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

Anterior Column Realignment Using an Anterior-To-Psoas Approach: A Radiographic-Anatomic Feasibility Study at L1-L5

STUDY DESIGN

Cross-sectional radioanatomic study.

OBJECTIVE

To determine the feasibility of performing an anterior column realignment (ACR) using an anterior-to-psoas (ATP) approach at L1-L5.

METHODS

Axial magnetic resonance images (MRI) of the L1-L5 disc levels obtained at a single institution were obtained and analyzed. The feasibility of performing an ACR was assessed using a combination of the size of the left oblique corridor (OC), the psoas morphology using the modified Moro classification, and the anterior disc edge to great vessel distance.

RESULTS

Three hundred MRI studies obtained from 300 patients were included. All patients had a measurable left OC at the L1-L4 levels. Twenty patients (6.7%) had no measurable OC at the L4-L5 level. According to the modified Moro's classification, a high-rising psoas was seen in 4 patients (1.3%) at the L3-L4 level and 57 patients (19.0%) at the L4-L5 level. An ALL release was considered high risk due to no measurable space between the anterior disc edge and the great vessels in 54 patients (18.0%) at the L1-L2 level, 39 patients (13.0%) at the L2-L3 level, 119 patients (39.7%) at the L3-L4 level, and 226 patients (75.3%) at the L4-L5 level.

CONCLUSION

ACR using an ATP approach is the most radioanatomically feasible at L2-L3. The L4-L5 level has the highest risk with regards to both the ATP approach and the ALL release for an ACR due to high rates of unmeasurable left OC and space between the anterior disc edge and the great vessels.

Access to the Lumbosacral Spine: A Current View

The surgical approach to the lumbosacral spine has been the subject of experimental and scientific anatomical studies since the Hippocratic era. However, it was in the 20th century that, with the evolution of asepsis and antibiotic therapy, spine surgery began to evolve at breakneck speed, and the various possibilities of access roads became objects of development and discussion. As a result, pathologies of the lumbosacral spine can be accessed in different ways and positions, from the traditional posterior approach in the prone position to the anterior, oblique, lateral, and endoscopic approaches. The current article brings state-of-the-art access routes to the lumbosacral spine. This article objective is to elucidate the possibilities of accesses the lumbar spine for any purposes, as decompression, fusion, tumour resections, reconstruction or deformity correction, despites type of implants or implants positioning.

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.

Outpatient Minimally Invasive Lumbar Fusion Using Multimodal Analgesic Management in the Ambulatory Surgery Setting

BACKGROUND

The transition of minimally invasive (MIS) spine surgery from the inpatient to outpatient setting has been aided by advances in multimodal analgesic (MMA) protocols. This clinical case series of patients demonstrates the feasibility of ambulatory MIS transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) procedures while using an enhanced MMA protocol.

METHODS

Consecutive MIS TLIF or LLIF procedures with percutaneous pedicle screw fixation and direct decompression in the ambulatory setting were reviewed. The procedures were performed using an MMA protocol. The ambulatory surgery center (ASC) did not allow for observation of patients for periods of time greater than 23 hours. We recorded patient demographics, perioperative, and postoperative characteristics.

RESULTS

Fifty consecutive patients were identified from September 2016 to July 2019. Forty-one patients (82%) underwent MIS TLIF, and 9 patients underwent MIS LLIF (18.0%). All patients were discharged on the same day of surgery. The mean length of stay was 4.5 hours and 3.8 hours for the TLIF and LLIF cohorts, respectively. Our review of medical records revealed no postoperative complications following either the TLIF or the LLIF procedures.

CONCLUSIONS

The present study of 50 consecutive patients is the largest clinical series of ASC patients undergoing lumbar fusion procedures in a stand-alone facility with no extended postoperative observation capability. While using MMA protocol within the ASC, no postoperative complications were observed for either MIS TLIF or LLIF procedures. All patients were discharged from the ambulatory surgical center on the day of surgery with well-controlled postoperative pain.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

The MMA protocol is an essential aspect in transitioning minimally invasive lumbar spine surgery to the ASC. Our findings indicate that MIS lumbar fusion spine surgery with an enhanced MMA protocol can lead to safe and timely ASC discharge while minimizing hospital admission.

Defining a safe working zone for lateral lumbar interbody fusion: a radiographic, cross-sectional study

PURPOSE

To present a radiographic analysis of the anatomy of the lumbar plexus and retroperitoneal blood vessels with respect to psoas morphology and safe working zones (SWZ) for LLIF.

METHODS

A retrospective radiographic analysis of 158 MRI scans was performed. Selected morphometric measurements were performed at L1-L2, L2-L3, L3-L4 and L4-L5 levels: disc anteroposterior distance, psoas anteroposterior distance, lumbar plexus-anterior disc distance, lumbar plexus-anterior psoas distance, vena cava-anterior disc distance and calculation of SWZ in psoas on both left and right sides. The morphometric measurements were analysed for differences with sex and the level.

RESULTS

All the morphometric parameters differed significantly at all levels between males and females. The SWZ was significantly wider on the left side compared to the right-at L2-L3, L3-L4 and L4-L5 levels in females and at L3-L4 and L4-L5 levels in males. The SWZ at L4-L5 was narrowest on both left and right sides-and significantly reduced compared to other levels. 6.9% patients had a SWZ > 20 mm on the left side, and 44.9% patients had SWZ < 20 mm on the right side. With caudal progression of levels, the lumbar plexus and psoas muscle migrated anteriorly and the vena cava/right iliac vein migrated posteriorly.

CONCLUSION

A detailed study of preoperative MRI scans should be carried out in patients planned for LLIF-particularly, at L4-L5 level and in females. A left-sided trans-psoas approach is safer to perform compared to the right side-a right-sided approach should be avoided at L4-L5 considering the narrow SWZ at that level.

Lumbar spinal fusion in the outpatient setting: an update on management, surgical approaches and planning

Outpatient lumbar spinal fusion surgery has the potential for improved patient satisfaction, speed of recovery, and economic advantages when compared to inpatient surgery. Despite the rise in the number of these procedures performed annually, the literature on this topic remains scarce. As such, there is a need for a comprehensive review of current concepts in indications and management. The current review will present the most recent literature regarding pre-operative, intra-operative, and post-operative considerations when performing outpatient lumbar spinal fusion surgery.

Lateral and Oblique Lumbar Interbody Fusion-Current Concepts and a Review of Recent Literature

PURPOSE

To review the relevant recent literature regarding minimally invasive, lateral, and oblique approaches to the anterior lumbar spine, with a particular focus on the operative and postoperative complications.

METHODS

A literature search was performed on Pubmed and Web of Science using combinations of the following keywords and their acronyms: lateral lumbar interbody fusion (LLIF), oblique lateral interbody fusion (OLIF), anterior-to-psoas approach (ATP), direct lateral interbody fusion (DLIF), extreme lateral interbody fusion (XLIF), and minimally invasive surgery (MIS). All results from January 2016 through January 2019 were evaluated and all studies evaluating complications and/or outcomes were included in the review.

RECENT FINDINGS

Transient neurological deficit, particularly sensorimotor symptoms of the ipsilateral thigh, remains the most common complication seen in LLIF. Best available current literature demonstrates that approximately 30-40% of patients have postoperative deficits, primarily of the proximal leg. Permanent symptoms are less common, affecting 4-5% of cases. Newer techniques to reduce this rate include different retractors, direct visualization of the nerves, and intraoperative neuromonitoring. OLIF may have lower deficit rates, but the available literature is limited. Subsidence rates in both LLIF and OLIF are comparable to ALIF (anterior lumbar interbody fusion), but further study is required. Supplemental posterior fixation is an active area of investigation that shows favorable biomechanical results, but additional clinical studies are needed. Minimally invasive lumbar interbody fusion techniques continue to advance rapidly. As these techniques continue to mature, evidence-based risk-stratification systems are required to better guide both the patient and clinician in the joint decision-making process for the optimal surgical approach.