIF were found to have significant improvements in ODI and EQ-5D at 6-week follow-up that remained durable up to 5 years postoperatively. VAS scores were found to be significantly improved at 6 weeks and up to 2 years postoperatively but failed to reach significance at 5 years. These findings demonstrate that patients undergoing stand-alone LLIF show significant improvement in overall disability after surgery that remains durable at long-term follow-up.

Lateral approach to the lumbar spine: The utility of an access surgeon

Background

Lateral lumbar interbody fusions (LLIFs) utilize a retroperitoneal approach that avoids the intraperitoneal organs and manipulation of the anterior vasculature encountered in anterior approaches to the lumbar spine. The approach was championed by spinal surgeons; however, general/vasculature surgeons may be more comfortable with the approach.

Objective

The objective of this study was to compare short-term outcomes following LLIF procedures based on whether a spine surgeon or access surgeon performed the approach.

Materials and Methods

We retrospectively identified all one- to two-level LLIFs at a tertiary care center from 2011 to 2021 for degenerative spine disease. Patients were divided into groups based on whether a spine surgeon or general surgeon performed the surgical approach. The electronic medical record was reviewed for hospital readmissions and complication rates.

Results

We identified 239 patients; of which 177 had approaches performed by spine surgeons and 62 by general surgeons. The spine surgeon group had fewer levels with posterior instrumentation (1.40 vs. 2.00; P < 0.001) and decompressed (0.94 vs. 1.25, P = 0.046); however, the two groups had a similar amount of two-level LLIFs (29.9% vs. 27.4%, P = 0.831). This spine surgeon approach group was found to have shorter surgeries (281 vs. 328 min, P = 0.002) and shorter hospital stays Length of Stay (LOS) (3.1 vs. 3.6 days, P = 0.019); however, these differences were largely attributed to the shorter posterior fusion construct. On regression analysis, there was no statistical difference in postoperative complication rates whether or not an access surgeon was utilized (P = 0.226).

Conclusion

Similar outcomes may be seen regardless of whether a spine or access surgeon performs the approach for an LLIF.

Lateral versus posterior approaches to treat degenerative lumbar pathologies-systematic review and meta-analysis of recent literature

INTRODUCTION

The lateral lumbar interbody fusion arose as a revolutionary approach to treating several spinal pathologies because the techniques were able to promote indirect decompression and lordosis restoration through a minimally invasive approach allowing for reduced blood loss and early recovery for patients. However, it is still not clear how the technique compares to other established approaches for treating spinal degenerative diseases, such as TLIF, PLIF, and PLF.

MATERIAL AND METHODS

This is a systematic review and meta-analysis of articles published in the last 10 years comparing lateral approaches to posterior techniques. The authors included articles that compared the LLIF technique to one or more posterior approaches, treating only degenerative pathologies, and containing at least one of the key outcomes of the study. Exclusion articles that were not original and the ones that the authors could not obtain the full text; also articles without the possibility to calculate the standard deviation or mean were excluded. For count variables, the odds ratio was used, and for continuous variables, the standard means difference (SMD) was used, and the choice between random or fixed-effects model was made depending on the presence or not of significant (p < 0.05) heterogeneity in the sample.

RESULTS

Twenty-four articles were included in the quantitative review. As for the intra-/perioperative variables, the lateral approaches showed a significant reduction in blood loss (SMD-1.56, p < 0.001) and similar operative time (SMD =  - 0.33, p = 0.24). Moreover, the use of the lateral approaches showed a tendency to lead to reduced hospitalization days (SMD =  - 0.15, p = 0.09), with significantly reduced odds ratios of complications (0.53, p = 0.01). As for the clinical outcomes, both approaches showed similar improvement both at improvement as for the last follow-up value, either in ODI or in VAS-BP. Finally, when analyzing the changes in segmental lordosis and lumbar lordosis, the lateral technique promoted significantly higher correction in both outcomes (p < 0.05).

CONCLUSION

Lateral approaches can promote significant radiological correction and similar clinical improvement while reducing surgical blood loss and postoperative complications.

Single-Position Transpsoas Corpectomy and Posterior Instrumentation in the Thoracolumbar Spine for Different Clinical Scenarios

BACKGROUND

The concept of single-position spine surgery has been gaining momentum because it has proven to reduce operative time, blood loss, and hospital length of stay with similar or better outcomes than traditional dual-position surgery. The latest development in single-position spine surgery techniques combines either open or posterior pedicle screw fixation with transpsoas corpectomy while in the lateral or prone positioning.

OBJECTIVE

To provide, through a multicenter study, the results of our first patients treated by single-position corpectomy.

METHODS

This is a multicenter retrospective study of patients who underwent corpectomy and instrumentation in the lateral or prone position without repositioning between the anterior and posterior techniques. Data regarding demographics, diagnosis, neurological status, surgical details, complications, and radiographic parameters were collected. The minimum follow-up for inclusion was 6 months.

RESULTS

Thirty-four patients were finally included in our study (24 male patients and 10 female patients), with a mean age of 51.2 (SD ± 17.5) years. Three-quarter of cases (n = 27) presented with thoracolumbar fracture as main diagnosis, followed by spinal metastases and primary spinal infection. Lateral positioning was used in 27 cases, and prone positioning was used in 7 cases. The overall rate of complications was 14.7%.

CONCLUSION

This is the first multicenter series of patients who underwent single-position corpectomy and fusion. This technique has shown to be safe and effective to treat a variety of spinal conditions with a relatively low rate of complications. More series are required to validate this technique as a possible standard approach when thoracolumbar corpectomies are indicated.

Long-Term Motor versus Sensory Lumbar Plexopathy After Lateral Lumbar Interbody Fusion: Single-Center Experience, Intraoperative Neuromonitoring Results, and Multivariate Analysis of Patient-Level Predictors

BACKGROUND

Although lateral lumbar interbody fusion (LLIF) is an effective surgical option for lumbar arthrodesis, postoperative plexopathies are a common complication. We characterized post-LLIF plexopathies in a large cohort and analyzed potential risk factors for each.

METHODS

A single-institutional cohort who underwent LLIF between May 2015 and December 2019 was retrospectively reviewed for postoperative lumbar plexopathies. Plexopathies were divided based on sensory and motor symptoms and duration, as well as by laterality relative to the surgical approach. We assessed these subgroups for associations with patient and surgical characteristics as well as psoas dimensions. We then evaluated risk of developing plexopathies after intraoperative neuromonitoring observations.

RESULTS

A total of 127 patients were included. The overall rate of LLIF-induced sensory or motor lumbar plexopathy was 37.8% (48/127). Of all cases, 42 were ipsilateral to the surgical approach (33.1%); conversely, 6 patients developed contralateral plexopathies (4.7%). Most (31/48; 64.6%) resolved with a follow-up interval of 402 days in the plexopathy group. Of ipsilateral cases, 24 patients experienced persistent (>90 days) postoperative sensory symptoms (18.9%), whereas 20 experienced persistent weakness (15.7%). More levels fused predicted persistent sensory symptoms (odds ratio, 1.714 [1.246-2.359]; P = 0.0085), whereas surgical duration predicted persistent weakness (odds ratio, 1.004 [1.002-1.006]; P = 0.0382). Psoas anatomic variables were not significantly associated with plexopathy. Nonresolution of intraoperative evoked motor potential alerts was a significant risk factor for developing plexopathies (relative risk, 2.29 [1.17-4.45]).

CONCLUSIONS

Post-LLIF plexopathies are common but usually resolve. Surgical complexity and unresolved neuromonitoring alerts are possible risk factors for persistent plexopathy.

Technical nuances and approach-related morbidity of anterolateral and posterolateral lumbar corpectomy approaches-a systematic review of the literature

Purpose

Approaches for lumbar corpectomies can be roughly categorized into anterolateral (AL) and posterolateral (PL) approaches. It remains controversial to date whether one approach is superior to the other, and no comparative studies exist for the two approaches for lumbar corpectomies.

Methods

A systematic review of the literature was performed through a MEDLINE/PubMed search. Studies and case reports describing technique plus outcomes and possible complications were included. Thereafter, estimated blood loss (EBL), length of operation (LOO), utilized implants, neurological outcomes, complication rates, and reoperation rates were analyzed.

Results

A total of 64 articles reporting on 702 patients including 513 AL and 189 PL corpectomies were included in this paper. All patients in the PL group were instrumented via the same approach used for corpectomy, while in the AL group the majority (68.3%) of authors described the use of an additional approach for instrumentation. The EBL was higher in the AL group (1393 ± 1341 ml vs. 982 ± 567 ml). The LOO also was higher in the AL group (317 ± 178 min vs. 258 ± 93 min). The complication rate (20.5% vs. 29.1%, p = 0.048) and the revision rate (3.1% vs. 9.5%, p = 0.004) were higher in the PL group. Neurological improvement rates were 43.8% (AL) vs. 39.2% (PL), and deterioration was only noted in the AL group (6.0%), while 50.2% (AL) and 60.8% (PL) showed no change from initial presentation to the last follow-up.

Conclusion

While neurological outcomes of both approaches are comparable, the results of the present review demonstrated lower complication and revision rates in anterolateral corpectomies. Nevertheless, individual patient characteristics must be considered in decision-making.

Predictors of subsidence after lateral lumbar interbody fusion

OBJECTIVE

Lateral lumbar interbody fusion (LLIF) facilitates the restoration of disc height and the indirect decompression of neural elements. However, these benefits are lost when the graft subsides into the adjacent endplates. The factors leading to subsidence after LLIF are poorly understood. This article presents a case series of patients who underwent LLIF and reports factors correlating with subsidence.

METHODS

A retrospective review of a consecutive, prospectively collected, single-institution database of patients who underwent LLIF over a 29-month period was performed. The degree of subsidence was measured on the basis of postoperative imaging. The timing of postoperative subsidence was determined, and intraoperative fluoroscopic images were reviewed to determine whether subsidence occurred as a result of endplate violation. The association of subsidence with age, sex, cage size and type, bone density, and posterior instrumentation was investigated.

RESULTS

One hundred thirty-one patients underwent LLIF at a total of 204 levels. Subsidence was observed at 23 (11.3%) operated levels. True subsidence, attributable to postoperative cage settling, occurred for 12 (5.9%) of the levels; for the remaining 11 (5.4%) levels, subsidence was associated with intraoperative endplate violation noted on fluoroscopy during cage placement. All subsidence occurred within 12 weeks of surgery. Univariate analysis showed that the prevalence of true subsidence was significantly lower among patients with titanium implants (0 of 55; 0%) than among patients with polyetheretherketone cages (12 of 149; 8.1%) (p = 0.04). In addition, the mean ratio of graft area to inferior endplate area was significantly lower among the subsidence levels (0.34) than among the nonsubsidence levels (0.42) (p < 0.01). Finally, subsidence among levels with posterior fixation (4.4% [6/135]) was not significantly different than among those without posterior fixation (8.7% [6/69]) (p = 0.23). Multivariate analysis results showed that the ratio of cage to inferior endplate area was the only significant predictor of subsidence in this study (p < 0.01); increasing ratios were associated with a decreased likelihood of subsidence.

CONCLUSIONS

Overall, the prevalence of subsidence after LLIF was low in this clinical series. Titanium cages were associated with a lower prevalence of observed subsidence on univariate analysis; however, multivariate analysis demonstrated that this effect may be attributable to the increased surface area of these cages relative to the inferior endplate area.

Prone-lateral access to the lumbar spine: single-level corpectomy with approach discussion

The lateral lumbar interbody fusion has evolved as newly envisioned access corridors become feasible with technological advances. Prone lateral access has evolved as a single-access approach to combine the benefits of minimally invasive surgery with direct and indirect decompression of the neural elements with synergistic anterior and posterior column correction. In this video, the authors discuss the pearls, pitfalls, and adjuvant technologies they use in a high-volume prone lateral center via case demonstration of a prone lateral corpectomy.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2216

Radiographic analysis of neuroforaminal and central canal decompression following lateral lumbar interbody fusion

Background

Lateral lumbar interbody fusion (LLIF) is a minimally invasive surgical option for treating symptomatic degenerative lumbar spinal stenosis (DLSS) in select patients. However, the efficacy of LLIF for indirectly decompressing the lumbar spine in DLSS, as well as the best radiographic metrics for evaluating such changes, are incompletely understood.

Methods

A single-institutional cohort of patients who underwent LLIF for DLSS between 5/2015 – 12/2019 was retrospectively reviewed. Diameter, area, and stenosis grades were measured for the central canal (CC) and neural foramina (NF) at each LLIF level based on preoperative and postoperative T2-weighted MRI. Baseline facet joint (FJ) space, degree of FJ osteoarthritis, presence of spondylolisthesis, interbody graft position, and posterior disc height were analyzed as potential predictors of radiographic outcomes. Changes to all metrics after LLIF were analyzed and compared across lumbar levels. Preoperative and intraoperative predictors of decompression were then assessed using multivariate linear regression.

Results

A total of 102 patients comprising 153 fused levels were analyzed. Pairwise linear regression of stenosis grade to diameter and area revealed significant correlations for both the CC and NF. All metrics except CC area were significantly improved after LLIF (p < 0.05, 2-tailed t-test). Worse FJ osteoarthritis ipsilateral to the surgical approach was predictive of greater post-operative CC and NF stenosis grade (p < 0.05, univariate and multivariate ordinary least squares linear regression). Lumbar levels L3-5 had significantly higher absolute postoperative CC stenosis grades while relative change in CC stenosis at the L2-3 was significantly greater than other lumbar levels (p < 0.05, one-way ANOVA). There were no baseline or postoperative differences in NF stenosis grade across lumbar levels.

Conclusions

Radiographically, LLIF is effective at indirect compression of the CC and NF at all lumbar levels, though worse FJ osteoarthritis predicted higher degrees of post-operative stenosis.

Saphenous somatosensory-evoked potentials monitoring of femoral nerve health during prone transpsoas lateral lumbar interbody fusion

PURPOSE

To assess whether saphenous somatosensory-evoked potentials (saphSSEP) monitoring may provide predictive information of femoral nerve health during prone lateral interbody fusion (LIF) procedures.

METHODS

Intraoperative details were captured prospectively in consecutive prone LIF surgeries at a single institution. Triggered electromyography was used during the approach; saphSSEP was monitored throughout using a novel system that enables acquisition of difficult signals and real-time actionable feedback facilitating intraoperative intervention. Postoperative neural function was correlated with intraoperative findings.

RESULTS

Fifty-nine patients (58% female, mean age 64, mean BMI 32) underwent LIF at 95 total levels, inclusive of L4-5 in 76%, fixated via percutaneous pedicle screws (81%) or lateral plate, with direct decompression in 39%. Total operative time averaged 149 min. Psoas retraction time averaged 16 min/level. Baseline SSEPs were unreliable in 3 due to comorbidities in 2 and anesthesia in 1; one of those resulted in transient quadriceps weakness, fully recovered at 6 weeks. In 25/56, no saphSSEP changes occurred, and none had postoperative femoral nerve deficits. In 24/31 with saphSSEP changes, responses recovered intraoperatively following intervention, with normal postoperative function in all but one with delayed quadriceps weakness, improved at 4 months and recovered at 9 months, and a second with transient isolated anterior thigh numbness. In the remaining 7/31, saphSSEP changes persisted to close, and resulted in 2 transient isolated anterior thigh numbness and 2 combined sensory and motor femoral nerve deficits, both resolved at between 4 and 8 months.

CONCLUSIONS

SaphSSEP was reliably monitored in most cases and provided actionable feedback that was highly predictive of neurological events during LIF.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Setting for single position surgery: survey from expert spinal surgeons

PURPOSE

To describe a comprehensive setting of the different alternatives for performing a single position fusion surgery based on the opinion of leading surgeons in the field.

METHODS

Between April and May of 2021, a specifically designed two round survey was distributed by mail to a group of leaders in the field of Single Position Surgery (SPS). The questionnaire included a variety of domains which were focused on highlighting tips and recommendations regarding improving the efficiency of the performance of SPS. This includes operation room setting, positioning, use of technology, approach, retractors specific details, intraoperative neuromonitoring and tips for inserting percutaneous pedicle screws in the lateral position. It asked questions focused on Lateral Single Position Surgery (LSPS), Lateral ALIF (LA) and Prone Lateral Surgery (PLS). Strong agreement was defined as an agreement of more than 80% of surgeons for each specific question. The number of surgeries performed in SPS by each surgeon was used as an indirect element to aid in exhibiting the expertise of the surgeons being surveyed.

RESULTS

Twenty-four surgeons completed both rounds of the questionnaire. Moderate or strong agreement was found for more than 50% of the items. A definition for Single Position Surgery and a step-by-step recommendation workflow was built to create a better understanding of surgeons who are starting the learning curve in this technique.

CONCLUSION

A recommendation of the setting for performing single position fusion surgery procedure (LSPS, LA and PLS) was developed based on a survey of leaders in the field.

Laterally Placed Expandable Interbody Spacers With and Without Adjustable Lordosis Improve Radiographic and Clinical Outcomes: A Two-Year Follow-Up Study

Introduction

Interbody spacers are necessary for achieving disc height restoration when surgical intervention is used for the treatment of severe degenerative disc disease. Minimally invasive lateral lumbar interbody fusion (MIS LLIF) is a popular surgical approach that historically uses large static interbody spacers through a lateral approach. However, static spacers have been associated with iatrogenic distraction and excessive impaction forces, which may increase the risk of subsidence and loss of lordosis, compromising stability. Expandable interbody spacers with or without adjustable lordosis may help address these concerns by maximizing segmental lordosis and aiding in sagittal balance correction. This study describes the clinical and radiographic outcomes of patients treated with expandable interbody spacers with or without adjustable lordosis, for MIS LLIF.

Materials and methods

This is retrospective, single-surgeon Institutional Review Board-exempt chart review was of 103 consecutive patients who had undergone MIS LLIF at one to two contiguous level(s) utilizing expandable interbody spacers with or without adjustable lordosis (66/103 patients had adjustable lordosis spacers). Collection of clinical and radiographic functional outcomes occurred at preoperative and postoperative time points through 24 months.

Results

One-hundred and three consecutive patients were evaluated-average age, 58.2 ± 12.1 years; 42.1% (45/107) were female. There were 78.6% (81/103) one-level cases and 21.4% (22/103) two-level cases for a total of 125 levels; 44.8% (56/125) were performed at L4-5 and 34.4% (43/125) at L3-4. The average estimated blood loss was 24.6 ± 12.3cc. Mean operative time was 61.0 ± 19.1 min, and mean fluoroscopic time was 28.2 ± 14.6 sec. Visual Analog Scale (VAS) back and leg pain scores decreased significantly by an average of 7.1 ± 1.0 points at 24 months (p<0.001). Oswestry Disability Index (ODI) scores significantly decreased by a mean of 67.4 ± 8.9 points at 24 months (p<0.001). Lumbar lordosis significantly improved by a mean of 3.1 ± 8.8° at 24 months (p=0.001). Anterior, middle, and posterior disc height significantly increased at 24 months by averages of 4.7 ± 3.1, 4.0 ± 3.0, and 2.1 ± 2.2mm, respectively (p<0.001). Neuroforaminal height had significantly increased at 24 months by a mean of 3.0 ± 3.6mm (p<0.001). Segmental lordosis significantly improved by 3.7 ± 2.9° at 24 months (p<0.001). There were 51 patients with abnormal preoperative Pelvic Incidence-Lumbar Lordosis (PI-LL) measurements that significantly improved by 9.1 ± 4.9° (p<0.001) and 52 patients with normal preoperative PI-LL measurements that improved by 0.2 ± 4.6° (p=0.748) at 24 months. One-hundred percent fusion occurred at all levels, and no findings of radiolucency were observed. One case of subsidence (1/125, 0.8%) was reported at 24 months. No implanted-related complications were reported, with 0% pseudoarthrosis and no secondary surgery required at the operative levels.

Conclusion

Indirect decompression and sagittal correction were achieved and maintained through a 24-month follow-up. Functional clinical outcomes significantly improved based on decreased VAS pain and ODI scores at 24 months. This study resulted in positive clinical and radiographic outcomes for patients who underwent MIS LLIF with expandable interbody spacers with or without adjustable lordosis.

Single-position prone lateral transpsoas approach: early experience and outcomes

OBJECTIVE

Lateral lumbar interbody fusion (LLIF) via a transpsoas approach is a workhorse minimally invasive approach for lumbar arthrodesis that is often combined with posterior pedicle screw fixation. There has been increasing interest in performing single-position surgery, allowing access to the anterolateral and posterior spine without requiring patient repositioning. The feasibility of the transpsoas approach in patients in the prone position has been reported. Herein, the authors present a consecutive case series of all patients who underwent single-position prone transpsoas LLIF performed by an individual surgeon since adopting this approach.

METHODS

A retrospective review was performed of a consecutive case series of adult patients (≥ 18 years old) who underwent single-position prone LLIF for any indication between October 2019 and November 2020. Pertinent operative details (levels, cage use, surgery duration, estimated blood loss, complications) and 3-month clinical outcomes were recorded. Intraoperative and 3-month postoperative radiographs were reviewed to assess for interbody subsidence.

RESULTS

Twenty-eight of 29 patients (97%) underwent successful treatment with the prone lateral approach over the study interval; the approach was aborted in 1 patient, whose data were excluded. The mean (SD) age of patients was 67.9 (9.3) years; 75% (21) were women. Thirty-nine levels were treated: 18 patients (64%) had single-level fusion, 9 (32%) had 2-level fusion, and 1 (4%) had 3-level fusion. The most commonly treated levels were L3-4 (n = 15), L2-3 (n = 12), and L4-5 (n = 11). L1-2 was fused in 1 patient. The mean operative time was 286.5 (100.6) minutes, and the mean retractor time was 29.2 (13.5) minutes per level. The mean fluoroscopy duration was 215.5 (99.6) seconds, and the mean intraoperative radiation dose was 170.1 (94.8) mGy. Intraoperative subsidence was noted in 1 patient (4% of patients, 3% of levels). Intraoperative lateral access complications occurred in 11% of patients (1 cage repositioning, 2 inadvertent ruptures of anterior longitudinal ligament). Subsidence occurred in 5 of 22 patients (23%) with radiographic follow-up, affecting 6 of 33 levels (18%). Postoperative functional testing (Oswestry Disability Index, SF-36, visual analog scale-back and leg pain) identified significant improvement.

CONCLUSIONS

This single-surgeon consecutive case series demonstrates that this novel technique is well tolerated and has acceptable clinical and radiographic outcomes. Larger patient series with longer follow-up are needed to further elucidate the safety profile and long-term outcomes of single-position prone LLIF.

Differences in surgical outcome after anterior corpectomy and reconstruction with an expandable cage with rectangular footplates between thoracolumbar and lumbar osteoporotic vertebral fracture

Background

Anterior and posterior spinal fixation (APSF) can provide rigid structural anterior column support in patients with osteoporotic vertebral fracture (OVF). A new rectangular footplate designed based on biomechanical studies of endplates provides better resistance to subsidence. However, differences in characteristics exist between the thoracolumbar and lower lumbar spine. The purpose of this study was to evaluate the surgical outcomes following APSF using an expandable cage with rectangular footplates in the thoracolumbar/lumbar region.

Methods

Consecutive patients who underwent APSF for OVF at multiple centers were retrospectively reviewed. Clinical and radiographic evaluations were performed by dividing the patients into thoracolumbar (TL, T10–L2) and lumbar (L, L3–L5) groups. Surgical indications were incomplete neurologic deficit or intractable back pain with segmental spinal instability. Surgical outcomes including the Japanese Orthopaedic Association (JOA) score and reoperation rate were compared between TL and L groups.

Results

Sixty-nine patients were followed-up for more than 12 months and analyzed. Operative intervention was required for 35 patients in the TL group and 34 patients in the L group. Mean ages in the TL and L groups were 76.5 years and 75.1 years, respectively. Intra-vertebral instability was more frequent in the TL group (p<0.001). Screw fixation range was significantly longer in the TL group (p=0.012). The rate of cage subsidence did not differ significantly between the TL group (46%) and L group (44%). Reoperation rate tended to be higher in the TL group (p=0.095). Improvement ratio of JOA score was significantly better in the L group (60%) than in the TL group (46.9%, p=0.029).

Conclusion

APSF using an expandable cage was effective to treat OVF at both lumbar and thoracolumbar levels. However, the improvement ratio of the JOA score was better in the L group than in the TL group.

Initial multi-centre clinical experience with prone transpsoas lateral interbody fusion: Feasibility, perioperative outcomes, and lessons learned

Background

Methods

Results

Conclusion

Single-Position Prone Lateral Interbody Fusion Improves Segmental Lordosis in Lumbar Spondylolisthesis

OBJECTIVE

Single-position surgery in prone position is a novel technique for lateral interbody fusion with pedicle screw fixation. We performed a radiographic comparison of patients treated for spondylolisthesis using the prone lateral (PL) transpsoas approach versus the traditional dual position (DP) approach (lateral decubitus then prone).

METHODS

Thirty consecutive patients with spondylolisthesis were treated using the PL approach (n = 15) versus the dual position approach (n = 15). Radiographic factors in the groups were retrospectively compared.

RESULTS

The groups were similar for age, sex, body mass index, and implant size, but there were more 15° (vs. 10°) cages inserted in the dual position group. Radiographically the groups had similar baseline spinopelvic parameters, lumbar lordosis (LL), segmental lordosis, anterolisthesis, and disc height (P > 0.05). Postoperatively the PL group demonstrated a larger improvement in segmental lordosis (5.1° vs. 2.5°, P = 0.02), but not overall LL (6.3° vs. 3.1°, P = 0.14). Both groups had similar improvements in pelvic tilt, disc height, and spondylolisthesis reduction (P > 0.05). The mean relative distance of the implant from the posterior edge of the vertebral body was greater in the PL group (26% vs. 17%, P < 0.001) indicating a tendency for more anterior cage placement. However, there was no significant correlation between the relative cage position and the increase in segmental lordosis (P = 0.35), so this result alone did not explain the relative increase in lordosis seen.

CONCLUSIONS

This is the first study to our knowledge to demonstrate an improvement in segmental lordosis for patients with single-level spondylolisthesis using the PL approach.

Single-Position Surgery versus Lateral-Then-Prone-Position Circumferential Lumbar Interbody Fusion: A Systematic Literature Review

OBJECTIVE

We sought to compare the outcomes of single-position (SP) circumferential lumbar interbody fusion in lateral decubitus versus dual-position (DP) fusion.

METHODS

A systematic literature review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in PubMed, Web of Science, and Scopus databases to identify comparative studies reporting the outcomes of SP lumbar interbody fusion versus DP. For risk of bias assessment, the ROBINS-I (risk of bias in nonrandomized studies of interventions) tool was used.

RESULTS

Four comparative studies were included from an initial search of 3780 papers. All 4 studies were retrospective cohort studies comparing outcomes of SP versus DP LLIF. A total of 349 patients were operated using SP versus 254 using DP. All studies involved reported operating time, estimated blood loss, length of stay, change in segmental lordosis, and complications. From a general perspective, baseline variables were similar in both groups in all the studies and all reported a significant decrease in operative time and length of stays with SP.

CONCLUSIONS

Literature comparing SP versus lateral-then-prone lumbar fusion shows a tendency toward shorter operating time and hospital stays in SP lumbar fusion while maintaining similar perioperative outcomes.

An In Vitro Biomechanical Evaluation of a Lateral Lumbar Interbody Fusion Device With Integrated Lateral Modular Plate Fixation

STUDY DESIGN

In vitro cadaveric biomechanical study.

OBJECTIVE

Biomechanically characterize a novel lateral lumbar interbody fusion (LLIF) implant possessing integrated lateral modular plate fixation (MPF).

METHODS

A human lumbar cadaveric (n = 7, L1-L4) biomechanical study of segmental range-of-motion stiffness was performed. A ±7.5 Nċm moment was applied in flexion/extension, lateral bending, and axial rotation using a 6 degree-of-freedom kinematics system. Specimens were tested first in an intact state and then following iterative instrumentation (L2/3): (1) LLIF cage only, (2) LLIF + 2-screw MPF, (3) LLIF + 4-screw MPF, (4) LLIF + 4-screw MPF + interspinous process fixation, and (5) LLIF + bilateral pedicle screw fixation. Comparative analysis of range-of-motion outcomes was performed between iterations.

RESULTS

Key biomechanical findings: (1) Flexion/extension range-of-motion reduction with LLIF + 4-screw MPF was significantly greater than LLIF + 2-screw MPF (P < .01). (2) LLIF with 2-screw and 4-screw MPF were comparable to LLIF with bilateral pedicle screw fixation in lateral bending and axial rotation range-of-motion reduction (P = 1.0). (3) LLIF + 4-screw MPF and supplemental interspinous process fixation range-of-motion reduction was comparable to LLIF + bilateral pedicle screw fixation in all directions (P ≥ .6).

CONCLUSIONS

LLIF with 4-screw MPF may provide inherent advantages over traditional 2-screw plating modalities. Furthermore, when coupled with interspinous process fixation, LLIF with MPF is a stable circumferential construct that provides biomechanical utility in all principal motions.

A minimally invasive lateral approach with CT navigation for open biopsy and diagnosis of Nocardia nova L4–5 discitis osteomyelitis: illustrative case

BACKGROUND

Lumbar spine osteomyelitis can be refractory to conventional techniques for identifying a causal organism. In cases in which a protracted antibiotic regimen is indicated, obtaining a conclusive yield on biopsy is particularly important. Although lateral transpsoas approaches and intraoperative computed tomography (CT) navigation are well documented as techniques used for spinal arthrodesis, their utility in vertebral biopsy has yet to be reported in any capacity.

OBSERVATIONS

In a 44-year-old male patient with a history of Nocardia bacteremia, CT-guided biopsy failed to confirm the microbiology of an L4–5 discitis osteomyelitis. The patient underwent a minimally invasive open biopsy in which a lateral approach with intraoperative guidance was used to access the infected disc space retroperitoneally. A thin film was obtained and cultured Nocardia nova, and the patient was treated accordingly with a long course of trimethoprim-sulfamethoxazole.

LESSONS

The combination of a lateral transpsoas approach with intraoperative navigation is a valuable technique for obtaining positive yield in cases of discitis osteomyelitis of the lumbar spine refractory to CT-guided biopsy.

Expandable Technology Improves Clinical and Radiographic Outcomes of Minimally Invasive Lateral Lumbar Interbody Fusion for Degenerative Disc Disease

BACKGROUND

Static interbody spacers are standard of care for minimally invasive lateral lumbar interbody fusion (MIS LLIF). However, placement of large static interbody spacers typically requires multiple trialing, endplate preparation, and forceful impaction. A lateral expandable interbody spacer with adjustable lordosis can be inserted at a reduced height, to optimize the endplate-to-endplate fit. This study describes radiographic and clinical outcomes in patients treated using lateral titanium expandable interbody spacers with adjustable lordosis using MIS LLIF.

METHODS

This is a single-surgeon, retrospective, institutional review board-exempt chart review of 24 consecutive patients who underwent MIS LLIF at 1-2 contiguous level(s) using expandable spacers with adjustable lordosis. Radiographic and clinical functional outcomes were collected and compared at preoperative and postoperative time points up to 24 months. Parametric and nonparametric tests were used when appropriate. Statistical results were significant if P < .05.

RESULTS

Twenty-four consecutive patients were evaluated with an average age of 57.8 ± 12.6 years; 45.8% were female. Visual analog scale for back pain improved by 7.3 ± 1.0 points, whereas Oswestry Disability Index scores improved by a mean of 67.5 ± 11.3 points at 24 months (P < .001). Lumbar lordosis improved by a mean of 6.3 ± 10.1° at 24 months (P < .001). There were 29 spinal levels, with 41.4% at L4-5 and 34.5% at L3-4. Anterior, middle, and posterior disc height significantly increased at 24 months by means of 4.5 ± 2.9 mm, 4.0 ± 2.8 mm, and 2.6 ± 1.9 mm, respectively (P < .001). Neuroforaminal height significantly improved by 3.3 ± 3.9 mm at 24 months (P < .001). Segmental lordosis improved by 3.6 ± 3.0° at 24 months.

CONCLUSIONS

This study showed significant positive clinical and radiographic outcomes for patients who underwent MIS LLIF using expandable interbody spacers with adjustable lordosis. Correction of sagittal alignment was achieved and maintained up to 2-year follow-up. The use of expandable spacers with adjustable lordosis was shown to be safe and effective in this cohort.

LEVEL OF EVIDENCE

3.

Single-Position Prone Transpsoas Lateral Interbody Fusion Including L4L5: Early Postoperative Outcomes

BACKGROUND

The lateral lumbar interbody fusion (LLIF) was a revolutionary approach devised by Luiz Pimenta that allowed the surgeon to access the lumbar spine through the major psoas muscle. Although the traditional LLIF had enabled enormous advances, the technique has its drawbacks. A new concept to perform the traditional LLIF has been proposed, with the patient being prone to decubitus with slightly extended legs. Our study aims to analyze the early outcomes of patients who had undergone the prone transpsoas (PTP) for degenerative spine pathologies including the L4/5 level.

METHODS

This study was multicentric, retrospective, nonrandomized, noncomparative, and observational. Only participants who received PTP in L4/5, with no more than 3 levels of intersomatics and fixation no further than S1, were included. The primary outcomes were the onset of new neurologic deficits and postoperative complications. Also, surgery details, such as blood loss and surgery duration, were measured. Neurologic deficits were accessed at the postoperative visit, which ranged from 7 to 14 days after surgery.

RESULTS

Twenty-seven patients fulfilled the inclusion and exclusion criteria, with the majority receiving PTP only in L4/5 (66.6%). The mean surgery time was 182, with 29 minutes of mean transpsoas time. Of the patients, only 1 presented the onset of a motor deficit, while 3 patients presented a new sensory deficit. Five complications occurred, none intraoperative and 5 postoperative, with only 1 directly correlated with the access.

CONCLUSIONS

The prone transpsoas is safe and feasible for approaching the L4/5 disk, presenting with a low rate of complication and new-onset neurologic deficits.

Effects of Surgical Positioning on L4-L5 Accessibility and Lumbar Lordosis in Lateral Transpsoas Lumbar Interbody Fusion: A Comparison of Prone and Lateral Decubitus in Asymptomatic Adults

BACKGROUND

Lateral interbody fusion (LIF) is traditionally performed in lateral decubitus on a breaking surgical table to improve L4-L5 access. Prone transpsoas (PTP) LIF may improve sagittal alignment and facilitate single-position circumferential procedures; but may require manipulation of the iliac crest for L4-L5 accessibility.

METHODS

Healthy adult volunteers (n = 41) were positioned as if for surgery in right-lateral decubitus on a radiolucent breaking table, and also prone on a Jackson-style surgical frame atop a custom PTP bolster. Iliac crest distance from the L5 superior endplate, and coronal and sagittal plane alignments were measured from fluororadiographs obtained in each of 5 positions: standard lateral decubitus (LD), prone-hips and spine neutral (PR-NN), prone-hips neutral and spine coronally bent (PR-NCB), prone-hips extended and spine neutral (PR-EN), and prone-hips extended and spine coronally bent (PR-ECB).

RESULTS

L4-L5 accessibility was lowest in prone-neutral and improved in all augmented positional configurations: PR-NN<>PR-EN<LD<PR-ECB<PR-NCB. Coronal bending with the PTP positioner created greater accessibility than that achieved by lateral decubitus breaking (PR-NCB>LD, P = 0.0480). Coronal angulations were greatest in LD, and statistically different from both prone neutral (LD>PR-NN, P < 0.0001) and prone coronally bent (LD>PR-NCB, P < 0.0001). Lordosis was greatest in extended prone positions and lowest in lateral decubitus: PR-EN>PR-ECB>PR-NCB<>PR-NN>LD. All prone positions showed significantly greater lordosis than lateral decubitus (P < 0.001).

CONCLUSIONS

Compared with lateral decubitus, prone positioning provides equivalent or better L4-L5 LIF access around the iliac crest when a positioner is used that enables coronal bending, and improved positional lordosis, which may facilitate segmental correction and achievement of surgical alignment goals.

Outpatient Minimally Invasive Lumbar Fusion Using Multimodal Analgesic Management in the Ambulatory Surgery Setting

BACKGROUND

The transition of minimally invasive (MIS) spine surgery from the inpatient to outpatient setting has been aided by advances in multimodal analgesic (MMA) protocols. This clinical case series of patients demonstrates the feasibility of ambulatory MIS transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) procedures while using an enhanced MMA protocol.

METHODS

Consecutive MIS TLIF or LLIF procedures with percutaneous pedicle screw fixation and direct decompression in the ambulatory setting were reviewed. The procedures were performed using an MMA protocol. The ambulatory surgery center (ASC) did not allow for observation of patients for periods of time greater than 23 hours. We recorded patient demographics, perioperative, and postoperative characteristics.

RESULTS

Fifty consecutive patients were identified from September 2016 to July 2019. Forty-one patients (82%) underwent MIS TLIF, and 9 patients underwent MIS LLIF (18.0%). All patients were discharged on the same day of surgery. The mean length of stay was 4.5 hours and 3.8 hours for the TLIF and LLIF cohorts, respectively. Our review of medical records revealed no postoperative complications following either the TLIF or the LLIF procedures.

CONCLUSIONS

The present study of 50 consecutive patients is the largest clinical series of ASC patients undergoing lumbar fusion procedures in a stand-alone facility with no extended postoperative observation capability. While using MMA protocol within the ASC, no postoperative complications were observed for either MIS TLIF or LLIF procedures. All patients were discharged from the ambulatory surgical center on the day of surgery with well-controlled postoperative pain.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

The MMA protocol is an essential aspect in transitioning minimally invasive lumbar spine surgery to the ASC. Our findings indicate that MIS lumbar fusion spine surgery with an enhanced MMA protocol can lead to safe and timely ASC discharge while minimizing hospital admission.

Comparative Effectiveness of Expandable Versus Static Interbody Spacers via MIS LLIF: A 2-Year Radiographic and Clinical Outcomes Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The purpose of this study is to compare the radiographic and clinical outcomes of expandable interbody spacers to static interbody spacers.

METHODS

This is a retrospective, institutional review board-exempt chart review of 62 consecutive patients diagnosed with degenerative disc disease who underwent minimally invasive spine surgery lateral lumbar interbody fusion (MIS LLIF) using static or expandable spacers. There were 27 patients treated with static spacers, and 35 with expandable spacers. Radiographic and clinical functional outcomes were collected. Statistical results were significant if P < .05.

RESULTS

Mean improvement in visual analogue scale back and leg pain scores was significantly greater in the expandable group compared to the static group at 6 and 24 months by 42.3% and 63.8%, respectively (P < .05). Average improvement in Oswestry Disability Index scores was significantly greater in the expandable group than the static group at 3, 6, 12, and 24 months by 28%, 44%, 59%, 53%, and 89%, respectively (P < .05). For disc height, the mean improvement from baseline to 24 months was greater in the static group compared to the expandable group (P < .05). Implant subsidence was significantly greater in the static group (16.1%, 5/31 levels) compared with the expandable group (6.7%, 3/45 levels; P < .05).

CONCLUSIONS

This study showed positive clinical and radiographic outcomes for patients who underwent MIS LLIF with expandable spacers compared to those with static spacers. Sagittal correction and pain relief was achieved and maintained through 24-month follow-up. The expandable group had a lower subsidence rate than the static group.

Assessment of Surgical Procedural Time, Pedicle Screw Accuracy, and Clinician Radiation Exposure of a Novel Robotic Navigation System Compared With Conventional Open and Percutaneous Freehand Techniques: A Cadaveric Investigation

STUDY DESIGN

Cadaveric study.

OBJECTIVE

To evaluate accuracy, radiation exposure, and surgical time of a new robotic-assisted navigation (RAN) platform compared with freehand techniques in conventional open and percutaneous procedures.

METHODS

Ten board-certified surgeons inserted 16 pedicle screws at T10-L5 (n = 40 per technique) in 10 human cadaveric torsos. Pedicle screws were inserted with (1) conventional MIS technique (L2-L5, patient left pedicles), (2) MIS RAN (L2-L5, patient right pedicles), (3) conventional open technique (T10-L1, patient left pedicles), and (4) open RAN (T10-L1, patient right pedicles). Output included (1) operative time, (2) number of fluoroscopic images, and (3) screw accuracy.

RESULTS

In the MIS group, compared with the freehand technique, RAN allowed for use of larger screws (diameter: 6.6 ± 0.6 mm vs 6.3 ± 0.5 mm; length: 50.3 ± 4.1 mm vs 46.9 ± 3.5 mm), decreased the number of breaches >2 mm (0 vs 7), fewer fluoroscopic images (0 ± 0 vs 108.3 ± 30.9), and surgical procedure time per screw (3.6 ± 0.4 minutes vs 7.6 ± 2.0 minutes) (all P < .05). Similarly, in the open group, RAN allowed for use of longer screws (46.1 ± 4.1 mm vs 44.0 ± 3.8 mm), decreased the number of breaches >2 mm (0 vs 13), fewer fluoroscopic images (0 ± 0 vs 24.1 ± 25.8) (all P < .05), but increased total surgical procedure time (41.4 ± 8.8 minutes vs 24.7 ± 7.0 minutes, P = .000) while maintaining screw insertion time (3.31.4 minutes vs 3.1 ± 1.0 minutes, P = .650).

CONCLUSION

RAN significantly improved accuracy and decreased radiation exposure in comparison to freehand techniques in both conventional open and percutaneous surgical procedures in cadavers. RAN significantly increased setup time compared with both conventional procedures.

Complications associated with L4-5 anterior retroperitoneal trans-psoas interbody fusion: a single institution series

Background

Lateral lumbar interbody fusion (LLIF), first described in the literature in 2006 by Ozgur et al., involves direct access to the lateral disc space via a retroperitoneal trans-psoas tubular approach. Neuromonitoring is vital during this approach since the surgical corridor traverses the psoas muscle where the lumbar plexus lies, risking injury to the lumbosacral plexus that could result in sensory or motor deficits. The risk of neurologic injury is especially higher at L4-5 due to the anatomy of the plexus at this level. Here we report our single-center clinical experience with L4-5 LLIF.

Methods

A retrospective chart review of all patients who underwent an L4-5 LLIF between May 2016 and March 2019 was performed. Baseline demographics and clinical characteristics, such as body mass index (BMI), medical comorbidities, surgical history, tobacco status, operative time and blood loss, length of stay (LOS), and post-op complications were recorded.

Results

A total of 220 (58% female and 42% male) cases were reviewed. The most common presenting pathology was spondylolisthesis. The average age, BMI, operative time, blood loss, and LOS were 64.6 years, 29 kg/m², 214 min, 75 cc, and 2.5 days respectively. A review of post-operative neurologic deficits revealed 31.4% transient hip flexor weakness and 4.5% quadricep weakness on the approach side. At 3-week follow-up, 9.1% of patients experienced mild hip flexor weakness (4 or 4+/5), 0.9% reported mild quadricep weakness, and 9.5% reported anterior thigh dysesthesias; 93.2% of patients were discharged home and 2.3% were readmitted within the first 30 days post discharge. Female sex, higher BMI and longer operative time were associated with hip flexor weakness.

Conclusions

LLIF at L4-5 is a safe, feasible, and versatile approach to the lumbar spine with an acceptable approach-related sensory and motor neurologic complication rates.

PEEK versus titanium cages in lateral lumbar interbody fusion: a comparative analysis of subsidence

OBJECTIVE

The authors have provided a review of radiographic subsidence after lateral lumbar interbody fusion (LLIF) as a comparative analysis between titanium and polyetheretherketone (PEEK) cages. Many authors describe a reluctance to use titanium cages in spinal fusion secondary to subsidence concerns due to the increased modulus of elasticity of metal cages. The authors intend for this report to provide observational data regarding the juxtaposition of these two materials in the LLIF domain.

METHODS

A retrospective review of a prospectively maintained database identified 113 consecutive patients undergoing lateral fusion for degenerative indications from January to December 2017. The surgeons performing the cage implantations were two orthopedic spine surgeons and two neurosurgeons. Plain standing radiographs were obtained at 1–2 weeks, 8–12 weeks, and 12 months postoperatively. Using a validated grading system, interbody subsidence into the endplates was graded at these time points on a scale of 0 to III. The primary outcome measure was subsidence between the two groups. Secondary outcomes were analyzed as well.

RESULTS

Of the 113 patients in the sample, groups receiving PEEK and titanium implants were closely matched at 57 and 56 patients, respectively. Cumulatively, 156 cages were inserted and recombinant human bone morphogenetic protein–2 (rhBMP-2) was used in 38.1%. The average patient age was 60.4 years and average follow-up was 75.1 weeks. Subsidence in the titanium group in this study was less common than in the PEEK cage group. At early follow-up, groups had similar subsidence outcomes. Statistical significance was reached at the 8- to 12-week and 52-week follow-ups, demonstrating more subsidence in the PEEK cage group than the titanium cage group. rhBMP-2 usage was also highly correlated with higher subsidence rates at all 3 follow-up time points. Age was correlated with higher subsidence rates in univariate and multivariate analysis.

CONCLUSIONS

Titanium cages were associated with lower subsidence rates than PEEK cages in this investigation. Usage of rhBMP-2 was also robustly associated with higher endplate subsidence. Each additional year of age correlated with an increased subsidence risk. Subsidence in LLIF is likely a response to a myriad of factors that include but are certainly not limited to cage material. Hence, the avoidance of titanium interbody implants secondary solely to concerns over a modulus of elasticity likely overlooks other variables of equal or greater importance.

Reliability and quality of online patient education videos for lateral lumbar interbody fusion

OBJECTIVE

There is an increasing trend among patients and their families to seek medical knowledge on the internet. Patients undergoing surgical interventions, including lateral lumbar interbody fusion (LLIF), often rely on online videos as a first source of knowledge to familiarize themselves with the procedure. In this study the authors sought to investigate the reliability and quality of LLIF-related online videos.

METHODS

In December 2018, the authors searched the YouTube platform using 3 search terms: lateral lumbar interbody fusion, LLIF surgery, and LLIF. The relevance-based ranking search option was used, and results from the first 3 pages were investigated. Only videos from universities, hospitals, and academic associations were included for final evaluation. By means of the DISCERN instrument, a validated measure of reliability and quality for online patient education resources, 3 authors of the present study independently evaluated the quality of information.

RESULTS

In total, 296 videos were identified by using the 3 search terms. Ten videos met inclusion criteria and were further evaluated. The average (± SD) DISCERN video quality assessment score for these 10 videos was 3.42 ± 0.16. Two videos (20%) had an average score above 4, corresponding to a high-quality source of information. Of the remaining 8 videos, 6 (60%) scored moderately, in the range of 3-4, indicating that the publication is reliable but important information is missing. The final 2 videos (20%) had a low average score (2 or below), indicating that they are unlikely to be of any benefit and should not be used. Videos with intraoperative clips were significantly more popular, as indicated by the numbers of likes and views (p = 0.01). There was no correlation between video popularity and DISCERN score (p = 0.104). In August 2019, the total number of views for the 10 videos in the final analysis was 537,785.

CONCLUSIONS

The findings of this study demonstrate that patients who seek to access information about LLIF by using the YouTube platform will be presented with an overall moderate quality of educational content on this procedure. Moreover, compared with videos that provide patient information on treatments used in other medical fields, videos providing information on LLIF surgery are still exiguous. In view of the increasing trend to seek medical knowledge on the YouTube platform, and in order to support and optimize patient education on LLIF surgery, the authors encourage academic neurosurgery institutions in the United States and worldwide to implement the release of reliable video educational content.

Comparative Effectiveness of Laterally Placed Expandable versus Static Interbody Spacers: A 1-Year Follow-Up Radiographic and Clinical Outcomes Study

Study Design

Retrospective chart review.

Purpose

This study compared the clinical and radiographic outcomes of patients treated with expandable and static interbody spacers following minimally invasive lateral lumbar interbody fusion (MIS-LLIF) with 12-month follow-up.

Overview of Literature

A common surgical option for the treatment of degenerative disk disease (DDD) is MIS-LLIF using static or expandable spacers to restore disk height (DH), neuroforaminal height (NH), and segmental lordosis. Static spacers may require excessive trialing and aggressive impaction, potentially leading to endplate disruption and subsidence. Expandable spacers allow for in situ expansion to help address complications associated with static spacers.

Methods

This is an Institutional Review Board-exempt review of 69 patients (static, n=32; expandable, n=37) diagnosed with DDD who underwent MIS-LLIF at 1–2 contiguous level(s) using static or expandable spacers. Radiographic and clinical outcomes were collected and compared at pre- and postoperative time points up to 12 months.

Results

The expandable group had a significantly higher mean change in Visual Analog Scale (VAS) scores at 6 weeks, 6 months, and 12 months vs. static (∆VAS at 12 months: expandable, 6.7±1.3; static, 5.1±2.6). Mean improvement of Oswestry Disability Index (ODI) scores at 3, 6, and 12 months were significantly better for the expandable group vs. static (∆ODI at 12 months: expandable, 63.2±13.2; static, 29.8±23.4). Mean DH and NH significantly increased at final follow-up for both groups, with no significant difference in DH improvement between groups. The expandable mean NH improvement at 6 weeks and 6 months was significantly greater vs. static. Segmental lordosis significantly improved in the expandable group at all time intervals vs static. Subsidence rate at 12 months was significantly lower in the expandable group (1/46, 2.2%) vs. static (12/37, 32.4%).

Conclusions

Expandable spacers resulted in a significantly lower subsidence rate, improve segmental lordosis, and VAS and ODI outcomes at 12 months vs. static.

Comparative Effectiveness of Adjustable Lordotic Expandable versus Static Lateral Lumbar Interbody Fusion Devices: One Year Clinical and Radiographic Outcomes

Aims:

This study aims to understand the clinical and radiographic outcomes between patients treated with static and expandable interbody spacers with adjustable lordosis for minimally invasive (MIS) lateral lumbar interbody fusion (LLIF).

Background:

The use of large interbody spacers in MIS LLIF offers favorable clinical and radiographic results. Static interbody spacers may cause iatrogenic endplate damage and implant subsidence due to forceful impaction and excessive trialing. Expandable interbody spacers with adjustable lordosis offerin situexpansion that may optimize endplate contact and maximize and maintain sagittal alignment correction until fusion occurs.

Objective:

The objective of this study is to compare the clinical and radiographic outcomes between patients treated with static and expandable interbody spacers with adjustable lordosis for MIS LLIF.

Methods:

This is a multi-surgeon, retrospective, Institutional Review Board-exempt chart review of consecutive patients who underwent MIS LLIF at 1-2 contiguous level(s) using either a polyetheretherketone (PEEK) static (32 patients) or a titanium expandable spacer with adjustable lordosis (57 patients). The mean differences of radiographic and clinical functional outcomes were collected and compared from preoperative up to 12-month postoperative follow-up. Statistical results were significant if P<0.05.

Results:

The mean improvement of VAS back pain scores from preoperative to 6 and 12 months was significantly higher in the expandable group compared to the static group (P<0.05). Mean improvement of Oswestry Disability Index (ODI) scores from preoperative to 3, 6, and 12 months were significantly higher in the expandable group compared to the static group (P<0.001). The expandable group had a significantly greater mean improvement in segmental lordosis from preoperative to 6 weeks, 3, 6, and 12 months (P<0.001). For disc height, the mean improvement from preoperative to 6 weeks and 3 months was more significant in the expandable group compared to the static group (P<0.05). In the expandable group, the mean improvement from preoperative to 6 weeks, 3, and 6 months was significantly greater compared to the static group for neuroforaminal height (P<0.001). Subsidence was 0% in the expandable group and 32.4% (12/37) in the static group.

Conclusion:

This study showed significant positive clinical and radiographic outcomes for patients who underwent MIS LLIF using titanium expandable interbody spacers with adjustable lordosis based on significant changes in VAS back pain scores, ODI scores, and radiographic parameters at 12-month follow-up. There was a 0% subsidence rate in the expandable group, compared to a 32% subsidence rate in the static group.

Impact of endplate-implant area mismatch on rates and grades of subsidence following stand-alone lateral lumbar interbody fusion: an analysis of 623 levels

OBJECTIVE

Stand-alone lateral lumbar interbody fusion (LLIF) is a useful minimally invasive approach for select spinal disorders, but implant subsidence may occur in up to 30% of patients. Previous studies have suggested that wider implants reduce the subsidence rate. This study aimed to evaluate whether a mismatch of the endplate and implant area can predict the rate and grade of implant subsidence.

METHODS

The authors conducted a retrospective review of prospectively collected data on consecutive patients who underwent stand-alone LLIF between July 2008 and June 2015; 297 patients (623 surgical levels) met inclusion criteria. Imaging studies were examined to grade graft subsidence according to Marchi criteria. Thirty patients had radiographic evidence of implant subsidence. The endplates above and below the implant were measured.

RESULTS

A total of 30 patients with implant subsidence were identified. Of these patients, 6 had Marchi grade 0, 4 had grade I, 12 had grade II, and 8 had grade III implant subsidence. There was no statistically significant correlation between the endplate-implant area mismatch and subsidence grade or incidence. There was also no correlation between endplate-implant width and length mismatch and subsidence grade or incidence. However, there was a strong correlation between the usage of the 18-mm-wide implants and the development of higher-grade subsidence (p = 0.002) necessitating surgery. There was no significant association between the degree of mismatch or Marchi subsidence grade and the presence of postoperative radiculopathy. Of the 8 patients with 18-mm implants demonstrating radiographic subsidence, 5 (62.5%) required reoperation. Of the 22 patients with 22-mm implants demonstrating radiographic subsidence, 13 (59.1%) required reoperation.

CONCLUSIONS

There was no correlation between endplate-implant area, width, or length mismatch and Marchi subsidence grade for stand-alone LLIF. There was also no correlation between either endplate-implant mismatch or Marchi subsidence grade and postoperative radiculopathy. The data do suggest that the use of 18-mm-wide implants in stand-alone LLIF may increase the risk of developing high-grade subsidence necessitating reoperation compared to the use of 22-mm-wide implants.

The effect of vascular approach surgeons on perioperative complications in lateral transpsoas lumbar interbody fusions

BACKGROUND CONTEXT

Lateral lumbar interbody fusion (LLIF) is a popular technique used in spine surgery. It is minimally invasive, provides indirect decompression, and allows for coronal plane deformity correction. Despite these benefits, the approach to LLIF has been linked to complications associated with the lumbosacral plexus and vascular anatomy. As a result, vascular surgeons may be recruited for the exposure portion of the procedure.

PURPOSE

The purpose of this study was to compare exposure-related complication and postoperative (postop) neuropraxia rates between exposure (EXP) and spine surgeon only (SSO) groups while performing the approach for LLIF.

STUDY DESIGN/SETTING

Retrospective analysis of patients treated at a single institution.

PATIENT SAMPLE

Patients undergoing LLIF procedures between 2012 and 2018.

OUTCOME MEASURES

Operative time, estimated blood loss, fluoroscopy, length of stay (LOS), intra- and postoperative complications, and physiologic measures including pre- and postoperative motor examinations and unresolved neuropraxia.

METHODS

Patients who underwent LLIF were separated into EXP and SSO groups based on the presence or absence of vascular/general surgeon during the approach. The entire clinical history of patients with a decrease in pre- and postop motor examination was reviewed for the presence of neuropraxia. All other intra- and postop exposure-related complications were recorded for comparison. Propensity score matching (PSM) was performed to account for age, Charlson Comorbidity Index (CCI) percentage of LLIFs including L4-L5, and number of levels fused. Independent t test and chi-square analyses were used to identify significant differences between EXP and SSO groups. Statistical significance was set at p<.05.

RESULTS

Two hundred and seventy-five patients underwent LLIF procedures, 155 SSO and 120 EXP. Postoperatively, 26 patients (11.1%) experienced a drop in any Medical Research Council (MRC) score, and two patients (0.7%) experienced unresolved quadriceps palsies. The mean recovery time for MRC scores was 84.4 days. Other complications included 2 pneumothoraces (0.7%), 1 iliac vein injury (0.4%), 14 cases of ileus (5.1%), 3 pulmonary emboli (1.1%), 2 deep vein thrombosis (0.7%), 3 cases of abdominal wall paresis (1.1%), and one abdominal hematoma (0.4%). After PSM, demographics including age, gender, body mass index, CCI, levels fused, and operative time were similar between cohorts. Twenty patients had changes in pre- to postop motor scores (SSO 9.4%, EXP 12.4%, p>.05). Iliopsoas motor scores decreased at the highest rate (EXP 12.4%, SSO 8.2%, p>.05) followed by quadriceps (EXP 5.2%, SSO 4.7%, p>.05). One SSO patient's postop course was complicated by a foot drop but returned to baseline within 1 year. One patient in EXP group developed an unresolved quadriceps palsy (EXP 1.0%, SSO 0.0%, p>.05). Intraoperative exposure complications included one pneumothorax (EXP 1.0%, SSO 0.0%, p>.05). There were no differences in PE/DVT, Ileus, or LOS. In the EXP cohort, three patients experienced abdominal wall paresis (EXP 2.9%, SSO 0.00%, p=.246).

CONCLUSIONS

Comparing the LLIF exposures performed by EXP and SSO, we found no significant difference in the rates of complications. Additional research is needed to determine the etiology of the abdominal wall complications. In conclusion, neuropraxia- and approach-related complications are similarly low between exposure and spine surgeons.

Early outcomes and safety of outpatient (surgery center) vs inpatient based L5-S1 Anterior Lumbar Interbody Fusion

We seek to determine the outcomes of patients undergoing outpatient-based ALIF compared to a consecutive series of inpatient based ALIF performed during the same time period. 58 consecutive patients at a single outpatient surgery center underwent ALIF from June 2015 - August 2017 and 79 ALIF's were performed at 2 Inpatient hospitals. Electronic medical records were reviewed for perioperative and postoperative complications as well as secondary interventions. 62 patients met inclusion criteria (29 Outpatient, 33 Inpatient). The inpatient group was significantly older (44 vs 51; p = 0.01). There were 8 postoperative complications. There was no difference in secondary interventions; 28 patients underwent a total of 36 interventions postoperatively for pain. Secondary interventions were performed at an average of 128(outpatient) and 158(inpatient) days (p = 0.55). There was no difference in outcome scores between the inpatient/outpatient groups at any time. Patients receiving a secondary intervention showed no significant improvement in Back VAS scores but, demonstrated a strong trend (p = 0.06) towards leg pain improvement. Patients who did not undergo secondary intervention had significant improvement in both Back and Leg VAS scores at all time points (p < 0.05). Outpatient ALIF is a safe and reproducible procedure with complication rates consistent with or lower than published rates. Patients outcome scores were no different in the inpatient versus outpatient group. Interestingly, there was a high number of secondary interventions performed in both groups. Patients undergoing a secondary procedure did not get statistically significant improvement in Back VAS but, demonstrated a strong trend in Leg VAS patient reported outcome scores.

Magnetic Resonance Imaging Study of Oblique Corridor and Trajectory to L1-L5 Intervertebral Disks in Lateral Position

OBJECTIVE

This study investigated the retroperitoneal oblique corridor and trajectory of L1-L5 as the lateral surgical access to the intervertebral disks in the Chinese population and detected the potential relationship between the corridor or trajectory and vertebral parameters, including disk axis, psoas muscle, and retroperitoneal vessel.

METHODS

Seventy magnetic resonance imaging studies performed from January 2017 to January 2019 were investigated. The oblique corridor was defined as the distance between the left lateral border of the retroperitoneal vessel and the anterior border of psoas. The trajectory was defined as the distance between the retroperitoneal vessel and lumbar plexus.

RESULTS

The oblique corridor analysis to L1-L5 disks have the following mean distances: L1-2 13.36 mm, L2-3 13.36 mm, L3-4 12.37 mm, and L4-5 10.36 mm. There was no difference in the L1-L5 corridor between genders. And the position of retroperitoneal vessel was negatively correlated with the corridor width. The trajectory measurements to L1-L5 disks have the following mean distances: L1-2 27.44 mm, L2-3 30.86 mm, L3-4 30.73 mm, and L4-5 24.36 mm. Moreover, the vertebral parameters, including the disk axis and psoas muscle, were positively correlated with the trajectory width. Otherwise, the position of retroperitoneal vessel was negatively correlated with the trajectory width.

CONCLUSIONS

Compared with previous studies, the safe surgical area of the Chinese is generally smaller than that of Caucasian. The position of the retroperitoneal vessel is the vital potential to limit the corridor and trajectory. Preoperative assessment of vertebral parameters, especially vascular structure, is essential for planning surgical process.

Lumbar spinal fusion in the outpatient setting: an update on management, surgical approaches and planning

Outpatient lumbar spinal fusion surgery has the potential for improved patient satisfaction, speed of recovery, and economic advantages when compared to inpatient surgery. Despite the rise in the number of these procedures performed annually, the literature on this topic remains scarce. As such, there is a need for a comprehensive review of current concepts in indications and management. The current review will present the most recent literature regarding pre-operative, intra-operative, and post-operative considerations when performing outpatient lumbar spinal fusion surgery.

Neural decompression in challenging cases: advantages and disadvantages

The peculiarity of extreme lateral interbody fusion (LLIF) is the achievement of indirect neural decompression of the spinal canal while distracting the intervertebral disc space using an interbody cage. In this manuscript we will review the potentials and limitations of this technique when treating degenerative disc disease of the lumbar spine. A literature search of the PubMed-National Library of Medicine was performed. Only articles in English were included. The current available literature demonstrates that LLIF is an effective method to decompress foraminal and central canal stenosis. Based on the current available literature LLIF effects on lateral recess stenosis are less consistent. The aim of this review is to provide with a thorough overview of the latest literature available and provide the audience with targeted-oriented published results that will eventually improve the decision-making process when using the LLIF technique.

Elective lumbar fusion in the United States: national trends in inpatient complications and cost from 2002-2014

BACKGROUND

Elective fusions for degenerative spine disease have increased over the past two decades in the United States, with variability in complications and hospital costs. The additional service costs associated with adverse perioperative events remain unknown. Our objective is to improve understanding of trends in safety and cost of elective lumbar fusions on a national scale.

METHODS

A weighted sample of 1,526,386 adults undergoing elective lumbar fusion for degenerative indications were identified in the National Inpatient Sample (NIS) years 2002-2014. Twelve categories of major complications by system, and patient/hospital variables, were evaluated as predictors of the overall reimbursed cost. Mean differences (B) and 95% confidence intervals [95% CI] are reported. Significance is assessed at p<0.001.

RESULTS

Nineteen percent of patients experienced inpatient complication. After adjusting for inflation, the mean overall cost was $32802±19557. Costs increased with presence of each of the 12 categories of complications, and by number of levels fused. Rates of most frequent complications and their adjusted cost-of-care were acute postoperative anemia (11.2%, B=$1817 [$1722-$1913], p<0.001), renal/urinary (1.9%, B=$510 [$288-$732], p<0.001), pulmonary (1.8%, B=$6014 [$5785-6243], p<0.001) and gastrointestinal (1.8%, B=$3699 [$3490-$3908, p<0.001). The costliest adverse events were infection (B=$15882 [$15424-$16339], p<0.001), thromboembolism (B=$8856 [$8400-$9311], p<0.001), hematoma/seroma/vascular (B=$8050 [$7784-$8316], p<0.001).

CONCLUSIONS

The number of elective lumbar fusions for degenerative spine disease increased 276% in the United States from 2002-2014 with growing surgeon preference for lateral techniques, and an increasing proportion of combined anterior and posterior approaches. Overall complication rates decreased from 2002-2014, despite an older patient population. After adjusting for inflation, cost was relatively stable across years 2002-2014. Complications by system were associated with increased cost, underscoring the need to address sources of complications and optimize early postoperative recovery in order to reduce healthcare expenditure.

New Intramuscular Electromyographic Monitoring with a Probe in Lateral Lumbar Interbody Fusion Surgery

INTRODUCTION

The lateral lumbar interbody fusion (LLIF) surgical approach is minimally invasive and safely accesses the target region. Therefore, it is widely used in cases of lumbar spinal stenosis and spinal deformity. Intraoperative neuromonitoring is necessary to avoid nerve injury, whereas postoperative anterior thigh symptoms are not necessarily prevented.

TECHNICAL NOTE

In our institute, 85 LLIF operations have been performed. The first 30 cases were excluded from the present study to avoid surgical learning curve effects; conventional monitoring was used in 30 cases, whereas a new method with a probe to monitor intramuscular potential was used in 25 other cases. Anterior thigh symptoms and motor deficits were assessed postoperatively. The location of the electromyographic threshold decrease was at the posterior part of the disc at L2-3, but at the anterior part at L4-5. Compared with conventional monitoring, the new intramuscular monitoring significantly decreased the prevalence of motor deficits of the iliopsoas at 1 day and 30 days; anterior thigh pain at 1 day, 30, and 90 days; and anterior thigh numbness at 30 and 90 days postoperatively.

CONCLUSIONS

Compared with conventional monitoring, the new intramuscular monitoring with a less invasive probe may reduce anterior thigh symptoms.

Evidence Based Medicine Review of Posterior Thoracolumbar Minimally Invasive Technology

Background

Evaluate the current evidence in meta-analyses on posterior thoracolumbar minimally invasive surgery techniques and outcomes for degenerative conditions.

Methods

A systematic review of the literature from 1950 to 2015.

Results

The review of the literature yielded 34 meta-analysis studies evaluating posterior thoracolumbar minimally invasive techniques and outcomes for degenerative conditions. There were 11 studies included which investigated minimally invasive surgery (MIS) versus open posterior lumbar decompressions. There were 14 studies included which investigated MIS versus open posterior lumbar interbody fusions. Finally, there were 9 studies focused on navigation techniques and radiation safety within MIS procedures.

Conclusions

There are 34 meta-analysis studies evaluating minimally invasive to open thoracolumbar surgery for degenerative disease. The studies show a trend toward decreased estimated blood loss, decreased length of stay, decreased complications, similar fusion rates, improved accuracy, and decreased radiation when minimally invasive techniques are used.

Accuracy of the lateral cage placement under intraoperative C-arm fluoroscopy in oblique lateral interbody fusion

BACKGROUND

In oblique lateral interbody fusion (OLIF), the lateral cage enters into the disc space obliquely, and is then turned to the true lateral direction to achieve a lateral lumbar interbody fusion. The OLIF cage is sometimes placed asymmetrically although it seemed to be placed accurately on intraoperative C-arm images. The present study aimed to investigate the accuracy of cage placement and its effect on the radiological outcome in OLIF.

METHODS

This study involved a retrospective radiological analysis of 127 lateral cages in 75 consecutive OLIF patients. The cage deviations from the midline and cage obliquity were evaluated using three sets of images: (1) intraoperative C-arm fluoroscopy, (2) postoperative standing radiographs, and (3) postoperative computed tomography (CT).

RESULTS

The mean cage deviation from the midline was measured as 2.5 ± 2.7 mm on intraoperative C-arm images, but was found to be more deviated on postoperative radiographs and CT (5.4 ± 3.8 mm and 3.8 ± 3.7 mm; P = 0.000 and 0.005, respectively). The cage obliquity on the intraoperative lateral C-arm was minimal in 26 (20.5%) cases, mild in 69 (54.3%), and moderate in 32 (25.2%), but was found to be more obliquely on postoperative radiographs as minimal in 9 (7.1%), mild in 55 (43.3%), and moderate in 63 (49.6%) (P < 0.001). Anterior/posterior disc heights, disc lordotic angle, fusion rate, and cage subsidence rate were not different according to cage obliquity (all P > 0.05).

CONCLUSIONS

Cage deviation from the midline and obliquity is underestimated on intraoperative C-arm images in OLIF. Although minimal cage deviation and obliquity did not affect the radiological outcome, great care should be made for the orthogonal cage insertion.

Delayed hardware complication after lateral retroperitoneal lumbar surgery: an unusual case of painless hematuria

Lateral approaches to the spine are becoming increasingly popular methods for decompression, restoration of alignment, and arthrodesis. Although individual cases of intraoperative injuries to the renal vasculature and the ureters have been documented as rare complications of lateral approaches to the spine, the authors report the first known case of postoperative renal injury due to the delayed extrusion of the screw of a lateral plate/screw construct directly into the renal parenchyma. The migration of the screw from the L1 vertebra into the superior pole of the left kidney occurred nearly 5 years after the index procedure, and presented as painless hematuria. A traditional left-sided retroperitoneal approach had been used at the time of the initial surgery, and the same exposure was used to remove the hardware, which was done in conjunction with general surgery and urology.