Systematic Review of Thigh Symptoms after Lateral Transpsoas Interbody Fusion for Adult Patients with Degenerative Lumbar Spine Disease

Clinical Analysis and Imaging Study of Lateral Lumbar Intervertebral Fusion in the Treatment of Degenerative Lumbar Scoliosis

OBJECTIVE

As the population ages and technology advances, lateral lumbar intervertebral fusion (LLIF) is gaining popularity for the treatment of degenerative lumbar scoliosis (DLS). This study investigated the feasibility, minimally invasive concept, and benefits of LLIF for the treatment of DLS by observing and assessing the clinical efficacy, imaging changes, and complications following the procedure.

METHODS

A retrospective analysis was performed for 52 DLS patients (12 men and 40 women, aged 65.84 ± 9.873 years) who underwent LLIF from January 2019 to January 2023. The operation time, blood loss, complications, clinical efficacy indicators (visual analogue scale [VAS], Oswestry disability index [ODI], and 36-Item Short Form Survey), and imaging indicators (coronal position: Cobb angle and center sacral vertical line-C7 plumbline [CSVL-C7PL]; and sagittal position: sagittal vertical axis [SVA], lumbar lordosis [LL], pelvic incidence angle [PI], and thoracic kyphosis angle [TK] were measured). All patients were followed up. The above clinical evaluation indexes and imaging outcomes of patients postoperatively and at last follow-up were compared to their preoperative results.

RESULTS

Compared to the preoperative values, the Cobb angle and LL angle were significantly improved after surgery (p < 0.001). Meanwhile, CSVL-C7PL, SVA, and TK did not change much after surgery (p > 0.05) but improved significantly at follow-up (p < 0.001). There was no significant change in PI at either the postoperative or follow-up timepoint. The operation took 283.90 ± 81.62 min and resulted in a total blood loss of 257.27 ± 213.44 mL. No significant complications occurred. Patients were followed up for to 21.7 ± 9.8 months. VAS, ODI, and SF-36 scores improved considerably at postoperative and final follow-up compared to preoperative levels (p < 0.001). After surgery, the Cobb angle and LL angle had improved significantly compared to preoperative values (p < 0.001). CSVL-C7PL, SVA, and TK were stable after surgery (p > 0.05) but considerably improved during follow-up (p < 0.001). PI showed no significant change at either the postoperative or follow-up timepoints.

CONCLUSION

Lateral lumbar intervertebral fusion treatment of DLS significantly improved sagittal and coronal balance of the lumbar spine, as well as compensatory thoracic scoliosis, with good clinical and radiological findings. Furthermore, there was less blood, less trauma, and quicker recovery from surgery.

Advancing Prone-Transpsoas Spine Surgery: A Narrative Review and Evolution of Indications with Representative Cases

The Prone Transpsoas (PTP) approach to lumbar spine surgery, emerging as an evolution of lateral lumbar interbody fusion (LLIF), offers significant advantages over traditional methods. PTP has demonstrated increased lumbar lordosis gains compared to LLIF, owing to the natural increase in lordosis afforded by prone positioning. Additionally, the prone position offers anatomical advantages, with shifts in the psoas muscle and lumbar plexus, reducing the likelihood of postoperative femoral plexopathy and moving critical peritoneal contents away from the approach. Furthermore, operative efficiency is a notable benefit of PTP. By eliminating the need for intraoperative position changes, PTP reduces surgical time, which in turn decreases the risk of complications and operative costs. Finally, its versatility extends to various lumbar pathologies, including degeneration, adjacent segment disease, and deformities. The growing body of evidence indicates that PTP is at least as safe as traditional approaches, with a potentially better complication profile. In this narrative review, we review the historical evolution of lateral interbody fusion, culminating in the prone transpsoas approach. We also describe several adjuncts of PTP, including robotics and radiation-reduction methods. Finally, we illustrate the versatility of PTP and its uses, ranging from 'simple' degenerative cases to complex deformity surgeries.

Effect of Unintended Tissue Injury on the Development of Thigh Symptoms After Lateral Lumbar Interbody Fusion in Patients With Adult Spinal Deformity: A Retrospective Case Series

STUDY DESIGN

A retrospective case series.

OBJECTIVE

This study aimed to investigate the effects of lateral lumbar interbody fusion (LLIF)-induced unintended tissue damage, including cage subsidence, cage malposition, and hematoma in the psoas major muscle, on the development of thigh symptoms.

SUMMARY OF BACKGROUND DATA

Thigh symptoms are the most frequent complications after LLIF and are assumed to be caused by lumbar plexus compression and/or direct injury to the psoas major muscle. However, the causes and risk factors of thigh symptoms are yet to be fully understood.

MATERIALS AND METHODS

Adult patients with spinal deformity who underwent two-stage surgery using LLIF and a posterior open fusion for the first and second stages, respectively, were included. Computed tomography and magnetic resonance imaging were routinely performed after LLIF before posterior surgery to investigate cage subsidence, cage malposition, and hematoma in the psoas muscle. We evaluated the development of thigh symptoms after LLIF and examined the effects of tissue injury on the occurrence of thigh symptoms. The differences in demographics and surgical and tissue damage parameters were compared between the groups with and without thigh symptoms using unpaired t tests and chi-squared tests. Factors associated with the development of thigh symptoms and muscle weakness were also assessed using logistic regression analysis.

RESULTS

Overall, 130 patients [17 men and 113 women; mean age, 68.7 (range, 47-84)] were included. Thigh symptoms were observed in 52 (40.0%) patients, including muscle weakness and contralateral side symptoms in 20 (15.4%) and 9 (17.3%) patients, respectively. The factors significantly associated with thigh symptoms identified after multiple logistic regression analysis included hematoma (odds ratio: 2.27, 95% CI, 1.03-5.01) and approach from the right side (odds ratio: 2.64, 95% CI, 1.21-5.75). The presence of cage malposition was the only significant factor associated with muscle weakness (odds ratio: 4.12, 95% CI, 1.37-12.4).

CONCLUSIONS

We found unintended tissue injury during LLIF was associated with thigh symptoms. We found that hematoma in the psoas major muscle and cage malposition were the factors associated with thigh symptoms and muscle weakness, respectively.

Complications of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicenter Study

BACKGROUND AND OBJECTIVES

The prone transpsoas (PTP) approach for lateral lumbar interbody fusion (LLIF) is a novel technique for degenerative lumbar spine disease. However, there is a paucity of information in the literature on the complications of this procedure, with all published data consisting of small samples. We aimed to report the intraoperative and postoperative complications of PTP in the largest study to date.

METHODS

A retrospective electronic medical record review was conducted at 11 centers to identify consecutive patients who underwent LLIF through the PTP approach between January 1, 2021, and December 31, 2021. The following data were collected: intraoperative characteristics (operative time, estimated blood loss [EBL], intraoperative complications [anterior longitudinal ligament (ALL) rupture, cage subsidence, vascular and visceral injuries]), postoperative complications, and hospital stay.

RESULTS

A total of 365 patients were included in the study. Among these patients, 2.2% had ALL rupture, 0.3% had cage subsidence, 0.3% had a vascular injury, 0.3% had a ureteric injury, and no other visceral injuries were reported. Mean operative time was 226.2 ± 147.9 minutes. Mean EBL was 138.4 ± 215.6 mL. Mean hospital stay was 2.7 ± 2.2 days. Postoperative complications included new sensory symptoms-8.2%, new lower extremity weakness-5.8%, wound infection-1.4%, cage subsidence-0.8%, psoas hematoma-0.5%, small bowel obstruction and ischemia-0.3%, and 90-day readmission-1.9%.

CONCLUSION

In this multicenter case series, the PTP approach was well tolerated and associated with a satisfactory safety profile.

Establishing a Standardized Clinical Consensus for Reporting Complications Following Lateral Lumbar Interbody Fusion

Background and Objectives: Mitigating post-operative complications is a key metric of success following interbody fusion. LLIF is associated with a unique complication profile when compared to other approaches, and while numerous studies have attempted to report the incidence of post-operative complications, there is currently no consensus regarding their definitions or reporting structure. The aim of this study was to standardize the classification of complications specific to lateral lumbar interbody fusion (LLIF). Materials and Methods: A search algorithm was employed to identify all the articles that described complications following LLIF. A modified Delphi technique was then used to perform three rounds of consensus among twenty-six anonymized experts across seven countries. Published complications were classified as major, minor, or non-complications using a 60% agreement threshold for consensus. Results: A total of 23 articles were extracted, describing 52 individual complications associated with LLIF. In Round 1, forty-one of the fifty-two events were identified as a complication, while seven were considered to be approach-related occurrences. In Round 2, 36 of the 41 events with complication consensus were classified as major or minor. In Round 3, forty-nine of the fifty-two events were ultimately classified into major or minor complications with consensus, while three events remained without agreement. Vascular injuries, long-term neurologic deficits, and return to the operating room for various etiologies were identified as important consensus complications following LLIF. Non-union did not reach significance and was not classified as a complication. Conclusions: These data provide the first, systematic classification scheme of complications following LLIF. These findings may improve the consistency in the future reporting and analysis of surgical outcomes following LLIF.

Outpatient outcomes of patients with femoral nerve neurapraxia after prone lateral lumbar interbody fusion at L4-5

OBJECTIVE

Single-position prone lateral lumbar interbody fusion (LLIF) improves the efficiency of staged minimally invasive lumbar spine surgery. However, laterally approaching the lumbar spine, especially L4-5 with the patient in the prone position, could increase the risk of complications and presents unique challenges, including difficult ergonomics, psoas migration, and management of the nearby lumbar plexus. The authors sought to identify postoperative femoral neurapraxia after single-position prone LLIF at L4-5 to better understand how symptoms evolve over time.

METHODS

This retrospective analysis examined a prospectively maintained database of LLIF patients who were treated by two surgeons (J.S.U. and J.D.T.). Patients who underwent single-position prone LLIF at L4-5 and percutaneous pedicle screw fixation for lumbar stenosis or spondylolisthesis were included if they had at least 6 weeks of follow-up. Outpatient postoperative neurological symptoms were analyzed at 6-week, 3-month, and 6-month follow-up evaluations.

RESULTS

Twenty-nine patients (16 women [55%]; overall mean ± SD age 62 ± 11 years) met the inclusion criteria. Five patients (17%) experienced complications, including 1 (3%) who had a femoral nerve injury with resultant motor weakness. The mean ± SD transpsoas retractor time was 14.6 ± 6.1 minutes, the directional anterior electromyography (EMG) threshold before retractor placement was 20.1 ± 10.2 mA, and the directional posterior EMG threshold was 10.4 ± 9.1 mA. All patients had 6-week clinical follow-up evaluations. Ten patients (34%) reported thigh pain or weakness at their 6-week follow-up appointment, compared with 3/27 (11%) at 3 months and 1/20 (5%) at 6 months. No association was found between directional EMG threshold and neurapraxia, but longer transpsoas retractor time at L4-5 was significantly associated with femoral neurapraxia at 6-week follow-up (p = 0.02). The only case of femoral nerve injury with motor weakness developed in a patient with a retractor time that was nearly twice as long as the mean time (27.0 vs 14.6 minutes); however, this patient fully recovered by the 3-month follow-up evaluation.

CONCLUSIONS

To our knowledge, this is the largest study with the longest follow-up duration to date after single-position prone LLIF at L4-5 with percutaneous pedicle screw fixation. Although 34% of patients reported ipsilateral sensory symptoms in the thigh at the 6-week follow-up evaluation, only 1 patient sustained a nerve injury; this resulted in temporary weakness that resolved by the 3-month follow-up evaluation. Thus, longer transpsoas retractor time at L4-5 during prone LLIF is associated with increased ipsilateral thigh symptoms at 6-week follow-up that may resolve over time.

Efficacy of Single-Position Oblique Lateral Interbody Fusion Combined With Percutaneous Pedicle Screw Fixation in Treating Degenerative Lumbar Spondylolisthesis: A Cohort Study

Objective

To investigate the surgical outcomes of single-position oblique lateral interbody fusion (OLIF) combined with percutaneous pedicle screw fixation (PPSF) in treating degenerative lumbar spondylolisthesis (DLS).

Methods

We retrospectively analyzed 85 patients with DLS who met the inclusion criteria from April 2018 to December 2020. According to the need to change their position during the operation, the patients were divided into a single-position OLIF group (27 patients) and a conventional OLIF group (58 patients). The operation time, intraoperative blood loss, hospitalization days, instrumentation accuracy and complication rates were compared between the two groups. The visual analog scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy. The surgical segment's intervertebral space height (IDH) and lumbar lordosis (LL) angle were used to evaluate the imaging effect.

Results

The hospital stay, pedicle screws placement accuracy, and complication incidence were similar between the two groups (P > 0.05). The operation time and intraoperative blood loss in the single-position OLIF group were less than those in the conventional OLIF group (P < 0.05). The postoperative VAS, ODI, IDH and LL values were significantly improved (P < 0.05), but there was no significant difference between the two groups (P > 0.05).

Conclusions

Compared with conventional OLIF, single-position OLIF combined with PPSF is also safe and effective, and it has the advantages of a shorter operation time and less intraoperative blood loss.

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.

Lateral interbody release for fused vertebrae via transpsoas approach in adult spinal deformity surgery: a preliminary report of radiographic and clinical outcomes

BACKGROUND

Lateral interbody release (LIR) via a transpsoas lateral approach is a surgical strategy to address degenerative lumbar scoliosis (DLS) patients with anterior autofusion of vertebral segments. This study aimed to characterize the clinical and radiographic outcomes of this lumbar reconstruction strategy using LIR to achieve anterior column correction.

METHODS

Data for 21 fused vertebrae in 17 consecutive patients who underwent LIR between January 2014 and March 2020 were reviewed. Demographic and intraoperative data were recorded. Radiographic parameters were assessed preoperatively and at final follow-up, including segmental lordotic angle (SLA), segmental coronal angle (SCA), bone union rate, pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt, sacral slope, PI-LL mismatch, sagittal vertical axis, Cobb angle, and deviation of the C7 plumb line from the central sacral vertical line. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), visual analog scale (VAS) scores for low back and leg pain, and the short form 36 health survey questionnaire (SF-36) postoperatively and at final follow-up. Complications were also assessed.

RESULTS

Mean patient age was 70.3 ± 4.8 years and all patients were female. Average follow-up period was 28.4 ± 15.3 months. Average procedural time to perform LIR was 21.3 ± 9.7 min and was not significantly different from traditional lateral interbody fusion at other levels. Blood loss per single segment during LIR was 38.7 ± 53.2 mL. Fusion rate was 100.0% in this cohort. SLA improved significantly from - 7.6 ± 9.2 degrees preoperatively to 7.0 ± 8.8 degrees at final observation and SCA improved significantly from 19.1 ± 7.8 degrees preoperatively to 8.7 ± 5.9 degrees at final observation (P < 0.0001, and < 0.0001, respectively). All spinopelvic and coronal parameters, as well as ODI and VAS, improved significantly. Incidence of peri- and postoperative complications such as iliopsoas muscle weakness and leg numbness in patients who underwent LIR was as much as XLIF. Incidence of postoperative mechanical failure following LIR was also similar to XLIF. Reoperation rate was 11.8%. However, there were no reoperations associated with LIR segments.

CONCLUSIONS

The LIR technique for anterior column realignment of fused vertebrae in the context of severe ASD may be an option of a safe and effective surgical strategy.

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.

COMPARISON OF PSOAS MORPHOLOGY AND LUMBAR LORDOSIS IN DIFFERENT POSTURES

ABSTRACT Objective: To compare the interobserver reliability of measurements of psoas morphology and lumbar lordosis in different positions and to standardize the performance of magnetic resonance imaging in the prone and lateral positions. Methods: This is a cross-sectional study carried out with asymptomatic volunteers of both sexes, aged over 18 years, with no known pathological changes in the lumbar region. Magnetic resonance imaging of the lumbar spine was performed in the supine, right lateral decubitus and prone positions, obtaining images in T2-weighted sequences in the sagittal and axial planes. The distances were measured from the psoas to the vertebral plateau and from the psoas to the lumbar plexus. The exams were assessed by two independent, blinded orthopedists. Results: There was excellent agreement between the measurements of vertebral size (ICC=0.92), low agreement for plexus distance (ICC=0.63) and high agreement for the anterior margin (ICC=0.84). Conclusion: There was good reproducibility of 2 of the 3 measures proposed, suggesting that the technique in the lateral and prone positions is capable of generating quality images. Level of Evidence 3B; Prospective.

Lateral lumbar interbody fusion in adult spine deformity - A review of literature

INTRODUCTION

Surgery for adult spine deformity presents a challenging issue for spinal surgeons with high morbidity rates reported in the literature. The minimally invasive lateral approach aims at reducing these complications while maintaining similar outcomes as associated with open spinal surgeries. The aim of this paper is to review the literature on the use of lateral lumbar interbody fusion in the cases of adult spinal deformity.

METHODS

A literature review was done using the healthcare database Advanced Research on NICE and NHS website using Medline. Search terms were "XLIF" or "LLIF" or "DLIF" or "lateral lumbar interbody fusion" or "minimal invasive lateral fusion" and "adult spinal deformity" or "spinal deformity".

RESULTS

A total of 417 studies were considered for the review and 44 studies were shortlisted after going through the selection criteria. The data of 1722 patients and 4057 fusion levels were analysed for this review. The mean age of the patients was 65.18 years with L4/5 being the most common level fused in this review. We found significant improvement in the radiological parameters (lordosis, scoliosis, and disk height) in the pooled data. Transient neurological symptoms and cage subsidence were the two most common complications reported.

CONCLUSION

LLIF is a safe and effective approach in managing adult spinal deformity with low morbidity and acceptable complication rates. It can be used alone for lower grades of deformity and as an adjuvant procedure to decrease the magnitude of open surgeries in high-grade deformities.

Psoas Major Muscle Volume Does Not Affect the Postoperative Thigh Symptoms in XLIF Surgery

Background: Extreme lateral interbody fusion (XLIF) is a minimally invasive surgery that accesses the lumbar spine through the psoas muscle. This study aimed to evaluate the correlation between the psoas major muscle volume and anterior thigh symptoms after XLIF. Methods: Eighty-one patients (mean age 63 years) with degenerative spine diseases underwent XLIF (total = 94 levels). Thirty-eight patients were female (46.9%), and 24 patients (29.6%) had a history of lumbar surgery. Supplemental pedicle screws were used in 48 patients, and lateral plates were used in 28 patients. Neuromonitoring devices were used in all cases. The patients were classified into two groups (presence of thigh symptoms and no thigh symptoms after the surgery). The psoas major volumes were measured and calculated by CT (computed tomography) scan and compared between the two patient groups. Results: In the first 24 h after surgery, 32 patients (39.5%) had thigh symptoms (20 reported pain, 9 reported numbness, and 18 reported weakness). At one year postoperatively, only 3 of 32 patients (9.4%) had persistent symptoms. Conclusions: As a final observation, no statistically significant difference in the mean psoas major volume was found between the group of patients with new postoperative anterior thigh symptoms and those with no thigh symptoms. Preoperative psoas major muscle volume seems not to correlate with postoperative anterior thigh symptoms after XLIF.

The Safety and Efficacy of Stand-Alone Lateral Lumbar Interbody Fusion for Adjacent Segment Disease in a Cohort of 44 Patients

BACKGROUND

A mainstay of treatment for symptomatic adjacent segment disease (ASD) has consisted of revision with posterior decompression and fusion. This carries significant morbidity and can be technically difficult. An alternative is stand-alone lateral lumbar interbody fusion (LLIF), which may avoid complications associated with revision surgery. We describe the largest cohort of patients treated with LLIF for ASD to our knowledge.

METHODS

We conducted a retrospective cohort study on all patients who underwent transpsoas LLIF for ASD at a single academic center between 2012 and 2019. Postoperative improvement was measured using the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI).

RESULTS

Forty-four patients who underwent LLIF for ASD were identified. Median age was 65 years. Median time from index surgery to ASD development was 78 months. Median levels fused via LLIF was 1. Our median follow-up was 358 days. At follow-up, the median VAS back pain score was 0 (mean, 0.884), median VAS leg pain score was 1 (mean, 0.953), and median ODI was 8. The median improvement for VAS back pain was 8, for VAS leg pain was 6, and for ODI was 40. No patients suffered new neurologic symptoms postoperatively. Of the 17 patients who initially presented with non-pain neurologic symptoms, 8 (47.1%) experienced complete resolution of symptoms, and 5 (29.4%) experienced only some improvement.

CONCLUSIONS

To our knowledge, this is the largest cohort study of patients to date evaluating stand-alone LLIF for ASD. Our patient outcomes show it is safe and effective with low risk of morbidity.

State of the art advances in minimally invasive surgery for adult spinal deformity

Adult spinal deformity (ASD) can be associated with substantial suffering due to pain and disability. Surgical intervention for achieving neural decompression and restoring physiological spinal alignment has shown to result in significant improvement in pain and disability through patient-reported outcomes. Traditional open approaches involving posterior osteotomy techniques and instrumentation are effective based on clinical outcomes but associated with high complication rates, even in the hands of the most experienced surgeons. Minimally invasive techniques may offer benefit while decreasing associated morbidity. Minimally invasive surgery (MIS) for ASD has evolved over the past 20 years, driven by improved understanding of open procedures along with novel technique development and technologic advancements. Early efforts were hindered due to suboptimal outcomes resulting from high pseudarthrosis, inadequate correction, and fixation failure rates. To address this, multi-center collaborative groups have been established to study large numbers of ASD patients which have been vital to understanding optimal patient selection and individualized management strategies. Different MIS decision-making algorithms have been described to better define appropriate candidates and interbody selection approaches in ASD. The purpose of this state of the review is to describe the evolution of MIS surgery for adult deformity with emphasis on landmark papers, and to discuss specific MIS technology for ASD, including percutaneous pedicle screw instrumentation, hyperlordotic grafts, three-dimensional navigation, and robotics.

Anterior Column Realignment: Analysis of Neurological Risk and Radiographic Outcomes

BACKGROUND

Anterior column realignment (ACR) is a less invasive alternative to 3-column osteotomy for the correction of sagittal imbalance. We hypothesized that ACR would correct sagittal imbalance with an acceptable neurological risk.

OBJECTIVE

To assess long-term neurological and radiographic outcomes after ACR.

METHODS

Patients ≥18 yr who underwent ACR from 2005 to 2013 were eligible. Standing scoliosis radiographs were studied at preoperation, postoperation (≤6 wk), and at minimum 2 yr of follow-up. Clinical/radiographic data were collected through a retrospective chart review, with thoracic 1 spino-pelvic inclination (T1SPi) used as the angular surrogate for sagittal vertical axis.

RESULTS

A total of 26 patients had complete data, with a mean follow-up of 2.8 yr (1.8-7.4). Preoperative, sagittal parameters were lumbar lordosis (LL) of -16.1°, pelvic incidence (PI)-LL of 41.7°, T1SPi of 3.6°, and pelvis tilt (PT) of 32.4°. LL improved by 30.6° (P < .001) postoperation. Mean changes in PT (-8.3), sacral slope (8.9), T1SPi (-4.9), and PI-LL (-33.5) were all significant. The motion segment angle improved by 26.6°, from 5.2° to -21.4° (P < .001). Neurological complications occurred in 32% patients postoperation (n = 8; 1 patient with both sensory and motor). New thigh numbness/paresthesia developed in 3 (13%) patients postoperation; only 1 (4%) persisted at latest follow-up. A total of 6 (24%) patients developed a new lower extremity motor deficit postoperation, with 4 (8%) having persistent new weakness at last follow-up. Out of 8 patients with preoperative motor deficit, half saw improvement postoperation and 75% improved by last follow-up.

CONCLUSION

There was net motor improvement, with 24% of patients improving and 16% having persistent new weakness at latest follow-up; 60% were unchanged. Radiographic results demonstrate that ACR is a useful tool to treat severe sagittal plane deformity.

The feasibility of computer-assisted 3D navigation in multiple-level lateral lumbar interbody fusion in combination with posterior instrumentation for adult spinal deformity

OBJECTIVE

The lateral lumbar interbody fusion (LLIF) technique is used to treat many common spinal degenerative pathologies including kyphoscoliosis. The use of spinal navigation for LLIF has not been broadly adopted, especially in adult spinal deformity. The purpose of this study was to evaluate the feasibility as well as the intraoperative and navigation-related complications of computer-assisted 3D navigation (CaN) during multiple-level LLIF for spinal deformity.

METHODS

Retrospective analysis of clinical and operative characteristics was performed for all patients > 18 years of age who underwent multiple-level CaN LLIF combined with posterior instrumentation for adult spinal deformity at the University of Michigan between 2014 and 2020. Intraoperative CaN-related complications, LLIF approach–related postoperative complications, and medical postoperative complications were assessed.

RESULTS

Fifty-nine patients were identified. The mean age was 66.3 years (range 42–83 years) and body mass index was 27.6 kg/m2 (range 18–43 kg/m2). The average coronal Cobb angle was 26.8° (range 3.6°–67.0°) and sagittal vertical axis was 6.3 cm (range −2.3 to 14.7 cm). The average number of LLIF and posterior instrumentation levels were 2.97 cages (range 2–5 cages) and 5.78 levels (range 3–14 levels), respectively. A total of 6 intraoperative complications related to the LLIF stage occurred in 5 patients. Three of these were CaN-related and occurred in 2 patients (3.4%), including 1 misplaced lateral interbody cage (0.6% of 175 total lateral cages placed) requiring intraoperative revision. No patient required a return to the operating room for a misplaced interbody cage. A total of 12 intraoperative complications related to the posterior stage occurred in 11 patients, with 5 being CaN-related and occurring in 4 patients (6.8%). Univariate and multivariate analyses revealed no statistically significant risk factors for intraoperative and CaN-related complications. Transient hip weakness and numbness were found to be in 20.3% and 22.0% of patients, respectively. At the 1-month follow-up, weakness was observed in 3.4% and numbness in 11.9% of patients.

CONCLUSIONS

Use of CaN in multiple-level LLIF in the treatment of adult spinal deformity appears to be a safe and effective technique. The incidence of approach-related complications with CaN was 3.4% and cage placement accuracy was high.

Minimally Invasive Lateral Lumbar Interbody Fusion for Clinical Adjacent Segment Pathology: A Comparative Study With Conventional Posterior Lumbar Interbody Fusion

STUDY DESIGN

This was a retrospective comparative study.

OBJECTIVE

The main objective of this article was to evaluate the clinical and radiologic efficacies of minimally invasive lateral lumbar interbody fusion (LLIF) for clinical adjacent segment pathology (ASP).

SUMMARY OF BACKGROUND DATA

Minimally invasive techniques have been increasingly applied for spinal surgery. No report has compared LLIF with conventional posterior lumbar interbody fusion for clinical ASP.

METHODS

Forty patients undergoing LLIF with posterior fusion (hybrid surgery) were compared with 40 patients undergoing conventional posterior lumbar interbody fusion (posterior surgery). The radiologic outcomes including indirect decompression in hybrid surgery group, and clinical outcomes such as the Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) were assessed. Postoperative major complications and reoperations were also compared between the 2 groups.

RESULTS

Correction of coronal Cobb's angle and segmental lordosis in the hybrid surgery were significantly greater postoperatively (2.8 vs. 0.9 degrees, P=0.012; 7.4 vs. 2.5 degrees, P=0.009) and at the last follow-up (2.4 vs. 0.5 degrees, P=0.026; 4.8 vs. 0.8 degrees, P=0.016) compared with posterior surgery. As regards indirect decompression of the LLIF, significant increases in thecal sac (83.4 vs. 113.8 mm) and foraminal height (17.8 vs. 20.9 mm) were noted on postoperative magnetic resonance imaging. Although postoperative back VAS (4.1 vs. 5.6, P=0.011) and ODI (48.9% vs. 59.6%, P=0.007) were significantly better in hybrid surgery, clinical outcomes at the last follow-up were similar. Moreover, intraoperative endplate fractures developed in 17.7% and lower leg symptoms occurred in 30.0% of patients undergoing hybrid surgery.

CONCLUSIONS

Hybrid surgery for clinical ASP has advantages of segmental coronal and sagittal correction, and indirect decompression compared with conventional posterior surgery. However, LLIF-related complications such as endplate fracture and lower leg symptoms also developed. LLIF should be performed considering advantages and approach-related complications for the clinical ASP.

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.

Unilateral versus bilateral lower extremity motor deficit following complex adult spinal deformity surgery: is there a difference in recovery up to 2-year follow-up?

BACKGROUND CONTEXT

Scoli-RISK-1 is a multicenter prospective cohort designed to study neurologic outcomes following complex adult spinal deformity (ASD). The effect of unilateral versus bilateral postoperative motor deficits on the likelihood of long-term recovery has not been previously studied in this population.

PURPOSE

To evaluate whether bilateral postoperative neurologic deficits have a worse recovery than unilateral deficits.

STUDY DESIGN

Secondary analysis of a prospective, multicenter, international cohort study.

METHODS

In a cohort of 272 patients, neurologic decline was defined as deterioration of the American Spinal Injury Association Lower Extremity Motor Scores (LEMS) following surgery. Patients with lower extremity neurologic decline were grouped into unilateral and bilateral cohorts. Differences in demographics, surgical variables, and patient outcome measures between the two cohorts were analyzed.

RESULTS

A total of 265 patients had LEMS completed at discharge. Unilateral decline was seen in 32 patients (12%), while 29 (11%) had bilateral symptoms. At 2 years, there was no significant difference in either median LEMS (unilateral 50.0, interquartile range [IQR] 47.5-50.0; bilateral 50.0, IQR 48.0-50.0, p=.939) or change in LEMS from baseline (unilateral 0.0, IQR -1.0 to 0.0; bilateral 0.0, IQR -1.0 to 0.0, p=.920). In both groups, approximately two-thirds of patients saw recovery to at least their preoperative baseline by 2 years postoperatively (unilateral n=15, 63%; bilateral n=14, 67%). The mean Scoliosis Research Society-22R (SRS-22R) score at 2 years was 3.7±0.6 versus 3.2±0.6 (p=.009) for unilateral and bilateral groups, respectively.

CONCLUSIONS

The prognosis for neurologic recovery of new motor deficits following complex adult spinal deformity is similar with both unilateral and bilateral weaknesses. Despite similar rates of neurologic recovery, patient reported outcomes for those with bilateral motor decline measured by SRS-22R are worse at 2 years after surgery.

Minimally Invasive Lateral Lumbar Interbody Fusion for Adult Spinal Deformity: Clinical and Radiological Efficacy With Minimum Two Years Follow-up

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To evaluate the clinical and radiological efficacies of supplementing minimally invasive lateral lumbar interbody fusion (LLIF) with open posterior spinal fusion (PSF) in adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

Minimally invasive techniques have been increasingly applied for surgery of ASD. Few reports have been published that directly compare LLIF combined with PSF to conventional PSF for ASD.

METHODS

To evaluate the advantages of minimally invasive LLIF for ASD, patients who underwent minimally invasive LLIF followed by open PSF (combined group) were compared with patients who only underwent PSF (only PSF group). The clinical and radiological outcomes for deformity correction and indirect decompression were assessed. The occurrence of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) were also evaluated.

RESULTS

No significant differences were observed in the clinical outcomes of the Oswestry Disability Index (ODI), visual analog scale, and major complications including reoperations between the groups. No additional advantage was found for coronal deformity correction, but the restoration of lumbar lordosis in the combined group was significantly higher postoperatively (15.3° vs. 8.87°, P = 0.003) and last follow-up (6.69° vs. 1.02°, P = 0.029) compared to that of the only PSF group. In the subgroup analysis for indirect decompression for the combined group, a significant increase of canal area (104 vs. 122 mm) and foraminal height (16.2 vs. 18.5 mm) was noted. The occurrence of PJK or PJF was significantly higher in the combined group than in the only PSF group (P = 0.039).

CONCLUSION

LLIF has advantages of indirect decompression and greater improvements of sagittal correction compared to only posterior surgery. LLIF should be conducted considering the above-mentioned benefits and complications including PJK or PJF in ASD.

LEVEL OF EVIDENCE

4.

Morphometric MRI Imaging Study of the Corridor for the Oblique Lumbar Interbody Fusion Technique at L1-L5

BACKGROUND

Anterior lumbar interbody fusion and lateral lumbar interbody fusion are associated with approach-related disadvantages. Oblique lumbar interbody fusion (OLIF) is the proposed solution, especially for upper lumbar levels. We analyzed the size and regional anatomy of the corridor used in the OLIF technique between levels L1 and L5.

METHODS

This is a morphometric study of 200 randomly selected magnetic resonance imaging (MRI) studies with features of lumbar degenerative disease. On MRI, the oblique corridor was defined as the smallest distance between the psoas major muscle and aorta or inferior vena cava (or common iliac artery) and measured at the L1/L2, L2/L3, L3/L4, and L4/L5 disc levels on both the left and right on the axial images at the mid-disc level.

RESULTS

Mean distances of the oblique corridor on the left side were L1/L2 = 18.90 mm, L2/L3 = 15.50 mm; L3/L4 = 12.75 mm, and L4/L5 = 8.92 mm; on the right side, they were L1/L2 = 14.80 mm, L2/L3 = 5.50 mm, L3/L4 = 3.00 mm, and L4/L5 = 1.46 mm. For both sides, the corridor size was not significantly affected by sex, and it increased with age and decreased at the inferior lumbar disc levels. The L1/L2 and L2/L3 levels may be obstructed by the ipsilateral kidney and renal vasculature on both sides and the liver on the right side.

CONCLUSIONS

A left-sided OLIF approach is viable for both sexes. Oblique access to the L1/L2 and L2/L3 disc levels is feasible regardless of age, whereas the L3/L4 and L4/L5 levels may be more suitable in older patients, especially for male patients. The right-sided approach is less likely to be performed effectively.

Understanding Retroperitoneal Anatomy for Lateral Approach Spine Surgery

Lateral approach spine surgery provides effective interbody stabilization, and correction and indirect neural decompression with minimal-incision and less invasive surgery compared with conventional open anterior lumbar fusion. It may also avoid the trauma to paraspinal muscles or facet joints found with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. However, because lateral approach surgery is fundamentally retroperitoneal approach surgery, it carries potential risk to intra- and retroperitoneal structures, as seen in a conventional open anterior approach. There is an innovative lateral approach technique that reveals different anatomical views; however, it requires reconsideration of the traditional surgical anatomy in more detail than a traditional open anterior approach. The retroperitoneum is the compartmentalized space bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. The retroperitoneum is divided into three compartments by fascial planes: anterior and posterior pararenal spaces and the perirenal space. Lateral approach surgery requires mobilization of the peritoneum and its content and accurate exposure to the posterior pararenal space. The posterior pararenal space is confined anteriorly by the posterior renal fascia, anteromedially by the lateroconal fascia, and posteriorly by the transversalis fascia. The posterior renal fascia, the lateroconal fascia or the peritoneum should be detached from the transversalis fascia and the psoas fascia to allow exposure to the posterior pararenal space. The posterior pararenal space, however, does not allow a clear view and identification of these fasciae as this relationship is variable and the medial extent of the posterior pararenal space varies among patients. Correct anatomical recognition of the retroperitoneum is essential to success in lateral approach surgery. Spine surgeons must be aware that the retroperitoneal membrane and fascia is multilayered and more complex than is commonly understood. Preoperative abdominal images would facilitate more efficient surgical considerations of retroperitoneal membrane and fascia in lateral approach surgery.

Oblique Lumbar Interbody Fusion: Technical Aspects, Operative Outcomes, and Complications

OBJECTIVE

Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) are commonly used approaches for lumbar spine fusion surgery, each with their own unique advantages and disadvantages. ALIF requires mobilization of the great vessels and peritoneum, and dissection of the psoas muscle in the LLIF technique is associated with postoperative neurologic complications in the proximal lower limb. The anterior-to-psoas (ATP) or oblique lumbar interbody fusion (OLIF) technique is the proposed solution to accessing the L1-L5 levels without the issues encountered with ALIF and LLIF. In this review, the technical nuances, operative outcomes, and complications with the ATP/OLIF technique in the current literature are summarized.

METHODS

A systematic search of the literature was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Data collected included operative time, blood loss, postoperative hospital stay, and complications, which were then pooled together.

RESULTS

From the 16 studies selected, the mean blood loss was 109.9 mL, average operating time was 95.2 minutes, and mean postoperative hospital stay was 6.3 days. Fusion was achieved in 93% of levels operated. Incidence of intraoperative and postoperative complications was 1.5% and 9.9%, respectively. Transient thigh pain and/or numbness and hip flexion weakness occurred in 3.0% and 1.2% of patients, respectively.

CONCLUSIONS

Early results on the ATP/OLIF technique are promising and warrant further investigation with well-designed prospective randomized studies to provide high-level evidence of the potential advantages over the ALIF and LLIF approaches.