The Feasibility of Anterior Spinal Access: The Vascular Corridor at the L5-S1 Level for Anterior Lumbar Interbody Fusion

An Update in Complication Rates Associated With Anterior Lumbar Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and meta-analysis.

OBJECTIVE

To conduct an updated systematic review and meta-analysis of complications associated with different anterior fusion techniques/approaches and adjuvant resources (i.e., computed tomography angiography (CTA), rhBMP-2, and access surgeons).

METHODS

A systematic review was conducted from 1/1/2014-4/1/2024 for studies evaluating the incidence of complications associated with anterior lumbar procedures. Comparisons of complications were made between surgical approach, use of CTA, rhBMP-2, and access surgeons. Meta-analyses were conducted using a generalized linear mixed model.

RESULTS

54 studies were included in the final analysis with 8066 patients and an average follow-up of 31.2 months. The overall complication rate associated with anterior lumbar surgery was 13.1%, including an intraoperative complication rate of 3.8%, postoperative complication rate of 7.4%, infection rate of 1.5%, and reoperation rate of 1.7%. Forest plot analysis showed no significant difference in overall complication rates between open and mini-open techniques, although mini-open techniques were associated with lower overall reoperation rates. The use of CTA was associated with an increase in intraoperative and overall complications, and the use of an access surgeon was associated with a decreased risk of reoperation. The use of rhBMP-2 was not associated with overall complication risk.

CONCLUSIONS

While anterior lumbar surgery provides numerous benefits, surgeons and patients alike should be aware of the complication and safety profile prior to surgery. High quality studies are warranted to help elucidate the true benefit of certain techniques and adjuvant resources in reducing complications.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Iliac vein variation in the sacral promontory on three-dimensional computed tomography angiography: a prospective observational study before laparoscopic sacrocolpopexy

INTRODUCTION AND HYPOTHESIS

Venous injury may occur during exposure of the anterior longitudinal ligament at the anterior sacral promontory (SP). We aimed to quantitatively measure the extent of the vascular window (VW) in front of the SP in patients with internal iliac vein (IIV) variations using preoperative three-dimensional computed tomography angiography (3DCTA). We hypothesized that patients with IIV variations would have a narrow VW.

METHODS

This prospective observational study included patients scheduled for laparoscopic sacrocolpopexy (LSC) between July 2022 and April 2023 who underwent preoperative 3DCTA. The primary endpoint was the VW measurement in the standard and variant IIV groups using 3DCTA before LSC. The secondary endpoint was the difference between the two IIV groups adjusted for age, body mass index, hypertension, and diabetes using an analysis of covariance (ANCOVA) model. Multiple regression analysis was performed to analyze the effect of factors on the distance from the SP to great vascular bifurcations.

RESULTS

There were 20 cases of IIV variation (20.2%). VW was 28.8 ± 12.4 mm in the variant group and 39.6 ± 12.6 mm in the standard group (p = 0.001). In the ANCOVA model, IIV variations affected VW (coefficient, -11.8; 95% confidence interval [CI], -18.4 to -5.08, p < 0.001). Multivariate analysis revealed that the aorta-SP distance decreased with age (coefficient, -0.44; 95% CI, -0.77 to -0.11, p = 0.009).

CONCLUSIONS

One in five women has a vascular variant at the SP that restricts the "safe" zone of fixation to < 3 cm.

Feasibility of total and partial uncinectomy during anterior cervical approach: MRI-based analysis of 176 patients regarding vertebral artery location

PURPOSE

To determine the technical feasibility of uncinate process (UP) resection (uncinectomy) during anterior cervical approach with risk-avoidance of vertebral artery (VA) injury.

METHODS

One hundred and seventy-six magnetic resonance imaging images with cervical spondylosis were evaluated. The diameter between UP and VA (UP-VA distance), the presence of a fat plane, and the VA's anterior-posterior position relative to UP (anterior[A], middle[M], posterior[P]) at C3-4 to C6-7 segments were investigated. Subsequently, easy-to-use classifications were developed according to the feasibility of total and partial uncinectomy. Total uncinectomy: easy (distance: > 2 mm); moderate (distance: ≤ 2 and fat plane: +); advanced (no fat plane). Partial uncinectomy: easy (distance: > 2 mm and P, A, or M position); moderate (distance: ≤ 2; fat plane: + and P position), and advanced (no fat plane and P position).

RESULTS

UP-VA distance of C5-6 on the right side (left/right: 0.41/0.31 mm) was the smallest. The ratio of no fat plane of C5-6 (46.6%/49.4%) was the highest. C5-6 had a high rate of P position (7.4%/8.5%) while C6-7 had a high rate of A position (19.3%/18.2%). More than 90% individuals were classified as easy for partial uncinectomy at any vertebral segment (C3-7), while more than 30% were classified as advanced at C4-7 with the highest rate at C5-6 for total uncinectomy.

CONCLUSION

When performing uncinectomy during the anterior cervical approach, the C5-6 segment may be at the greatest risk of VA injury. Hence, preoperative MR images should be thoroughly evaluated to avoid VA injury.

Antepsoas Approaches to the Lumbar Spine

Lumbar interbody fusion (LIF) is a well-established approach in treating spinal deformity and degenerative conditions of the spine. Since its inception in the 20th century, LIF has continued to evolve, allowing for minimally invasive approaches, high fusion rates, and improving disability scores with favorable complication rates. The anterior to the psoas (ATP) approach utilizes a retroperitoneal pathway medial to the psoas muscle to access the L1-S1intervertebral disc spaces. In contrast to the transpsoas arppoach, its primary advantage is avoiding transgressing the psoas muscle and the contained lumbar plexus, which potentially decreases the risk of injury to the lumbar plexus. Avoiding transgression of the psoas may minimize the risk of transient or permanent neurological deficits secondary to lumbar plexus injury. Indications for ATP approaches may expand as it is shown to be a safe and effective method of achieving spinal arthrodesis.

The anatomical feasibility of anterior intra- and extra-bifurcation approaches to L5-S1: an anatomic study based on lumbar MRI

BACKGROUND CONTEXT

The anterior approach at L5-S1 has many advantages, however, vascular complications are challenging for spinal surgeons who may not be familiar with the variability of vascular anatomy. There are three different anterior approaches (intra-bifurcation approach and extra-bifurcation: left-, and right-sided prepsoas approaches) described in previous studies to respond to the variability of anterior vascular anatomy for reduction in vascular injury, while no guidance for the choice of approach preoperatively.

PURPOSE

To analyze the anatomical feasibility of three anterior approaches to access the L5-S1 disc space according to a practical framework.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Lumbar magnetic resonance imaging (MRI) from patients who visited our outpatient clinic were reviewed, with 150 cases meeting the inclusion criteria.

OUTCOME MEASURES

The following radiographic parameters were measured on axial T2-weighted MRI at the lower endplate of L5 and the upper endplate of S1: width of the vascular corridor, position of the left and right common iliac vein (CIV), and presence of perivascular adipose tissue (PAT). Moreover, we designed a safe line to evaluate the feasibility of left- and right-sided prepsoas approaches. Cases of lumbosacral transitional vertebrae were identified.

METHODS

The feasibility of the intra-bifurcation approach was determined by the width of the vascular corridor, presence of PAT, and the position of the CIV. The feasibility of the prepsoas approach was determined by the relative position of the CIV to the safe line, presence of PAT, and the intersection point of the CIV and vertebral body.

RESULTS

Sixty-eight percent, 64.7%, and 75.3% cases allowed the intra-bifurcation, left-, and right-sided prepsoas approach to L5-S1, respectively. The cases in this study had at least one of three anterior approaches to access L5-S1 disc space, and 74% of cases had more than one anatomical feasibility of anterior approach. The right-sided prepsoas approach was feasible in the majority of cases because of the vertical course of the right CIV with a significantly higher proportion of presence of PAT. Patients with lumbosacral transitional vertebrae (24 cases) may prefer the prepsoas approaches, and only six cases (25.0%) were determined to be feasible for the intra-bifurcation approach.

CONCLUSIONS

Our study proposes a practical framework to determine whether the three different anterior approaches are feasible access at L5-S1. According to the framework, all cases had the anatomical feasibility of using an anterior approach to access L5-S1, and three-fourths of cases had a replaceable anterior approach when encountering intraoperative difficulties.