Visceral, vascular, and wound complications following over 13,000 lateral interbody fusions: a survey study and literature review

Lateral lumbar interbody fusion - clinical outcomes, fusion rates and complications with recombinant human bone morphogenetic protein-2

BACKGROUND

The authors report an Australian experience of lateral lumbar interbody fusion (LLIF) with respect to clinical outcomes, fusion rates, and complications, with recombinant human bone morphogenetic protein-2 (rhBMP-2) and other graft materials.

METHODS

Retrospective cohort study of LLIF patients 2011-2021. LLIFs performed lateral decubitus by four experienced surgeons past their learning curve. Graft materials classified rhBMP-2 or non-rhBMP-2. Patient-reported outcomes assessed by VAS, ODI, and SF-12 preoperatively and postoperatively. Fusion rates assessed by CT postoperatively at 6 and 12 months. Complications classified minor or major. Clinical outcomes and complications analysed and compared between rhBMP-2 and non-rhBMP-2 groups.

RESULTS

A cohort of 343 patients underwent 437 levels of LLIF. Mean age 67 ± 11 years (range 29-89) with a female preponderance (65%). Mean BMI 29kg/m2 (18-56). Most common operated levels L3/4 (36%) and L4/5 (35%). VAS, ODI and SF-12 improved significantly from baseline. Total complication rate 15% (53/343) with minor 11% (39/343) and major 4% (14/343). Ten patients returned to OR (2-wound infection, 8-further instrumentation and decompression). Most patients (264, 77%) received rhBMP-2, the remainder a non-rhBMP-2 graft material. No significant differences between groups at baseline. No increase in minor or major complications in the rhBMP-2 group compared to the non-rhBMP-2 group respectively; (10.6% vs 13.9% [p = 0.42], 2.7% vs 8.9% [p < 0.01]). Fusion rates significantly higher in the rhBMP-2 group at 6 and 12 months (63% vs 40%, [p < 0.01], 92% vs 80%, [p < 0.02]).

CONCLUSION

LLIF is a safe and efficacious procedure. rhBMP-2 in LLIF produced earlier and higher fusion rates compared to available non-rhBMP-2 graft substitutes.

Indications, complications and outcomes of minimally-invasive lateral lumbar interbody fusion with anterior column realignment vs. standard LLIF using expandable interbody spacers

Background

Anterior column realignment (ACR), using a lateral lumbar or thoracic interbody fusion (LLIF) approach to release the anterior longitudinal ligament (ALL), is a powerful technique to increase segmental lordosis. We here report our experience with the use of expandible LLIF cages for ACR.

Methods

Retrospective, single-center observational cohort study including consecutive patients treated by LLIF using an expandible interbody implant. Patients with ACR were compared to patients without ACR. Our outcomes include adverse events (AEs), radiological (segmental sagittal cobb angle, spinopelvic parameters) and clinical outcomes until 12 months postoperative.

Results

We identified 503 patients, in which we performed LLIF at 732 levels. In 63 patients (12.5%) and 70 levels (9.6%) an expandable cage was used. Of those, in 30 patients (47.6%) and 30 levels, the ALL was released (42.8%). Age (mean 61.4 years), sex (57.1% female), comorbidities and further demographic features were similar, but patients in the ACR group had a higher anesthesiologic risk, were more frequently operated for degenerative deformity and had a more severely dysbalanced spine (all p < 0.05). ACR was most frequently done at L3/4 (36.7%) and L4/5 (23.3%), entailing multilevel fusions in 50% (3-7 levels) and long constructs in 26.7% (>7 levels). Intraoperative AEs occurred in 3.3% (ACR) and 3.0% (no ACR; p = 0.945). In ACR cases, mean segmental lordosis changed from -2.8° (preoperative) to 16.4° (discharge; p < 0.001), 15.0° (3 months; p < 0.001) and 16.9° (12 months; p < 0.001), whereas this change was less in non-ACR cases [4.3° vs. 10.5° (discharge; p < 0.05), 10.9 (3 months; p < 0.05) and 10.4 (12 months; p > 0.05)]. Total lumbar lordosis increased from 27.8° to 45.2° (discharge; p < 0.001), 45.8° (3 months; p < 0.001) and 41.9° (12 months; p < 0.001) in ACR cases and from 37.4° to 46.7° (discharge; p < 0.01), 44.6° (3 months; n.s.) and 44.9° (12 months; n.s.) in non-ACR cases. Rates of AEs and clinical outcomes at 3 and 12 months were similar (all p > 0.05) and no pseudarthrosis at the LLIF level was noted.

Conclusions

ACR using an expandible LLIF interbody implant was safe, promoted solid fusion and restored significantly more segmental lordosis compared to LLIF without ALL release, which was maintained during follow-up.

Unique characteristics of bone union at the infected vertebrae after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis: a retrospective multicenter cohort study

BACKGROUND

The current study aimed to evaluate the bone union rate between infected vertebrae after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis.

METHODS

This retrospective multicenter cohort study evaluated 75 patients of posterior fixation for thoracolumbar pyogenic spondylitis that have been recorded at six relevant institutions from January 2016 to December 2022. Data on age, sex, location of infected vertebrae, number of infected disks, comorbidity, Pola classification, number of vertebrae fixed according to surgery, implant failure requiring revision surgery, and distance according to the type of infected vertebrae after surgery were evaluated. Further, their association with postoperative bone union was investigated > 12 months postoperatively.

RESULTS

Finally, 40 patients were included in the study. In total, 32 (80%) patients achieved bone union at the infected vertebrae after minimally invasive posterior fixation without bone grafting. The mean duration from surgery to union was 10.7 months. Twenty-six (65%) patients initially achieved bone union at the lateral and/or anterior bridging callus. Patients with multiple-level infected disks (33%, 2/6 patients) had a lower bone union rate than those with a single-level infected disk (88%, 30/34 patients) (p = 0.0095).

CONCLUSIONS

In 80% of patients, bone union at the infected vertebrae was achieved after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis. A total of 65% of the patients achieved initial bone union at the lateral and/or anterior bridging callus. Moreover, patients with multiple-level infected disks had a low bone union rate. Hence, the treatment strategy should be cautiously considered.

TRIAL REGISTRATION

This study was registered retrospectively and all procedures used in this study including the review of patient records were approved by the institutional review board.

Survey Research Among Neurosurgeons: A Bibliometric Review of the Characteristics, Quality, and Citation Predictors of the Top 50 Most-Influential Publications in the Neurosurgical Literature

Survey research enables the gathering of information on individual perspectives in a large cohort. It can be epidemiological, attitude or knowledge focussed. Assessment of survey studies sampling neurosurgeons is currently lacking in the literature. This study aimed to highlight the characteristics, quality, and citation predictors of the most influential survey research studies published in the neurosurgical literature. Using PubMed and Google Scholar, the 50 most cited survey research publications were identified and reviewed. Data relating to the characteristics of the articles, participants and questionnaires were retrieved. The studies' quality and citation patterns were assessed. The median articles' age and publishing journal impact factor (IF) were 15.5 years and 2.82, respectively. Thirty-two (64%) articles were first authored by researchers from the USA while 28(56%) studies were focussed on specific disease management. The median number of participants and response rates were 222 and 51%, respectively. A full version of the questionnaire was provided in 18 (36%) articles. Only four (8%) articles reported validation of the questionnaire. The overall quality of reporting of the surveys was considered fair (based on good grading in five parameters, fair grading in one parameter, and poor grading in four parameters). The median citation number was 111. The citation analysis showed that the participant number, article age (≥15.5 years), and questionnaire category (surgical complications) were significant predictors of citation numbers. The citation rates were not influenced by the response rates or the journal's IF. In conclusion, high-impact survey publications in the neurosurgical literature were moderately cited and of fair quality. Their citation numbers were not affected by response rates but were positively influenced by the publication age, number of participants, and by novel data or the questions raised in the survey category. Surveys are valuable forms of research that require extensive planning, time, and effort in order to produce meaningful results. Increasing awareness of the factors that could affect citations may be useful to those who wish to undertake survey research.

Survey of major complications after prone transpsoas surgery: an analysis of early adopters' practice

INTRODUCTION

The prone transpsoas technique (PTP) is a modification of the traditional lateral lumbar interbody fusion approach, which was first published in the literature in 2020. The technique provides several advantages, such as lordosis correction and redistribution, single-position surgery framework, and ease of performing posterior techniques when needed. However, the prone position also leads to the movement of some retroperitoneal, vascular, and neurological structures, which could impact the complication profile. Therefore, this study aimed to investigate the occurrence of major complications in the practice of early adopters of the PTP approach.

METHODS

A questionnaire containing 8 questions was sent to 50 participants and events involving early adopters of the prone transpsoas technique. Of the 50 surgeons, 32 completed the questionnaire, which totaled 1963 cases of PTP surgeries.

RESULTS

Nine of the 32 surgeons experienced a major complication (28%), with persistent neurological deficit being the most frequent (7/9). Of the total number of cases, the occurrence of permanent neurological deficits was approximately 0,6%, and the rate of vascular and visceral injuries were both 0,05% (1/1963 for each case).

CONCLUSION

Based on the analysis of the questionnaire responses, it can be concluded that PTP is a safe technique with a very low rate of serious complications. However, future studies with a more heterogeneous group of surgeons and a more rigorous linkage between answers and patient data are needed to support the findings of this study.

Bibliometric and trend analysis of the top 100 most-cited articles on lateral interbody fusion (LIF)

PURPOSE

Lateral interbody fusion (LIF) is an increasingly popular minimally-invasive spine procedure. This study identifies notable trends in LIF literature and provides a detailed review of the bibliometric aspects of the top 100 most-cited articles.

METHODS

Articles were queried from the Web of Science database. Inclusion criteria consisted of peer-reviewed articles, full-text availability, and LIF focus. Network analysis including co-authorship mapping and bibliographic coupling were complemented by trend analysis to determine prominent contributors and themes. Analyses were conducted using VOSviewer and Bibliometrix (RStudio).

RESULTS

There has been a rapid increase in LIF publication and citation count since 1998. Leading journals were Spine (n = 24), Journal of Neurosurgery Spine (n = 22), and European Spine Journal (n = 12). NuVasive funded the most publications (n = 17), followed by DePuy Synthes Spine (n = 4). The United States was the most represented country (n = 81); however, trend analysis suggests a steadily growing international contribution. The most prolific author was J.S. Uribe (n = 16), followed by a tie in second place by E. Dakwar and L. Pimenta (n = 8). The most frequent keywords, "complication" (n = 34), "surgery" (n = 30), and "outcomes" (n = 24), demonstrated a patient-centric theme.

CONCLUSIONS

This bibliometric analysis provides in-depth insights into the evolution and trends of LIF over the last two decades. The trends and themes identified demonstrate the innovative, collaborative, and patient-focused characteristics of this subfield. Future researchers can use this as a foundation for understanding the past and present state of LIF research while designing investigations.

Intra-abdominal Content Movement in Prone Versus Lateral Decubitus Position Lateral Lumbar Interbody Fusion (LLIF)

STUDY DESIGN

A prospective, anatomical imaging study of healthy volunteer subjects in accurate surgical positions.

OBJECTIVE

To establish if there is a change in the position of the abdominal contents in the lateral decubitus (LD) versus prone position.

SUMMARY OF BACKGROUND DATA

Lateral transpsoas lumbar interbody fusion (LLIF) in the LD position has been validated anatomically and for procedural safety, specifically in relation to visceral risks. Recently, LLIF with the patient in the prone position has been suggested as an alternative to LLIF in the LD position.

MATERIALS AND METHODS

Subjects underwent magnetic resonance imaging of the lumbosacral region in the right LD position with the hips flexed and the prone position with the legs extended. Anatomical measurements were performed on axial magnetic resonance images at the L4-5 disc space.

RESULTS

Thirty-four subjects were included. The distance from the skin to the lateral disc surface was 134.9 mm in prone compared with 118.7 mm in LD ( P <0.0001). The distance between the posterior aspect of the disc and the colon was 20.3 mm in the prone compared with 41.1 mm in LD ( P <0.0001). The colon migrated more posteriorly in relation to the anterior margin of the psoas in the prone compared with LD (21.7  vs . 5.5 mm, respectively; P <0.0001). 100% of subjects had posterior migration of the colon in the prone compared with the LD position, as measured by the distance from the quadratum lumborum to the colon (44.4  vs . 20.5 mm, respectively; P <0.001).

CONCLUSION

There were profound changes in the position of visceral structures between the prone and LD patient positions in relation to the LLIF approach corridor. Compared with LD LLIF, the prone position results in a longer surgical corridor with a substantially smaller working window free of the colon, as evidenced by the significant and uniform posterior migration of the colon. Surgeons should be aware of the potential for increased visceral risks when performing LLIF in the prone position.

LEVEL OF EVIDENCE

Level II-prospective anatomical cohort study.

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.

Prone Transpsoas Lateral Interbody Fusion (PTP LIF) with Anterior Docking: Preliminary functional and radiographic outcomes

Background

Disadvantages of lateral interbody fusion (LIF) through a direct, transpsoas approach include difficulties associated with lateral decubitus positioning and limited sagittal correction without anterior longitudinal ligament release or posterior osteotomy. Prior technical descriptions advocate anchoring or docking the retractor into the posterior to middle aspect of the disc space.

Methods

72 patients who underwent 116 total levels of Prone Transpsoas (PTP) LIF with anterior docking with a single surgeon between December 2021 and May 2023 were included. Patient characteristics, perioperative data, as well as postoperative functional and radiographic outcomes were recorded. Subgroup analysis was performed for patients who underwent single-level PTP LIF with single-level percutaneous fixation (SLP). Patients in the SLP subgroup did not undergo direct decompression, release, or osteotomy.

Results

N=41 (56.9%) of cases included the L4-5 level. No vascular, bowel, or other visceral complications occurred. No patients developed a permanent motor deficit. Both the total cohort and the SLP group demonstrated statistically significant improvements in functional outcomes including Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) as well as all radiographic parameters measured. Mean total operative time (incision to completion of closure for lateral and posterior fusion) in the SLP group was 104.3 minutes with a significant downward trend with increasing surgeon experience. The SLP group demonstrated a 9.9° increase in segmental lordosis (SL), a 7.5° increase in lumbar lordosis (LL), 5.3° reduction in pelvic tilt (PT), and a decrease in pelvic incidence - lumbar lordosis mismatch (PI-LL) from 11.0° preoperatively to 3.9°, postoperatively (p<.01).

Conclusions

PTP LIF with anterior docking may address shortcomings associated with traditional lateral interbody fusion by producing safe and reproducible access with improved restoration of segmental lordosis and optimization of spinopelvic parameters.

[Translated article] The role of minimally invasive spine surgery in the treatment of vertebral metastasis: A narrative review

BACKGROUND

Spinal metastases are a very common problem which dramatically affects the quality of life of cancer patients. The objective of this review is to address the issue of how minimally invasive surgery can play an important role in treating this pathology.

METHODS

A literature review was performed, searching in the Google Scholar, PubMed, Scopus and Cochrane databases. Relevant and quality papers published within the last 10 years were included in the review.

RESULTS

After screening the 2184 initially identified registers, a total of 24 articles were included for review.

CONCLUSION

Minimally invasive spine surgery is specially convenient for fragile cancer patients with spinal metastases, because of its reduced comorbidity compared to conventional open surgery. Technological advances in surgery, such as navigation and robotics, improve accuracy and safety in this technique.

The role of minimally invasive spine surgery in the treatment of vertebral metastasis: A narrative review

BACKGROUND

Spinal metastases are a very common problem which dramatically affects the quality of life of cancer patients. The objective of this review is to address the issue of how minimally invasive surgery can play an important role in treating this pathology.

METHODS

A literature review was performed, searching in the Google Scholar, PubMed, Scopus and Cochrane databases. Relevant and quality papers published within the last 10 years were included in the review.

RESULTS

After screening the 2184 initially identified registers, a total of 24 articles were included for review.

CONCLUSION

Minimally invasive spine surgery is specially convenient for fragile cancer patients with spinal metastases, because of its reduced comorbidity compared to conventional open surgery. Technological advances in surgery, such as navigation and robotics, improve accuracy and safety in this technique.

Anterior Column Realignment: Adult Sagittal Deformity Treatment Through Minimally Invasive Surgery

This article focuses on the treatment of sagittal spinal deformity using a minimally invasive technique, anterior column realignment. Traditional methods to address sagittal spine deformity have been associated with high morbidity, long operative times, and excessive blood loss. This technique uses a minimally invasive lateral retroperitoneal approach to release the anterior longitudinal ligament and apply a hyperlordotic implant for interbody fusion to restore lumbar lordosis and sagittal alignment.

Risk of Injury to Retroperitoneal Structures in Prone and Lateral Decubitus Transpsoas Approaches to Lumbar Interbody Fusion: A Pilot Cadaveric Anatomical Study

Introduction The retroperitoneal approach for lateral lumbar interbody fusion (LLIF) originally described an initial posterolateral fascial incision enabling finger dissection from behind the peritoneum and guidance of instruments through a second direct-lateral fascial incision. It has since become common for single direct-lateral incisional access to the retroperitoneum. This study attempted to quantify the distance of the peritoneum from posterior landmarks in the space, assess the risk of peritoneal violation in each access trajectory (i.e., posterolateral versus direct lateral retroperitoneal dissection), and determine whether there are differences based on patient position (prone versus lateral decubitus). Methods In three prone cadaveric torsos, Steinman pins were percutaneously placed mid-disc at each level L2-5 bilaterally (for a total of 18 prone approaches). Open dissections exposed the retroperitoneum including the quadratus lumborum and psoas muscles, maintaining the natural reflection of the peritoneum. Visual assessment qualified whether any pin violated any retroperitoneal structure. Distance from the anterior border of the quadratus lumborum to the posterior-most reflection of the peritoneum was measured. For comparison, three additional torsos were positioned in lateral decubitus, and the above steps were repeated, only unilaterally (for a total of nine lateral decubitus approaches). Results In prone, no pin violated the peritoneum; three (3/18 total approaches) violated the kidney, all at L2-3 (3/6 approaches at L2-3). In lateral decubitus, all three L2-3 pins violated the kidney (3/3 approaches at L2-3); five of the six remaining pins from L3-5 violated the peritoneum (totaling eight violations in the nine total approaches). The incidence of any violation was significantly greater in lateral decubitus vs. prone (8/9 vs. 3/18, p=0.0006). The structure at risk (kidney vs. peritoneum) was significantly associated with disc level (p=0.0041): all kidney violations occurred at L2-3 and all peritoneal violations occurred at L3-4 or L4-5. Distance from the quadratus lumborum to the posterior-most reflection of the peritoneum averaged 8.7 cm (range: 6-10) in prone, and 2.9 cm (range: 2.5-3.2) in lateral decubitus (p=0.0129). Conclusion A cadaveric study of retroperitoneal anatomy demonstrates that there is an increased distance from the quadratus lumborum to the peritoneum in prone versus lateral decubitus and that the trajectory of approach to the lumbar discs risks violation of the peritoneum more frequently when accessing directly laterally versus posterolaterally. In either approach, care should be taken to identify and release the peritoneal reflection to create a safe passage to the lumbar discs.

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.

The anatomical positioning change of retroperitoneal organs in prone and lateral position: an assessment for single-prone position lateral lumbar surgery

PURPOSE

There are reports that performing lateral lumbar interbody fusion (LLIF) in a prone, single position (single-prone LLIF) can be done safely in the prone position because the retroperitoneal organs reflect anteriorly with gravity. However, only a few study has investigated the safety of single-prone LLIF and retroperitoneal organ positioning in the prone position. We aimed to investigate the positioning of retroperitoneal organs in the prone position and evaluate the safety of single-prone LLIF surgery.

METHODS

A total of 94 patients were retrospectively reviewed. The anatomical positioning of the retroperitoneal organs was evaluated by CT in the preoperative supine and intraoperative prone position. The distances from the centre line of the intervertebral body to the organs including aorta, inferior vena cava, ascending and descending colons, and bilateral kidneys were measured for the lumbar spine. An "at risk" zone was defined as distance less than 10 mm anterior from the centre line of the intervertebral body.

RESULTS

Compared to supine preoperative CTs, bilateral kidneys at the L2/3 level as well as the bilateral colons at the L3/4 level had statistically significant ventral shift with prone positioning. The proportion of retroperitoneal organs within the at-risk zone ranged from 29.6 to 88.6% in the prone position.

CONCLUSIONS

The retroperitoneal organs shifted ventrally with prone positioning. However, the amount of shift was not large enough to avoid risk for organ injuries and substantial proportion of patients had organs within the cage insertion corridor. Careful preoperative planning is warranted when considering single-prone LLIF.

A retrospective review of single-position prone lateral lumbar interbody fusion cases: early learning curve and perioperative outcomes

PURPOSE

The objective of this study was to discuss our experience performing LLIF in the prone position and report our complications.

METHODS

A retrospective chart review was conducted that included all patients who underwent single- or multi-level single-position pLLIF alone or as part of a concomitant procedure by the same surgeon from May 2019 to November 2022.

RESULTS

A total of 155 patients and 250 levels were included in this study. Surgery was most commonly performed at the L4-L5 level (n = 100, 40%). The most common preoperative diagnosis was spondylolisthesis (n = 74, 47.7%). In the first 30 cases, 3 surgeries were aborted to an MIS TLIF. Complications included 3 unintentional ALL ruptures (n = 3/250, 1.2%), and 1 malpositioned implant impinging on the contralateral foramen requiring revision (n = 1/250, 0.4%), which all occurred within the first 30 cases. Out of 147 patients with more than 6-week follow-ups, there were 3 cases of femoral nerve palsy (n = 3/147, 2.0%). Two cases of femoral nerve palsy improved to preoperative strength by the 6th week postoperatively, while one improved to 4/5 preoperative strength by 1 year. There were no cases of bowel perforation or vascular injury.

CONCLUSION

Our single-surgeon experience demonstrates the initial learning curve when adopting pLLIF. Thereafter, we experienced reproducibility in our technique and large improvements in our operative times, and complication profile. We experienced no technical complications after the 30th case. Further studies will include long-term clinical and radiographic outcomes to understand the complete utility of this approach.

The Prone Lateral Approach for Lumbar Fusion-A Review of the Literature and Case Series

Lateral lumbar interbody fusion is an evolving procedure in spine surgery allowing for the placement of large interbody devices to achieve indirect decompression of segmental stenosis, deformity correction and high fusion rates through a minimally invasive approach. Traditionally, this technique has been performed in the lateral decubitus position. Many surgeons have adopted simultaneous posterior instrumentation in the lateral position to avoid patient repositioning; however, this technique presents several challenges and limitations. Recently, lateral interbody fusion in the prone position has been gaining in popularity due to the surgeon's ability to perform simultaneous posterior instrumentation as well as decompression procedures and corrective osteotomies. Furthermore, the prone position allows improved correction of sagittal plane imbalance due to increased lumbar lordosis when prone on most operative tables used for spinal surgery. In this paper, we describe the evolution of the prone lateral approach for interbody fusion and present our experience with this technique. Case examples are included for illustration.

Entrapment of a metal foreign body in the heart during surgical procedure: A case report and literature review

A rongeur had been used to remove thin bones in both orthopedic surgery and neurosurgery, featured with a tip holding and cutting bone effectively while protecting the underlying instruments. The authors describe a case of a 40-year-old man who proceeded with the second lumbar vertebrae osteotomy and presented to be ankylosing spondylitis with kyphosis and limited mobility for 10 years. During the surgery, we found that the rongeur tip was missing. C-arm fluoroscopy showed the high-density body just in front of the vertebral body intraoperatively. However, the CT scan showed the foreign body migrated to the right auricle of the heart postoperatively. This case is unique in that there was no exact vessel injury detected intraoperatively. There were few reports about the surgical instrument migrating to the heart. Our case showed the rare experience of the function of multidisciplinary collaboration in the migration of foreign bodies in the cervical spinal canal.

Anterior column reconstruction of the lumbar spine in the lateral decubitus position: anatomical and patient-related considerations for ALIF, anterior-to-psoas, and transpsoas LLIF approaches

PURPOSE

Circumferential (AP) lumbar fusion surgery is an effective treatment for degenerative and deformity conditions of the spine. The lateral decubitus position allows for simultaneous access to the anterior and posterior aspects of the spine, enabling instrumentation of both columns without the need for patient repositioning. This paper seeks to outline the anatomical and patient-related considerations in anterior column reconstruction of the lumbar spine from L1-S1 in the lateral decubitus position.

METHODS

We detail the anatomic considerations of the lateral ALIF, transpsoas, and anterior-to-psoas surgical approaches from surgeon experience and comprehensive literature review.

RESULTS

Single-position AP surgery allows simultaneous access to the anterior and posterior column and may combine ALIF, LLIF, and minimally invasive posterior instrumentation techniques from L1-S1 without patient repositioning. Careful history, physical examination, and imaging review optimize safety and efficacy of lateral ALIF or LLIF surgery. An excellent understanding of patient spinal and abdominal anatomy is necessary. Each approach has relative advantages and disadvantages according to the disc level, skeletal, vascular, and psoas anatomy.

CONCLUSIONS

A development of a framework to analyze these factors will result in improved patient outcomes and a reduction in complications for lateral ALIF, transpsoas, and anterior-to-psoas surgeries.

Perspective on the true incidence of bowel perforations occurring with extreme lateral lumbar interbody fusions. How should they be treated?

Background

What is the risk of bowel perforation (BP) with open or minimally invasive (MI) extreme lateral lumbar interbody fusion (XLIF)? What is the truth? Further, if peritoneal symptoms/signs arise following XLIF/MI XLIF, it is critical to obtain an emergent consultation with general surgery who can diagnose and treat a potential BP.

Literature Review

In multiple series, the frequency of BP ranged markedly from 0.03% (i.e. 1 of 2998 patients), to 0.08% (11/13,004), to 0.5%, to 8.3% (1 in 12 patients), up to 12.5% (1 in 8 patients). BPs attributed to different causes carry high mortality rates varying from 11.1% to 23%. For the 11 (0.08%) BP occurring out of 13,004 patients undergoing XLIF in one series, there was one (9.09%) death due to uncontrolled sepsis. In another series, where 31 BP were identified for multiple lumbar surgical procedures identified through PubMed (1960-2016), including 10 (32.2%) for lateral lumbar surgery including XLIF, the overall mortality rate was 12.9% (4/31).

Conclusion

The incidence of BPs occurring following XLIF/MI XLIF procedures ranged from 0.03% to 12.5% in various reports. What is the true incidence of these errors? Certainly, it is more critical that when spine surgeons' patients develop acute peritoneal symptoms/signs following these procedures, they immediately consult general surgery to both diagnose, and treat potential BP in a timely fashion to avoid the high morbidity (87.1%) and mortality rates (12.9%) attributed to these perforations.

Minimally Invasive Surgery for Spinal Metastasis: A Review

OBJECTIVE

Minimally invasive surgery (MIS) techniques have advanced the treatment of metastatic diseases to the spine. The objective of this review is to describe clinical outcomes, benefits, and complications of these techniques.

METHODS

All relevant clinical studies describing the role of MIS, computer-assisted navigation (CAN), robot-assisted (RA) procedures, and laser interstitial thermal therapy (LITT) in the treatment of metastatic spine diseases were identified from PubMed, MEDLINE, and relevant article bibliographies.

RESULTS

For MIS articles, we filtered 1480 results and identified 26 studies. For CAN, we searched 464 articles to identify 18 articles for review. For RA, we searched 321 results to identify 7 studies for review. For LITT, we identified 21 articles for review.

CONCLUSIONS

MIS for the treatment of spine metastasis has significant potential benefits in reducing surgical site infections, hospital stay, and blood loss without compromising instrument accuracy or overall outcomes. Overall, MIS and its adjuncts have the potential to reduce the risks involved in the treatment of patients with metastatic disease to the spinal column without compromising the benefits of decompression and stabilization of the spine.

Bowel Injury and Insidious Pneumoperitoneum after Lateral Lumbar Interbody Fusion

Study Design

Retrospective review of prospectively collected cases.

Purpose

To report bowel injury cases and determine the incidence and risk factors of insidious pneumoperitoneum after lateral lumbar interbody fusion (LLIF).

Overview of Literature

Minimally invasive LLIF is considered a safe surgical approach with a low risk of complications. Visceral injury after LLIF is rare and, to our knowledge, no studies on pneumoperitoneum after LLIF have been performed. Bowel injury is a catastrophic complication, but the clinical signs may not be apparent. After we encountered two cases of bowel injury after LLIF, we decided to perform computed tomography of the abdomen and pelvis (APCT) after surgery for all patients who underwent LLIF.

Methods

A total of 90 patients underwent APCT within 48 hours of surgery. Medical records were reviewed to determine each patient’s age, sex, body mass index, medical and surgical histories, characteristics of LLIF procedures, and subjective symptoms and abnormal findings in the physical examination related to acute abdomen after surgery. Various parameters were compared between patients with and without pneumoperitoneum.

Results

Bowel injuries were identified in the first two patients and five patients (5.5%) were diagnosed with pneumoperitoneum only on APCT. We found that the greater the number of fused segments, the higher the incidence of postoperative bowel injury and/or pneumoperitoneum. The incidence was significantly high when the L2–3 level was included in the LLIF surgery.

Conclusions

Pneumoperitoneum after LLIF indicates damage to the peritoneum and the presence of bowel injury that may lead to peritonitis. However, it is difficult to distinguish pneumoperitoneum and/or bowel injury from general abdominal pain after surgery because patients may present with a wide range of symptoms. We recommend that APCT be routinely performed after LLIF surgery in order to promptly identify pneumoperitoneum and bowel injury.

Extreme Lateral Interbody Fusion for Thoracic and Thoracolumbar Disease: The Diaphragm Dilemma

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Complication profiles for lateral approaches to the spine are well established. However, the influence of level of surgery on complication rates and subtypes are less well established. To determine risk factors for complications as determined by level and surgery type in patients undergoing a lateral (retroperitoneal or retropleural approach) to the thoracolumbar spine.

METHODS

All adult patients undergoing a lateral thoracolumbar fusion with or without posterior instrumentation performed at a single institution were identified. Primary outcomes assessed were presence of complication, complication subtype, and need for reoperation. The primary independent variables were spinal level (thoracic, thoracolumbar, or lumbar) and type of surgery (discectomy or corpectomy). Categorical outcomes were compared using chi-square test. Unadjusted and adjusted odds ratios for corpectomy status were calculated to determine risk of complication by level. P < .05 was considered statistically significant.

RESULTS

A total of 165 patients aged 18 to 75 years were identified as having undergone a lateral fusion. Complication rates were 28.6%, 36.4%, and 11% for thoracic, thoracolumbar, and lumbar lateral approach fusions, respectively. Under univariate analysis, patients undergoing lateral approach in the thoracic spine group had significantly higher rates of postoperative complications than those in the lumbar group (P = .005). After adjusting for corpectomy status, there was no difference in complication rates.

CONCLUSIONS

Lateral (retroperitoneal or retropleural) approaches to the thoracic and thoracolumbar spine may be used with complication rates comparable to well-established lumbar approaches. Extent of surgery (corpectomy vs discectomy) rather than level of surgery may represent the primary driver of complications.

Variations in the position of the aorta and vertebral safe zones in supine, prone, and lateral decubitus for adolescent idiopathic scoliosis

PURPOSE

Analyze the modifications in the "safe zones" of T4-L4 vertebral bodies relative to aorta according to patient positioning, as well as in the relationship between the aorta and the vertebrae.

METHODS

Patients with adolescent idiopathic scoliosis who underwent surgical treatment during 2017 were included. Preoperative whole spine MRI in supine, prone, and LD positions was performed. The safe zone right (SZR) was defined as the angle formed between X-axis (0º) and a line connecting the origin and the edge of the aorta, and the safe zone left (SZL) was the angle between the edge of the aorta to 180º (X-axis).

RESULTS

A total of 21 patients were studied, median age was 15.2 years, and 71.4% were female. The mean SZR lied from 0°-86.1º at T4 to 0°-76.9º at L4 in supine, from 0°-84.05º at T4 to 0º-78.5º at L4 in prone, and from 0° to 91.75º at T4 to 0°-80.4º at L4 in LD. While the mean SZL was located from 155.4º-180º at T4 to 107.9º-180º at L4 in supine, from 134°-180° at T4 to 103.9°-180° at L4 in prone, and from 143.8º-180º at T4 to 106º-180º at L4 in LD. Statistically significant differences were found almost at all levels when comparing supine versus prone and LD.

CONCLUSIONS

Patient positioning during spinal surgery significantly modifies T4-L4 vertebral safe zones relative to aorta. These variations should be taken into account when analyzing an MRI performed in supine if the patient is undergoing surgery in a different position, to avoid vascular-related injuries.

Microendoscopy-assisted extraforaminal lumbar interbody fusion for treating single-level spondylodesis

Background

Lumbar interbody fusion is a standard technique for treating degenerative lumbar disorders involving instability. Due to its invasiveness, a minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF), was introduced. On surgically approaching posterolaterally, the posterior muscles and spinal canal are barely invaded. Despite its theoretical advantage, ELIF is technically demanding and has not been popularised. Therefore, we developed a microendoscopy-assisted ELIF (mELIF) technique which was designed to be safe and less invasive. Here, we aimed to report on the surgical technique and clinical results.

Methods

Using a posterolateral approach similar to that of lateral disc herniation surgery, a tubular retractor, 16 or 18 mm in diameter, was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was cleaned. A cage and local bone graft were inserted into the disc space. All disc-related procedures were performed under microendoscopy. The spinal canal was not invaded. Bilateral percutaneous screw-rod constructs were inserted and fixed.

Results

Fifty-five patients underwent the procedure. The Oswestry Disability Index and visual analogue scale scores greatly improved. Over 90% of the patients obtained excellent or good results based on Macnab’s criteria. There were neither major adverse clinical effects nor the need for additional surgery.

Conclusions

mELIF is minimally invasive because the spinal canal and posterior muscles are barely invaded. It produces good clinical results with fewer complications. This technique can be applied in most single-level spondylodesis cases, including those involving L5/S1 disorders.

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.

Incidence and Risk Factors of Anterior Longitudinal Ligament Rupture After Posterior Corrective Surgery Using Lateral Lumbar Interbody Fusion for Adult Spinal Deformity

STUDY DESIGN

A retrospective single-center study.

OBJECTIVE

The objective of this study was to assess the incidence of anterior longitudinal ligament rupture (ALLR) and to identify the risk factors for ALLR in patients with adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

Lateral lumbar interbody fusion (LIF) has been widely used for ASD surgery. However, ALLR has been occasionally identified after posterior spinal correction surgery.

MATERIALS AND METHODS

The study included 43 consecutive patients (8 male and 35 female patients) who underwent posterior corrective surgery involving LIF (128 levels) for ASD between 2014 and 2018. The mean age was 72±7 years (range: 62-81 y), and the minimum follow-up period was 1 year [mean: 34±15 mo (range: 12-58 mo)]. Posterior correction and fusion surgery using the cantilever technique was performed following LIF. Oblique LIF was performed in 27 patients, and extreme lateral interbody fusion (XLIF) was performed in 16 patients. The mean number of spinal fused levels was 8.9±1.8 levels (range: 8-15), and the mean number of LIF levels was 3±0.6 levels (range: 2-4). ALLR was considered if a LIF cage showed no contact with the vertebral endplates. The radiographic parameters were thoracic kyphosis, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt, and sagittal vertical axis.

RESULTS

ALLR occurred in 10 patients (22%) and at 11 levels (8.6%). XLIF and preexisting osteoporotic vertebral fracture were identified as independent risk factors for ALLR. The change in LL was ∼10 degrees greater in the ALLR group than in the non-ALLR group (P=0.017), and overcorrection was observed in the ALLR group (PI-LL: -7.9±7 degrees). The change in the segmental lordotic angle at the ALLR level was much larger than after LIF and correction surgery. ALLR-related reoperation was performed in 2 cases (decompression surgery owing to posterior impingement and rod breakage).

CONCLUSIONS

ALLR occurred in 10 patients (22%). XLIF and preexisting osteoporotic vertebral fracture were independent risk factors for ALLR. Overcorrection was observed in patients with ALLR.

Limited Cost Benefit of Lateral Interbody Fusion for Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective case series.

OBJECTIVE

The aim of this study was to compare the utility and cost-effectiveness of multilevel lateral interbody fusion (LIF) combined with posterior spinal fusion (PSF) (L group) and conventional PSF (with transforaminal lumbar interbody fusion) (P group) in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

The clinical and radiographic outcomes of multilevel LIF for ASD have been reported favorable; however, the cost benefit of LIF in conjunction with PSF is still controversial.

METHODS

Retrospective comparisons of 88 surgically treated ASD patients with minimum 2-year follow-up from a multicenter database (L group [n = 39] and P group [n = 49]) were performed. Demographic and radiographic data, health-related quality of life (HRQoL), and the direct hospitalization cost for the initial surgery and 2-year total hospitalization cost were analyzed.

RESULTS

Analyses of sagittal spinal alignment showed no significant difference between the two groups at baseline and 2 years post-operation. Surgical time was longer in the L group (L vs. P: 354 vs. 268 minutes, P < 0.01), whereas the amount of blood loss was greater in the P group (494 vs. 678 mL, P = 0.03). The HRQoL was improved similarly at 2 years post-operation (L vs. P: SRS-22 total score, 3.86 vs. 3.80, P = 0.54), with comparable revision rates (L vs. P: 18% vs. 10%, P = 0.29). The total direct cost of index surgery was significantly higher in the L group (65,937 vs. 49,849 USD, P < 0.01), which was mainly due to the operating room cost, including implant cost (54,466 vs. 41,328 USD, P < 0.01). In addition, the 2-year total hospitalization cost, including revision surgery, was also significantly higher in the L group (70,847 vs. 52,560 USD, P < 0.01).

CONCLUSION

LIF with PSF is a similarly effective surgery for ASD when compared with conventional PSF. However, due to the significantly higher cost, additional studies on the cost-effectiveness of LIF in different ASD patient cohorts are warranted.

LEVEL OF EVIDENCE

3.

Restoring spinopelvic harmony with lateral lumbar interbody fusion: is it a realistic goal?

Background

The importance of spinopelvic harmony [pelvic incidence (PI) = lumbar lordosis (LL) ±10 degrees] is well established in the literature. We aimed to determine whether lateral lumbar interbody fusion (LLIF) surgery in isolation is successful in restoring spinopelvic harmony, and whether the surgery maintained the relationship in those who present in a balanced state.

Methods

A retrospective radiographic analysis was performed on patients who underwent LLIF surgery, followed by posterior instrumented fusion, between January 2012 to August 2019 by a single surgeon (AD). Pre- and post-operative X-rays were reviewed by two authors using Surgimap spinal imaging 2.2.15.5. The LL, PI, and PI-LL mismatch, as well as a range of coronal and segmental sagittal radiographic parameters, were recorded.

Results

A total of 71 patients with 170 levels treated via LLIF were analysed. A mean pre-operative PI-LL of 14.3 degrees and post-operative value of 13.4 degrees was recorded (P=0.43). Of the 41 patients who were imbalanced pre-operatively, 13 (31.7%) were restored to a LL within 10 degrees of PI post-LLIF procedure. 30 patients presented in spinopelvic harmony, and 25 (83.3%) of those maintained that relationship following LLIF. Mean coronal global Cobb angles (13.7 degrees pre-operatively to 7.7 degrees post-operatively), segmental coronal Cobb angles (3.8 to 0.9 degrees), and anterior (5.2 to 9.8 mm) and posterior (3.2 to 6.7 mm) disc heights all improved significantly post-LLIF surgery (P<0.0001).

Conclusions

Although an effective treatment for coronal deformities and providing indirect decompression for degenerative lumbar disc disease, LLIF surgery alone is unlikely to result in correction of sagittal deformity and in particular spinopelvic harmony.

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.

Contraindication of Minimally Invasive Lateral Interbody Fusion for Percutaneous Reduction of Degenerative Spondylolisthesis: A New Radiographic Indicator of Bony Lateral Recess Stenosis Using I Line

Study Design

Retrospective cohort study.

Purpose

This study aimed to evaluate aggravated lateral recess stenosis and clarify the indirect decompression threshold by combined lateral interbody fusion and percutaneous pedicle screw fixation (LIF/PPS).

Overview of Literature

No previous reports have described an effective radiographic indicator for determining the surgical indication for LIF/PPS.

Methods

A retrospective review of 185 consecutive patients, who underwent 1- or 2-level lumbar fusion surgery for degenerative spondylolisthesis (DS). According to their symptomatic improvement, they were placed into either the “recovery” or “no-recovery” group. Preoperative computed tomography (CT) images were evaluated for the position of the superior articular processes at the slipping level, followed by a graded classification (grades 0–3) using the impingement line (I line), a new radiographic indicator. All 432 superior articular facets in 216 slipped levels were classified, and both groups’ characteristics were compared.

Results

There were 171 patients (92.4%) in the recovery group and 14 patients in the no-recovery group (7.6%). All patients in the no-recovery group were diagnosed with symptoms associated with deteriorated bony lateral recess stenosis. All superior articular processes of the lower vertebral body in affected levels reached and exceeded the I line (I line-; grade 2 and 3) on preoperative sagittal CT images. In the recovery group, most superior articular processes did not reach the I line (I line+; grade 0 and 1; p=0.0233).

Conclusions

In DS cases that are classified as grade 2 or greater, the risk of aggravated bony lateral recess stenosis due to corrective surgery is high; therefore, indirect decompression by LIF/PPS is, in principle, contraindicated.

The impact of age on approach-related complications with navigated lateral lumbar interbody fusion

OBJECTIVE

Age is known to be a risk factor for increased complications due to surgery. However, elderly patients can gain significant quality-of-life benefits from surgery. Lateral lumbar interbody fusion (LLIF) is a minimally invasive procedure that is commonly used to treat degenerative spine disease. Recently, 3D navigation has been applied to LLIF. The purpose of this study was to determine whether there is an increased complication risk in the elderly with navigated LLIF.

METHODS

Patients who underwent 3D-navigated LLIF for degenerative disease from 2014 to 2019 were included in the analysis. Patients were divided into elderly and nonelderly groups, with those 65 years and older categorized as elderly. Ninety-day medical and surgical complications were recorded. Patient and surgical characteristics were compared between groups, and multivariate regression analysis was used to determine independent risk factors for complication.

RESULTS

Of the 115 patients included, 56 were elderly and 59 were nonelderly. There were 15 complications (25.4%) in the nonelderly group and 10 (17.9%) in the elderly group, which was not significantly different (p = 0.44). On multivariable analysis, age was not a risk factor for complication (p = 0.52). However, multiple-level LLIF was associated with an increased risk of approach-related complication (OR 3.58, p = 0.02).

CONCLUSIONS

Elderly patients do not appear to experience higher rates of approach-related complications compared with nonelderly patients undergoing 3D navigated LLIF. Rather, multilevel surgery is a predictor for approach-related complication.

Definition of safe zone in vertebral body in relation to anterior instrumentation

OBJECTIVES

We set out to determine the "safe zone" for anterior instrumentation in scoliosis surgery assessing the relationship of the great vessels to the spine.

METHODS

A total of 34 children undergoing posterior idiopathic scoliosis surgery were included in the study between 2010 and 2016. The preoperative scans were assessed to identify the position of the great vessels relative to the spine from T4 to L4. A coordinate system was specifically designed to determine safe zones for device locations. The safe zone right (SZR) was defined as the angle formed between X-axis (0°) and a line connecting the origin and the edge of the aorta and the safe zone left (SZL), the angle between the edge of the aorta to 180°.

RESULTS

The average age was 14 years, with 30 females (88.2%). Lenke classification, the most common curve was 1BN (20.6%), followed by 1AN, 3C- and 6CN (8.8% each). The Apex was T8 and T9 (29.4 and 23.5% respectively). 58% of the curves were right sided. The mean SZL was from 155.7° to 180° at the T4 level to 104.3°-180° at L4. The mean SZR was from 0 to 110.7° at T4 to 0-76.18° at L4. The side of the curves was correlated at p level with the SZL and SZR. There was a significant correlation in the following levels: from T4 to L2 in the SZL, and from T7 to L2 in the SZR.

CONCLUSIONS

Between T4 and T11, the right side of the vertebrae is safe, and from T12 to L4 the safe zones are more lateral and smaller. In a right-sided scoliosis, the danger zone moves more posterolateral at every level. In a left-sided curve, the danger zone is more anteromedial. Knowledge of these safe zones should allow safer placement of anterior devices.

LEVEL OF EVIDENCE

Level III.

Minimally Invasive Anterior Longitudinal Ligament Release for Anterior Column Realignment

STUDY DESIGN

Review of the literature.

OBJECTIVES

Anterior column realignment (ACR) is a powerful but relatively new minimally invasive technique for deformity correction. The purpose of this study is to provide a literature review of the ACR surgical technique, reported outcomes, and future directions.

METHODS

A review of the literature was performed regarding the ACR technique. A review of patients at our single center who underwent ACR was performed, with illustrative cases selected to demonstrate basic and nuanced aspects of the technique.

RESULTS

Clinical and cadaveric studies report increases in segmental lordosis in the lumbar spine by 73%, approximately 10° to 33°, depending on the degree of posterior osteotomy and lordosis of the hyperlordosis interbody spacer. These corrections have been found to be associated with a similar risk profile compared with traditional surgical options, including a 30% to 43% risk of proximal junctional kyphosis in early studies.

CONCLUSIONS

ACR represents a powerful technique in the minimally invasive spinal surgeon's toolbox for treatment of complex adult spinal deformity. The technique is capable of significant sagittal plane correction; however, future research is necessary to ascertain the safety profile and long-term durability of ACR.

Minimally Invasive Lateral Retroperitoneal Approach for Resection of Extraforaminal Lumbar Plexus Schwannomas: Operative Techniques and Literature Review

BACKGROUND

Traditional approaches for retroperitoneal lumbar plexus schwannomas involve anterior open or laparoscopic resection. For select tumors, the lateral retroperitoneal approach provides a minimally invasive alternative.

OBJECTIVE

To describe a minimally invasive lateral transpsoas approach for the resection of retroperitoneal schwannomas.

METHODS

A lateral retroperitoneal transpsoas approach was used to resect a 3.1 × 2.7 × 4.1 cm schwannoma embedded within the psoas muscle. A minimally invasive retractor system allows for appropriate visualization and complete resection with the aid of the microscope. The patient tolerated the procedure without complication and was discharged on postoperative day 2 in good condition at her neurological baseline.

RESULTS

The lateral retroperitoneal approach provides a minimally invasive alternative for select retroperitoneal schwannomas. In theory, this procedure allows for faster recovery and less blood loss compared to traditional open anterior approaches. For a subset of tumors, anterior laparoscopy may provide better access, but the lateral approach is well known to most neurosurgeons who perform lateral interbody fusions and can be easily tailored to extraforaminal tumor resection.

CONCLUSION

Retroperitoneal schwannomas pose a challenge due to their deep location. The lateral retroperitoneal approach provides a useful alternative for resection of a subset of retroperitoneal schwannomas.

Intraoperative ultrasound visualization of paravertebral anatomy in the retroperitoneal space during lateral lumbar spine surgery

OBJECTIVE

Lumbar surgery via a lateral approach is a minimally invasive and highly useful procedure. However, care must be taken to avoid its potentially fatal complications of intestinal and vascular injuries. The object of this study was to evaluate the usefulness of intraoperative ultrasound in improving the safety of lateral lumbar spine surgery.

METHODS

A transvaginal ultrasound probe was inserted into the operative field, and the intestinal tract, kidney, psoas muscle, and vertebral body were identified using B-mode ultrasound. The aorta, vena cava, common iliac vessels, and lumbar arteries and their associated branches were identified using the color Doppler mode.

RESULTS

The study cohort comprised 100 patients who underwent lateral lumbar spine surgery, 92 via a left-sided approach. The intestinal tract and kidney lateral to the psoas muscle on the anatomical approach pathway were visualized in 36 and 26 patients, respectively. A detachment maneuver displaced the intestinal tract and kidneys in an anteroinferior direction, enabling confirmation of the absence of organ tissues above the psoas. In all patients, the major vessels anterior to the vertebral bodies and the lumbar arteries and associated branches in the psoas on the approach path were clearly visualized in the Doppler mode, and their orientation, location, and positional relationship with regard to the vertebral bodies, intervertebral discs, and psoas were determined.

CONCLUSIONS

When approaching the lateral side of the lumbar spine in the retroperitoneal space, intraoperative ultrasound allows real-time identification of the blood vessels surrounding the lumbar spine, intestinal tract, and kidney in the approach path and improves the safety of surgery without increasing invasiveness.

Intercostal artery hemorrhage with hemothorax following combined lateral and posterior lumbar interbody fusion: a case report

Introduction

Lateral lumbar interbody fusion (LLIF) is a safe treatment for degenerative spine conditions. However, risk of complications such as vascular injuries remains. We report a unique case of an intercostal artery (ICA) hemorrhage with hemothorax following LLIF.

Case presentation

One hour after a right-sided LLIF L3-4 with posterior decompression L2-4 and L3-5 instrumentation, the patient became hypotensive, anemic and required vasopressor support. Evaluation revealed a right-sided hemothorax, which was caused by a bleeding intercostal artery, laterally at the 10th intercostal space. A lateral thoracotomy was performed to stop the bleeding. After vessel ligation and placement of two chest tubes, the patients' hemodynamics improved. The patient remained intubated overnight and was extubated on the first postoperative day.

Discussion

Vascular injury is a rare complication of LLIF procedures. Most vascular injuries are segmental vessel lacerations, which resolve postoperatively. This is the first case description of ICA bleeding associated with LLIF surgery. Spontaneous ICA bleeding exists, but surgeons should be aware of careful handling in patients with vascular risk factors, especially with regard to patient positioning required in certain spinal surgical approaches. Timely vascular injury identification is critical for hemostasis and clinical management.

Iatrogenic Bowel Injury Following Minimally Invasive Lateral Approach to the Lumbar Spine: A Retrospective Analysis of 3 Cases

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Anterior approaches are often used during lumbar interbody fusion procedures. Visceral injuries (bowel injuries) are rare but represent a primary risk during anterior approaches to the lumbar spine. Left untreated, these injuries can result in significant complications. The aim of this study was to investigate the presentation and management of bowel injury cases following anterior approaches to the lumbar spine to raise the surgeon's awareness of this rare complication.

METHODS

All direct anterior, oblique anterior, and transpsoas lumbar interbody fusion surgeries performed at our institution between 2012 and 2016 were analyzed retrospectively. Charts were screened for cases requiring return to the operating room owing to a suspected bowel injury and details of the case were extracted for illustrative purposes.

RESULTS

A total of 775 anterior lumbar surgeries were conducted at a single tertiary care institution between July 2012 and June 2017. A total of 590 transpsoas lumbar interbody fusion (TPIF) surgeries were performed. Four patients, each having undergone TPIF, were suspected of bowel injury and underwent an exploratory laparotomy. At surgery, 3 patients were confirmed to have a bowel injury, giving a procedure-specific incidence of 0.51% and overall incidence of 0.39%. Among the 3 confirmed bowel injury cases, average delay between surgery and visceral injury diagnosis was 4.7 days (range 3-7 days).

CONCLUSIONS

We noted abdominal pain, distention, and fever as the most common findings in the setting of a visceral injury. A high index of suspicion and computed tomography imaging remain critical for identifying postoperative bowel injuries.

Anatomic Considerations in the Lateral Transpsoas Interbody Fusion: The Impact of Age, Sex, BMI, and Scoliosis

STUDY DESIGN

This is a retrospective case series.

OBJECTIVE

Define the anatomic variations and the risk factors for such within the operative corridor of the transpsoas lateral interbody fusion.

SUMMARY OF BACKGROUND DATA

The lateral interbody fusion approach has recently been associated with devastating complications such as injury to the lumbosacral plexus, surrounding vasculature, and bowel. A more comprehensive understanding of anatomic structures in relation to this approach using preoperative imaging would help surgeons identify high-risk patients potentially minimizing these complications.

MATERIALS AND METHODS

Age-sex distributed, naive lumbar spine magnetic resonance imagings (n=180) were used to identify the corridor for the lateral lumbar interbody approach using axial images. Bilateral measurements were taken from L1-S1 to determine the locations of critical vascular, intraperitoneal, and muscular structures. In addition, a subcohort of scoliosis patients (n=39) with a Cobb angle >10 degrees were identified and compared.

RESULTS

Right-sided vascular anatomy was significantly more variant than left (9.9% vs. 5.7%; P=0.001). There were 9 instances of "at-risk" vasculature on the right side compared with 0 on the left (P=0.004). Age increased vascular anatomy variance bilaterally, particularly in the more caudal levels (P≤0.001). A "rising-psoas sign" was observed in 26.1% of patients. Bowel was identified within the corridor in 30.5% of patients and correlated positively with body mass index (P<0.001). Scoliosis increased variant anatomy of left-sided vasculature at L2-3/L3-4. Nearly all variant anatomy in this group was found on the convex side of the curvature (94.2%).

CONCLUSIONS

Given the risks and complications associated with this approach, careful planning must be taken with an understanding of vulnerable anatomic structures. Our analysis suggests that approaching the intervertebral space from the patient's left may reduce the risk of encountering critical vascular structures. Similarly, in the setting of scoliosis, an approach toward the concave side may have a more predictable course for surrounding anatomy.

LEVEL OF EVIDENCE

Level 3-study.

Complications for minimally invasive lateral interbody arthrodesis: a systematic review and meta-analysis comparing prepsoas and transpsoas approaches

OBJECTIVE

Minimally invasive anterolateral retroperitoneal approaches for lumbar interbody arthrodesis have distinct advantages attractive to spine surgeons. Prepsoas or transpsoas trajectories can be employed with differing complication profiles because of the inherent anatomical differences encountered in each approach. The evidence comparing them remains limited because of poor quality data. Here, the authors sought to systematically review the available literature and perform a meta-analysis comparing the two techniques.

METHODS

A systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A database search was used to identify eligible studies. Prepsoas and transpsoas studies were compiled, and each study was assessed for inclusion criteria. Complication rates were recorded and compared between approach groups. Studies incorporating an analysis of postoperative subsidence and pseudarthrosis rates were also assessed and compared.

RESULTS

For the prepsoas studies, 20 studies for the complications analysis and 8 studies for the pseudarthrosis outcomes analysis were included. For the transpsoas studies, 39 studies for the complications analysis and 19 studies for the pseudarthrosis outcomes analysis were included. For the complications analysis, 1874 patients treated via the prepsoas approach and 4607 treated with the transpsoas approach were included. In the transpsoas group, there was a higher rate of transient sensory symptoms (21.7% vs 8.7%, p = 0.002), transient hip flexor weakness (19.7% vs 5.7%, p < 0.001), and permanent neurological weakness (2.8% vs 1.0%, p = 0.005). A higher rate of sympathetic nerve injury was seen in the prepsoas group (5.4% vs 0.0%, p = 0.03). Of the nonneurological complications, major vascular injury was significantly higher in the prepsoas approach (1.8% vs 0.4%, p = 0.01). There was no difference in urological or peritoneal/bowel injury, postoperative ileus, or hematomas (all p > 0.05). A higher infection rate was noted for the transpsoas group (3.1% vs 1.1%, p = 0.01). With regard to postoperative fusion outcomes, similar rates of subsidence (12.2% prepsoas vs 13.8% transpsoas, p = 0.78) and pseudarthrosis (9.9% vs 7.5%, respectively, p = 0.57) were seen between the groups at the last follow-up.

CONCLUSIONS

Complication rates vary for the prepsoas and transpsoas approaches owing to the variable retroperitoneal anatomy encountered during surgical dissection. While the risks of a lasting motor deficit and transient sensory disturbances are higher for the transpsoas approach, there is a reciprocal reduction in the risks of major vascular injury and sympathetic nerve injury. These results can facilitate informed decision-making and tailored surgical planning regarding the choice of minimally invasive anterolateral access to the spine.

Evidence Based Medicine Review of Posterior Thoracolumbar Minimally Invasive Technology

Background

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

Methods

A systematic review of the literature from 1950 to 2015.

Results

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

Conclusions

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

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.

Anterior Column Release/Realignment

Lateral anterior column release (ACR) is a powerful extension of the minimally invasive lateral lumbar interbody fusion procedure that incorporates division of the anterior longitudinal ligament to allow manipulation of the anterior and middle spinal columns. The resulting surgical control permits restoration of significant segmental lordosis that, when combined with varying posterior column releases, can achieve global sagittal realignment on par with traditional 3-column osteotomies. As a result, ACR is a factor in the growth of minimally invasive strategies for the correction of spinal deformities.

Extreme lateral lumbar interbody fusion (XLIF) in the management of degenerative scoliosis: a retrospective case series

Background

Surgical treatment of adult degenerative scoliosis (DS) always remains a challenge and often necessitates complex multilevel surgery via traditional open approaches. However, the severity of the procedure, in association with the fact that many of these patients are at an advanced age with several comorbidities, results in high rate of complications. Therefore, during the last decade, minimally invasive procedures have gained a place in the treatment of this pathology. Our aim is to determine the safety and efficacy of extra lateral lumbar interbody fusion (XLIF) with or without supplemented instrumentation in the treatment of DS.

Methods

In a retrospective case series study, we reviewed the files of patients who underwent XLIF in our Hospital between 2008 and 2017. We recorded the patients' demographic characteristics, clinical parameters such as back-pain [visual analogue scale (VAS)] and back-related disability [Oswestry Disability Index (ODI)], as well as radiological parameters including the Cobb angle. Comparison of the before and after results were performed with the t-test and Chi-square test, where appropriate.

Results

Twelve patients fulfilled the eligibility criteria of our study. All patients were female, with a mean age of 64.5 years (SD =7.8 years) and 28 months (SD =13 months) follow-up. The XLIF decreased the pain intensity by 4.66 cm (SD =1.23 cm), and improved the back-related disability by 26% (SD =8.35%) in the ODI scale at the 6-month follow-up. Similarly, scoliosis improved by an average of 11.5° (SD =7°) and lordosis changed by an average of 13.5° (SD =10.86°). All changes were statistically significant. There were three complications, two patients presented meralgia paresthetica, which resolved spontaneously in 3 months, and in one patient occurred an intraoperative bowel perforation treated with bowel anastomosis.

Conclusions

XLIF is a feasible and efficient alternative in the treatment of DS. It can be the treatment of choice in elderly patients in whom comorbidities increase the perioperative risk of complications.