Exiting root injury in transforaminal endoscopic discectomy: preoperative image considerations for safety

How to Prevent Nerve Root Injury in Uniportal Full Endoscopic Lumbar Fusion Surgery? Insights From a Cadaveric Anatomic Study With Simulation Surgery

STUDY DESIGN

The study included 2 fresh-frozen cadavers.

OBJECTIVE

To elucidate the positional relationship between surgical instruments and nerve roots during full endoscopic facet-sparing (FE fs-TLIF) and full endoscopic facet-resecting (FE fr-TLIF) transforaminal lumbar interbody fusion and propose safe instrumentation insertion procedures and recommend cage glider designs aimed at protecting nerve roots.

BACKGROUND

Endoscopic surgical techniques are increasingly used for minimally invasive lumbar fusion surgery, with FE fr-TLIF and FE fs-TLIF being common approaches. However, the risk of nerve root injury remains a significant concern during these procedures.

PATIENTS AND METHODS

Eight experienced endoscopic spine surgeons performed uniportal FE fr-TLIF and FE fs-TLIF on cadaveric lumbar spines, totaling 16 surgeries. Postoperation, soft tissues were removed to assess the positional relationship between the cage entry point and nerve roots. Distances between the cage entry point, traversing nerve root, and exiting nerve root were measured. Safe instrumentation design and insertion procedures were determined.

RESULTS

In FE fr-TLIF, the mean distance between the cage entry point and traversing nerve root was significantly shorter compared with FE fs-TLIF (3.30 ± 1.35 vs . 8.58 ± 2.47 mm, respectively; P < 0.0001). Conversely, the mean distance between the cage entry point and the exiting nerve root was significantly shorter in FE fs-TLIF compared with FE fr-TLIF (3.73 ± 1.97 vs . 6.90 ± 1.36 mm, respectively; P < 0.0001). For FE fr-TLIF, prioritizing the protection of the traversing root using a 2-bevel tip cage glider was crucial. In contrast, for FE fs-TLIF, a single-bevel tip cage glider placed in the caudal location was recommended.

CONCLUSION

This study elucidates the anatomic relationship between cage entry points and nerve roots in uniportal endoscopic lumbar fusion surgery. Protection strategies should prioritize the traversing root in FE fr-TLIF and the exiting root in FE fs-TLIF, with corresponding variations in surgical techniques.

LEVEL OF EVIDENCE

Level V.

Full-Endoscopic Posterior Lumbar Interbody Fusion: A Review and Technical Note

Remarkable innovations in spinal endoscopic surgery have broadened its applications over the past 20 years. Full-endoscopic fusions have been widely reported, and several full-endoscopic approaches for interbody fusion have been published. In general, full-endoscopic lumbar interbody fusion (LIF) is called Endo-LIF, and facet-preserving Endo-LIF through the transforaminal route is called trans-Kambin's triangle LIF, which has a relatively longer history than facet-sacrificing Endo-LIF via the posterolateral route. Both approaches can reduce intraoperative and postoperative bleeding. However, there is a higher risk of subsidence and exit nerve root injury. There is no direct decompression in either of the interbody fusions, and additional decompression is required if there is severe lumbar bony canal stenosis. However, the posterior interlaminar approach, which is a well-known standard in full-endoscopic spine surgery, has rarely been applied in the field of endoscopic lumbar fusion surgery. Full-endoscopic posterior LIF (FE-PLIF) via an interlaminar approach can accomplish direct decompression of bony canal stenosis and safe interbody fusion. FE-PLIF via an interlaminar approach demonstrated a longer operation time, less blood loss, and shorter hospitalization duration than minimally invasive transforaminal LIF. FE-PLIF, which can accomplish direct decompression for bony spinal canal stenosis, is superior to other Endo-LIFs. However, FE-PLIF requires technical dexterity to improve efficiency and reduce technical complexity.

Comparing the Efficacy and Safety of Unilateral Biportal Endoscopic Decompression with Percutaneous Endoscopic Lumbar Decompression for Lumbar Degenerative Diseases: A Meta-Analysis

OBJECTIVE

Unilateral biportal endoscopic decompression (UBED) offers the advantages of minimal tissue damage, operational flexibility, and clear visualization, positioning it as an innovative and minimally invasive endoscopic technique. Nevertheless, the clinical evidence supporting the use of UBED in the treatment of degenerative lumbar diseases is limited and conflicting.

METHODS

As of October 1, 2023, a comprehensive search was conducted across databases including Web of Science, PubMed, Embase, and the Cochrane Library to identify all published studies on minimally invasive UBED for the treatment of degenerative lumbar diseases. Data pertaining to patient demographics, fluoroscopy time, operative duration, intraoperative hemorrhage, hospitalization length, visual analog scale (VAS) score for back and leg pain, MacNab criteria, Oswestry Disability Index (ODI), and complication rates were extracted. The Newcastle-Ottawa scale was utilized to assess the quality.

RESULTS

Twelve articles were included, involving 816 patients. The back VAS score (95% confidence interval [CI]: -0.09-0.07, P = 0.75), MacNab criteria (95% CI: 0.52-2.3, P = 0.82), fluoroscopy time (95% CI: -7.03 to -0.4, P = 0.08), and the incidence of complications (95% CI: 0.5-1.73, P = 0.82) were not significantly different, while the leg VAS score (95% CI: 0.01-0.18, P = 0.03), ODI score (95% CI: -1.03 to -0.09, P = 0.02), operation time (95% CI: 5.76-20.62, P = 0.0005), hospitalization length (95% CI: 0.41-2.76, P = 0.008), and intraoperative hemorrhage (95% CI: 21.92-72.44, P = 0.0003) were significantly different.

CONCLUSIONS

UBED offers superiority in ODI, flexibility, and visual field clarity. Conversely, percutaneous endoscopic lumbar decompression presents advantages in terms of operation duration, blood loss, hospitalization length, and leg VAS score. These factors should be thoroughly considered when selecting a surgical approach.

Utilization of a novel patient-specific 3D-printing template for percutaneous endoscopic transforaminal discectomy: results from a randomized controlled trial

Background

The learning curve for percutaneous endoscopic transforaminal discectomy (PETD) is steep, especially for the puncturing and localization procedures. The implementation of 3D printing technology may solve this problem.

Methods

A novel individualized 3D-printing template (3D-PT) was designed and utilized in PETD. A prospective randomized controlled trial was performed. A total of 28 patients with lumbar disc herniation treated with PETD were analyzed. Of these, 14 patients were treated with the assistance of 3D printing technology (3D-PT group) in conjunction with fluoroscopy, while the remaining 14 patients were treated exclusively under the guidance of C-arm fluoroscopy (control group).

Results

The number of puncture attempts in the 3D-PT group was significantly less than in the control group (1.36 ± 0.63 vs. 6.07 ± 3.08, p = 0.000). The 3D-PT group exhibited a significant reduction in both intraoperative puncture fluoroscopies (2.71 ± 1.27 vs. 12.14 ± 6.15, p = 0.000) and the overall number of fluoroscopies (2.71 ± 1.27 vs. 17.43 ± 6.27, p = 0.000). In the 3D-PT group, there was a significant reduction in both the puncture time (5.77 ± 1.82 vs. 13.99 ± 4.36, p = 0.000) and the total operation time (60.39 ± 9.78 vs. 76.25 ± 17.78, p = 0.007). Complications were not observed in either group.

Conclusion

The application of the novel individualized 3D-PT for PETD is effective and safe. The technique has substantial potential and is worth widely promoting.

Using Augmented Reality Technology to Optimize Transfacet Lumbar Interbody Fusion: A Case Report

The transfacet minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a novel approach available for the management of lumbar spondylolisthesis. It avoids the need to manipulate either of the exiting or traversing nerve roots, both protected by the bony boundaries of the approach. With the advancement in operative technologies such as navigation, mapping, segmentation, and augmented reality (AR), surgeons are prompted to utilize these technologies to enhance their surgical outcomes. A 36-year-old male patient was complaining of chronic progressive lower back pain. He was found to have grade 2 L4/5 spondylolisthesis. We studied the feasibility of a trans-Kambin or a transfacet MIS-TLIF, and decided to proceed with the latter given the wider corridor it provides. Preoperative trajectory planning and level segmentation in addition to intraoperative navigation and image merging were all utilized to provide an AR model to guide us through the surgery. The use of AR can build on the safety and learning of novel surgical approaches to spine pathologies. However, larger high-quality studies are needed to further objectively analyze its impact on surgical outcomes and to expand on its application.

Transforaminal Full-Endoscopic Ventral Facetectomy: Midterm Results and Factors Associated with Poor Surgical Outcomes

BACKGROUND

 Full-endoscopic spine surgery (FESS) is a well-established procedure for herniated nucleus pulposus. It is a minimally invasive surgery that can be performed under local anesthesia through only an 8-mm skin incision. With improvements in surgical equipment such as high-speed drills, the indications for FESS have expanded to include lumbar spinal stenosis (LSS). We perform a transforaminal full-endoscopic ventral facetectomy (TF-FEVF) for unilateral nerve root-type lateral recess stenosis (LRS) using a transforaminal approach under local anesthesia.The aim of this study was to examine the postoperative results of TF-FEVF for LRS and to identify factors associated with poor surgical outcomes. 85 patients who underwent TF-FEVF for LRS under local anesthesia. Clinical outcomes were determined by visual analog scale (VAS) and the modified MacNab criteria. Evaluation was performed using magnetic resonance imaging (MRI), computed tomography (CT), and flexion-extension radiographs.

METHODS

 This study involved 85 patients (47 males and 38 females) who underwent TF-FEVF for LRS. The mean age was 70.5 years and the mean follow-up duration was 14.8 months. Data were collected on sex, age, level of operation, diagnosis, history of spine surgery at the same level, and duration of follow-up. The diagnosis was categorized as LSS with or without disk bulging. Clinical evaluation was performed using the VAS and modified MacNab criteria. MRI was used to evaluate the degree of disk degeneration, vertebral endplate degeneration, disk height, thickening of the ligamentum flavum, and stenosis. Bony stenosis was evaluated using CT. Sagittal translation and sagittal angulation were also measured by flexion-extension radiographs, and the Cobb angle was measured using a standing front view radiograph. All variables were compared between patients with excellent/good outcomes (E/G group) and those with fair/poor outcomes (F/P group) using the modified MacNab criteria.

RESULTS

 Postoperative VAS showed that leg pain decreased from 59.0 ± 28.6 preoperatively to 17.9 ± 27.2 at the final follow-up (p < 0.01) and that lower back pain also decreased from 60.7 ± 26.6 preoperatively to 27.3 ± 28.6 at final follow-up (p < 0.01). According to the modified MacNab criteria, the results during the final follow-up were excellent in 39 cases, good in 21 cases, fair in 13 cases, and poor in 12 cases. There were no significant differences in sex, age, diagnosis, history of spine surgery, and duration of follow-up periods between the 60 cases (70.6%) in the E/G group and the 25 cases (29.4%) in the F/P group. Imaging evaluation revealed statistically significant differences between the E/G group and the F/P group in intervertebral angle flexion (3.2 vs. 0.4 degrees; p < 0.05), sagittal angulation (4.3 vs. 8.1 degrees; p < 0.05), slip in flexion (0.9 vs. 2.8 mm; p < 0.05), sagittal translation (0.7 vs. 1.6 mm; p < 0.05), and Cobb angle (-0.5 vs. -1.9 degrees; p < 0.05).

CONCLUSION

 Midterm results of TF-FEVF were generally favorable; factors contributing to good or poor TF-FEVF outcomes were large sagittal angulation, large sagittal translation, and concave side.

Ultrasound-guided erector spinae plane block for awake spine surgery: A case report and review of the literature

Percutaneous endoscopic lumbar discectomy is increasingly gaining recognition as an alternative to open microdiscectomy for the treatment of intervertebral disk herniation. Apart from the neuraxial blockade, and general anesthesia, there is literature demonstrating the performance of endoscopic lumbar discectomy under sole local anesthesia infiltration. This is particularly advantageous as an awake patient assists the surgeon by verbalizing and preventing any inadvertent nerve root damage. However, marked pain has been reported during key steps such as endoscope port installation and radiculolysis. The erector spinae plane (ESP) block is an interfascial paraspinal block that soaks the spinal nerve roots with epidural spread providing superior analgesia for endoscopic discectomy. The utility of ESP block as a perioperative analgesic technique following spine surgery is well established; there are no reports of successful endoscopic discectomy performed using this block. This article emphasizes the utility of ESP block as the sole anesthetic technique for minimally invasive spine surgery in the awake state.

Epidural Versus Local Anesthesia for Percutaneous Endoscopic Lumbar Discectomy: A Systematic Review and Meta-Analysis

STUDY DESIGNS

Systematic Review.

OBJECTIVE

To examine the impact of anesthesia type on patient-reported outcomes (PROs) and complications after percutaneous endoscopic lumbar discectomy (PELD).

SUMMARY OF BACKGROUND DATA

A significant advantage of PELD involves the option to use alternative sedation to general anesthesia (GA). Two options include local anesthesia (LA) and epidural anesthesia (EA). While EA is more involved, it may yield improved pain control and surgical results compared with LA. However, few studies have directly examined outcomes for PELD after LA versus EA, and it remains unknown which technique results in superior outcomes.

MATERIALS AND METHODS

A systematic review and meta-analysis of the PubMed, EMBASE, and SCOPUS databases examining PELD performed with LA or EA from inception to August 16, 2021 were conducted. All studies reported greater than 6 months of follow-up in addition to PRO data. PROs, including visual analog scale (VAS)-leg/back, and Oswestry Disability Index (ODI) scores were collected. Complications, recurrent disk herniation, durotomy, and reoperation rates, as well as surgical data, were recorded. All outcomes were compared between pooled studies examining LA or EA.

RESULTS

Fifty-six studies consisting of 4465 patients (366 EA, 4099 LA) were included. Overall complication rate, durotomy rate, length of stay, recurrent disk herniation, and reoperation rates were similar between groups. VAS back/leg and ODI scores were all significantly improved at the first and last follow-up appointments in the LA group. VAS leg and ODI scores were significantly improved at the first and last follow-up appointments in the EA group, but VAS back was not.

CONCLUSIONS

EA can be a safe and feasible alternative to LA, potentially minimizing patient discomfort during PELD. Conclusions are limited by a high level of study bias and heterogeneity. Further investigation is necessary to determine if PELD under EA may have greater short-term PRO benefits compared with LA.

Lumbar dorsal root ganglion displacement between supine and prone positions evaluated with 3D MRI

OBJECTIVE

Pre-operative lumbar spine MRI is usually acquired with the patient supine, whereas lumbar spine surgery is most commonly performed prone. For MRI to be used reliably and safely for intra-operative navigation for foraminal and extraforaminal decompression, the magnitude of dorsal root ganglion (DRG) displacement between supine and prone positions needs to be understood.

METHODS

A prospective study of a degenerative lumbar spine cohort of 18 subjects indicated for lumbar spine surgery. Three-dimensional T2-weighted fast spin echo and T1-weighted spoiled gradient echo sequences were acquired at 3 T. Displacement and cross-sectional area (CSA) of the bilateral DRGs at 5 motion levels (L1-2 to L5-S1) were determined via 3D segmentation by 2 independent evaluators. Wilcoxon rank-sum tests without correction for multiple comparison were performed against hypothesized 1-mm absolute displacement and corresponding 24% CSA change.

RESULTS

DRG mean absolute displacement was <1 mm (p > 0.99, mean = 0.707 mm, 95% confidence interval (CI) = 0.659 to 0.755 mm), with the largest directional displacement in the dorsal-to-ventral direction from supine to prone (mean = 0.141 mm, 95% CI = 0.082 to 0.200 mm). Directional displacements caudal-to-cephalad were 0.087 mm (95% CI = 0.022 to 0.151 mm), and left-right were -0.030 mm (95%CI = -0.059 to -0.001 mm). Mean CSA change was within 24% (p > 0.99, mean = -8.30%, 95% CI = -10.5 to -6.09%). Mean absolute displacement was largest for the L1 (mean = 0.811 mm) and L2 (mean = 0.829 mm) DRGs.

CONCLUSIONS

Minimal, non-statistically significant soft tissue displacement and morphological area differences were demonstrated between supine and prone positions during 3D lumbar spine MRI.

Evaluation of Augmented Reality Surgical Navigation in Percutaneous Endoscopic Lumbar Discectomy: Clinical Study

BACKGROUND

The puncture procedure in percutaneous endoscopic lumbar discectomy (PELD) is non-visual, and the learning curve for PELD is steep.

METHODS

An augmented reality surgical navigation (ARSN) system was designed and utilized in PELD. The system possesses three core functionalities: augmented reality (AR) radiograph overlay, AR puncture needle real-time tracking, and AR navigation. We conducted a prospective randomized controlled trial to evaluate its feasibility and effectiveness. A total of 20 patients with lumbar disc herniation treated with PELD were analyzed. Of these, 10 patients were treated with the guidance of ARSN (ARSN group). The remaining 10 patients were treated using C-arm fluoroscopy guidance (control group).

RESULTS

The AR radiographs and AR puncture needle were successfully superimposed on the intraoperative videos. The anteroposterior and lateral AR tracking distance errors were 1.55 ± 0.17 mm and 1.78 ± 0.21 mm. The ARSN group exhibited a significant reduction in both the number of puncture attempts (2.0 ± 0.4 vs. 6.9 ± 0.5, p = 0.000) and the number of fluoroscopies (10.6 ± 0.9 vs. 18.5 ± 1.6, p = 0.000) compared with the control group. Complications were not observed in either group.

CONCLUSIONS

The results indicate that the clinical application of the ARSN system in PELD is effective and feasible.

Lumbar safety triangle: comparative study of coronal and coronal oblique planes in 3.0-T magnetic resonance imaging

Objective

To compare the measurements of the lumbar safety triangle (Kambin's triangle) and the invasion of the dorsal root ganglion in the triangle in coronal and coronal oblique planes.

Materials and Methods

A cross-sectional study, in which 210 3.0-T magnetic resonance images of L2-L5 were analyzed in coronal and coronal oblique planes. Exams with lumbar spine anomalies were excluded. Demographic (sex and age) and radiological variables were recorded by a single evaluator.

Results

Most sample was female (57.1%), mean age 45.5 ± 13.3 (18-98 years). The measurements average, as well as the areas, gradually increased from L2 to L5. The dorsal root ganglion invaded the triangle in all images. The safety triangle average area was smaller in the coronal oblique plane than in the coronal plane. Of the seven dimensions of safety triangle obtained for each level of the lumbar spine, six were significantly smaller in the coronal oblique plane than in the coronal plane. The only dimension that showed no difference was the smallest ganglion dimension.

Conclusion

The dimensions and areas investigated were smaller in coronal oblique plane, especially the area (difference > 1 mm). The analysis of the triangular zone in this plane becomes important in the preoperative assessment of minimally invasive procedures.

Development and Validation of a Nomogram to Predict the Risk of Recurrent Lower Extremity Radiating Pain Within 1 Week Following Full-Endoscopic Lumbar Discectomy

BACKGROUND

Accurately predicting the risk of lower extremity (LE) radiating pain after surgery is an important endeavor for spinal surgeons. Our study aimed to identify risk factors for LE radiating pain after decompression with full-endoscopic lumbar discectomy (FELD) and develop a nomogram.

METHODS

We retrospectively reviewed the medical data of patients with lumbar disc herniation who underwent FELD. Two hundred thirty-five patients diagnosed at our hospital from January 2015 to December 2020 were used for model development. The independent risk factors for LE radiating pain after surgery were determined by least absolute shrinkage and selection operator logistic regression and multivariate logistic regression analysis. A nomogram was developed to predict the risk of LE radiating pain based on independent risk factors. Receiver operating characteristic curve, calibration curve, and decision curve analyses were used to evaluate the predictive performance. The nomogram was further verified by an independent cohort.

RESULTS

Three hundred seventy-five patients were enrolled in this study, with 102 patients in the training cohort reporting LE radiating pain after FELD, while 133 patients did not. In the validation cohort, 57 patients reported LE radiating pain after FELD, while 83 patients did not. The model was established by multivariate logistic regression analysis. The risk factors included a higher Michigan State University classification of herniated discs, increased disease course, increased time of surgery, reduced lateral recess width, and an interlaminar surgical approach, compared to transforaminal approach. The C-indices and the area under the receiver operating characteristic curve of the predictive model demonstrated good discrimination. Good predictive performance and accuracy were also observed in the validation cohort.

CONCLUSIONS

A novel nomogram for predicting recurrent LE radiating pain within 1 week after FELD was established and validated. More aggressive pain management strategies should be considered for patients at high risk of LE radiating pain after surgery, as predicted by this model.

Augmented Reality Surgical Navigation in Minimally Invasive Spine Surgery: A Preclinical Study

BACKGROUND

In minimally invasive spine surgery (MISS), where the surgeon cannot directly see the patient's internal anatomical structure, the implementation of augmented reality (AR) technology may solve this problem.

METHODS

We combined AR, artificial intelligence, and optical tracking to enhance the augmented reality minimally invasive spine surgery (AR-MISS) system. The system has three functions: AR radiograph superimposition, AR real-time puncture needle tracking, and AR intraoperative navigation. The three functions of the system were evaluated through beagle animal experiments.

RESULTS

The AR radiographs were successfully superimposed on the real intraoperative videos. The anteroposterior (AP) and lateral errors of superimposed AR radiographs were 0.74 ± 0.21 mm and 1.13 ± 0.40 mm, respectively. The puncture needles could be tracked by the AR-MISS system in real time. The AP and lateral errors of the real-time AR needle tracking were 1.26 ± 0.20 mm and 1.22 ± 0.25 mm, respectively. With the help of AR radiographs and AR puncture needles, the puncture procedure could be guided visually by the system in real-time. The anteroposterior and lateral errors of AR-guided puncture were 2.47 ± 0.86 mm and 2.85 ± 1.17 mm, respectively.

CONCLUSIONS

The results indicate that the AR-MISS system is accurate and applicable.

General vs Local Anesthesia for Percutaneous Endoscopic Lumbar Discectomy (PELD): A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review.

OBJECTIVES

It remains unknown whether general anesthesia (GA) or local ± epidural anesthesia (LA) results in superior outcomes with percutaneous endoscopic lumbar discectomy (PELD). The present study sought to examine the impact of anesthesia type on patient-reported outcomes (PROs) and complications with PELD.

METHODS

Systematic review and meta-analysis examining PELD performed under GA or LA was conducted. Patient-reported outcomes including Visual Analog Scale (VAS)-leg/back, and Oswestry Disability Index (ODI) scores were collected. Complication, recurrent disc herniation, durotomy, and reoperation rates as well as surgical data were recorded. All outcomes were compared between pooled studies examining GA or LA.

RESULTS

Sixty-eight studies consisting of 5269 patients (724 GA, 4465 LA) were included in the meta-analysis. Overall complication rate was significantly higher in the GA group (9% vs 4%, P = .003). Durotomy rates, length of stay, recurrent disc herniation and reoperation rates were similar between groups. At the first follow-up timepoint, the LA group demonstrated significant improvements in VAS back and ODI scores (P < .05) while the GA group did not (P > .05). At the final follow-up (> 6 months), the percent of patients achieving an excellent McNab score was significantly higher in the GA vs LA group (P < .001).

CONCLUSIONS

Percutaneous endoscopic lumbar discectomy with LA may be associated with greater short-term improvement in VAS back pain and ODI scores. General anesthesia may be associated with more durable pain relief but a higher complication rate. Further systematic investigation is necessary to determine what short and long term benefits are associated with PELD performed under LA and GA.

Full-endoscopic trans-pars interarticularis approach for far lateral lumbar discectomy

PURPOSE

Surgical management of far lateral disc herniations remains challenging. Current transforaminal full-endoscopic approaches require non-visualized docking in the Kambin's triangle and have been associated with significant risk of inadvertent nerve injury. We develop a full-endoscopic approach based on reliable bony landmarks allowing for visualization of the exiting nerve root prior to the far lateral discectomy.

METHODS

The surgical details of a full-endoscopic trans-pars interarticularis approach for far lateral discectomy are described. These descriptions include high quality intraoperative images and important surgical pearls. A small patient cohort is presented to demonstrate feasibility and safety of the procedure.

RESULTS

We demonstrate the feasibility of this approach in 14 patients with a mean age of 59.5 ± 14.7 years. At a mean follow up of 21.9 ± 6.8 months, improvement of the visual analogue scale (VAS) for leg pain was 4.3 ± 1.0 resulting in minimally clinically important difference in 78.6% of the patients. The mean improvement in VAS for the back pain was 2.6 ± 0.8 and for Oswestry disability index (ODI) was 20.6 ± 5.3. Nuances of the trans-pars surgical techniques are presented in a patient with a right-sided L4-5 far lateral disc herniation. Preoperative imaging studies, steps of the surgical progression, and intraoperative views are described in detail.

CONCLUSION

Using the pars interarticularis as the bony target area allows for safe visualized access to the extraforaminal compartment of the exiting nerve root. This novel surgical technique has the potential benefit of decreasing inadvertent neural injury and subsequent postoperative dysesthesias.

Evaluation of Surgical Indications for Full Endoscopic Discectomy at Lumbosacral Disc Levels Using Three-Dimensional Magnetic Resonance/Computed Tomography Fusion Images Created with Artificial Intelligence

Background and Objectives: Although full endoscopic lumbar discectomy with the transforaminal approach (FED-TF) is a minimally invasive spinal surgery for lumbar disc herniation, the lumbosacral levels present anatomical challenges when performing FED-TF surgery due to the presence of the iliac bone. Materials and Methods: In this study, we simulated whether FED-TF surgery could be safely performed on a total of 52 consecutive cases with L5-S1 or L5-L6 disc herniation using fused three-dimensional (3D) images of the lumbar nerve root on magnetic resonance imaging (MRI) created with artificial intelligence and of the lumbosacral spine and iliac on computed tomography (CT) images. Results: Thirteen of the fifty-two cases were deemed operable according to simulated FED-TF surgery without foraminoplasty using the 3D MRI/CT fusion images. All 13 cases underwent FED-TF surgery without neurological complications, and their clinical symptoms significantly improved. Conclusions: Three-dimensional simulation may allow for the assessment from multiple angles of the endoscope entry and path, as well as the insertion angle. FED-TF surgery simulation using 3D MRI/CT fusion images could be useful in determining the indications for full endoscopic surgery for lumbosacral disc herniation.

Background, techniques, applications, current trends, and future directions of minimally invasive endoscopic spine surgery: A review of literature

Across many of the surgical specialties, the use of minimally invasive techniques that utilize indirect visualization has been increasingly replacing traditional techniques which utilize direct visualization. Arthroscopic surgery of the appendicular skeleton has evolved dramatically and become an integral part of musculoskeletal surgery over the last several decades, allowing surgeons to achieve similar or better outcomes, while reducing cost and recovery time. However, to date, the axial skeleton, with its close proximity to critical neural and vascular structures, has not adopted endoscopic techniques at as rapid of a rate. Over the past decade, increased patient demand for less invasive spine surgery combined with surgeon desire to meet these demands has driven significant evolution and innovation in endoscopic spine surgery. In addition, there has been an enormous advancement in technologies that assist in navigation and automation that help surgeons circumvent limitations of direct visualization inherent to less invasive techniques. There are currently a multitude of endoscopic techniques and approaches that can be utilized in the treatment of spine disorders, many of which are evolving rapidly. Here we present a review of the field of endoscopic spine surgery, including the background, techniques, applications, current trends, and future directions, to help providers gain a better understanding of this growing modality in spine surgery.

Perioperative Management for Full-Endoscopic Lumbar Discectomy: Consideration From the Perspective of Preventing Complication

In recent years, full-endoscopic discectomy (FED) has expanded its range of indications with the development of devices and various techniques. The advantage of FED over conventional surgery is that it is a minimally invasive procedure. However, intraoperative and postoperative precautions must be taken to prevent complications. It is necessary to avoid complications that could compromise the outcome of the procedure. Effective perioperative management is necessary to avoid complications; however, there is no set view for perioperative management in FED. In this study, we perform a literature review to examine the effectiveness of perioperative management methods for FED. The key to ensuring the efficacy and minimal invasiveness of FED is prevention of complications. Based on the result and literature review, we believe that the most manageable postoperative management after FED is prevention of recurrent disc herniation and hematoma formation. A drain should be placed to prevent postoperative hematoma formation. It is advisable to evaluate the patient’s symptoms and monitor C-reactive protein and erythrocyte sedimentation rate levels during the first week after surgery. Postoperative antibiotics were administered for 1 day.

Neurological Safety of Endoscopic Transforaminal Lumbar Interbody Fusion: A Magnetic Resonance Neurography Study

OBJECTIVE

A magnetic resonance neurography (MRN) study was conducted to assess the neurological safety of endoscopic transforaminal lumbar intervertebral fusion (endo-TLIF).

MATERIALS AND METHODS

A total of 56 healthy volunteers (29 men, 27 women; average age, 44 yr; age range, 21-60 yr) were included in the study. Coronal MRN images were collected from L2/L3 to L5/S1. The working triangle, modified working zone, and safest working zone areas, as well as the vertical and horizontal safe operation diameters, were measured. Linear regression analyses were conducted to explore the correlations between general characteristics (sex, age, height, body mass index) and the measured radiographic indicators.

RESULTS

MRN can effectively evaluate the operation zone of endo-TLIF. The safest working zone, modified working zone, and working triangle areas were largest at L4/L5 (92.4±23.4, 136±35.6, and 197±41.7 mm 2 , respectively) and smallest at L2/L3 (45.5±12.9, 68.1±19.5, and 92.6±24.4 mm 2 , respectively). The vertical safe operation diameter was large at L4/L5 and L2/L3 (5.34±0.8 and 5.42±0.9 mm, respectively) and smallest at L5/S1 (2.94±0.9 mm). The horizontal safe operation diameter was large at L4/L5 (7.28±1.2 mm) and smaller at L5/S1 and L2/L3 (4.28±1.0 and 4.77±0.8 mm, respectively).

CONCLUSIONS

L4/L5 has the lowest risk of nerve injury, and may be the safest level for beginners initiating endo-TLIF in their practice. We recommend that coronal MRN is routinely performed before endo-TLIF to minimize the risk of neurological injury.

Novel Merging of CT and MRI to Allow for Safe Navigation into Kambin's Triangle for Percutaneous Lumbar Interbody Fusion-Initial Case Series Investigating Safety and Efficacy

BACKGROUND

For percutaneous lumbar fusion (percLIF), magnetic resonance imaging and computed tomography are critical to defining surgical corridors. Currently, these scans are performed separately, and surgeons then use fluoroscopy or neuromonitoring to guide instruments through Kambin's triangle. However, anatomic variations and intraoperative positional changes are possible, meaning that safely accessing Kambin's triangle remains a challenge because nerveroot visualization without endoscopes has not been thoroughly described.

OBJECTIVE

To overcome the known challenges of percLIF and reduce the likelihood of iatrogenic injuries by showing real-time locations of neural and bony anatomy.

METHODS

The authors demonstrate an intraoperative navigational platform that applies nerve root segmentation and image fusion to assist with percLIF. Five patients from a single institution were included.

RESULTS

Of the 5 patients, the mean age was 71 ± 8 years and 3 patients (60%) were female. One patient had general anesthesia while the remaining 4 patients underwent awake surgery with spinal anesthesia. The mean area for the L4-L5 Kambin's triangle was 76.1 ± 14.5 mm 2 . A case example is shown where the side of approach was based on the fact that Kambin's triangle was larger on one side compared with the other. The mean operative time was 170 ± 17 minutes, the mean blood loss was 32 ± 16 mL, and the mean hospital length of stay was 19.6 ± 8.3 hours. No patients developed postoperative complications.

CONCLUSION

This case series demonstrates the successful and safe application of nerve segmentation using magnetic resonance imaging/computed tomography fusion to perform percLIF and provide positive patient outcomes.

How dimensions can guide surgical planning and training: a systematic review of Kambin's triangle

OBJECTIVE

The authors sought to analyze the current literature to determine dimensional trends across the lumbar levels of Kambin's triangle, clarify the role of imaging techniques for preoperative planning, and understand the effect of inclusion of the superior articular process (SAP). This compiled knowledge of the triangle is needed to perform successful procedures, reduce nerve root injuries, and help guide surgeons in training.

METHODS

The authors performed a search of multiple databases using combinations of keywords: Kambin's triangle, size, measurement, safe triangle, and bony triangle. Articles were included if their main findings included measurement of Kambin's triangle. The PubMed, Scopus, Ovid, Cochrane, Embase, and Medline databases were systematically searched for English-language articles with no time frame restrictions through July 2022.

RESULTS

Eight studies comprising 132 patients or cadavers were included in the study. The mean ± SD age was 66.69 ± 9.6 years, and 53% of patients were male. Overall, the size of Kambin's triangle increased in area moving down vertebral levels, with L5-S1 being the largest (133.59 ± 4.36 mm2). This trend followed a linear regression model when SAP was kept (p = 0.008) and removed (p = 0.003). There was also a considerable increase in the size of Kambin's triangle if the SAP was removed.

CONCLUSIONS

Here, the authors have provided the first reported systematic review of the literature of Kambin's triangle, its measurements at each lumbar level, and key areas of debate related to the definition of the working safe zone. These findings indicate that CT is heavily utilized for imaging of the safe zone, the area of Kambin's triangle tends to increase caudally, and variation exists between patients. Future studies should focus on using advanced imaging techniques for preoperative planning and establishing guidelines for surgeons.

Determination of the Entry Point for Lower Lumbar Intradiscal Procedure Using Transforaminal Technique: Cross-Sectional Study Using Magnetic Resonance Imaging

Introduction

Triangular working area otherwise known as the Kambin triangle is designated as a safe place to position the instrument during the operation, with minimal risk to exiting nerves. This study aims to improve understanding and increase the safety of various transforaminal intradiscal procedures at L3/L4, L4/L5, and L5/S1 levels.

Methods

A cross-sectional analysis involving 102 MRIs that met the inclusion criteria was obtained and analyzed at the L3/L4, L4/L5, and L5/S1 discs level. For each level, the Kambin triangle was measured. By evaluating those measurements, the viability of this method was determined.

Results

Safe working zone approach angles were consistently getting wider from L3 to S1 levels. It was statistically significant to be wider for the left side for the mean angle of lateral nucleus trajectory at the L4/L5 level and L5/S1. The entry point is at 32, 45, and 55-60 mm from the midline, and the instrument should be directed at 12°, 20°, and 27° medially for the lateral nucleus at L3/L4, L4/L5, and L5/S1, respectively. The center of the nucleus pulposus entry point is at 64, 77, and 85 mm from the midline with a medial inclination of 40°, 47°, and 52°, respectively, for L3/L4, L4/L5, and L5/S1. For the posterior nucleus pulposus, the skin should be pierced 90, 140, and 180 mm from the midline and directed medially at 53°, 61°, and 68°, respectively, for L3/L4, L4/L5, and L5/S1. The posterior annulus fibrosis entry point is 172, 355, and 450 mm with a medial inclination of 69°, 80°, and 84° at L3/L4, L4/L5, and L5/S1, respectively. The sagittal inclination is 3° cephalad at L3/L4, 10° caudally at L4/L5, and 27° caudally at L5/S1.

Conclusions

Preoperative MRI assessment is important to determine the angle of trajectory for the safe entry point for intradiscal procedure via transforaminal approach.

Usefulness of 3D CT/MRI Fusion Imaging for the Evaluation of Lumbar Disc Herniation and Kambin's Triangle

Study design: Prospective study. Objective: The aim of this study is to visualize the morphology of a lumbar herniated disc and Kambin’s triangle in three dimensions (3D) based on preoperative CT/MRI fusion images. Methods: CT/MRI fusion images of 23 patients (10 males and 13 females; mean age 58.2 years) were used to evaluate Kambin’s triangle, which is created between the superior articular process (SAP), exiting nerve root (ENR), inferiorly by the superior endplate of the lower lumbar vertebra and dural canal medially at 60 degree and 45 degree endoscopic approach angles. The percentage of the safe usage of transforaminal endoscopic approach was evaluated to utilize a 5 mm dilater without partial facet resection in the fusion image. The 3D lumbar nerve root sleeve angulation (3DNRA), which is the angle between the axis of the thecal sac and the nerve root sleeve, was calculated. The herniated discs were also visualized in the CT/MRI fusion image. Results: The 3DNRA became smaller from L2 to S1. The L2 3DNRA was statistically larger than those of the other root, and the S1 3DNRA was significantly smaller than the others (p < 0.05). (L2, 41.0°; L3, 35.6°; L4, 36.4°; L5, 33.9°; and S1, 23.2°). The SAP-ENR distance at 60° was greatest at L4/5 (5.9 mm). Possible needle passages at 60° to each disc level were 89.1% at L2/3, 87.0% at L3/4 and 84.8% at L4/5. However, the safe 5 mm dilater passage at 60° without bony resection to each disc level were 8.7% at L2/3, 28.3% at L3/4 and 37.0% at L4/5. The 60° corridor at L2/3 was the narrowest (p < 0.01). All herniated discs were visualized in the fusion image and the root compression site was clearly demonstrated especially with foraminal/extraforaminal herniations. Conclusion: The 3D lumbar CT/MRI fusion image enabled a combined nerve-bony assessment of Kambin’s triangle and herniated disc. A fully endoscopic 5 mm dilater may retract the exiting nerve root in more than 60% of total cases. This new imaging technique could prove to be very useful for the safety of endoscopic lumbar disc surgery.

Percutaneous endoscopic lumbar foraminotomy: how I do it

BACKGROUND

Percutaneous endoscopic lumbar foraminotomy (PELF) is a good alternative for foraminal stenosis. The steep learning curve and lack of a practical manual can make this technique challenging.

METHOD

We describe a step-by-step technique based on the literature review and our experience in actual practice: (1) posterolateral foraminal landing, (2) bony unroofing of the superior articular process, and (3) full-scale soft tissue decompression. Technical tips for preventing complications are also discussed.

CONCLUSION

PELF may be effective and minimally invasive. Standardized surgical techniques are essential for clinical success.

Determining the Minimum Effective Concentration of Ropivacaine in Epidural Anesthesia for Tolerable Pain in Transforaminal Percutaneous Endoscopic Lumbar Discectomy to Avoid Nerve Injury: A Double-Blind Study Using a Biased-Coin Design

Purpose

Epidural anesthesia (EA) is the main anesthesia method for transforaminal percutaneous endoscopic lumbar discectomy (PELD). Reducing the concentration of ropivacaine can help preserve tactile sensation, allowing patients to provide timely feedback to the surgeons when a nerve root is contacted to avoid nerve injury. Therefore, a 90% effective concentration (EC₉₀) that allows for mild pain [visual analog scale (VAS) score ≤3] while maximizing tactile sensation must be identified.

Methods

The concentration of ropivacaine for EA was varied for consecutive patients in this study using a two-stage biased-coin design (BCD) according to the response of the previous patient; the concentration used for the first patient was 0.2%. When the previous patient had a negative response (VAS score >3), the concentration used for the next one was increased by 0.015%. When the previous patient had a positive response (VAS score ≤3), the concentration used for the next one had an 89% probability of remaining the same and an 11% probability of being reduced by 0.015%. The EC₉₀ of ropivacaine was estimated using isotonic regression, and the 95% confidence interval (CI) was estimated using the bootstrapping method in R.

Results

A total of 58 patients were included in the study. The calculated EC₉₀ was 0.294% [95% CI (0.271%, 0.303%)]. Among 13 patients who reported unintended nerve root contact during the operation, none were found to have irreversible nerve injury after the operation.

Conclusion

To preserve maximum tactile sensation, the EC₉₀ of ropivacaine was 0.294% for patients with allowed mild pain. This concentration could allow for timely feedback when the nerve root is contacted, to avoid nerve injury.

Potential Application of MR-MR-US Fusion Imaging Navigation with Needle Tail Intelligent Positioning in Guiding Puncture in Percutaneous Transforaminal Endoscopic Discectomy

This study sought to investigate the feasibility of using magnetic resonance-magnetic resonance-ultrasound (MR-MR-US) fusion imaging navigation (FIN) with needle tail intelligent positioning (NTIP) to guide puncture in percutaneous transforaminal endoscopic discectomy (PTED). First, in a pig experiment, we found that puncture errors in lumbar intervertebral foramen (LIF) puncture using magnetic resonance-magnetic resonance-ultrasound (MR-MR-US) FIN with NTIP for experienced and novice operators were 2.00 ± 1.00 and 2.57 ± 0.98 mm, respectively (p = 0.231), suggesting this technique was minimally dependent on experience. Then, two experienced surgeons agreed (inter-observer agreement к=0.801) that the quality of MR-MR fusion images was good or sufficient. Finally, we performed PTED in eight patients using MR-MR-US FIN with NTIP, and no significant complications were reported during LIF puncture. Overall, MR-MR-US FIN with NTIP may be a potential application for guiding puncture in PTED, but more clinical studies with a larger sample size are required to further evaluate the advantages of MR-MR-US FIN with NTIP.

Lumbar degenerative disease treated by percutaneous endoscopic transforaminal lumbar interbody fusion or minimally invasive surgery-transforaminal lumbar interbody fusion: a case-matched comparative study

Purpose

This study aimed to evaluate the clinical efficacy and imaging results of percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF) through comparing it with minimally invasive surgery-transforaminal lumbar interbody fusion (MISTLIF).

Materials and methods

We performed a retrospective analysis on patients with lumbar degenerative disease treated by PETLIF or MISTLIF from September 2017 to January 2019, and the patients were divided into two groups: the PETLIF group and the MISTLIF group. The clinical and imaging parameters of the two groups were evaluated.

Results

There was no significant difference between the two groups in complication rate. The operative time in the PETLIF group was significantly less than that in the MISTLIF group. Compared with those before operation, the postoperative VAS-L and VAS-B scores were significantly improved after operation in the both groups. In addition, the postoperative VAS-B score of the PETLIF group was significantly lower than that of the MISTLIF group. At the last follow-up, there was no significant difference between the two groups in the VAS-L score, VAS-B score, ODI score, and bony fusion rate.

Conclusions

Both PETLIF and MISTLIF could achieve satisfactory clinical outcomes in the treatment of lumbar degenerative disease, but our study suggested that PETLIF had less damage, rapid recovery after operation, and short discharge time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02841-4.

The irony of the transforaminal approach: A comparative cohort study of transforaminal endoscopic lumbar discectomy for foraminal versus paramedian lumbar disc herniation

Transforaminal endoscopic lumbar discectomy (TELD) is useful for soft lumbar disc herniation (LDH). Although the transforaminal approach can reach the foraminal disc zone, the risk of exiting nerve root irritation along the path is considerable. Few studies have assessed the difficulties of TELD for foraminal LDH. The objective of this study is to compare the clinical results of TELD between foraminal or far-lateral LDH and paramedian LDH.Between June 2016 and July 2017, 135 consecutive patients with single-level LDH were treated with TELD for 2 years. Among them, 25 patients had foraminal or far-lateral LDH (foraminal group), and the remaining 110 patients had central or subarticular LDH (paramedian group). Perioperative data and clinical outcomes were evaluated using the visual analog pain scale, Oswestry Disability Index, and modified Macnab criteria.The foraminal group showed a higher rate of significant access pain (24.00% vs 8.19%, P < .05). The foraminal group also had a longer duration of surgery, length of hospital stay, and return to work (all P < .05). Pain scores and functional status were significantly improved in both groups. Although there were no differences in the outcomes at 2 years postoperatively, early pain and disability at 6 weeks were higher in the foraminal group.Ironically, the early clinical results of TELD for foraminal LDH may be less favorable than those for paramedian LDH. Therefore, great care should be taken during TELD for foraminal or far-lateral LDH.

Morphological analysis of Kambin's triangle using 3D CT/MRI fusion imaging of lumbar nerve root created automatically with artificial intelligence

PURPOSE

We developed a software program that automatically extracts a three-dimensional (3D) lumbar nerve root image from magnetic resonance imaging (MRI) lumbar nerve volume data using artificial intelligence. The aim of this study is to evaluate the morphology of Kambin's triangle in three dimensions based on an actual endoscopic transforaminal surgical approach using three-dimensional (3D) computed tomography (CT)/ magnetic resonance imaging (MRI) fusion images of the lumbar spine and nerve tissue.

METHODS

Three-dimensional lumbar spine/nerve images of 100 patients (31 males and 69 females; mean age, 66.8 years) were used to evaluate the relationship between the superior articular process (SAP), exiting nerve root (ENR), and dural canal at the L2/3, L3/4, and L4/5 levels at 45° and 60° approach angles.

RESULTS

The SAP-ENR distance at 60° was the greatest at L4/5 and was significantly greater at L2/3 and L4/5 than at L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distance at 45° was the greatest at L2/3, and it was larger in L2/3 and L4/5 than in L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distances at L4/5 were significantly greater at 60° than at 45° (P < 0.01). The dural canal was located within Kambin's triangle on the plane of the upper endplate of the lower vertebra at L2/3 in 41.5% of the cases and at L3/4 in 14% of the cases at 60° but not at L4/5.

CONCLUSION

The 3D lumbar spine/nerve image enabled a combined assessment of the positional relationship between the SAP, ENR, and dural canal to quantify the safety zone of practical endoscopic spinal surgery using a transforaminal approach. Three-dimensional lumbar spine/nerve images could be useful for examining parameters, including bones and nerves, to ensure the safety of surgery.

Comparison of post-operative wound pain between interlaminar and transforaminal endoscopic spine surgery: which is superior?

STUDY DESIGN

Prospective cohort study PURPOSE: The objective is to compare post-operative wound pain in patients treated by endoscopic surgery between interlaminar and transforaminal approach at lumbar region.

OVERVIEW OF LITERATURE

There are two common approaches for endoscopic lumbar spine surgery, interlaminar and transforaminal approach. The wound size of these two approaches is about the same. However, post-operative wound pain may differ according to the entrance area.

METHODS

We conducted a prospectively cohort study including all patients underwent full endoscopic lumbar spine surgery by single surgeon between January 2016 to October 2019. Wound pain using visual analog scale (VAS) at post-operative day 1 and day 14 were collected. VAS back pain, VAS leg pain, Oswestry Disability Index (ODI), modified McNab criteria and complications were also collected.

RESULTS

There were 313 patients included in the study. There was no significant difference in VAS wound pain between interlaminar and transforaminal group. Interestingly, subgroup analysis in interlaminar group found statistically significant higher VAS for wound pain at post-operative day 1 when significant bone resection was done by power burr. VAS back-leg pain and ODI have improved significantly between pre-operative and last follow up in both approaches.

CONCLUSIONS

Wound pain from endoscopic spine surgery is minimal. This study found no difference in wound pain between endoscopic interlaminar and transforaminal approach. Both approaches show favorable clinical outcomes with few serious complications rate. Further study with long term follow up is needed.

Application of a targeted and quantificational foraminoplasty device in percutaneous transforaminal endoscopic discectomy for L5-S1 disc herniation: preliminary clinical outcomes

OBJECTIVE

Percutaneous transforaminal endoscopic discectomy (PTED) is minimally invasive and has been widely used to treat patients with lumbar disc herniation (LDH) due to its safety and efficiency. However, due to the unique anatomy of the L5-S1 level, the PTED procedure is often difficult to perform in the region. ZESSYS, a targeted and quantificational foraminoplasty device, may help to overcome these anatomical limitations. In this study, we assessed the efficiency and the short-term effects of PTED with ZESSYS at the L5-S1 level.

METHODS

Between January and August of 2018, fifty-six patients with lumbar disc herniation at the single level of L5-S1 and who underwent percutaneous transforaminal endoscopic discectomy were enrolled in this retrospective cohort study. They were segregated into the transforaminal endoscopic surgical system (TESSYS) group and the ZESSYS group. The puncture time, foraminoplasty time, decompression time, and fluoroscopy time were evaluated for operation efficiency. Clinical outcomes were assessed by the visual analog scale (VAS) score and Oswestry Disability Index (ODI) score. The MacNab criteria were used to evaluate patient subjective satisfaction at 12-month follow-up postoperatively.

RESULTS

The average puncture time (5.29 ± 2.05 min), foraminoplasty time (12.82 ± 2.52 min), and fluoroscopy time (26.29 ± 5.96 s) were all significantly shorter in the ZESSYS group than in the TESSYS group (average puncture time 8.07 ± 3.13 min, p < 0.01; foraminoplasty time, 17.18 ± 2.92 min, p < 0.01; fluoroscopy time, 34.73 ± 6.86 s; p < 0.01). No significant differences were observed between the 2 groups in the decompression time (p = 0.057). The VAS score of low back pain and leg pain, as well as the ODI score, improved at all time points postoperatively compared with preoperative, in both the TESSYS group and the ZESSYS group (P < 0.05). There were no significant differences in the VAS score of low back pain, VAS score of leg pain, and ODI score between the TESSYS group and the ZESSYS group at the same time points (P > 0.05). According to the MacNab criteria, the excellent and good rate at 12-month follow-up postoperatively was 85.7% in the TESSYS group and 89.3% in the ZESSYS group (P > 0.05).

CONCLUSION

The targeted and quantificational foraminoplasty device named ZESSYS was more efficient in the puncture and foraminoplasty procedures, effectively protecting the exiting nerve and minimizing the level of radiation exposure. The device is efficient and safe for PTED in treating lumbar disc herniation at the L5-S1 level.

The Endoscopic Trans-Superior Articular Process Approach: A Novel Minimally Invasive Surgical Corridor to the Lateral Recess

BACKGROUND

Transforaminal approaches to the lumbar spine are typically performed utilizing Kambin's triangle as approach corridor; however, degenerative changes can distort anatomy and expose the exiting nerve root to inadvertent injury.

OBJECTIVE

To describe the surgical technique of a novel full-endoscopic approach to access the lateral recess and report clinical outcomes.

METHODS

The trans-superior articular process (SAP) approach involves partial resection of the SAP, allowing access to the lateral recess both ventral and dorsal to the traversing nerve root. A retrospective review of 40 patients who had undergone a trans-SAP approach for decompression of lateral recess pathology was conducted. Outcomes were measured using visual analog scores (VAS) and Oswestry Disability Index (ODI) at 2 wk, 3 mo, and at last follow-up.

RESULTS

At a mean follow-up of 24 mo, patients experienced statistically significant improvement of the VAS for ipsilateral leg pain, VAS for back pain, and ODI when comparing preoperative values to all postoperative time points. The percentage of patients reaching a minimally clinically important difference for VAS leg pain and ODI was approximately 90% and 88%, respectively. The complication profile was favorable with no dural tears and no postoperative motor or sensory deficits. One patient required revision, with a total reoperation rate of 3%.

CONCLUSION

The trans-SAP approach is a novel approach that utilizes a safe surgical corridor via the SAP to access lateral recess pathology. Our initial clinical experience suggests that the trans-SAP approach allows for treatment of lateral recess and foraminal pathology with low complication rates.

Evaluation of full-endoscopic lumbar discectomy in the treatment of obese adolescents with lumbar disc herniation: a retrospective study

Background

Obese patients are at risk of complications after spinal surgery. Full-endoscopic lumbar discectomy (FELD) has advantages over conventional open surgery in the treatment of obese adult patients with lumbar disc herniation (LDH) because it can decrease perioperative complications and enhance the degree of patient satisfaction. However, no clinical studies have evaluated the efficacy of FELD in obese adolescents with LDH (ALDH). This study aimed to evaluate the efficacy of FELD for the treatment of obese ALDH.

Methods

We retrospectively collected clinical data from 208 patients with single-segment ALDH who underwent FELD in our hospital between January 2015 and December 2019. According to the WHO classification of obesity, the patients were divided into obese (BMI ≥30 kg/m²) and non-obese (BMI < 30 kg/m²) groups (control group). Based on the preoperative baseline data of the two groups, propensity score matching was performed to select patients from these groups for a comparative study. Perioperative data included operative time, intraoperative blood loss, and length of postoperative hospitalization. The visual analog scale (VAS), Oswestry disability index (ODI), and modified MacNab criteria were recorded as the main indicators of the surgical outcome. Recurrence rate and incidence of complications were recorded as minor indicators.

Results

Twenty-eight patients and 80 patients were included in the obese and non-obese groups, respectively, after 1:4 propensity score matching. Both groups showed improvements in VAS and ODI scores after surgery and at each follow-up time point (p < 0.05). However, there was no significant statistical difference in the surgical outcomes between the two groups at each follow-up time point (p > 0.05). The differences in operative time, intraoperative blood loss, and length of postoperative hospitalization were not statistically significant between the two groups (p > 0.05).

Conclusion

FELD is a safe and effective minimally invasive technique for treating obese patients with ALDH. The efficacy of FELD in obese and non-obese patients with ALDH was comparable.

Endoscopic Lumbar Interbody Fusion and Minimally Invasive Transforaminal Lumbar Interbody Fusion for the Treatment of Lumbar Degenerative Diseases: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare clinical efficacy and safety of endoscopic lumbar interbody fusion (Endo-LIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in treatment of lumbar degenerative diseases.

METHODS

A literature search was performed using PubMed, Embase, Web of Science, and Cochrane Library databases. Studies published up to November 15, 2020, that compared Endo-LIF with MIS-TLIF for treating lumbar degenerative diseases were retrieved. Data were extracted according to predefined clinical outcome measures. Primary outcomes were preoperative and postoperative visual analog scale for leg and back pain and Oswestry Disability Index scores. Secondary outcomes were operative time and intraoperative blood loss; length of hospitalization; and complication, reoperation, and fusion rates. Data analysis was conducted with statistical software.

RESULTS

The meta-analysis included 6 studies comprising 480 patients. Results of the merged analysis revealed similar complication, reoperation, and fusion rates and preoperative and postoperative visual analog scale for leg and back pain and Oswestry Disability Index scores (P > 0.05) for Endo-LIF and MIS-TLIF. Nevertheless, with the exception of longer operative time (P < 0.05), Endo-LIF compared favorably with MIS-TLIF, with less intraoperative blood loss, shorter hospital stay (P < 0.05), and better long-term functional outcome.

CONCLUSIONS

Based on the evidence provided by this study, there is no significant difference in clinical efficacy and safety between Endo-LIF and MIS-TLIF in the treatment of lumbar degenerative diseases. Although Endo-LIF has a longer operative time, it has the advantages of less tissue trauma and rapid recovery after operation.

Minimum Seven-Year Follow-Up Outcomes of Percutaneous Endoscopic Lumbar Discectomy for Lumbar Degenerative Disease

Purpose

To investigate the long-term (> 7 years) clinical outcomes of percutaneous endoscopic lumbar discectomy for lumbar degenerative disease to address postoperative problems including postoperative dysesthesia (POD), residual back pain and segmental instability.

Methods

Inclusion and exclusion criteria were established. All patients who met the above criteria were treated by PELD using the transforaminal approach. Limited discectomy was performed to preserve the disc material in the intervertebral space as much as possible. The Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) score for back pain (VAS-B) and leg pain (VAS-L) and Modified MacNab’s criterion were used for clinical evaluation. Radiographic parameters including height of intervertebral disc and segmental instability were also evaluated.

Results

Forty-two patients (24 men and 18 women) who met our inclusion and exclusion criteria were included in our study. The average follow-up period was 95.71±5.63 months (ranging from 87 to 105 months). There were no neurological complications associated with the operation. POD was found in 14.29% of patients, while only 2 patients (4.76%) complained of mild dysesthesia at final follow-up. Two patients (4.76%) required revision surgery during the follow-up period. The final follow-up ODI, JOA score, VAS-B and VAS-L were significantly better than preoperative values. The average disc-height ratio was 84.52±5.66% of the preoperative disc height. No instability at the operation level was noted at final follow-up.

Conclusion

Our study showed that PELD using the transforaminal approach can provide favorable results after a long-term follow-up period. POD is a common complication at initial prognosis. Limited discectomy can preserve the disc height well and minimize the risk of residual back pain.

Treatment of single-segment suppurative spondylitis with the transforaminal endoscopic focal cleaning and drainage

Objective: To evaluate the clinical value of the transforaminal endoscopic focal cleaning and drainage for suppurative spondylitis.Design: Retrospective study.Participants: Twenty-one patients with single-segment suppurative spondylitis.Interventions: All patients were treated with the transforaminal endoscopic focal cleaning and drainage.Outcome Measures: The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured before and after the operation. Visual analogue scale (VAS) was used to evaluate the relief of pain symptoms. Neurological function American Spinal Injury Association (ASIA) grade was used to evaluate the recovery of neurological function. The postoperative clinical efficacy of the patients was evaluated using the Kirkaldy-Willis functional scoring criteria. The stability of the spine and the recurrence of infection were evaluated by imaging data.Results: Postoperative bacteriological culture results showed positive in 15 cases and no bacteria growth in 6 cases. Besides, 16 cases were pathologically diagnosed. The ESR, CRP, and VAS scores at 2 weeks postoperatively and at the last follow-up were significantly improved compared with those at pre-operation. At the last follow-up, the clinical outcome was excellent in 17 cases, good in 3 cases, and fair in 1 case, according to the Kirkaldy-Willis functional scoring criteria; and the ASIA grade returned to normal. There was no significant difference in the Cobb angle between the last follow-up and the pre-operation. There was no recurrence of infection during the follow-up period.Conclusion: The transforaminal endoscopic focal cleaning and drainage is a minimally invasive, effective and safe surgical procedure for suppurative spondylitis.

Risk Factor for Additional Intravenous Medication during Transforaminal Full-endoscopic Lumbar Discectomy under Local Anesthesia

Transforaminal full-endoscopic lumbar discectomy (TELD) can be performed under local anesthesia. However, there have been no reports on risk factors for a change in vital signs or the need for additional medications to maintain adequate analgesia during this procedure. The purpose of this study was to identify risk factors for additional intravenous medication during TELD under local anesthesia. The following factors were retrospectively evaluated in 113 consecutive patients who underwent TELD under local anesthesia at our institution: demographic characteristics, radiological features at the intervertebral disc level, distance between the superior articular process and the exiting nerve root, height of the intervertebral disc, height of the bulging disc, height of the intervertebral foramen, and distance from the insertion site to the spinous process on magnetic resonance imaging (MRI) and computed tomography (CT) scans of the lumbar spine. Logistic regression analysis was performed to determine factors associated with the need for additional drugs. In all, 23 cases (20.4%) required additional intraoperative medications because of hypertension, hypotension, bradycardia, or pain. Logistic regression analysis revealed that age (partial regression coefficient 0.05, p = 0.02) and bulging disc height (partial regression coefficient −0.7, p = 0.003) influenced the need for additional drugs. There were significant associations of need for additional intravenous medication with older age (>62 years) and a smaller bulging disc height (<8.2 mm). Patients with these factors require close monitoring for changes in vital signs or increasing pain when performing TELD under local anesthesia and may need additional intravenous medication.

A matched comparison of outcomes between percutaneous endoscopic lumbar discectomy and open lumbar microdiscectomy for the treatment of lumbar disc herniation: a 2-year retrospective cohort study

BACKGROUND CONTEXT

Although open lumbar microdiscectomy (OLMD) is considered to be the gold standard method for discectomy, recent progress in endoscopic spinal surgery has increased the popularity of percutaneous endoscopic lumbar discectomy (PELD) for this indication. However, one of the main drawbacks of PELD is incomplete decompression, especially at the start of the surgeon's learning curve. The functional outcomes of PELD and OLMD in patients matched for age, hernia level, and hernia location have not previously been compared.

PURPOSE

To compare OLMD with PELD in terms of the clinical outcome and the time to recovery.

STUDY DESIGN

Retrospective, matched cohort study.

PATIENT SAMPLE

Data of all patients who underwent elective spinal surgery between January 2015 and June 2017 were extracted from the local database.

OUTCOME MEASURES

Clinical outcomes were assessed using a 0-to-10 visual analogue scale (VAS) for lower back pain (LBP) and leg pain were scored before surgery and at postoperative day 1 and at each follow-up visit (3, 12, and 24 months), the Oswestry Disability Index (ODI: 0%-100%), the length of hospital stay, time to resumption of work, recurrence of Lumbar disc herniation, procedure failures, and complications.

METHODS

The participants were matched for age, disc level, and location of the herniated disk (central and paracentral vs. far-lateral). The participants' mean±standard deviation age was 47.09±12.55 (range: 28-70). We compared the various clinical outcomes between the two groups to identify which procedure had better immediate and long-term functional outcomes. The differences in mortality and occurrence of postoperative complications were also compared in patients with PELD versus controls.

RESULTS

Fifty-eight patients were enrolled (29 with PELD and 29 with OLMD). Both groups reported significant reductions in LBP and leg pain (p<0.01) postoperatively and an improvement in the ODI at 24 months postsurgery. The intergroup difference in the VAS for LBP at 1 day and 3 months was statistically significant (1.48 vs. 3.5, and 1.62 vs. 2.72, respectively; p=0.01 and 0.026, respectively) but the intergroup difference in the ODI was not. The mean length of hospital stay and the time to resumption of work were significantly shorter in the PELD group than in the OLMD group (2.55 vs. 3.21 days, and 4.45 vs. 6.62 weeks, respectively; p=0.037 and 0.01, respectively. There were no significant intergroup differences in terms of complications, recurrence, or procedure failures.

CONCLUSIONS

Both PELD and OLMD can provide equivalent, satisfactory outcomes. However, PELD demonstrated several potential advantages, including more rapid recovery and lower LBP early on. Further large-scale, randomized studies with long-term follow-up are now warranted.

Comparison of Percutaneous Endoscopic Lumbar Discectomy with Minimally Invasive Transforaminal Lumbar Interbody Fusion as a Revision Surgery for Recurrent Lumbar Disc Herniation after Percutaneous Endoscopic Lumbar Discectomy

Objective

The purpose of this study was to compare the outcomes between percutaneous endoscopic lumbar discectomy (PELD) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for the revision surgery for recurrent lumbar disc herniation (rLDH) after PELD surgery.

Patients and Methods

A total of 46 patients with rLDH were retrospectively assessed in this study. All the patients had received a PELD in Peking University First Hospital between January 2015 and June 2019, before they underwent a revision surgery by either PELD (n=24) or MIS-TLIF (n=22). The preoperative data, perioperative conditions, complications, recurrence condition, and clinical outcomes of the patients were compared between the two groups.

Results

Compared to the MIS-TLIF group, the PELD group had significantly shorter operative time, less intraoperative hemorrhage, and shorter postoperative hospitalization, but higher recurrence rate (P<0.05). Complication rates were comparable between the two groups. Both groups had satisfactory clinical outcomes at a 12-month follow-up after the revision surgery. The PELD group also showed significantly lower visual analog scale (VAS) scores of back pain and Oswestry disability index (ODI) in one month after the revision surgery, whereas the difference was not detectable at six- and 12-month follow-ups.

Conclusion

Both PELD and MIS-TLIF are effective as a revision surgery for rLDH after primary PELD. PELD is superior to MIS-TLIF in terms of operative time amount of intraoperative hemorrhage and postoperative hospitalization. However, its higher postoperative recurrence rate must be considered and patients should be well informed, when making a decision between the two surgical approaches.

Debridement for Infectious Spondylodiscitis in a 9-year-old Girl Using Full-Endoscopic Discectomy System : a Case Report and literature review

Objective : Infectious spondylodiscitis (IS) is rarely seen in healthy elementary school age children. Conservative treatment with antibiotics is usually preferable but sometimes fails because of the low identification rate of the pathogen by percutaneous needle biopsy. When surgical treatment is indicated, selecting the appropriate procedure is crucial in terms of invasiveness for such young children. Case report : We present the case of a 9-year-old otherwise healthy girl with IS who successfully underwent debridement and identification of the causative pathogen using full endoscopic discectomy (FED) system. Methicillin-susceptible Staphylococcus aureus was identified on several cultures of samples. Immediately after the surgery, the LBP was significantly decreased and the remittent fever resolved dramatically. At the 1-year follow-up, she had no symptoms and plain radiographs showed bony fusion. Conclusion : This is the first report on IS in elementary school-age children treated with the FED system. Debridement using this system could provide minimally invasive and effective curettage of the infected disc space and can be helpful in identifying the pathogen even for small children. J. Med. Invest. 67 : 351-354, August, 2020.

Real-time ultrasonography-magnetic resonance image fusion navigation for percutaneous transforaminal endoscopic discectomy

OBJECTIVE

Percutaneous transforaminal endoscopic discectomy (PTED) is usually performed under fluoroscopic guidance and is associated with a large radiation dose. Ultrasonography (US)-MR image fusion navigation combines the advantages of US and MRI and requires significantly less radiation than fluoroscopy. The purpose of this study was to evaluate the safety and effectiveness of US-MR image fusion navigation for PTED.

METHODS

From January to September 2018, patients with L4-5 lumbar disc herniation requiring PTED were randomized to have the procedure conducted with US-MR image fusion navigation or fluoroscopy. The number of fluoroscopies, radiation dose, duration of imaging guidance, intraoperative visual analog scale (VAS) pain score, intraoperative complications, and clinical outcomes were compared between the groups.

RESULTS

There were 10 patients in the US-MR navigation group and 10 in the fluoroscopy group, and there were no significant differences in age, sex ratio, or BMI between the 2 groups (all p > 0.05). Intraoperatively, the total radiation dose, number of fluoroscopies performed, duration of image guidance, and VAS low-back and leg pain scores were all significantly lower in the US-MRI navigation group than in the fluoroscopy group (all p < 0.05). There were no intraoperative complications in either group. Postoperative improvements in Japanese Orthopaedic Association, Oswestry Disability Index, and VAS pain scale scores were similar between the 2 groups.

CONCLUSIONS

US-MR image fusion navigation is a promising technology for performing PTED and requires significantly less radiation than fluoroscopy.Clinical trial registration no.: NCT03403244 (ClinicalTrials.gov).

Interlaminar Endoscopic Lumbar Discectomy Using a New 8.4-mm Endoscope and Nerve Root Retractor

STUDY DESIGN

Surgical technique.

OBJECTIVE

Using an 8.4-mm endoscope and endoscopic nerve root retractor, the interlaminar endoscopic lumbar discectomy (IELD) technique is introduced for lumbosacral levels.

SUMMARY OF BACKGROUND DATA

Although spine surgeons are familiar with IELD, this technique is only used for L5-S1 disk herniations and requires a wide interlaminar space.

METHODS

Using an 8.4 mm-endoscope, high-speed drill, and endoscopic Kerrison punches, a nerve-root retractor facilitated the simultaneous medial retraction of the nerve root and removal of the disk fragment by the instrument's cannula. Clinical parameters such the visual analog scale scores for back and leg pain, modified Macnab criteria, and Oswestry Disability Index were analyzed.

RESULTS

A total of 101 patients were enrolled. The visual analog scale scores for back and leg pain significantly decreased from 6.8±2.1 and 7.8±1.5 to 2.0±0.6 and 1.78±1.1, respectively, at the 1-year follow up (P<0.01). The Oswestry Disability Index score significantly improved from 28.6±11.7 to 7.4±2.9 (P<0.01). Ninety-nine patients (97.1%) showed good outcomes.

CONCLUSIONS

A new IELD technique and instruments can overcome the drawbacks of existing IELD with adequate bone work and control of the affected nerve root.

Correlation between preoperative CT imaging parameters and clinical outcome of lumbar spinal stenosis treated with endoscopic transforaminal decompression

Objective

To evaluate clinical effects, and their correlations with preoperative computed tomography imaging parameters, in cases of lumbar spinal stenosis treated by endoscopic transforaminal decompression.

Methods

This retrospective study included orthopaedic patients who had undergone percutaneous endoscopic lumbar discectomy (PELD) for lumbar spinal stenosis. Clinical symptoms were evaluated by visual analogue scale (VAS), Oswestry Disability Index (ODI) and claudication distance. Overall clinical efficacy was evaluated by Macnab score.

Results

A total of 87 patients were included. Postoperative wound healing was good without complications. Macnab scores following PELD were ‘excellent’ in 41 cases (47.12%), ‘good’ in 30 cases (34.48%), ‘generally good’ in seven cases (8.04%), and ‘poor’ in nine cases (10.34%). The overall rate of optimal surgery was 81.60%. Postoperative pain (VAS) and ODI scores, and claudication distance, were significantly improved versus preoperative values. The soft tissue invasion ratio of the vertebral canal and invasion ratio of the nerve root canal were correlated with clinical efficacy.

Conclusion

Positive correlations were observed between clinical efficacy of endoscopic transforaminal decompression and preoperative vertebral canal soft tissue invasion ratio and nerve root canal invasion ratio in patients with lumbar spinal stenosis.

Comprehensive Anatomic and Morphometric Analyses of Triangular Working Zone for Transforaminal Endoscopic Approach in Lumbar Spine: A Fresh Cadaveric Study

OBJECTIVE

The aim of this study is to provide essential information for endoscopic transforaminal approach by performing morphometric analysis of the triangular working zone (TWZ) in fresh cadavers.

METHODS

Fifteen fresh human cadavers (9 women and 6 men) with no history of spinal surgery were used in this study. Anatomic dissection of 150 foraminal levels were performed. Significant surgical landmarks constructing TWZ were measured bilaterally from L1-2 to L5-S1 on 15 fresh cadavers. The relationship between traversing roots and intervertebral discs was defined.

RESULTS

Base, height, and hypotenuse measurements of TWZ were longer as the level lowered. Mean base height and hypotenuse of TWZ were 12.15 mm, 11.29 mm, and 16.69 mm (L1-2); 17.94 mm, 17.18 mm, and 28.03 mm (L5-S1), respectively. TWZ was triangular shaped at the upper lumbar levels (L1-2, L2-3, and L3-4), and trapezoid at the lower lumbar levels (L4-5 and L5-S1). Going down the levels, the exiting root angle was narrower, the mean exiting angle of the L5 root being 28.23°. All L2 and L3 traversing roots and nearly all L4 traversing roots (86.7%) originated from below the disc level. Forty percent of L5 traversing roots originated above the disc level, and 53.3% originated at the disc level. Most S1 traversing roots originated at the proximal margin of the disc level (80%).

CONCLUSIONS

Our study reveals a detailed morphometric analysis of TWZ. Understanding the foraminal anatomy is crucial for safely performing transforaminal endoscopic surgery. The learning curve of transforaminal surgery can be reduced by garnering knowledge of TWZ anatomy.

Transforaminal Endoscopic Lumbar Discectomy and Foraminotomy with Modified Radiofrequency Nerve Stimulator and Continuous Electromyography Under General Anesthesia

BACKGROUND

Transforaminal endoscopic lumbar approaches involve working in Kambin's triangle. These procedures are performed on awake patients or under general anesthesia with continuous electromyography. Potential morbidity of this approach includes injury to exiting and traversing nerve roots, as substantial dissection or cauterization of overlying tissues is required for visualization.

METHODS

We developed a novel connection system that accepts input from a bipolar radiofrequency probe to allow direct nerve stimulation in conjunction with electromyography. This study included 30 consecutive patients undergoing transforaminal endoscopic lumbar approaches for discectomies (73.3%), foraminal stenosis (23.3%), or lateral recess stenosis (3.3%). Demographic, operative, and outcomes data were collected.

RESULTS

Average age of patients was 61.4 years, and the L4-5 segment was most commonly treated (65.6%). Electrophysiologic mapping of the exiting nerve root was attempted in 28 patients with an average stimulation threshold of 8.6 ± 0.9 mA. Mapping of the traversing nerve root was attempted in 12 patients with an average stimulation threshold of 6.0 ± 0.8 mA. There were no instances of new postoperative sensorimotor deficits or dysesthesia. These findings persisted through mean and median follow-up of 294 days and 165 days, respectively. No patient required subsequent lumbar surgery.

CONCLUSIONS

Our modified instrumentation and technique allow for accurate identification of the exiting and traversing nerve roots with minimal changes to the workflow of transforaminal endoscopic lumbar approaches. Modification of a bipolar radiofrequency device connection arrangement is simple, inexpensive, and reusable. In this study, no patients developed injury or pain related to nerve root dysfunction.

Clinical effect evaluation and correlation between preoperative imaging parameters and clinical effect of endoscopic Transforaminal decompression for lumbar spinal stenosis

Background

The objective of this study was to evaluate the clinical effect and correlation between preoperative imaging parameters and the clinical effect of endoscopic transforaminal decompression for lumbar spinal stenosis.

Methods

In this prospective study, 87 patients from Shanxi Province People’s Hospital met the criteria for lumbar spinal stenosis and were recruited from June 2014 to January 2016. These patients underwent endoscopic transforaminal decompression. The clinical symptoms were evaluated by VAS, ODI, and claudication at 3 and 6 months after surgery. The overall clinical efficacy was evaluated using the MacNab score. Yellow ligament thickness and area of the dural sac were examined by MRI. Bony vertebral canal area, real spinal canal area, nerve root canal bony area, nerve root canal real area, distance between the articular joints, and vertebral canal sagittal diameter were examined by CT. The soft tissue invasion ratio of the vertebral canal and the invasion ratio of the nerve root canal were calculated. Correlations between imaging parameters and age, sex, and clinical efficacy were examined.

Results

The MacNab scores were excellent in 47% of cases, good in 34%, generally good in 8%, and poor in 11%. VAS, ODI, and claudication were significantly improved compared with the preoperative values (P < 0.01). A significant difference was observed between the 71–81 year age group and the other age groups (P < 0.05). There were good correlations between clinical efficacy and vertebral canal sagittal diameter, distance between the articular joints, soft tissue invasion ratio of the vertebral canal, and invasion ratio of the nerve root canal.

Conclusion

Treatment of lumbar spinal stenosis by endoscopic transforaminal decompression can achieve good clinical results. This operation is less effective in patients older than 71 years of age. There were positive correlations between clinical efficacy and the vertebral canal sagittal diameter, the articular joints, soft tissue invasion ratio of the vertebral canal, and invasion ratio of the nerve root canal.

Current techniques of endoscopic decompression in spine surgery

Endoscopic spine surgery has become a practical, minimally invasive technique for decompression in patients with spinal disc herniation or stenosis. This review aimed to summarize the current techniques of endoscopic decompression technique in spine surgery and to discuss the benefits, limitations, and future perspectives of this minimally invasive technique. Endoscopic spine decompression surgery can be categorized according to the endoscopic property: percutaneous endoscopic (full-endoscopic), microendoscopic, and biportal endoscopic. It can also be classified based on the approach: transforaminal, interlaminar, anterior, posterior, and caudal approaches. Theoretically, each technique can be applied in the lumbar, cervical, and thoracic spine. The various endoscopic spine surgery techniques should be appropriately conducted according to the disease entities, level, and zone of pathologies. Although the current level of evidence is relatively low and the relevance of the technique is controversial, recent clinical results and the critical concept are promising. Development in optics, instruments, and approach will improve its safety and reduce technical complexity. In the meantime, high-quality clinical studies, including randomized trials and meta-analyses, are due for publication. Eventually, endoscopic spine surgery is expected to become the golden standard for spinal surgery.