Nerve injury during the transpsoas approach for lumbar fusion

A novel surgical approach using the "lateral corridor" for minimally invasive oblique lumbar interbody fusion at L5-S1: a clinical series and technical note

PURPOSE

The minimally invasive oblique lumbar interbody fusion (MI-OLIF) L5-S1 was introduced to overcome the limitations of conventional fusion techniques, however, MI-OLIF is not possible using the standard method due to vascular structures in some cases. We aimed to introduce the "lateral corridor" and report the details of the surgical technique with a clinical case series.

METHODS

We utilized the lateral access route of the left common iliac vein and named it the "lateral corridor", to distinguish the technique from the standard technique (central corridor). The type and frequency of branch vessels that required additional manipulations were reviewed, and the frequency of intraoperative vascular injury was investigated.

RESULTS

Among the 107 patients who underwent MI-OLIF L5-S1, 26 patients (24.3%) who received the "lateral corridor" technique were included. Branch vessel ligation was required in 42.3% of the patients. The types of branch vessels that required ligation were seven cases (26.9%) of the iliolumbar vein (ILV) and six cases (23.1%) of ascending lumbar vein (ALV). The ILV and ALV were ligated in two cases. None of the patients developed intraoperative vascular injuries.

CONCLUSION

We introduced the "lateral corridor" as an alternative approach for MI-OLIF L5-S1, implemented it in 24.3% of the patient cohort, and reported favorable outcomes devoid of vascular complications. The "lateral corridor" necessitated ligation of the ILV or ALV in 42.3% of cases. The "lateral corridor" approach appears to be a promising surgical technique, offering feasibility even in instances where the vascular anatomy precludes the employment of the conventional approach.

Radiological and Clinical Outcomes comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spinal stenosis.

METHODS

Fifty three consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for degenerative lumbar spinal stenosis were enrolled. Twenty four patients underwent LLIF and 29 underwent TLIF.

RESULTS

Operative time and length of stay were similar between LLIF and TLIF (272.8 ± 82.4 vs 256.1 ± 59.4 minutes; 5.5 ± 2.8 vs 4.7 ± 3.3 days, P > .05), whereas blood loss was lower for LLIF (229.0 ± 125.6 vs 302.4 ± 97.1mls, P = .026). Neurological deficits were more common in LLIF (9 vs 3, P = .025), whereas persistent deficits were rare for both (1 vs 1, P = 1). For both groups, all patient reported outcomes visual analogue scale (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-years postoperative (P < .05), with both groups showing no significant differences in extent of improvement for any outcome. Lateral lumbar interbody fusion demonstrated superior restoration of disc height (L3-L4: 4.1 ± 2.4 vs 1.2 ± 1.9 mm, P < .001; L4-L5: 4.6 ± 2.4 vs .8 ± 2.8 mm, P < .001), foraminal height (FH) (L3-L4: 3.5 ± 3.6 vs 1.0 ± 3.6 mm, P = .014; L4-L5: 3.0 ± 3.5 vs -.1 ± 4.4 mm, P = .0080), segmental lordosis (4.1 ± 6.4 vs -2.1 ± 8.1°, P = .005), lumbar lordosis (LL) (4.1 ± 7.0 vs -2.3 ± 12.6°, P = .026) and pelvic incidence-lumbar lordosis (PI-LL) mismatch (-4.1 ± 7.0 vs 2.3 ± 12.6°, P = .019) at 2-years follow-up.

CONCLUSION

The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into difference in clinical outcomes compared to 2-level TLIF at the 2-years follow-up, suggesting both approaches are reasonable for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis.

Comparative Analysis of Vascular Structures in OLIF51 and the Lateral Corridor Approach under Supine MRI and Intraoperative Enhanced CT in the Lateral Decubitus Position

Background and Objectives: As the oblique lateral interbody fusion at L5/S1 (OLIF51) and the lateral corridor approach (LCA) have gained popularity, an understanding of the precise vascular structure at the L5/S1 level is indispensable. The objectives of this study were to investigate the vascular anatomy at the L5/S1 level, and to compare the movement of vascular tissue between the supine and lateral decubitus positions using intraoperative enhanced CT and MRI. Materials and Methods: A total of 43 patients who underwent either OLIF51 or LCA were investigated with an average age at surgery of 60.4 (37-80) years old. The preoperative MRI was taken to observe the axial and sagittal anatomy of the vascular position under the supine position. The intraoperative vein-enhanced CT was taken just before incision in the right decubitus position, and compared to supine MRI anatomy. Iliolumbar vein appearance and its types were also classified. Results: The average vascular window allowed for OLIF51 was 22.8 mm and 34.1 mm at either the L5 caudal endplate level or the S1 cephalad endplate level, respectively. The LCA was 14.2 mm and 12.6 mm at either level, respectively. The left common iliac vein moved 3.8 mm and 6.9 mm to the right direction at either level from supine to the right decubitus position, respectively. The bifurcation moved 6.3 mm to the caudal direction from supine to right decubitus. The iliolumbar vein was located at 31 mm laterally from the midline, and the MRI detection rate was 52%. Conclusions: The precise measurement of vascular anatomy indicated that the OLIF51 approach was the standard minimally invasive anterior approach for the L5/S1 disc level compared to LCA; however, there were many variations in quantitative anatomy as well as significant vascular movements between the supine and right decubitus positions. In the clinical setting of OLIF51 and LCA surgeries, careful preoperative evaluation and intraoperative 3D imaging are recommended for safe and accurate surgery.

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.

Multimodality Intraoperative Neuromonitoring in Lateral Lumbar Interbody Fusion: A Review of Alerts in 628 Patients

STUDY DESIGN

Retrospective review of private neuromonitoring databases.

OBJECTIVES

To review neuromonitoring alerts in a large series of patients undergoing lateral lumbar interbody fusion (LLIF) and determine whether alerts occurred more frequently when more lumbar levels were accessed or more frequently at particular lumbar levels.

METHODS

Intraoperative neuromonitoring (IONM) databases were reviewed and patients were identified undergoing LLIF between L1 and L5. All cases in which at least one IONM modality was used (motor evoked potentials (MEP), somatosensory evoked potentials (SSEP), evoked electromyography (EMG)) were included in this study. The type of IONM used and incidence of alerts were collected from each IONM report and analyzed. The incidence of alerts for each IONM modality based on number of levels at which at LLIF was performed and the specific level an LLIF was performed were compared.

RESULTS

A total of 628 patients undergoing LLIF across 934 levels were reviewed. EMG was used in 611 (97%) cases, SSEP in 561 (89%), MEP in 144 (23%). The frequency of IONM alerts for EMG, SSEP and MEPs did not significantly increase as the number of LLIF levels accessed increased. No EMG, SSEP, or MEP alerts occurred at L1-L2. EMG alerts occurred in 2-5% of patients at L2-L3, L3-L4, and L4-L5 and did not significantly vary by level (P = .34). SSEP and MEP alerts occurred more frequently at L4-L5 versus L2-L3 and L3-L4 (P < .03).

CONCLUSIONS

IONM may provide the greatest utility at L4-L5, particularly MEPs, and may not be necessary for more cephalad LLIF procedures such as at L1-L2.

A Comparative Clinical Study of Lateral Lumbar Interbody Fusion between Patients with Multiply Operated Back and Patients with First-Time Surgery

Background and Objectives: Patients with multiply operated back (MOB) may suffer from persistent lower-back pain associated with back muscle damage and epidural fibrosis following repeated back surgery (Failed Back Spinal Syndrome). Lateral lumbar interbody fusion (LLIF) is considered to be favorable for MOB patients. However, little scientific research has been carried out for this issue due to variety of the pathogenesis. The purpose of this study was to compare the clinical results of MOB patients and first-time surgery patients who underwent LLIF for lumbar spinal stenosis with degenerative scoliosis and/or degenerative spondylolisthesis (spinal instability). Materials and Methods: LLIF was performed for lumbar spinal stenosis with spinal instability in 55 consecutive cases of single hospital (30 males, 25 females, average age: 69). Clinical outcomes were compared between the MOB patient group (MOB group) and the first surgical patient group (F group). We evaluated the Japanese Orthopaedic Association (JOA) scores and JOA Back Pain Evaluation Questionnaire (JOABPEQ) before and 2 years after surgery. MOB patients were defined as those who have had one or more lumbar surgery on the same intervertebral or adjacent vertebrae in the past. Results: There were 20 cases (12 males, 8 females, average age: 71) in MOB group, and 35 cases (19 males, 16 females, average age: 68) in the F group. There was no significant difference between the two groups in terms of age, sex, number of intervertebral fixations, modic change in fused intervertebral end plate, score of brief scale for evaluation of psychiatric problem, lumbar lordosis, and sagittal vertical axis before and after surgery. The preoperative JOA scores averaged 12.5 points in the MOB group and averaged 11.6 points in the F group. The postoperative JOA scores averaged 23.9 points in the MOB group and averaged 24.7 points in the F group. The preoperative JOABPEQ averaged 36.3 points in the MOB group and averaged 35.4 points in the F group. The postoperative average JOA score was 75.4 in the MOB group and 70.2 in the F group. Conclusions: Based on the results, there was no significant difference in clinical outcomes of the two groups, and there was no new residual lower-back pain. Thus, we considered that LLIF one option for patients with MOB.

Multilevel tandem spondylolisthesis associated with a reduced "safe zone" for a transpsoas lateral lumbar interbody fusion at L4-5

OBJECTIVE

The aim of this study was to investigate the effect of degenerative spondylolisthesis (DS) on psoas anatomy and the L4-5 safe zone during lateral lumbar interbody fusion (LLIF).

METHODS

In this retrospective, single-institution analysis, patients managed for low-back pain between 2016 and 2021 were identified. Inclusion criteria were adequate lumbar MR images and radiographs. Exclusion criteria were spine trauma, infection, metastases, transitional anatomy, or prior surgery. There were three age and sex propensity-matched cohorts: 1) controls without DS; 2) patients with single-level DS (SLDS); and 3) patients with multilevel, tandem DS (TDS). Axial T2-weighted MRI was used to measure the apical (ventral) and central positions of the psoas relative to the posterior tangent line at the L4-5 disc. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch were measured on lumbar radiographs. The primary outcomes were apical and central psoas positions at L4-5, which were calculated using stepwise multivariate linear regression including demographics, spinopelvic parameters, and degree of DS. Secondary outcomes were associations between single- and multilevel DS and spinopelvic parameters, which were calculated using one-way ANOVA with Bonferroni correction for between-group comparisons.

RESULTS

A total of 230 patients (92 without DS, 92 with SLDS, and 46 with TDS) were included. The mean age was 68.0 ± 8.9 years, and 185 patients (80.4%) were female. The mean BMI was 31.0 ± 7.1, and the mean age-adjusted Charlson Comorbidity Index (aCCI) was 4.2 ± 1.8. Age, BMI, sex, and aCCI were similar between the groups. Each increased grade of DS (no DS to SLDS to TDS) was associated with significantly increased PI (p < 0.05 for all relationships). PT, PI-LL mismatch, center psoas, and apical position were all significantly greater in the TDS group than in the no-DS and SLDS groups (p < 0.05). DS severity was independently associated with 2.4-mm (95% CI 1.1-3.8 mm) center and 2.6-mm (95% CI 1.2-3.9 mm) apical psoas anterior displacement per increased grade (increasing from no DS to SLDS to TDS).

CONCLUSIONS

TDS represents more severe sagittal malalignment (PI-LL mismatch), pelvic compensation (PT), and changes in the psoas major muscle compared with no DS, and SLDS and is a risk factor for lumbar plexus injury during L4-5 LLIF due to a smaller safe zone.

A modified oblique lumbar interbody fusion: A better way to establish an exposure under direct microscopic vision

Study design

This is a retrospective study.

Objective

To demonstrate a modified oblique lumbar interbody fusion (OILF) technique for L1-L5.

Methods

The modified technique splits anterior portion of psoas belly to access the oblique corridor (OC) anteroinferior to psoas, minimizing psoas manipulation and retraction and avoiding nerve injury while offering excellent microscopic visualization. Psoas weakness and neurovascular complication rates in patients treated with traditional OLIF (T-OLIF) or anteroinferior psoas OLIF (AP-OLIF) were retrospectively reviewed. Clinical outcomes were also reviewed.

Results

A total of 162 cases treated with T-OLIF (n = 73) and AP-OLIF (n = 89) for degenerative lumbar disease were included. The mean operative time and blood loss were less with AP-OLIF (P < 0.01). Approach related complications were 14 (19.1%) with T-OLIF and 4 (4.5%) with AP-OLIF. Postoperative visual analog scale (VAS) and Oswestry Disability Index (ODI) scores improved in both T-OIF and AP-OIF groups (P < 0.01).

Conclusion

The modified OLIF technique (AP-OLIF) is characterized by an easy exposure of the lumbar spine under direct microscopic vision, resulting in less psoas weakness and neurovascular injury.

L4/5 accessibility for extreme lateral interbody fusion (XLIF): a radiological study

Introduction

Potential advantages of the Extreme Lateral Interbody Fusion (XLIF) approach are smaller incisions, preserving anterior and posterior longitudinal ligaments, lower blood loss, shorter operative time, avoiding vascular and visceral complications, and shorter length of stay. We hypothesize that not every patient can be safely treated at the L4/5 level using the XLIF approach. The objective of this study was to radiographically (CT-scan) evaluate the accessibility of the L4/5 level using a lateral approach, considering defined safe working zones and taking into account the anatomy of the superior iliac crest.

Methods

Hundred CT examinations of 34 female and 66 male patients were retrospectively evaluated. Disc height, lower vertebral endplate (sagittal and transversal), and psoas muscle diameter were quantified. Accessibility to intervertebral space L4/5 was investigated by simulating instrumentation in the transverse and sagittal planes using defined safe zones.

Results

The endplate L5 in the frontal plane considering defined safe zones in the sagittal and transverse plane (Zone IV) could be reached in 85 patients from the right and in 83 from the left side. Through psoas split, the safe zone could be reached through psoas zone II in 82 patients from the right and 91 patients from the left side. Access through psoas zone III could be performed in 28 patients from the right and 32 patients from the left side. Safe access and sufficient instrumentation of L4/5 through an extreme lateral approach could be performed in 76 patients of patients from the right and 70 patients from the left side.

Conclusion

XLIF is not possible and safe in every patient at the L4/5 level. The angle of access for instrumentation, access of the intervertebral disc space, and accessibility of the safe zone should be taken into account. Preoperative imaging planning is important to identify patients who are not suitable for this procedure.

Comparative Clinical Analysis of Oblique Lateral Interbody Fusion at L5/S1 versus Minimally Invasive Transforaminal Interbody Fusion (MIS-TLIF) for Degenerative Lumbosacral Disorders

Introduction

Since 2015, we have performed minimally invasive oblique lateral interbody fusion (OLIF) at L5/S1 for various lumbosacral spine disorders using percutaneous pedicle screws. This study evaluated the clinical and radiologic results between OLIF at L5/S1 and minimally invasive transforaminal interbody fusion (MIS-TLIF) for single to multilevel degenerative lumbosacral disorders.

Methods

A total of 124 patients underwent either OLIF (62 cases) or MIS-TLIF (62 cases). The applied disorders were L5 isthmic spondylolisthesis, foraminal stenosis, pseudarthrosis, adjacent segment degeneration, a combination of L4/5 and L5/S1 pathology, and others. We performed OLIF with posterior percutaneous fixation in the same lateral position. MIS-TLIF was performed with modified cortical bone trajectory screws. The operation time (OT), estimated blood loss (EBL), JOABPEQ effectiveness rate (%),Visual Analog Scale (VAS), fusion rate, radiologic segmental alignment, and complications were evaluated.

Results

The average follow-up periods were 51 and 69 months (24-95) in the OLIF and MIS-TLIF groups, respectively. Furthermore, the average fused segments were 1.6 and 1.5 in each group, respectively. The OT and EBL per segment were 130 min and 56 mL and 100 min and 64 mL, respectively. The JOABPEQ effectiveness rate in the OLIF group demonstrated a statistically higher value in the domains of pain, low-back function, and gait than the MIS-TLIF group (P<0.01). The follow-up VAS of low-back pain (LBP) and lower extremity numbness had lower values in the OLIF group (P<0.05). The fusion rates were 98% and 90%, respectively. Segmental lordosis at L5/S1 was significantly larger in the OLIF group (15° vs. 11°, P<0.01).

Conclusions

The OLIF group demonstrated less pain as well as better low-back and gait functions at follow-up. The minimally invasive anterolateral fusion employing OLIF at L5/S1 using percutaneous screws serves as a viable and effective procedure with less residual LBP and high fusion rate.

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.

Do evoked potentials matter? Pre-pathologic signal change and clinical outcomes with expandable cages in lateral lumbar interbody fusion surgery

Minimally Invasive Lateral Lumbar Interbody Fusion (MIS LLIF) is a reliable technique for treatment of degenerative disk disease, foraminal stenosis and spinal deformity. The retroperitoneal transpsoas approach risks lumbar plexus injury that may result in anterior thigh pain, sensory loss and weakness. A prospective study of 64 consecutive patients undergoing MIS LLIF with expandable cages (23 standalone, 41 integrated with lateral plate) using multimodal electrophysiological monitoring was performed. We measured sequential retraction times, complications, patient reported outcome scores and electrophysiologic findings with a minimum 12-month follow-up. Incidence of evoked potential and electromyographic signal change was moderate, and rarely resulted in post-operative neurologic deficit. Evoked potential signal changes were frequently resolved by the un-breaking of the surgical table or repositioning of the retractor. Average retraction times were 24 (15-41) minutes for standalone cages and 30 (15-41) minutes for integrated cages. At follow-up, the vast majority (97%) of patients reported significant clinical improvement post-operatively with only 2 patients reporting postoperative neurologic symptoms and subsequent recovery at 12-months. The present study shows that evoked potentials combined with electromyography is a more sensitive measure of pre-pathologic lumbar plexopathy in LLIF compared to electromyography alone, especially at L3/4 and L4/5 levels. Based on our findings, there is limited clinical indication for routine neural monitoring at rostral lumbar levels. The routine inclusion of multimodal electrophysiological monitoring in lateral transpsoas surgery is recommended to minimise the risk of neural injury by enabling optimal patient and retractor positioning and continued surveillance throughout the procedure.

Femoral nerve neuromonitoring for lateral lumbar interbody fusion surgery

BACKGROUND CONTEXT

The transpsoas lateral lumbar interbody fusion (LLIF) technique is an effective alternative to traditional anterior and posterior approaches to the lumbar spine; however, nerve injuries are the most reported postoperative complication. Commonly used strategies to avoid nerve injury (eg, limiting retraction duration) have not been effective in detecting or preventing femoral nerve injuries.

PURPOSE

To evaluate the efficacy of emerging intraoperative femoral nerve monitoring techniques and the importance of employing prompt surgical countermeasures when degraded femoral nerve function is detected.

STUDY DESIGN/SETTING

We present the results from a retrospective analysis of a multi-center study conducted over the course of 3 years.

PATIENT SAMPLE

One hundred and seventy-two lateral lumbar interbody fusion procedures were reviewed.

OUTCOME MEASURES

Intraoperative femoral nerve monitoring data was correlated to immediate postoperative neurologic examinations.

METHODS

Femoral nerve evoked potentials (FNEP) including saphenous nerve somatosensory evoked potentials (snSSEP) and motor evoked potentials with quadriceps recordings were used to detect evidence of degraded femoral nerve function during the time of surgical retraction.

RESULTS

In 89% (n=153) of the surgeries, there were no surgeon alerts as the FNEP response amplitudes remained relatively unchanged throughout the surgery (negative group). The positive group included 11% of the cases (n=19) where the surgeon was alerted to a deterioration of the FNEP amplitudes during surgical retraction. Prompt surgical countermeasures to an FNEP alert included loosening, adjusting, or removing surgical retraction, and/or requesting an increase in blood pressure from the anesthesiologist. All the cases where prompt surgical countermeasures were employed resulted in recovery of the degraded FNEP amplitudes and no postoperative femoral nerve injuries. In two cases, the surgeons were given verbal alerts of degraded FNEPs but did not employ prompt surgical countermeasures. In both cases, the degraded FNEP amplitudes did not recover by the time of surgical closure, and both patients exhibited postoperative signs of sensorimotor femoral nerve injury including anterior thigh numbness and weakened knee extension.

CONCLUSIONS

Multimodal femoral nerve monitoring can provide surgeons with a timely alert to hyperacute femoral nerve conduction failure, enabling prompt surgical countermeasures to be employed that can mitigate or avoid femoral nerve injury. Our data also suggests that the common strategy of limiting retraction duration may not be effective in preventing iatrogenic femoral nerve injuries.

Clinical and radiologic comparison of anterior-posterior single-position lateral surgery versus MIS-TLIF for degenerative lumbar spondylolisthesis

BACKGROUND

The lateral interbody fusion (LIF) has gained popularity for the surgical treatment of lumbar degenerative spondylolisthesis (DS), however, LIF often requires the position change for posterior screwing. We have performed the single-position lateral surgery of oblique lateral interbody fusion (OLIF) and posterior screwing (OLIF-LPF). The present study compared the clinical and radiologic results between OLIF-LPF and minimally invasive transforaminal interbody fusion (MIS-TLIF).

METHODS

A total of 142 patients underwent either OLIF-LPF (92 cases) or MIS-TLIF (50 cases) for L3 or L4 DS. The average age was 72 and 70 years old, respectively. The OLIF-LPF was performed in right decubitus position with allograft and percutaneous modified cortical bone trajectory screws (mCBT). The MIS-TLIF utilized a single 4 cm midline incision, allograft, boomerang cage and mCBTs. The operation time, estimated blood loss, and serum CRP levels were recorded. JOABPEQ effectiveness rate (%), Visual Analogue Scale (VAS), fusion rate, segmental radiologic alignment, and complications were also evaluated.

RESULTS

Average follow-up period was 31 and 57 months in OLIF-LPF and MIS-TLIF, respectively. The average operation time and estimated blood loss were 108min, 51 ml and 104 min and 69 ml, respectively. OLIF-LPF demonstrated significantly higher values of mental health domain of JOABPEQ effectiveness rate and VAS improvement of leg pain than those in MIS-TLIF. The less correction loss of posterior disc height was demonstrated in OLIF-LPF. The fusion rate and symptomatic adjacent segment degeneration (ASD) were statistically equivalent between two groups.

CONCLUSIONS

The single-position surgery of OLIF combined with posterior screwing serves as a safe, minimally invasive and effective surgical modality without the need of position change. It provides comparable fusion rate, segmental radiologic alignment, and symptomatic adjacent segment degeneration to MIS-TLIF surgery.

Intraoperative Neuromonitoring During Lateral Lumbar Interbody Fusion

Objective

To review the evidence for the use of electromyography (EMG), motor-evoked potentials (MEPs), and somatosensory-evoked potentials (SSEPs) intraoperative neuromonitoring (IONM) strategies during lateral lumbar interbody fusion (LLIF), as well as discuss the limitations associated with each technique.

Methods

A comprehensive review of the literature and compilation of findings relating to clinical studies investigating the efficacy of EMG, MEP, SSEP, or combined IONM strategies during LLIF.

Results

The evidence for the use of EMG is mixed with some studies demonstrating the efficacy of EMG in preventing postoperative neurologic injuries and other studies demonstrating a high rate of postoperative neurologic deficits with EMG monitoring. Multimodal IONM strategies utilizing MEPs or saphenous SSEPs to monitor the lumbar plexus may be promising strategies based on results from a limited number of studies.

Conclusion

The use of traditional EMG during LLIF remains without consensus. There is a growing body of evidence utilizing multimodal IONM with MEPs or saphenous SSEPs demonstrating a possible decrease in postoperative neurologic injuries after LLIF. Future prospective studies, with clear definitions of neurologic injury, that evaluate different multimodal IONM strategies are needed to better assess the efficacy of IONM during LLIF.

Single-level controlled comparison of OLIF51 and percutaneous screw in lateral position versus MIS-TLIF for lumbosacral degenerative disorders: Clinical and radiologic study

BACKGROUND

We have performed minimally invasive Oblique Lateral Interbody Fusion at L5/S1 (OLIF51) and simultaneous posterior screwing in lateral position for lumbosacral disorders. This study compared the clinical and radiologic results between OLIF51 versus Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF) in single-level fusion for lumbosacral degenerative disorders.

METHODS

A total of 71 patients underwent either OLIF51 (33 cases) or MIS-TLIF (38 cases) at L5/S1 spinal segment. The average age was 64 yrs (27-88). The disorders were L5 isthmic or degenerative spondylolisthesis, foraminal stenosis, pseudarthrosis and adjacent segment degeneration, and others. Using 35 mm oblique incision, OLIF51 was performed followed by posterior percutaneous fixation in same lateral position. MIS-TLIF was performed with midline 40 mm incision and modified cortical bone trajectory (CBT) screws. The operation time, estimated blood loss, JOABPEQ effectiveness rate (%), Visual Analogue Scale (VAS), fusion rate, radiologic alignment, and complications were evaluated.

RESULTS

Average follow-up period was 25 and 31 months (12-45) in OLIF51 and MIS-TLIF, respectively. The average operation time and estimated blood loss were 165min, 62 ml and 163 min and 68 ml, respectively. The JOABPEQ effectiveness rate in OLIF51 demonstrated higher value in low back function (44% vs 17%, P < 0.02). The fusion rate was 97% and 92% in OLIF51 and MIS-TLIF, respectively. The segmental lordosis was significantly larger in OLIF51 (17 vs 11 deg, P < 0.01). There were no vascular or neural complications.

CONCLUSIONS

Although two groups demonstrated the equivalent surgical invasiveness, there was the significant superiority of OLIF51 in terms of low back function over MIS-TLIF. The segmental lordosis creation was also better in OLIF51. Even in the single-level lumbosacral fusion, OLIF51 serves as the safe and viable surgical procedure with use of lateral position surgery, minimizing the residual low back dysfunction.

Saphenous Nerve Somatosensory-Evoked Potentials Monitoring During Lateral Interbody Fusion

STUDY DESIGN.

Retrospective cohort study.

OBJECTIVES

To clinically evaluate saphenous nerve somatosensory-evoked potentials (SSEPs) as a reliable and predictable way to detect upper lumbar plexus injury intraoperatively during lateral lumbar trans-psoas interbody fusion (LLIF).

METHODS

Saphenous nerve SSEPs were obtained by stimulation of inferior medial thigh with needle electrodes and recording from transcranial potentials. The primary outcome was measured by testing reproducibility of SSEPs at baseline, changes during the procedure, and relevance to standard modalities. Significant SSEP changes were compared with actual postoperative nerve complications. The sensitivity and specificity of saphenous SSEPs to detect postoperative lumbar plexus nerve injury was calculated.

RESULTS

A total of 62 patients were included in the study. Reliable saphenous SSEPs were recorded on the LLIF approach side in 52/62 patients. Persistent saphenous SSEP reduction of amplitude of >50% in 6 cases was observed during expansion of the tubular retractor or during the procedure. Two of 6 patients postoperatively had femoral nerve sensory deficits, and 5 of 6 patients had mild femoral nerve motor weakness, all of which resolved at an average of 12 weeks postoperatively (range 2-24 weeks). One patient had saphenous SSEP changes but demonstrated intraoperative recovery and had no postoperative clinical deficits. Saphenous SSEPs demonstrated 52% to 100% sensitivity and 90% to 100% specificity for detecting postoperative femoral nerve complications.

CONCLUSION

Saphenous SSEPs can be used to detect electrophysiological changes to prevent femoral nerve injury during LLIF. Intraoperative SSEP recovery after amplitude reduction or loss may be a prognostic factor for final clinical outcome.

Intraoperative Computed Tomography-Based Navigation with Augmented Reality for Lateral Approaches to the Spine

Background. Lateral approaches to the spine have gained increased popularity due to enabling minimally invasive access to the spine, less blood loss, decreased operative time, and less postoperative pain. The objective of the study was to analyze the use of intraoperative computed tomography with navigation and the implementation of augmented reality in facilitating a lateral approach to the spine. Methods. We prospectively analyzed all patients who underwent surgery with a lateral approach to the spine from September 2016 to January 2021 using intraoperative CT applying a 32-slice movable CT scanner, which was used for automatic navigation registration. Sixteen patients, with a median age of 64.3 years, were operated on using a lateral approach to the thoracic and lumbar spine and using intraoperative CT with navigation. Indications included a herniated disc (six patients), tumors (seven), instability following the fracture of the thoracic or lumbar vertebra (two), and spondylodiscitis (one). Results. Automatic registration, applying intraoperative CT, resulted in high accuracy (target registration error: 0.84 ± 0.10 mm). The effective radiation dose of the registration CT scans was 6.16 ± 3.91 mSv. In seven patients, a control iCT scan was performed for resection and implant control, with an ED of 4.51 ± 2.48 mSv. Augmented reality (AR) was used to support surgery in 11 cases, by visualizing the tumor outline, pedicle screws, herniated discs, and surrounding structures. Of the 16 patients, corpectomy was performed in six patients with the implantation of an expandable cage, and one patient underwent discectomy using the XLIF technique. One patient experienced perioperative complications. One patient died in the early postoperative course due to severe cardiorespiratory failure. Ten patients had improved and five had unchanged neurological status at the 3-month follow up. Conclusions. Intraoperative computed tomography with navigation facilitates the application of lateral approaches to the spine for a variety of indications, including fusion procedures, tumor resection, and herniated disc surgery.

Distal Stimulation Site at the Medial Tibia for Saphenous Nerve Somatosensory Evoked Potentials (DSn-SSEPs) in Lateral Lumbar Spine Procedures

Lateral lumbar interbody fusion procedures are performed with multimodality neuromonitoring of the femoral nerve to prevent lumbosacral plexus and peripheral nerve injury from positioning, dilation, retraction, and hardware implantation. The integrity of the femoral nerve can be continuously assessed during these procedures by Somatosensory Evoked Potentials of the Saphenous nerve (Sn-SSEPs). Sn-SSEPs are technically challenging to acquire and necessitate advanced troubleshooting skills with a more rigid anesthetic regimen and physiological parameters. We performed a retrospective analysis of Sn-SSEP data for 100 consecutive lateral lumbar surgeries where the stimulation electrodes were placed distally below the knee and medial to the tibia bone (i.e., DSn-SSEPs). Monitorable baseline responses were present in 87% of patients after the exclusion of fourteen cases where the tibial nerve SSEP was absent, quadriceps transcranial electrical motor evoked potentials (TCeMEPs) were absent or not utilized. Sex, age, body mass index (BMI), diagnosis, mean arterial pressure (MAP), inhalational anesthetic levels, reliability of ulnar and posterior tibial nerve SSEPs, and the reliability of femoral nerve innervated quadriceps TCeMEPs were evaluated but were not of statistically significant consequence between cases where the DSn-SSEP was present or absent in this study. We found the utilization of DSn-SSEPs to be a valuable adjunct to femoral nerve monitoring. Stimulation electrode placement is easy to palpate with clear anatomical borders. Significant muscle artifact and patient movement from stimulation do not affect waveform morphology, allowing for continuous and reliable monitoring. We recommend including DSn-SSEPs to optimize recordings during lateral lumbar procedures.

Perioperative Complications in 255 Patients Who Underwent Lateral Anterior Lumbar Interbody Fusion (LaLIF) Surgery

PURPOSE

To investigate the perioperative complications of lateral anterior lumbar interbody fusion (LaLIF) surgery.

METHODS

The participants were patients who underwent LaLIF surgery for degenerative lumbar diseases between April 2016 and November 2020. The collected data were classified into intraoperative and early-stage postoperative (1 month) complications. Intraoperative complications were subcategorized into nerve root injury, sympathetic chain injury, segmental artery injury, iliolumbar vein injury, peritoneum laceration, temporary psoas injury, endplate damage, and vertebral body fractures. Postoperative complications were subcategorized into surgical site infection, cage migration, cage subsidence and psoas major hematoma.

RESULTS

In the 255 included patients, 39 complications (15.3%) were reported. One patient (0.4%) had residual neurological symptoms (numbness) at the last follow-up after conservative management. The most common complications were temporary psoas injury (3.9%), followed by sympathetic chain injury (2.7%) and endplate damage (2.0%). The most frequent postoperative complication was cage migration (1.6%), followed by cage subsidence (1.2%), and surgical site infection (0.8%).

CONCLUSION

The complication rates for LaLIF are generally low and comparable to those for conventional OLIF and XLIF that have been reported in other studies. Almost all complications were transient after LaLIF. Severe complications can be avoided by using sufficient muscle relaxant, instruments with the required characteristics and vertical trajectories in multiple steps.

Transpsoas Lumbar Interbody Fusion Without Psoas Stimulated Electromyography

STUDY DESIGN

This is a retrospective case review.

OBJECTIVE

The objective of this study was to present an anatomic approach to transpsoas interbody fusion without psoas stimulated electromyography (sEMG) and to evaluate the rate of neurological and approach-related complications.

BACKGROUND

The transpsoas approaches have become commonly utilized for lumbar interbody fusion and may have certain advantages compared with other methods of interbody stabilization. Traditionally, transpsoas approaches have been performed utilizing sEMG as it has been purported to reduce the risk of injury to the lumbar plexus; however, an anatomic approach to transpsoas surgery is also possible as cadaveric studies have demonstrated the anatomy of the psoas muscle and lumbar plexus.

METHODS

Patients who underwent transpsoas interbody fusion using an anatomic approach without psoas sEMG between 2005 and 2018 were enrolled in this study. The preoperative and postoperative medical records for this cohort were carefully reviewed to identify any new or persistent radicular symptoms, neurological deficits or approach-related complications.

RESULTS

A total of 133 patients (48 males, 85 females) underwent transpsoas interbody fusion at 222 levels in this cohort-which had a mean age of 63 (61, 65) years and body mass index of 28.8 (27.8, 29.9). New neurological complications were seen in 5 patients (3.8%) and 5 patients (3.8%) were found to have new postoperative radicular pain, up to 3 months postoperatively. The total number of perioperative, approach-related complications was 7 (5.3%) for the entire cohort.

CONCLUSION

An anatomic transpsoas approach to the interbody space without psoas sEMG demonstrated a rate of neurological and approach-related complications that was comparable or superior to the rate of complications reported using the traditional transpsoas approach with sEMG.

Clinical Outcomes after Minimally Invasive Trans-Psoas Lateral Lumbar Interbody Fusion for the Treatment of Adult Degenerative Scoliosis: Four Years’ Multicenter Study

The use of minimally invasive transpsoas lateral lumbar interbody fusion (LLIF) surgery for treatment of adult degenerative scoliosis is rapidly increasing in popularity. However, limited data is available regarding its use in adult degenerative lumbar scoliosis surgery. The objective of this study was to evaluate the clinical outcomes of adults with degenerative lumbar scoliosis who were treated with minimally invasive LLIF. Thirty-two consecutive patients with adult degenerative scoliosis treated by a single surgeon at two spine centers were followed up for an average of 13.2 months. Interbody fusion was completed using the minimally invasive LLIF technique with supplemental 360 degrees’ posterior instrumentation. Oswestry disability index (ODI) scores were obtained preoperatively and at most recent follow-up. Complications were recorded. The study group demonstrated improvement in clinical outcome scores. ODI scores improved from 36.8 to 23.4 (p < 0.00001). A total of four complications (12%) were recorded, and two patients (6%) required additional surgery. Based on the significant improvement in validated clinical outcome scores, minimally invasive LLIF can be considered an effective procedure in the treatment of adult degenerative scoliosis.

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.

Neurologic Injury in Complex Adult Spinal Deformity Surgery: Staged Multilevel Oblique Lumbar Interbody Fusion (MOLIF) Using Hyperlordotic Tantalum Cages and Posterior Fusion Versus Pedicle Subtraction Osteotomy (PSO)

STUDY DESIGN

A retrospective review of prospectively collected data.

OBJECTIVE

The aim of this study was to determine the safety of MOLIF versus PSO.

SUMMARY OF BACKGROUND DATA

Complex adult spinal deformity (CASD) represents a challenging cohort of patients. The Scoli-RISK-1 study has shown a 22.18% perioperative risk of neurological injury. Restoration of sagittal parameters is associated with good outcome in ASD. Pedicle subtraction osteotomies (PSO) is an important technique for sagittal balance in ASD but is associated with significant morbidity. The multilevel oblique lumbar interbody fusion (MOLIF) is an extensile approach from L1 to S1.

METHODS

Single surgeon series from 2007 to 2015. Prospectively collected data. Scoli-RISK-1 criteria were refined to only include stiff or fused spines otherwise requiring a PSO. Roentograms were examined preoperatively and 2 year postoperatively. Primary outcome measure was the motor decline in American Spinal Injury Association (ASIA) at hospital discharge, 6 weeks, 6 months, and 2 years. Demographics, blood loss, operative time, spinopelvic parameters, and spinal cord monitoring (SCM) events.

RESULTS

Sixty-eight consecutive patients were included in this study, with 34 patients in each Group. Group 1 (MOLIF) had a mean age 62.9 (45-81) and Group 2 (PSO) had a mean age of 66.76 years (47-79); 64.7% female versus PSO 76.5%; Body Mass Index (BMI) Group 1 (MOLIF) 28.05 and Group 2 (PSO) 27.17. Group 1 (MOLIF) perioperative neurological injury was 2.94% at discharge but resolved by 6 weeks. Group 2 (PSO) had five neurological deficits (14.7%) with no recovery by 2 years. There were four SCM events (SCM). In Group 1 (MOLIF), there was one event (2.94%) versus three events (8.88%) in Group 2 (PSO).

CONCLUSION

Staged MOLIF avoids passing neurological structures or retraction of psoas and lumbar plexus. It is safer than PSO in CASD with stiff or fused spines with a lower perioperative neurological injury profile. MOLIF have less SCM events, blood loss, and number of levels fused.

LEVEL OF EVIDENCE

3.

Perioperative complications associated with minimally invasive surgery of oblique lumbar interbody fusions for degenerative lumbar diseases in 113 patients

OBJECTIVES

To describe perioperative complications occurring during oblique lumbar interbody fusion (OLIF) assisted by a retractor system for degenerative lumbar diseases.

PATIENTS AND METHODS

The perioperative complications in 113 cases series utilizing a minimally invasive approach were recorded and analyzed. One hundred thirteen patients who received OLIF for degenerative lumbar diseases between November 2014 and February 2017 at a single center were evaluated. The most frequent diagnosis was spondylolisthesis (59 cases, 52.2%), followed by lumbar instability (24 cases, 21.2%), adjacent segmental disease (12 cases, 10.6%), adult degenerative scoliosis (11 cases, 9.8%) and discogenic low back pain (7 cases, 6.2%). One hundred thirty-four levels were treated, 88.5% one-level, 4.4% two-level, and 7.1% three-level surgeries. The most fused level was L4-5 (94 levels, 70.2%), followed by L3-4 (31 levels, 23.1%), and L2-3 (9 levels, 6.7%).

RESULTS

All perioperative complications only included adverse events related to the OLIF procedure. The most observed complications were donor-site pain (24 cases, 21.2%), followed by vertebral endplate fracture (15 cases, 13.3%), thigh numbness/pain (12 cases, 10.6%), psoas/quadriceps weakness (5 cases, 4.4%), sympathetic nerve injury (2 case, 1.8%), paralytic ileus (one case, 0.9%), segmental artery injury (one case, 0.9%), intervertebral infection (one, 0.9%), and contralateral femoral nerve palsy (one, 0.9%). All complications, including postoperative ipsilateral or contralateral thigh paresthesia, pain, and psoas/quadriceps weakness, were observed when operating at L4-L5. The incidence of complications excluding donor-site pain was 24.8% (28/113 cases). The patients with donor-site pain, thigh numbness/pain, psoas/quadriceps weakness, sympathetic nerve injury and paralytic ileus recovered within two months following surgery. The patient with intervertebral infection recovered at 3 months after surgery. One case of contralateral femoral nerve palsy recovered completely with no residual sensory or motor deficit at 6 months.

CONCLUSIONS

OLIF performed using a retractor system is a validated option to treat a wide spectrum of degenerative lumbar diseases with few perioperative complications and a quick recovery. Judicious use of this technique at the L4/5 level is recommended. Close attention to detail during the procedure can minimize complications that may be associated with the learning curve.

Diffusion tensor tractography of the lumbar nerves before a direct lateral transpsoas approach to treat degenerative lumbar scoliosis

OBJECTIVE

The purpose of this study was to determine the relationship between vertebral bodies, psoas major morphology, and the course of lumbar nerve tracts using diffusion tensor imaging (DTI) before lateral interbody fusion (LIF) to treat spinal deformities.

METHODS

DTI findings in a group of 12 patients (all women, mean age 74.3 years) with degenerative lumbar scoliosis (DLS) were compared with those obtained in a matched control group of 10 patients (all women, mean age 69.8 years) with low-back pain but without scoliosis. A T2-weighted sagittal view was fused to tractography from L3 to L5 and separated into 6 zones (zone A, zones 1-4, and zone P) comprising equal quarters of the anteroposterior diameters, and anterior and posterior to the vertebral body, to determine the distribution of nerves at various intervertebral levels (L3-4, L4-5, and L5-S1). To determine psoas morphology, the authors examined images for a rising psoas sign at the level of L4-5, and the ratio of the anteroposterior diameter (AP) to the lateral diameter (lat), or AP/lat ratio, was calculated. They assessed the relationship between apical vertebrae, psoas major morphology, and the course of nerve tracts.

RESULTS

Although only 30% of patients in the control group showed a rising psoas sign, it was present in 100% of those in the DLS group. The psoas major was significantly extended on the concave side (AP/lat ratio: 2.1 concave side, 1.2 convex side). In 75% of patients in the DLS group, the apex of the curve was at L2 or higher (upper apex) and the psoas major was extended on the concave side. In the remaining 25%, the apex was at L3 or lower (lower apex) and the psoas major was extended on the convex side. Significant anterior shifts of lumbar nerves compared with controls were noted at each intervertebral level in patients with DLS. Nerves on the extended side of the psoas major were significantly shifted anteriorly. Nerve pathways on the convex side of the scoliotic curve were shifted posteriorly.

CONCLUSIONS

A significant anterior shift of lumbar nerves was noted at all intervertebral levels in patients with DLS in comparison with findings in controls. On the convex side, the nerves showed a posterior shift. In LIF, a convex approach is relatively safer than an approach from the concave side. Lumbar nerve course tracking with DTI is useful for assessing patients with DLS before LIF.

Curve Laterality for Lateral Lumbar Interbody Fusion in Adult Scoliosis Surgery: The Concave Versus Convex Controversy

BACKGROUND

Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degenerative scoliosis (ADS) surgery. LLIF approaches performed from the concavity or convexity have inherent approach-related risks and benefits.

OBJECTIVE

To analyze LLIF approach-related complications and radiographic and clinical outcomes in patients with ADS.

METHODS

A multicenter retrospective review of a minimally invasive adult spinal deformity database was queried with a minimum of 2-yr follow-up. Patients were divided into 2 groups as determined by the side of the curve from which the LLIF was performed: concave or convex.

RESULTS

No differences between groups were noted in demographic, and preoperative or postoperative radiographic parameters (all P > .05). There were 8 total complications in the convex group (34.8%) and 21 complications in the concave group (52.5%; P = .17). A subgroup analysis was performed in 49 patients in whom L4-5 was in the primary curve and not in the fractional curve. In this subset of patients, there were 6 complications in the convex group (31.6%) compared to 19 in the concave group (63.3%; P < .05) and both groups experienced significant improvements in coronal Cobb angle, Oswestry Disability Index, and Visual Analog Scale score with no difference between groups.

CONCLUSION

Patients undergoing LLIF for ADS had no statistically significant clinical or operative complication rates regardless of a concave or convex approach to the curve. Clinical outcomes and coronal plane deformity improved regardless of approach side. However, in cases wherein L4-5 is in the primary curve, approaching the fractional curve at L4-5 from the concavity may be associated with a higher complication rate compared to a convex approach.

Lateral Lumbar Interbody Fusion Revisited: Complication Avoidance and Outcomes with the Mini-Open Approach

OBJECTIVE

To discuss lessons learned from an initial lateral lumbar interbody fusion (LLIF) experience with a focus on evolving surgical technique, complication avoidance, and new motor and sensory outcomes after implementation of a modified surgical approach.

METHODS

A retrospective analysis of a prospectively collected series of all patients undergoing LLIF by the senior author (A.D.L.) from January 2010 to January 2018 after implementation of a modified surgical mini-open technique, compared with previously reported institutional results with the originally recommended percutaneous technique. LLIF-specific complications examined included groin/thigh sensory dysfunction, flank bulge/pseudohernia, psoas-pattern weakness, and femoral nerve injury.

RESULTS

The incidence (19%, n = 98 patients) of groin/thigh sensory dysfunction in our cohort was significantly lower than that of the historical control (60%, n = 59) (P < 0.0001). The incidence of abdominal flank bulge/pseudohernia (2.0%, n = 98 patients) in our cohort was improved but not significantly lower than that of the historical control (4.2%, n = 118) (P = 0.36). The incidence of psoas-pattern weakness (3.1%, n = 98) in our cohort was significantly lower than that of the historical control (23.7%, n = 59) (P = 0.0001). The incidence of femoral nerve injury (0%, n = 98 patients) in our cohort was improved but was not significantly lower than that of the historical control (1.7%, n = 118) (P = 0.20).

CONCLUSIONS

The adoption of an exclusive mini-open muscle-splitting approach with first-look inspection of the lumbosacral plexus nerve elements may improve motor and sensory outcomes in general and the incidence of postoperative groin/thigh sensory dysfunction and psoas-pattern weakness in particular.

Use of motor evoked potentials during lateral lumbar interbody fusion reduces postoperative deficits

BACKGROUND CONTEXT

Intraoperative neurophysiological monitoring (IONM) has gained rather widespread acceptance as a method to mitigate risk to the lumbar plexus during lateral lumbar interbody fusion (LLIF) surgery. The most common approach to IONM involves using only electromyography (EMG) monitoring, and the rate of postoperative deficit remains unacceptably high. Other test modalities, such as transcranial electric motor-evoked potentials (tcMEPs) and somatosensory-evoked potentials, may be more suitable for monitoring neural integrity, but they have not been widely adopted during LLIF. Recent studies have begun to examine their utility in monitoring LLIF surgery with favorable results.

PURPOSE

This study aimed to evaluate the efficacy of different IONM paradigms in the prevention of iatrogenic neurologic sequelae during LLIF and to specifically evaluate the utility of including tcMEPs in an IONM strategy for LLIF surgery.

STUDY DESIGN/SETTING

A non-randomized, retrospective analysis of 479 LLIF procedures at a single institution over a 4-year period was conducted. During the study epoch, three different IONM strategies were used for LLIF procedures: (1) surgeon-directed T-EMG monitoring ("SD-EMG"), (2) neurophysiologist-controlled T-EMG monitoring ("NC-EMG"), and (3) neurophysiologist-controlled T-EMG monitoring supplemented with MEP monitoring ("NC-MEP").

PATIENT SAMPLE

The patient population comprised 254 men (53.5%) and 221 women (46.5%). Patient age ranged from a minimum of 21 years to a maximum of 89 years, with a mean of 56.6 years.

OUTCOME MEASURES

Physician-documented physiological measures included manual muscle test grading of hip-flexion, hip-adduction, or knee-extension, as well as hypo- or hyperesthesia of the groin or anterolateral thigh on the surgical side. Self-reported measures included numbness or tingling in the groin or anterolateral thigh on the surgical side.

METHODS

Patient progress notes were reviewed from the postoperative period up to 12 months after surgery. The rates of postoperative sensory-motor deficit consistent with lumbar plexopathy or peripheral nerve palsy on the surgical side were compared between the three cohorts.

RESULTS

Using the dependent measure of neurologic deficit, whether motor or sensory, patients with NC-MEP monitoring had the lowest rate of immediate postoperative deficit (22.3%) compared with NC-EMG monitoring (37.1%) and SD-EMG monitoring (40.4%). This result extended to sensory deficits consistent with lumbar plexopathy (pure motor deficits being excluded); patients with NC-MEP monitoring had the lowest rate (20.5%) compared with NC-EMG monitoring (34.3%) and SD-EMG monitoring (36.9%). Additionally, evaluation of postoperative motor deficits consistent with peripheral nerve palsy (pure sensory deficits being excluded) revealed that the NC-MEP group had the lowest rate (5.7%) of motor deficit compared with the SD-EMG (17.0%) and NC-EMG (17.1%) cohorts. Finally, when assessing only those patients whose last follow-up was greater than or equal to 12 months (n=251), the rate of unresolved motor deficits was significantly lower in the NC-MEP group (0.9%) compared with NC-EMG (6.9%) and SD-EMG (11.0%). A comparison of the NC-MEP versus NC-EMG and SD-EMG groups, both independently and combined, was statistically significant (>95% confidence level) for all analyses.

CONCLUSIONS

The results of the present study indicate that preservation of tcMEPs from the adductor longus, quadriceps, and tibialis anterior muscles are of paramount importance for limiting iatrogenic sensory and motor injuries during LLIF surgery. In this regard, the inclusion of tcMEPs serves to compliment EMG and allows for the periodic, functional assessment of at-risk nerves during these procedures. Thus, tcMEPs appear to be the most effective modality for the prevention of both transient and permanent neurologic injury during LLIF surgery. We propose that the standard paradigm for protecting the nervous system during LLIF be adapted to include tcMEPs.

Minimally invasive direct lateral interbody fusion in the treatment of the thoracic and lumbar spinal tuberculosisMini-DLIF for the thoracic and lumbar spinal tuberculosis

BACKGROUND

To investigate the clinical efficacy of minimally invasive direct lateral approach debridement, interbody bone grafting, and interbody fusion in the treatment of the thoracic and lumbar spinal tuberculosis.

METHODS

From January 2013 to January 2016, 35 cases with thoracic and lumbar spinal tuberculosis received direct lateral approach debridement, interbody bone grafting, and interbody fusion. Of the 35 cases, 16 patients were male and 19 were female and the median age was 55.2 (range 25-83). The affected segments were single interspace, and the involved vertebral bodies included: 15 cases of thoracic vertebrae (1 cases of T5/6, 2 cases of T6/7, 4 cases of T7/8, 3 cases of T8/9, 5 cases of T9/10) and 20 cases of lumbar spine (2 cases of L1/2, 6 cases of L2/3, 6 cases of L3/4, 6 cases of L4/5). After MIDLIF operation, all the patients received medication of four anti-tubercular drugs for 12 to18 months.

RESULTS

The patients were followed up for 7 to 40 months with an average of 18.5 months. The visual analogue scale (VAS) at the last follow-up was 2.8 ± 0.5, which was significantly different from the preoperative VAS (8.2 ± 0.7). After MIDLIF, there was 5 cases occurred with transient numbness in one side of the thigh or inguinal region, and 10 cases suffered from flexion hip weakness. All the bone grafts were fused within 6~ 18 months (average of 11.5 months) after the operation.

CONCLUSION

Minimally invasive lateral approach interbody fusion technology have the advantage of less injury and quick recovery after surgery, which is the effective and safe treatment for thoracic and lumbar spinal tuberculosis.

Recent Advances in Technique and Clinical Outcomes of Minimally Invasive Spine Surgery in Adult Scoliosis

Objective:

Conventional open spinal surgery of adult scoliosis can be performed from anterior, posterior, or combined approach. Minimally invasive spine surgery (MISS) was developed for the purpose of reducing the undesirable effects and complications. This review aimed to make a brief summary of recent studies of the approach and clinical outcomes of MISS in adult scoliosis.

Data Sources:

We conducted a systematic search from PubMed, Medline, EMBASE, and other literature databases to collect reports of surgical methods and clinical outcomes of MISS in treatment of adult scoliosis. Those reports were published up to March 2017 with the following key terms: “minimally invasive,” “spine,” “surgery,” and “scoliosis.”

Study Selection:

The inclusion criteria of the articles were as followings: diagnosed with adult degenerative scoliosis (DS) or adult idiopathic scoliosis; underwent MISS or open surgery; with follow-up data. The articles involving patients with congenital scoliosis or unknown type were excluded and those without any follow-up data were also excluded from the study. The initial search yielded 233 articles. After title and abstract extraction, 29 English articles were selected for full-text review. Of those, 20 studies with 831 patients diagnosed with adult DS or adult idiopathic scoliosis were reviewed. Seventeen were retrospective studies, and three were prospective studies.

Results:

The surgical technique reported in these articles was direct or extreme lateral interbody fusion, axial lumbar interbody fusion, and transforaminal lumbar interbody fusion. Among the clinical outcomes of these studies, the operated levels was 3–7, operative time was 2.3–8.5 h. Both the Cobb angle of coronal major curve and evaluation of Oswestry Disability Index and Visual Analog Scale decreased after surgery. There were 323 complications reported in the 831 (38.9%) patients, including 150 (18.1%) motor or sensory deficits, and 111 (13.4%) implant-related complications.

Conclusions:

MISS can provide good radiological and self-evaluation improvement in treatment of adult scoliosis. More prospective studies will be needed before it is widely used.

A psoas splitting approach developed for outpatient lateral interbody fusion versus a standard transpsoas approach

Background

The technique of transpsoas lateral interbody fusion has been adopted to avoid direct anterior interbody fusion, but lateral fusions have been limited to disc spaces above L5 and are associated with neurologic injuries especially to the lumbar plexus when approaching L4-5. The authors aim to demonstrate a psoas splitting technique to decrease risk of complications associated with the standard transpsoas technique.

Methods

Medical records of 84 patients with prospectively collected data reviewed. Two groups created 44 patients with standard lateral transpsoas approach (group 1) and 40 patients with psoas splitting approach (group 2). The psoas splitting approach utilizes two blades placed anteriorly and posteriorly to split the psoas fibers anteriorly while keeping the posterior blade docked in place where it enters the psoas muscle. The cephalocaudal blades sit above the psoas muscle measuring 30-40 mm shorter than the posterior docking blade.

Results

Thirty-nine males and 45 females, age range 31-71 years, average 58±2 years. Average body mass index (BMI) was 28.4±1.1 kg/m². Mean preoperative standard approach Oswestry disability index (ODI) increased from 48.4±3.0 to 55.2±4.0 compared to psoas splitting approach preoperative ODI means reduced from 45.1±5.0 to 34.9±6.0 (P=0.010). Group 1 mean preoperative visual analogue scale (VAS) score improved from 7.8±0.3 to 3.8±0.6 compared to group 2 mean preoperative VAS score which improved from 7.2±0.4 to 2.7±0.5 (P=0.048). Major complication rate of 20.5% was noted in standard transpsoas approach patients, including inability to walk and dermatome numbness.

Conclusions

The outcomes of this study have shown that patients who had lateral lumbar interbody fusion (LLIF) with the psoas splitting approach had statistically significant improvement in ODI scores compared to the standard approach. Fusion was achieved in all patients and there was no evidence of implant failure or subsidence. In the psoas splitting group the major complication rate was only 5%.

Minimally Invasive Transforaminal Versus Direct Lateral Lumbar Interbody Fusion: Effect on Return to Work, Narcotic Use, and Quality of life

BACKGROUND

Direct lateral (DLIF) and transforaminal (TLIF) lumbar interbody fusions have been shown to produce satisfactory clinical outcomes with significant reduction in pain and functional disability. Despite their increasing use in complex spinal deformity surgeries, there is a paucity of data comparing outcome measures, which this study addresses.

METHODS

This is a retrospective, comparative study of patients who underwent minimally invasive, 1-level TLIF or DLIF between 2013 and 2015. Only patients 18 years and older were included. Preoperative and demographic variables were collected, and clinical outcome measures were compared between cohorts.

RESULTS

In total, 46 patients were included (DLIF: 17 patients; TLIF: 29 patients). Preoperatively, there was no difference in visual analog scale pain score or Oswestry Disability Index. Overall, there was a significant improvement in the postoperative visual analog scale score and Oswestry Disability Index in the separate cohorts, without significant difference when compared. The duration of postoperative narcotic use was similar in both cohorts (DLIF: 4.8 ± 4.7 months vs. TLIF: 5.2 ± 5.1 months, P = 0.82). Significantly more patients in DLIF cohort were cleared for work after surgery. Patients who underwent MIS TLIF had a significantly longer time to return to work (7.1 ± 4.8 months) compared with patients undergoing DLIF (2.3 ± 1.3, P = 0.006). There was a greater incidence of reoperation in the TLIF cohort.

CONCLUSIONS

Both MIS TLIF and DLIF provide long-term improvement in pain andfunctional outcomes, with an overall reduction in postoperative narcotic requirement. However, there was a significantly longer time to return to work and a greater incidence of reoperation in the TLIF cohort compared with the patients who underwent DLIF.

Clinical and radiological outcomes of spinal endoscopic discectomy-assisted oblique lumbar interbody fusion: preliminary results

OBJECTIVE Direct neural decompression cannot be achieved by performing lateral lumbar interbody fusion (LLIF). To overcome the indirect decompressive effect of LLIF, additional endoscopic discectomy with oblique lumbar interbody fusion (OLIF) has been attempted. The purpose of this study was to assess the clinical and radiological outcomes of patients who underwent OLIF with additional endoscopic discectomy. METHODS Spinal endoscopic discectomy-assisted OLIF was attempted to remove herniated disc material. Only patients with a follow-up time that exceeded 12 months were enrolled. Clinical parameters examined were the Oswestry Disability Index and visual analog scale scores of back and leg pain. Postoperative MRI was also performed. RESULTS Fourteen patients were enrolled. Central and foraminal disc herniations were evident in 8 and 6 patients, respectively. Concomitant central or foraminal herniated discs were removed completely after additional endoscopic discectomy, and disc removal was confirmed by postoperative MRI. Mean preoperative visual analog scale scores and Oswestry Disability Index scores improved postoperatively. CONCLUSIONS OLIF with additional endoscopic discectomy results in successful direct neural decompression without posterior decompressive procedures. Endoscopic assistance might overcome the limitations of LLIF.

Analysis of Intraoperative Cone-Beam Computed Tomography Combined With Image Guidance for Lateral Lumbar Interbody Fusion

BACKGROUND

Minimally invasive lateral lumbar interbody fusion (LLIF) is traditionally performed with biplanar fluoroscopy. Recent literature demonstrates that intraoperative cone-beam computed tomography combined with spinal navigation can be safely utilized for localization and cage placement in LLIF.

OBJECTIVE

To evaluate the accuracy and safety of cage placement using spinal navigation in LLIF, as well as to evaluate the radiation exposure to surgeon and staff during the procedure.

METHODS

The authors performed a retrospective analysis of a prospectively acquired database of patients undergoing LLIF with image-based navigation performed from April 2014 to July 2016 at a single institution. The medical records were reviewed, and data on clinical outcomes, cage accuracy, complications, and radiation exposure were recorded. All patients underwent a minimum 30-d clinical follow-up to assess intraoperative and short-term complications associated with their LLIF.

RESULTS

Sixty-three patients comprising 117 spinal levels were included in the study. There were 36 (57.1%) female and 27 (42.9%) male patients. Mean age was 62.7 yr (range 24-79 yr). A mean 1.9 (range 1-4) levels per patient were treated. Cages were placed in the anterior or middle of 115 (98.3%) disc spaces. Image-guided cage trajectory was accurate in 116/117 levels (99.1%). In a subgroup analysis of 18 patients, mean fluoroscopy time was 11.7 ± 9.7 s per level. Sixteen (25.4%) patients experienced a complication related to approach.

CONCLUSION

Use of intraoperative cone-beam computed tomography combined with spinal navigation for LLIF results in accurate and safe cage placement as well as significantly decreased surgeon and staff radiation exposure.

Anatomy of psoas muscle innervation: Cadaveric study

Hip flexion weakness is relatively common after lateral transpsoas surgery. Persistent weakness may result from injury to the innervation of the psoas major muscles (PMMs); however, anatomical texts have conflicting descriptions of this innervation, and the branching pattern of the nerves within the psoas major, particularly relative to vertebral anatomy, has not been described. The authors dissected human cadavers to describe the branching pattern of nerves supplying the PMMs. Sixteen embalmed cadavers were dissected, and the fine branching pattern of the innervation to the PMM was studied in 24 specimens. The number of branches and width and length of each branch of nerves to the PMMs were quantified. Nerve branches innervating the PMMs arose from spinal nerve levels L1-L4, with an average of 6.3 ± 1.1 branches per muscle. The L1 nerve branch was the least consistently present, whereas L2 and L3 branches were the most robust, the most numerous, and always present. The nerve branches to the psoas major commonly crossed the intervertebral (IV) disc obliquely prior to ramification within the muscle; 76%, 80%, and 40% of specimens had a branch to the PMM cross the midportion of the L2-3, L3-4, and L4-5 IV discs, respectively. The PMMs are segmentally innervated from the L2-L4 ventral rami branches, where these branches course obliquely across the L2-3, L3-4, and L4-5 IV discs. Knowledge of the mapping of nerve branches to the PMMs may reduce injury and the incidence of persistent weak hip flexion during lateral transpsoas surgery. Clin. Anat. 30:479-486, 2017. © 2017 Wiley Periodicals, Inc.

Anatomical evaluation of lumbar nerves using diffusion tensor imaging and implications of lateral decubitus for lateral transpsoas approach

PURPOSE

Recently, lateral interbody fusion (LIF) has become more prevalent, and evaluation of lumbar nerves has taken on new importance. We report on the assessment of anatomical relationships between lumbar nerves and vertebral bodies using diffusion tensor imaging (DTI).

METHODS

Fifty patients with degenerative lumbar disease and ten healthy subjects underwent DTI. In patients with lumbar degenerative disease, we studied nerve courses with patients in the supine positions and with hips flexed. In healthy subjects, we evaluated nerve courses in three different positions: supine with hips flexed (the standard position for MRI); supine with hips extended; and the right lateral decubitus position with hips flexed. In conjunction with tractography from L3 to L5 using T2-weighted sagittal imaging, the vertebral body anteroposterior span was divided into four equally wide zones, with six total zones defined, including an anterior and a posterior zone (zone A, zones 1-4, zone P). We used this to characterize nerve courses at disc levels L3/4, L4/5, and L5/S1.

RESULTS

In patients with degenerative lumbar disease, in the supine position with hips flexed, all lumbar nerve roots were located posterior to the vertebral body centers in L3/4 and L4/5. In healthy individuals, the L3/4 nerve courses were displaced forward in hips extended compared with the standard position, whereas in the lateral decubitus position, the L4/5 and L5/S nerve courses were displaced posteriorly compared with the standard position.

CONCLUSIONS

The L3/4 and L4/5 nerve roots are located posterior to the vertebral body center. These were found to be offset to the rear when the hip is flexed or the lateral decubitus position is assumed. The present study is the first to elucidate changes in the course of the lumbar nerves as this varies by position. The lateral decubitus position or the position supine with hips flexed may be useful for avoiding nerve damage in a direct lateral transpsoas approach. Preoperative DTI seems to be useful in evaluating the lumbar nerve course as it relates anatomically to the vertebral body.

Resolution of the more anteriorly positioned psoas muscle following correction of spinal sagittal alignment from spondylolisthesis: case report

Several studies have described the radiographic, histological, and morphological changes to the paraspinal muscle in patients with chronic low-back pain due to degenerative diseases of the spine. Gross anatomical illustrations have shown that the psoas muscle lies lateral to the L4–5 vertebrae and subsequently thins and dissociates from the vertebral body at L5–S1 in a ventrolateral course. A “rising psoas” may influence the location of the lumbar plexus and result in transient neurological injury on lateral approach to the spine. It is postulated that axial back pain may be exacerbated by anatomical changes of paraspinal musculature as a direct result of degenerative spine conditions. To their knowledge, the authors present the first reported case of a more anteriorly positioned psoas muscle and its resolution following correction of spondylolisthesis in a 62-year-old woman. This case highlights the dynamic nature of degenerative spinal disorders and illustrates that psoas muscle position can be affected by sagittal balance. Normal anatomical positioning can be restored following correction of spinal alignment.

Technical description of oblique lateral interbody fusion at L1-L5 (OLIF25) and at L5-S1 (OLIF51) and evaluation of complication and fusion rates

BACKGROUND CONTEXT

The oblique lateral interbody fusion (OLIF) procedure is aimed at mitigating some of the challenges seen with traditional anterior lumbar interbody fusion (ALIF) and transpsoas lateral lumbar interbody fusion (LLIF), and allows for interbody fusion at L1-S1.

PURPOSE

The study aimed to describe the OLIF technique and assess the complication and fusion rates.

STUDY DESIGN

This is a retrospective cohort study.

PATIENT SAMPLE

The sample is composed of 137 patients who underwent OLIF procedure.

OUTCOME MEASURES

The outcome measures were adverse events within 6 months of surgery: infection, symptomatic pseudarthrosis, hardware failure, vascular injury, perioperative blood transfusion, ureteral injury, bowel injury, renal injury, prolonged postoperative ileus (more than 3 days), incisional hernia, pseudohernia, reoperation, neurologic deficits (weakness, numbness, paresthesia), hip flexion pain, retrograde ejaculation, sympathectomy affecting lower extremities, deep vein thrombosis, pulmonary embolism, myocardial infarction, pneumonia, and cerebrovascular accident. The outcome measures also include fusion and subsidence rates based on computed tomography (CT) done at 6 months postoperatively.

METHODS

Retrospective chart review of 150 consecutive patients was performed to examine the complications associated with OLIF at L1-L5 (OLIF25), OLIF at L5-S1 (OLIF51), and OLIF at L1-L5 combined with OLIF at L5-S1 (OLIF25+OLIF51). Only patients who had at least 6 months of postoperative follow-up, including CT scan at 6 months after surgery, were included. Independent radiology review of CT data was performed to assess fusion and subsidence rates at 6 months.

RESULTS

A total of 137 patients underwent fusion at 340 levels. An overall complication rate of 11.7% was seen. The most common complications were subsidence (4.4%), postoperative ileus (2.9%), and vascular injury (2.9%). Ileus and vascular injuries were only seen in cases including OLIF51. No patient suffered neurologic injury. No cases of ureteral injury, sympathectomy affecting the lower extremities, or visceral injury were seen. Successful fusion was seen at 97.9% of surgical levels.

CONCLUSIONS

Oblique lateral interbody fusion is a safe procedure at L1-L5 as well as L5-S1. The complication profile appears acceptable when compared with LLIF and ALIF. The oblique trajectory mitigates psoas muscle and lumbosacral plexus-related complications seen with the lateral transpsoas approach. Furthermore, there is a high fusion rate based on CT data at 6 months.

Endoscope-assisted oblique lumbar interbody fusion for the treatment of cauda equina syndrome: a technical note

OBJECTIVE

The goal of this paper was to describe how endoscope-assisted oblique lumbar interbody fusion (OLIF) could remove huge lumbar disc herniation (HLDH) manifested with cauda equina syndrome (CES).

METHODS

In this study, the authors made an attempt to treat CES with a direct endoscopic decompression through the OLIF corridor and performed OLIF in two patients with HLDH.

RESULTS

Two patients with HLDH were successfully treated using OLIF with spinal endoscopic discectomy. We achieved direct ventral decompression by removal of herniated disc fragments located beyond the posterior longitudinal ligament (PLL). All preoperative symptoms in two patients improved postoperatively.

CONCLUSIONS

Endoscope-assisted oblique lumbar interbody fusion (OLIF) could successfully achieve neural decompression without additional posterior decompression in CES and could be used as an alternative treatment in well selected cases.

The Oblique Anterolateral Approach to the Lumbar Spine Provides Access to the Lumbar Spine With Few Early Complications

BACKGROUND

During the last 20 years several less-invasive anterior approaches to the lumbar spine have become standard, including the extreme lateral transpsoas approach. Although it is associated with a lower risk of vascular injury compared with anterior midline approaches, neuromonitoring is considered mandatory to avoid neurologic complications. Interestingly, despite neuromonitoring, the reported risk of neurologic deficits with the extreme lateral transpsoas approach is greater than observed with other anterior approaches. An alternative lateral, oblique, psoas-sparing approach, recently named the oblique lumbar interbody fusion, uses the anatomic pathway between the abdominal vessels anteriorly and the lumbar plexus laterally to decrease the risk of neurologic and vascular injury; however, as yet, little on this new approach has been reported.

QUESTIONS/PURPOSES

We asked: what proportion of patients experienced (1) perioperative complications (overall complications), (2) vascular complications, and (3) neurologic complications after less-invasive anterior lumbar interbody fusion through the oblique lumbar interbody approach at one high-volume center?

METHODS

We performed a chart review of intra- and perioperative complications of all patients who had undergone minimally invasive anterior lumbar interbody fusion through a lateral psoas-sparing approach from L1 to L5 during a 12-year period (1998-2010). During the study period, the oblique, psoas-sparing approach was the preferred approach of the participating surgeons in this study, and it was performed in 812 patients, all of whom are studied here, and all of whom have complete data for assessment of the short-term (inpatient-only) complications that we studied. In general, we performed this approach whenever possible, although it generally was avoided when a patient previously had undergone an open retro- or transperitoneal abdominal procedure, or previous implantation of hernia mesh in the abdomen. During the study period, posterior fusion techniques were used in an additional 573 patients instead of the oblique lumbar interbody fusion when we needed to decompress the spinal canal beyond what is possible through the anterior approach. In case of spinal stenosis calling for fusion in combination with a high disc space, severe endplate irregularity, or severe biomechanical instability, we combined posterior decompression with oblique lumbar interbody fusion in 367 patients. Complications were evaluated by an independent observer who was not involved in the decision-making process, the operative procedure, nor the postoperative care by reviewing the inpatient records and operative notes.

RESULTS

A total of 3.7% (30/812) of patients who underwent the oblique lumbar interbody fusion experienced a complication intraoperatively or during the hospital stay. During the early postoperative period there were two superficial (0.24%) and three deep (0.37%) wound infections and five superficial (0.62%) and six deep (0.86%) hematomas. There were no abdominal injuries or urologic injuries. The percentage of vascular complications was 0.37% (n = 3). The percentage of neurologic complications was 0.37% (n = 3).

CONCLUSIONS

The risk of vascular complications after oblique lumbar interbody fusion seems to be lower compared with reported risk for anterior midline approaches, and the risk of neurologic complications after oblique lumbar interbody fusion seems to be lower than what has been reported with the extreme lateral transpsoas approach; however, we caution readers that head-to-head studies will need to be performed to confirm our very preliminary comparisons and results with the oblique psoas-sparing approach. Similarly, future studies will need to evaluate this approach in terms of later-presenting complications, such as infection and pseudarthrosis formation, which could not be assessed using this inpatient-only approach. Nevertheless, with the results of this study the oblique psoas-sparing approach can be described as a less-invasive alternative for anterior lumbar fusion surgery from L1 to L5 with a low risk of vascular and neurologic damage and without costly intraoperative neuromonitoring tools.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Risk Management for Avoidance of Major Vascular Injury due to Lateral Transpsoas Approach

STUDY DESIGN

A retrospective study using 323 contrast-enhanced, multi-planner three-dimensional computed (3D-CT) scans.

OBJECTIVE

The aim of this study was to identify risk factors for injury to the major vessels in the lateral transpsoas approach.

SUMMARY OF BACKGROUND DATA

To avoid critical complications such as major vessel injury, it is essential to examine anatomical information related to preoperative risk management that is specific to the lateral transpsoas approach.

METHODS

The abdominal contrast-enhanced, multi-planner 3D-CT scans of 323 consecutive subjects (203 males and 120 females, 15-89 years old) were retrospectively reviewed. The true axial views were used for evaluation of the locations of the major vein and artery at L3 to L4 and L4 to L5. According to the Moro system, the axial view was divided into 6 zones from the front side (A, I II, III, IV, P) and the locations of the dorsal tangential line of the major vessels were evaluated.

RESULTS

At the L3 to L4 level, the dorsal tangential line of the major vein located in zone A was found in 18% of subjects, in zone I in 74%, and in zone II in 8%. The line of the major artery was located in zone A in 92.6% of subjects and in zone I in 7.1%. At the L4 to L5 level, the line of the major vein was located in zone A in 5% of subjects, in zone I in 75%, in zone II in 20%, and in zone III in only 1 subject. The line of the major artery was identified in zone A in 87% of subjects, in zone I in 12%, and in zone II in 1%. Women had significant dorsal-migrated veins and arteries at both spinal levels (P < 0.01).

CONCLUSION

To avoid critical complications in extreme lateral lumbar interbody fusion, careful preoperative radiological evaluation of the major vessels and intraoperative care are important.

LEVEL OF EVIDENCE

3.

Lateral Lumbar Interbody Fusion: Indications, Outcomes, and Complications

Lateral lumbar interbody fusion is a minimally invasive spinal fusion technique that uses the retroperitoneal approach to the anterior spinal column. Mechanical and technical results of the technique compare favorably with those of anterior lumbar interbody fusion in regard to large graft placement, graft volumes, and early initial stability. Lateral lumbar interbody fusion uses the transpsoas approach and traverses near the lumbar plexus. It is not, however, without its unique complications. Groin pain or numbness is well tolerated and often temporary; however, quadriceps palsy can be long-lasting and debilitating. Rarer but serious complications include vascular and visceral injury. Lateral lumbar interbody fusion has been used successfully to treat common degenerative spinal conditions such as spinal instability, stenosis, scoliosis, and degenerative disk disease. While understanding of the lumbar plexus and the technical challenges of the procedure improves, lateral lumbar interbody fusion will continue to provide safe and successful clinical outcomes with less morbidity than traditional procedures.