The Learning Curve in Foraminal Endoscopic Discectomy: Experience Needed to Achieve a 90% Success Rate

Treatment Concept and Technical Considerations of Biportal Endoscopic Spine Surgery for Lumbar Spinal Stenosis

Decompression is a major component of surgical procedures for degenerative lumbar spinal stenosis (LSS). In addition to sufficient decompression to guarantee the relief of neurological pain, compensating surgical instability after wider laminectomy and foraminotomy and instrumentation with caging and fusion with grafting are performed to secure or restore the foraminal dimension and correct coronal/sagittal imbalance for longer survival of the adjacent segment. Endoscopic spinal surgery (ESS) has been developed under the flag of successful decompression while preserving structural integrity as much as possible with the help of magnification and illumination. ESS provides a technical possibility and feasibility for solving LSS by decompression alone. Recently, many endoscopic trials have been conducted to overcome conventional surgical treatment that requires wider dissection, escape inevitable complications from surgical damage, and compensate for the fusion technique. However, biportal ESS has some technical limitations, including clinical difficulties in accessibility for more moderate to severe stenosis and challenges for complicated conditions with segmental ventral slip, isthmic defect, stenosis combined with foraminal stenosis or foraminal disk rupture, or degenerative segmental scoliosis with disk height collapsing and endplate fatigue fracture. Because decompression alone is a skill for eliminating pathologies, there is no function of preserving degenerative structure or stopping the recurrence of disk degeneration or subsidence. This review of clinical reports investigated the possibility of biportal ESS for treating degenerative lumbar disorders by sufficient decompression and adequate elimination of various pathologies and decreasing technical complications. The results of this study may help develop better innovative spinal surgical techniques in the near future.

Advances and Challenges of Endoscopic Spine Surgery

The purpose of this paper is to review the data supporting current endoscopic surgical techniques for the spine and the potential challenges and future of the field. The origins of endoscopic spine surgery can be traced back many decades, with many important innovations throughout its development. It can be applied to all levels of the spine, with many robust trials supporting its clinical outcomes. Continued clinical research is needed to explore its expanding indications. Although the limitations of starting an endoscopic program can be justified by its cost effectiveness and positive societal impact, challenges facing its widespread adoption are still present. As more residency and fellowship programs include endoscopy as part of their spine training, it will become more prevalent in hospitals in the United States. Technological advancements in spine surgery will further propel and enhance endoscopic techniques as they become an integral part of a spine surgeon's repertoire.

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.

Percutaneous Transforaminal Endoscopic Discectomy Learning Curve: A CuSum Analysis

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To describe the learning curve for percutaneous transforaminal endoscopic discectomy (PTED) and demonstrate its efficacy in treating lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

The learning curve for PTED has not yet been standardized in the literature.

PATIENTS AND METHODS

Consecutive patients who underwent lumbar PTED by a single surgeon between December 2020 and 2022 were included. Cumulative sum analysis was applied to operative and fluoroscopy time to assess the learning curve. Inflection points were used to divide cases into early and late phases. The 2 phases were analyzed for differences in operative and fluoroscopy time, length of stay, complications, and patient-reported outcome measures (PROMs). Patient characteristics and operative levels were also compared. PROMs entailed the Oswestry Disability Index, Patient-Reported Outcomes Measurement Information System, Visual Analog Scale Back/Leg, and 12-item Short Form Survey at preoperative, early postoperative (<6 mo), and late postoperative (≥6 mo) time points. PROMs between PTED cases and a comparable cohort of tubular microdiscectomy cases, performed by the same surgeon, were compared.

RESULTS

Fifty-five patients were included. Cumulative sum analysis indicated that both operative and fluoroscopy time diminished rapidly after case 31, suggesting a learning curve of 31 cases (early phase: n = 31; late phase: n = 24). Late-phase cases exhibited significantly lower operative times (85.7 vs . 62.2 min, P = 0.001) and fluoroscopy times (131.0 vs . 97.2 s, P = 0.001) compared with the early-phase cases. Both early and late-phase cases showed significant improvement in all PROMs. There were no differences in PROMs between the patients who underwent PTED and tubular microdiscectomy.

CONCLUSION

The PTED learning curve was found to be 31 cases and did not impact PROMs or complication rates. Although this learning curve reflects the experiences of a single surgeon and may not be broadly applicable, PTED can serve as an effective modality for the treatment of lumbar disc herniation.

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.

2nd and 3rd generation full endoscopic lumbar spine surgery: clinical safety and learning curve

AIM

2nd and 3rd generation endoscopic spine surgery techniques offer visualisation of familiar inter-laminar anatomy to spinal surgeons. We have prospectively evaluated the clinical outcome, complications and learning curve associated with these techniques in patients with lumbar spine radiculopathy.

METHODS

This is a prospective study of 50 consecutive patients with radicular pain from disc herniation and/or lateral recess stenosis. In 6 patients, endoscopy couldn't be done. Operating times, PROM's (VAS, ODI and EQ-5D scores) and complication rates of 44 patients were evaluated after mean FU of 52 months (range 39-65). MRI was used to divide these into protrusions (n = 19), extrusions (n = 17) and lateral recess stenosis (n = 8). Evidence about the learning curve was gathered by curvilinear regression analyses.

RESULTS

Using a composite clinical success criterion, 95% patients had a successful outcome, with no major complications. ODI, VAS and EQ-5D scores had a statistically significant improvement and achieved MCID. Revision discectomy rate was only 4.5% (n = 2). MRI based grouping, case sequence and degree of difficulty influenced the duration of surgery and a learning curve was found for protrusions and lateral recess decompressions, but not for extrusions. A learning curve effect was also observed with respect to the ODI.

CONCLUSIONS

Although anatomy visualised in 2nd and 3rd generation endoscopy is familiar to spinal surgeons, our learning curve experience suggests a careful and MRI pathology based take up of this technique in clinical practice, despite its clinical safety in our series.

LEVEL OF EVIDENCE

Level 3, prospective cohort study.

Development of an Endoscopic Spine Surgery Program: Overview and Basic Considerations for Implementation

Endoscopic spine surgery (ESS) is an innovative technique allowing for minimally invasive, direct visualization of spinal abnormalities. The growth of ESS in the United States has been stunted by high start-up costs, low reimbursement rates, and the steep learning curve associated with mastering endoscopic techniques. Hergrae, we describe the current state and future direction of ESS and provide key action items for ESS program implementation.

Outcome of Transforaminal Endoscopic Discectomy in Rural India in a Single-Level Lumbar Disc Prolapse Under Local Anesthesia

Aim  The aim of this study was to undertake a clinical study to evaluate the outcomes of transforaminal endoscopic discectomy under local anesthesia and to study the complication rate. Study Design  It is a prospective study. Methods  We prospectively analyzed outcomes of 60 patients with a single-level lumbar disc prolapse in rural India from December 2018 to April 2020 who underwent endoscopic discectomy under local anesthesia. Follow-up was done using the visual analogue score (VAS) and Oswestry Disability Index (ODI) scoring systems with a minimum follow-up up to 1 year postoperatively. Results  In our study of 60 patients, there was 38 cases of L4-L5 disc pathology, 13 L5-S1 discs, and 9 L3-L4 discs. Our study showed a significant clinical reduction in mean VAS score that was 7.07/10 preoperatively and reduced to 3.88/10 at the third month and 3.64/10 at 1 year of follow-up ( p -value < 0.05) showing clinical significance. The ODI scoring done preoperatively was an average mean of 57.37% pointing to how crippled the patients were with lumbar disc prolapse and showed a significant reduction to 29.32% postoperatively at 1 year ( p -value < 0.05) showing clinical significance. This reduction in ODI directly corelates to how almost all patients returned to normal life coping to all activities and were completely pain free at 1 year of follow-up. Conclusion  Endoscopic spine surgery in lumbar disc prolapse is highly effective and can deliver a good functional outcome if done with correct preoperative planning and approach.

Angulation error assessment for the trajectory in the anteroposterior and lateral fluoroscopic views during percutaneous endoscopic transforaminal lumbar discectomy

BACKGROUND

Anteroposterior (AP) and lateral fluoroscopies are often used to evaluate the intraoperative location and angulation of the trajectory in percutaneous endoscopic transforaminal lumbar discectomy (PETLD). Although the location of the trajectory shown in fluoroscopy is absolutely accurate, the angulation is not always reliable. This study aimed to evaluate the accuracy of the angle shown in the AP and lateral fluoroscopic views.

METHODS

A technical study was performed to assess the angulation errors of PETLD trajectories shown in AP and lateral fluoroscopic views. After reconstructing a lumbar CT image, a virtual trajectory was placed into the intervertebral foramen with gradient-changing coronal angulations of the cephalad angle plane (CACAP). For each angulation, virtual AP and lateral fluoroscopies were taken, and the cephalad angles (CA) of the trajectory shown in the AP and lateral fluoroscopic views, which indicated the coronal CA and the sagittal CA, respectively, were measured. The angular relationships among the real CA, CACAP, coronal CA, and sagittal CA were further demonstrated with formulae.

RESULTS

In PETLD, the coronal CA is approximately equal to the real CA, with a small angle difference and percentage error, whereas the sagittal CA shows a rather large angle difference and percentage error.

CONCLUSION

The AP view is more reliable than the lateral view in determining the CA of the PETLD trajectory.

Safe Electromyography Stimulation Thresholds Within Kambin's Triangle During Endoscopic Transforaminal Lumbar Interbody Fusion

BACKGROUND

Transforaminal endoscopic approaches through Kambin's triangle traditionally require surgery to be performed without general anesthesia to allow live patient feedback. No reliable intraoperative neuromonitoring method specific to the dorsal root ganglion (DRG), the structure most at risk during this approach, currently exists.

OBJECTIVE

To correlate evoked electromyography (EMG) thresholds within Kambin's triangle with new postoperative pain or sensorimotor symptoms potentially resulting from DRG irritation.

METHODS

Data were prospectively collected for all patients undergoing endoscopic transforaminal lumbar interbody fusion (TLIF) under general anesthesia at a single institution. A stimulation probe was inserted into Kambin's triangle under fluoroscopic and robotic guidance, before passage of endoscopic instruments. EMG thresholds required to elicit corresponding myotomal responses were measured. Postoperatively, any potential manifestations of DRG irritation were recorded.

RESULTS

Twenty-four patients underwent a total of 34 transforaminal lumbar interbody fusion levels during the study period, with symptoms of potential DRG irritation occurring in 5. The incidence of new onset symptoms increased with lower stimulation thresholds. Sensitivities for EMG thresholds of ≤4, ≤8, and ≤11 mA were 0.6, 0.8, and 1, respectively. Corresponding specificities were 0.90, 0.69, and 0.55, respectively.

CONCLUSION

We demonstrated for the first time the feasibility of direct intraoperative neuromonitoring within Kambin's triangle in transforaminal endoscopic surgery. Eight milliampere seems to be a reasonable compromise between sensitivity and specificity for this monitoring technique. In the future, larger-scale studies are required to refine safe stimulation thresholds.

The Learning Curve of Unilateral Biportal Endoscopic (UBE) Spinal Surgery by CUSUM Analysis

Objective

To assess the learning curve of the unilateral biportal endoscopic (UBE) technique for the treatment of single-level lumbar disc herniation by cumulative summation (CUSUM) method analysis.

Methods

A retrospective analysis was conducted to assess 97 patients' general condition, operation time, complications, and curative effect of single segmental UBE surgery performed by a spinal surgeon in his early stage of this technique. The learning curve of operation time was studied using a CUSUM method, and the cut-off point of the learning curve was obtained.

Results

The operation time was 30 – 241(97.9 ± 34.7) min. The visual analog scale score of lower limb pain decreased from 5.75 ± 0.81 before the operation to 0.39 ± 0.28 at the last follow-up (P &lt; 0.05). The Oswestry disability index score decreased from 66.48 ± 4.43 before the operation to 14.57 ± 3.99 at the last follow-up (P &lt; 0.05). The CUSUM assessment of operation time revealed the learning curve was the highest in 24 cases. In the learning stage (1–24 cases), the operation time was 120.3 ± 43.8 min. In the skilled stage (25–97 cases), the operation time was 90.5 ± 27.8 min.

Conclusions

About 24 cases of single segmental UBE operation are needed to master the UBE technique.

A Comparison Between Retaining and Resecting the Posterior Longitudinal Ligament in Percutaneous Endoscopic Transforaminal Discectomy for Disc Herniation: A Retrospective Cohort Study

Objective

To compare the efficacy and safety of retaining the posterior longitudinal ligament (PLL) with resecting the PLL in inside‐out percutaneous endoscopic transforaminal discectomy (PETD) surgery for lumbar disc herniation (LDH).

Method

A total of 135 patients with symptomatic LDH who were treated by inside‐out PETD surgery from January 2015 to January 2017were included in this retrospective analysis. There were 38 males and 30 females in the PLL resection group (mean age = 52.40 ± 8.73 years) and 35 males and 32 females in the PLL retention group (mean age = 53.50 ± 9.24 years). The visual analogue scale (VAS) score, Oswestry disability index (ODI), and modified MacNab criteria were used to evaluate clinical outcomes. Operation time, blood loss, recurrence of LDH, and complications were recorded. Three months after surgery, magnetic resonance imaging was performed to confirm that nerve root compression was relieved.

Results

The VAS and ODI scores improved significantly immediately after surgery, at 1 month after surgery, at 3 months after surgery, and at last follow‐up compared with those before surgery (P < 0.01). The scores also improved significantly between immediately after surgery and 1 month after surgery in the two groups (P < 0.001). Multivariate analysis indicated that age ≥ 50 years (odds ratio (OR) = 6.33, 95% confidence interval (CI): 1.64–21.98, P = 0.014), pain duration ≥6 months (OR = 4.68, 95% CI: 1.29–6.51, P = 0.025), pre‐ODI score ≥ 40% (OR = 5.97, 95% CI: 2.41–14.86, P = 0.003) were all associated with poor functional outcomes. There was no significant difference in the excellent/good ratio between the two groups and the mean operation time of the retention group was 71.5% of that of the resection group (82.7 ± 18.5 min vs 115.6 ± 24.6 min, P < 0.01). In the patients, no serious complications, such as dural tear, wound infection, or persistent nerve root injury, were observed during the follow‐up period. There was no significant difference in the complication rate between the two groups (6/68 vs 6/67, P = 0.979). Although the recurrence rate was higher in retention group, there was no significant difference between the two groups (1/68 vs 2/67, P = 0.551).

Conclusion

The PLL is recommended to be retained for inside‐out PETD surgery.

Endoscopic Transforaminal Lumbar Foraminotomy: A Systematic Review and Meta-Analysis

INTRODUCTION

Spinal endoscopic techniques have recently been applied to complex degenerative conditions or failed back surgery syndrome. We performed a systematic review and meta-analysis to assess transforaminal endoscopic lumbar foraminotomy (TELF) outcomes and adverse event rates. We also analyzed the effectiveness of the technique for chronic pain after arthrodesis or previous spinal surgery.

METHODS

Multiple databases were searched for studies published in the English language, involving patients > 18 years old who underwent endoscopic foraminotomy. Outcomes included the rate of patients who showed "excellent" and "good" postoperative improvement, decreased leg pain, and improved Oswestry Disability Index (ODI) scores. Adverse events considered in the analysis included nerve root damage and intraoperative dural tear, the proportion of patients requiring revision surgery or recurrences, and infections.

RESULTS

A total of 14 studies, encompassing 600 patients, were identified. Approximately 85% of patients improved significantly after TELF, without significant differences among different groups (85% vs. 78%, respectively). Mean leg pain decreased an average of 5.2 points, and ODI scores improved by 41.2%. Patients with previous spine surgery or failed back surgery syndrome had higher postoperative leg dysesthesia rates after TELF (14% vs. 1%, respectively).

CONCLUSION

TELF is a useful and safe method to achieve decompression in foraminal stenosis. This technique is indicated in the elderly or patients with comorbidities. Preoperative planning is paramount in determining the foraminal size and endoscope trajectory. A diamond burr is recommended because it has an advantage over the regular endoscopic shaver in bleeding control and complication avoidance.

Multi-Modality guidance based surgical navigation for percutaneous endoscopic transforaminal discectomy

OBJECTIVE

Fluoroscopic guidance is a critical step for the puncture procedure in percutaneous endoscopic transforaminal discectomy (PETD). However, two-dimensional observations of the three-dimensional anatomic structure suffer from the effects of projective simplification. To accurately assess the spatial relations between the patient vertebra tissues and puncture needle, a considerable number of fluoroscopic images from different orientations need to be acquired by the surgeons. This process significantly increases the radiation risk for both the patient and surgeons.

METHODS

In this paper, we propose an augmented reality (AR) surgical navigation system for PETD based on multi-modality information, which contains fluoroscopy, optical tracking, and depth camera. To register the fluoroscopic image with the intraoperative video, we design a lightweight non-invasive fiducial with markers and detect the markers based on the deep learning method. It can display the intraoperative video fused with the registered fluoroscopic images. We also present a self-adaptive calibration and transformation method between a 6-DOF optical tracking device and a depth camera, which are in different coordinate systems.

RESULTS

With the substantially reduced frequency of fluoroscopy imaging, the system can accurately track and superimpose the virtual puncture needle on fluoroscopy images in real-time. From operating theatre in vivo animal experiments, the results illustrate that the system average positioning accuracy can reach 1.98mm and the orientation accuracy can reach 1.19^∘. From the clinical validation results, the system significantly lower the frequency of fluoroscopy imaging (42.7%) and reduce the radiation risk for both the patient and surgeons.

CONCLUSION

Coupled with the user study, both the quantitative and qualitative results indicate that our navigation system has the potential to be highly useful in clinical practice. Compared with the existing navigation systems, which are usually equipped with a variety of large and high-cost medical equipments, such as O-arm, cone-beam CT, and robots, our navigation system does not need special equipment and can be implemented with common equipment in the operating room, such as C-arm, desktop, etc., even in small hospitals.

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.

SURGERY FOR LUMBAR DISC HERNIATION: OPEN X MINIMALLY INVASIVE TECHNIQUE

ABSTRACT Objective: In Brazil, there are no studies comparing endoscopic treatment of lumbar disc herniation with the conventional open technique in SUS (Unified Health System) with regard to hospitalization time and complications occurring within one year, which is the objective of this study. Methods: A survey of 32 surgeries performed in 2019 (11 open and 21 endoscopic) to evaluate pain parameters before and after surgery (VAS), days of hospitalization, and complications. The data were submitted to statistical analysis (ANOVA) using the Kruskal-Wallis test. Results: Fourteen patients were female and eighteen were male, with a mean age of 41.35 years (p> 0.05 between sexes). The pre- and postoperative VAS for pain radiating to the lower limb were similar between the groups: 8.5 ± 0.82 with the open technique and 8.19 ± 1.15 with endoscopic technique. In both groups there was an improvement in the pain pattern with a significant reduction in the VAS (p < 0.05) and there was no statistical relevance between the groups in terms of pain improvement. There was statistical relevance between the groups in the comparison of days of hospitalization required, with the group submitted to endoscopic surgery having a lower number of days. The complications reported were compatible with those found in the literature (postoperative dysesthesia, new herniation). Conclusions: The endoscopic technique resulted in an important reduction in the number of days of hospitalization, a factor with a high impact on the costs of any surgical procedure, which can be a determining factor in the feasibility of minimally invasive techniques. Level of evidence IV; Therapeutic Study.

Differences in the Exposure of the Lumbar Nerve Root Between Experts and Novices: Results From a Realistic Simulation Pilot Study With Force Sensors

STUDY DESIGN

Nonrandomized prospective trial.

OBJECTIVE

Several studies could demonstrate "learning curves" in almost every single surgical procedure for unexperienced surgeons. This is in sharp contrast to the rising quality requirements in public health care to provide surgical training at patients "expense." The aim of this study was to visualize, measure, and set a baseline of the pressure load on the spinal nerve root during a simulated microdiscectomy on a standardized and validated model (RealSpine) under the influence of the level of surgical experience and individual skills.

METHODS

Five highly experienced spine surgeons and 5 trainees without considerable surgical experience were selected to perform a standardized microsurgical discectomy on a validated RealSpine simulator. Force-torque sensors were integrated in this simulator to measure the load on the nerve root. The forces were recorded every 125 ms.

RESULTS

We could identify cumulative for the total intervention as well as for defined single surgical steps of this procedure and as well in between the single subjects a significant higher tension and contusion forces on the nerve for the trainee group (Δp contusion 83-765 Nċs and Δp tension 159-1131 Nċs for the trainees. Δp contusion 16-171 Nċs and Δp tension 27-146 Nċs for the experts).

CONCLUSION

We could measure a difference between unexperienced and experienced surgeons regarding the manipulations of the nerve root during a standardized simulated microdiscectomy. This possibility could be the starting point for a new and innovative surgical education to improve outcome without negative side effects of "learning curves."

Learning Curve for Transforaminal Percutaneous Endoscopic Lumbar Discectomy: A Systematic Review

BACKGROUND

Transforaminal percutaneous endoscopic lumbar discectomy (TPELD) has become an alternative and minimally invasive surgical technique for soft lumbar disc herniation. However, the learning curve has been relatively long and difficult. In the present study, we have summarized the characteristics of the learning curve of TPELD, including the number of cases required to achieve technical proficiency, and discussed the strategies to improve the learning curve.

METHODS

The PubMed, Embase, Cochrane Library, and KoreaMed databases were searched for reports describing the learning curve for TPELD. Clinical studies involving human patients and evaluating the learning curve of TPELD with quantitative data were included. A strict quality assessment was completed, and descriptive statistics were calculated.

RESULTS

Of the 6884 screened titles and abstracts, 10 full-text reports, including 958 cases, were included in the analysis. All were cohort studies, which were grouped into early and late groups according to surgeon experience with TPELD. The most commonly used cutoff to differentiate between these groups was 20 (mean, 24.70 ± 18.99 cases; range, 10-72 cases). The most widely used measure was the operative time. Although most studies had reported better results in the operative time or pain scores in the late group, only 1 study had proposed a bona fide learning curve.

CONCLUSIONS

We found insufficient evidence to support a cutoff point of 20 or other numbers of cases for determining when the learning curve has reached a plateau. Therefore, these numbers should be interpreted with great care, and high-quality prospective studies evaluating the actual learning curve are required.

A surgical decompression procedure for effective treatment of calcified lumbar disc herniation

OBJECTIVE

To present our experience in managing calcified lumbar disc herniation (cLDH) using a surgical decompression procedure.

METHODS

Patients who had low back pain radiating to the leg, were preoperatively diagnosed with cLDH by computed tomography and/or magnetic resonance imaging, and were treated with a surgical decompression procedure were studied. Those without cLDH or who were treated with a method other than decompression were excluded. The treatment outcome was analyzed using the visual analog scale (VAS) score, Oswestry Disability Index, and modified Macnab criteria.

RESULTS

Thirty-seven patients aged 60.5 ± 9.6 years were evaluated. The VAS scores were significantly decreased 1 day after surgery and remained low at the 3-month and 1-year follow-ups. The Oswestry Disability Index was also significantly lower at the 3-month and 1-year follow-ups. Ninety-four percent of patients rated the results as "excellent" or "good" according to the modified Macnab criteria at the 3-month follow-up. The patients developed few postoperative complications and no recurrence during 1 year of follow-up.

CONCLUSION

Our data suggest that the decompression approach is effective for management of cLDH at least in the short term (1 year) with respect to reducing pain and improving patient satisfaction with few complications.

Scientific View on Endoscopic Spine Surgery: Can Spinal Endoscopy Become a Mainstream Surgical Tool?

With the health care environment becoming increasingly patient centric and cost-conscious, interest levels in spinal endoscopy are at an all-time high. Patient demand for the least invasive procedures combined with surgeon desire to maximally shorten the postoperative recovery period has further driven this surgical evolution. Mounting scientific evidence demonstrates the noninferiority and perhaps even superiority of endoscopic techniques to more conventional spinal surgery for the treatment of spinal stenosis and disc herniations. Although higher level evidence is much needed to support the clinical utility of the latest endoscopic techniques and surgical indications, it appears that the entrance of spinal endoscopy into the mainstream arena of spinal surgery is inevitable.

Percutaneous Transforaminal Endoscopic Discectomy Versus Microendoscopic Discectomy for Lumbar Disc Herniation: Two-Year Results of a Randomized Controlled Trial

STUDY DESIGN

A prospective randomized controlled study.

OBJECTIVE

To clarify whether percutaneous transforaminal endoscopic discectomy (PTED) has better clinical outcomes and less surgical trauma compared with microendoscopic discectomy (MED).

SUMMARY OF BACKGROUND DATA

Two kinds of minimally invasive spine surgeries, PTED and MED, are now widely used for the treatment of lumbar disc herniation (LDH). It is still a controversial issue to choose the proper surgical approach.

METHODS

In this single-center, open-label, randomized controlled trial, patients were included if they had persistent signs and symptoms of radiculopathy with corresponding imaging-confirmed LDH, and were randomly allocated to PTED or MED group. The primary outcome was the score of Oswestry Disability Index (ODI) and the secondary outcomes included the score of Medical Outcomes Study 36-Item Short-Form Health Survey bodily pain and physical function scales, European Quality of Life-5 Dimensions, and Visual Analogue Scales for back pain and leg pain.

RESULTS

A total of 250 participants were randomly assigned to two treatment groups, 241 of that received the specific surgical procedure. Two hundred twenty-two patients (92.1%) have completed the 2-year follow-up. Both the primary and secondary outcomes did not differ significantly between the two treatment groups at each prespecified follow-up time (P > 0.05). For PTED, the postoperative improvement of ODI score in the median herniation subgroup was less compared with paramedian subgroup. For MED, less improvement of ODI score was found in far-lateral herniation subgroup compared with paramedian subgroup. Total complication rate over the course of 2 year was 13.44% in PTED group and 15.57% in MED group (P = 0.639). Ten cases (8.40%) in PTED group and five cases (4.10%) in MED group suffered from residue/recurrence of herniation, for which reoperation was required.

CONCLUSION

Over the 2-year follow-up period, PTED did not show superior clinical outcomes and did not appear to be safer procedure for patients with LDH compared with MED. PTED had inferior results for median disc herniation, whereas MED did not appear to be the best option for far-lateral disc herniation.

LEVEL OF EVIDENCE

2.

The Endoscopic Approach to Lumbar Discectomy, Fusion, and Enhanced Recovery: A Review

STUDY DESIGN

Review.

OBJECTIVES

To review the current state of endoscopic spine surgery with regard to discectomy, interbody fusion, and combination with Enhanced Recovery After Surgery programs in order to evaluate its relevance to the future of spine care.

METHODS

A review of the literature and expert opinion is used to accomplish the objectives.

RESULTS

The greatest strength of endoscopic spine surgery lies in its adherence to the basic tenets of minimally invasive surgery and its innate compatibility with Enhanced Recovery After Surgery programs, which aim to improve outcomes and reduce health care costs. The greatest challenge faced is the unique surgical skill set and significant learning curve.

CONCLUSIONS

Endoscopic spine surgery strives to achieve the core goals of minimally invasive surgery, while reducing cost and enhancing quality. In a healthcare market that is becoming increasingly burdened by cost and regulatory constraints, the utilization of endoscopy may become more widespread in the coming years.

Transforaminal full-endoscopic lumbar discectomy under local anesthesia in awake and aware conditions: the inside-out and outside-in techniques

PURPOSE OF THE REVIEW

Transforaminal full-endoscopic lumbar discectomy (TELD) under local anesthesia was first introduced in Japan in 2003. Initially referred to as percutaneous endoscopic discectomy, in 2018, a consensus was reached worldwide and the preferred term is now TELD. The procedure requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles. Thus, it is the least invasive disc surgery. In this review, we introduce two types of the TELD surgery.

RECENT FINDINGS

Initially, TELD was performed as the "inside-out" technique but was associated with reports of postoperative dysesthesia due to exiting nerve injury. Recently, the "outside-in" technique after foraminoplasty was proposed for safer insertion of the cannula into the disc. Foraminoplasty can widen the narrow foramen, thereby allowing the 8-mm cannula to pass through easily and safely, and thus injury to the exiting nerve root can be theoretically avoided. We described two types of the TELD in this review. Surgeons should be familiar with the inside-out and outside-in techniques for TELD; therefore, we can select appropriate technique for each case.

Comparison of Transforaminal Percutaneous Endoscopic Lumbar Discectomy with and without Foraminoplasty for Lumbar Disc Herniation: A 2-Year Follow-Up

Background

Both transforaminal percutaneous endoscopic lumbar discectomy with foraminoplasty (TF PELF) and transforaminal percutaneous endoscopic lumbar discectomy without foraminoplasty (TF PELD) were developed for lumbar disc herniation (LDH) patients. However, the safety and effectiveness between the TF PELF and TF PELD have not been investigated.

Methods

Of the included 140 LDH patients, 62 patients received TF PELF (PELF group) and 78 patients received TF PELD (PELD group). The operation time, the duration of staying at the hospital, and complication incidences were recorded. All patients were followed up for 2 years, where low back and leg visual analogue scale (VAS) pain ratings and Oswestry Disability Index (ODI) were compared between the 2 groups before and after surgery. Modified Macnab criterion was estimated for all patients at postoperative 2 years.

Results

There were no significant difference of the operation time, number of days staying at the hospital, and the incidence of complications between the 2 groups (P > 0.05). Two cases in the PELF group and 1 case in the PELD group received a second surgery due to unrelieved symptoms postoperatively. Low back and leg VAS and ODI scores decreased in both groups after operation (P < 0.01), respectively, but were not significant between the 2 groups over time (P > 0.05). Six patients in the PELF group and 3 patients in the PELD group did not continue the follow-up; thus, only 131 patients completed Macnab evaluation. The satisfactory rate was reported as 80.4% in the PELF group and 90.7% in the PELD group (P > 0.05).

Conclusions

This study suggested that the safety and effectiveness of TF PELF are comparable to TF PELD for LDH patients.

State-of-the-art transforaminal percutaneous endoscopic lumbar surgery under local anesthesia: Discectomy, foraminoplasty, and ventral facetectomy

Transforaminal (TF) percutaneous endoscopic surgery for the lumbar spine under the local anesthesia was initiated in 2003 in Japan. Since it requires only an 8-mm skin incision and damage of the paravertebral muscles would be minimum, it would be the least invasive spinal surgery at present. At the beginning, the technique was used for discectomy; thus, the procedure was called PELD (percutaneous endoscopic lumbar discectomy). TF approach can be done under the local anesthesia, there are great benefits. During the surgery patients would be in awake and aware condition; thus, severe nerve root damage can be avoided. Furthermore, the procedure is possible for the elderly patients with poor general condition, which does not allow the general anesthesia. Historically, the technique was first applied for the herniated nucleus pulposus. Then, foraminoplasty, which is the enlargement surgery of the narrow foramen, became possible thanks to the development of the high speed drill. It was called the percutaneous endoscopic lumbar foraminoplasty (PELF). More recently, this technique was applied to decompress the lateral recess stenosis, and the technique was named percutaneous endoscopic ventral facetectomy (PEVF). In this review article, we explain in detail the development of the surgical technique of with time with showing our typical cases.

Endoscopic lumbar discectomy under local anesthesia may be an alternative to microdiscectomy: A single centre's experience using the far lateral approach

OBJECTIVES

Since the turn of the century, minimally invasive surgery has become increasingly widespread. Discectomy surgery has evolved from wide open to microscopic and now endoscopic. This study aims to demonstrate that transforaminal endoscopic discectomy is an alternative and safe approach for degenerative disk surgery.

PATIENTS AND METHODS

Two year retrospective assessments of patients who underwent transforaminal endoscopic discectomy at a tertiary neurosurgical center in the United Kingdom by a single surgeon. Under strict confidentiality, data was collected from online patient data and PACS systems. Patient feedback was achieved using phone call follow up and clinic appointments. Standard statistical analysis was performed.

RESULTS

201 patients had endoscopic discectomy and the mean age was 41 years. Male:female ratio was 1.3:1.0. Mean time of onset of symptoms was 5.5 months and the most common level was L4/5 (53%). All endoscopic discectomies were performed under local anesthesia. Theater time was on average 110 min. 10 patients were lost to follow up. 95% of patients were discharged within 7h post operatively. Visual acuity score of the pain dropped from an average of 7/10 pre-operatively to 0-1/10 in 95% of patients two weeks post operatively. 87% patients went back to their normal daily activities within two weeks. There were no cases of CSF leak, hematoma formation or wound infection. 1% of patients developed a nerve root injury. 6% of patients had recurrent herniation and require microdiscectomy.

CONCLUSION

Endoscopic discectomy can be an alternative approach to microdiscectomy. While it can take more expertise to perform endoscopic discectomy, our data shows that the far lateral endoscopic discectomy using the TESSYS technique has comparable outcomes to microdiscectomy.