Integrated anatomy of the neuromuscular, visceral, vascular, and urinary tissues determined by MRI for a surgical approach to lateral lumbar interbody fusion in the presence or absence of spinal deformity

The modern application of anterior lumbar interbody fusion (ALIF): a narrative review of perioperative considerations and surgical pearls

Background and Objective

Anterior lumbar interbody fusion (ALIF) has become a pivotal technique in managing chronic back pain, radiculopathy, neurogenic claudication, and spinal deformity. This review aims to compare ALIF with other fusion methods, highlight its advantages and disadvantages, and provide surgical insights to enhance perioperative outcomes.

Methods

A comprehensive literature search was conducted using databases such as PubMed, Embase, and Cochrane Library, focusing on publications from the past two decades. Articles were selected based on relevance, study design, and the inclusion of key perioperative considerations and surgical techniques. Only English-language studies were considered.

Key Content and Findings

This review examines the historical evolution of ALIF, its current clinical applications, and the development of associated surgical techniques. It discusses preoperative evaluations, imaging strategies, and patient selection criteria. Key findings highlight that ALIF offers superior disc height restoration and segmental lordosis compared to other fusion techniques. However, it presents unique challenges such as potential vascular and visceral injuries. The review also outlines critical surgical pearls for effective ALIF execution and strategies to mitigate common complications like subsidence and nerve root injuries.

Conclusions

ALIF is a robust technique for lumbar spine pathology, providing significant benefits in appropriate patient populations. This review underscores the importance of meticulous surgical planning and technique to optimize outcomes. Future research should focus on long-term comparative studies and the development of enhanced surgical instruments and protocols. Implementing these insights into clinical practice may improve patient outcomes and influence surgical guidelines and policies.

Anatomical study of the relationship between the lumbar intervertebral disc, nerves, and psoas major

Cadaveric study; To describe the characteristics of the nerve and its relationship with the lumbar intervertebral disc and psoas major muscle. Nerve injury is an understudied complication of extreme lateral interbody fusion. A detailed description of the nerve anatomy would be helpful for surgeons to minimize the risk of this complication. The lumbar plexus and lumbar sympathetic nerve of 10 embalmed male cadavers were dissected, and the distribution, number, and spatial orientation of the nerves on the L1/2 to L4/5 intervertebral discs were examined. Metal wires were applied along nerve paths through the psoas major muscle. The position of the nerves was examined on CT. In zone III at L1/2 and L4/5, no nerves were found. In zone II and zone III at L2/3, no lumbar plexus was found, and only the ramus communicans passed through. At the L1-L5 level, the density of nerves in the posterior half of the psoas major muscle was greater than that in the anterior half. The lumbar plexus was found in all of zone IV. The genitofemoral nerve emerges superficially and anteriorly from the medial border of the psoas major at the L3-4 level, but at the L1/2 level, the sympathetic trunk is located in zone II. The remaining disc-level sympathetic trunks appear in zone I. No nerves were found in zone III of the L1/2 or L4/5 disc. In zones II and III of L2/3, the lumbar plexus appears safe. The genitofemoral nerve travels through zones II and III of L3/4. The distribution density of nerves in the posterior half of the psoas major muscle was greater than that in the anterior half of that muscle at the L1-L5 level.

L4-L5 anatomy classification system for lateral lumbar interbody fusion

Lateral lumbar interbody fusion (LLIF), developed by Dr. Luiz Pimenta in 2006, allows access to the spinal column through the psoas major muscle. The technique has many advantages, such as reduced bone and muscular tissue damage, indirect decompression, larger implants, and lordosis correction capabilities. However, this technique also has drawbacks, with the most notorious being the risk of spinal pathologies due to indirect injury of the lumbar plexus, but with low rates of persistent injuries. Therefore, several groups have proposed classifications to help identify patients at a greater risk of presenting with neurological deficits. The present work proposes a classification system that relies on simple observation of easily identifiable key structures to guide lateral L4-L5 LLIF decision-making. Patients aged > 18 years who underwent preoperative magnetic resonance imaging (MRI) between 2022 and 2023 were included until 50 high-quality images were acquired. And excluded as follow Anatomical changes in the vertebral body or major psoas muscles prevent the identification of key structures or poor-quality MRIs. Each anatomy was classified as type I, type II, or type III according to the consensus among the three observers. Fifty anatomical sites were included in this study. 70% of the L4-L5 anatomy were type I, 18% were type II, and 12% were type III. None of the type 3 L4-L5 anatomies were approached using a lateral technique. The proposed classification is an easy and simple method for evaluating the feasibility of a lateral approach to-L4-L5.

Lumbar plexus safe working zones with lateral lumbar interbody fusion: a systematic review and meta-analysis

PURPOSE

Significant risk of injury to the lumbar plexus and its departing motor and sensory nerves exists with lateral lumbar interbody fusion (LLIF). Several cadaveric and imaging studies have investigated the lumbar plexus position with respect to the vertebral body anteroposterior plane. To date, no systematic review and meta-analysis of the lumbar plexus safe working zones for LLIF has been performed.

METHODS

This systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies reporting on the position of the lumbar plexus with relation to the vertebral body in the anteroposterior plane were identified from a PubMed database query. Quantitative analysis was performed using Welch's t test.

RESULTS

Eighteen studies were included, encompassing 1005 subjects and 2472 intervertebral levels. Eleven studies used supine magnetic resonance imaging (MRI) with in vivo subjects. Seven studies used cadavers, five of which performed dissection in the left lateral decubitus position. A significant correlation (p < 0.001) existed between anterior lumbar plexus displacement and evaluation with in vivo MRI at all levels between L1-L5 compared with cadaveric measurement. Supine position was also associated with significant (p < 0.001) anterior shift of the lumbar plexus at all levels between L1-L5.

CONCLUSIONS

This is the first comprehensive systematic review and meta-analysis of the lumbar neural components and safe working zones for LLIF. Our analysis suggests that the lumbar plexus is significantly displaced ventrally with the supine compared to lateral decubitus position, and that MRI may overestimate ventral encroachment of lumbar plexus.

Revisiting anterior longitudinal ligament release: Are we ready for an endoscopic approach?

Anterior longitudinal ligament release is a proven method for restoring spinopelvic parameters. This technique is mostly described using either lateral or anterior approaches with paucity regarding a posterior method. This paper is the first to provide descriptive analysis of the neurovascular anatomy in the context of planning for a posterior endoscopic ALL release. A retrospective chart review was performed on patients underwent any lumbar surgery by a single surgeon. Anatomical data was obtained from pre-operative CT to describe the location of key neurovascular structures in relation to the ALL with focus on posterior approach. A total of 20 patients were included in data analysis. A posterior approach with endoscopic assistance would be feasible at L4/5 and L5/S1, where the bifurcation of the abdominal aorta has occurred with a vessel window that ranges from 18.85 mm to 33.45 mm with at least 2 mm space between the vessels and the corresponding disc spaces in the anterior-posterior dimension with slight predilection of the left side at the L5/S1 level to avoid any neurovascular structures. Our study confirmed the findings of previous studies examining the vascular anatomy associated with the lumbar spine. Interestingly, we found that direct midline would likely not be the best location for a posterior annulotomy, and that both the window between the iliac vessels as well as the distance in AP dimension between the spine and vessels increases as you descend the lumbar spine. This information will help guide future efforts to fully develop a safe and reproducible posterior endoscopic ALL release.

Delayed Ureter Stricture and Kidney Atrophy After Oblique Lumbar Interbody Fusion

BACKGROUND

Oblique lumbar interbody fusion (OLIF) is a surgical technique for lumbar interbody fusion that allows surgeons to use a large cage while preserving the spine muscles. The surgical corridor of OLIF is close to the ureter in the retroperitoneal space and therefore entails a potential for injury to this organ. Although there are some published cases of ureteral injury that were identified during OLIF, to our knowledge, there have been no reports about delayed ureteral strictures and kidney atrophy after OLIF. We report a case of ureter stricture and ipsilateral kidney atrophy that was incidentally identified a few months postoperatively without signs of ureter injury during the operation.

CASE DESCRIPTION

A 49-year-old woman presented with low back and right leg pain. On lumbar magnetic resonance imaging, a Meyerding grade 1 spondylolisthesis of L4 on L5 with L4 nerve root encroachment was confirmed. The patient underwent L4/L5 OLIF and was discharged on the 10th day after surgery with improved symptoms. Three months later, an abdominopelvic computed tomography performed for an unrelated condition showed left kidney atrophy. A retrograde ureteropyelogram confirmed a stricture near the operation site. A ureter stent was successfully inserted to overcome the stricture, but renal atrophy was not reversed.

CONCLUSIONS

Ureter injury may be observed with several months' delay after OLIF in patients without symptoms or laboratory abnormalities, even if no direct injury was noted during the procedure.

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

INTRODUCTION

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

TECHNICAL NOTE

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

CONCLUSIONS

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