Full-Endoscopic Visualized Foraminoplasty and Discectomy Under General Anesthesia in the Treatment of L4-L5 and L5-S1 Disc Herniation

Foraminoplasty Performed with a Trephine and a New Tool in Transforaminal Endoscopic Lumbar Discectomy: A Single-Center Retrospective Study

OBJECTIVE

Foraminoplasty is an important step in transforaminal endoscopic lumbar discectomy (TELD). A trephine is widely used in foraminoplasty. However, foraminoplasty using a trephine alone sometimes fails to remove the resected bone, resulting in the bone remaining in the foramen or spinal canal, which can potentially cause neurological irritation or injury. The objective of this study is to introduce a self-designed tool, referred to as an anchoring drill, for use with a trephine in foraminoplasty in TELD and to evaluate its advantages.

METHODS

A retrospective review was performed to identify patients who underwent L4-5 TELD between January 2019 to January 2022. Foraminoplasty was performed in all patients. Depending on whether the anchoring drill was used or not, patients were divided into two groups. Surgery-related parameters and complications were reviewed. Visual analog scale (VAS) and Japanese Orthopaedic Association (JOA) scores were also assessed for all patients. SPSS statistical software was used for statistical calculation.

RESULTS

A total of 100 patients were included (55 in the anchoring drill group and 45 in the trephine group). The incidence of residual bone fragments after foraminoplasty of the anchoring drill group was 9.09%, which was lower than that of the trephine group, at 33.33% (p < 0.05). The mean endoscopic operation time of the anchoring drill group was shorter than that of the trephine group (p < 0.05). The mean fluoroscopy time and duration of foraminoplasty showed no significant differences between the two cohorts. The total perioperative complication incidence was lower in the anchoring drill group, in which the neural irritation incidence showed a significant difference (anchoring drill group: 3.64%, trephine group: 17.78%, p < 0.05). VAS and JOA scores were significantly improved after the operation for all patients (p < 0.001), however, no statistical differences were found between the two groups at each follow-up visit.

CONCLUSION

The combination of a trephine with an anchor drill was demonstrated to be safe and effective in foraminoplasty in TELD, improving the success rate of foraminoplasty and reducing neurological complications compared to using trephine alone.

EFFICACY OF FULL-ENDOSCOPIC INTERLAMINAR AND TRANSFORAMINAL DISCECTOMY FOR LUMBER DISC HERNIATION

A previous study has reported the therapeutic effects of interlaminar/transforaminal approaches under full-endoscopic visualization to treat L5-S1 lumber disc herniation (LDH). However, the comparison of interlaminar/transforaminal approaches to treat other segments of LDH remains unclear.

OBJECTIVE

To evaluate the clinical efficacy of full-endoscopic interlaminar and transforaminal lumbar discectomy to treat LDH.

METHODS

A total of 93 patients with LDH who underwent fully-endoscopic lumbar interlaminar/transforaminal discectomy were retrospectively collected. Patients were divided into a Transforaminal group (n=41) and an Interlaminar group (n=52). Clinical efficacy was evaluated by visual analogue scale (VAS), the Oswestry disability index (ODI), and the modified MacNab scoring system.

RESULTS

Of the 93 patients, involving segments in LDH referred to L3-4, L4-5, and L5-S1. The fluoroscopy times in the Interlaminar group were smaller than that of the Transforaminal group. We found no obvious significances between the Transforaminal and Interlaminar groups regarding operation time, incision length, postoperative landing time, hospitalization, and incision healing time. Postoperative VAS and ODI scores notably improved at follow-up. Besides, almost 90% LDH patients achieved excellent/good outcomes.

CONCLUSION

The full-endoscopic visualization technique via interlaminar and transforaminal approaches safely and effectively treat LDH. Level of Evidence III, Retrospective Study.

Clinical Outcomes of Percutaneous Endoscopic Interlaminar Discectomy Using a Laminotomy Technique With Modified Stepwise Local Anesthesia

BACKGROUND

Percutaneous endoscopic interlaminar discectomy (PEID) has been widely used in minimally invasive treatment of lumbar disc herniation (LDH) but is difficult to perform because of the narrow interlaminar window and painful for the patient. Therefore, further research is needed to find a safe and effective method to facilitate the development of PEID.

METHODS

Seventy-one consecutive patients with LDH who underwent PEID using a laminotomy technique with modified stepwise local anesthesia between July 2017 and June 2020. All patients were followed up for at least 6 months. Preoperative patient demographics, perioperative outcomes, and clinical outcomes were recorded. Visual Analog Scale (VAS) scores, Oswestry Disability Index (ODI) scores, and Macnab criteria were used to assess clinical results.

RESULTS

All patients underwent successful surgery under local anesthesia with no conversions to open surgery. The mean operation time was 79.56 ± 32.78 minutes and the average hospital stay was 6.44 ± 2.98 nights. Before surgery, the mean VAS score was 5.66 ± 1.206 and the mean ODI score was 68.41 ± 6.634; the respective scores were decreased to 0.65 ± 0.635 and 7.06 ± 1.594 after 4 weeks of follow-up (P < 0.001) and to 0.56 ± 0.691 and 7.11 ± 0.176 after 6 months (P < 0.001). According to the MacNab criteria, the outcome was excellent in 60 cases and good in the remaining 11 cases.

CONCLUSIONS

PEID via a laminotomy technique with stepwise local anesthesia is safe and effective for L4-5 and L5-S1 LDH.

Extraforaminal Full-Endoscopic Approach for the Treatment of Lateral Compressive Diseases of the Lumbar Spine

Background: The authors conducted a 2-year retrospective follow-up to investigate the efficiency of an extraforaminal full-endoscopic approach with foraminoplasty used to treat lateral compressive diseases of the lumbar spine in 247 patients. Methods: The visual analogue scale (VAS), Oswestry disability index (ODI), and MacNab scale were used to analyze the results collected during the preoperative and postoperative periods. Results: The most common diagnosis was disk herniation with lateral recess stenosis, and the most common surgical level among patients was between L4 and L5 on the left side. Pain decreased over time, as determined during sessions held to evaluate pain in the lumbar, gluteal, led, and foot regions. The ODI demonstrated significant enhancement over the evaluation period and the MacNab scale classified the surgery as good or excellent. The most common complication was dysesthesia. Conclusions: An extraforaminal full-endoscopic approach with foraminoplasty can be recommended in cases of lateral herniation or stenosis for patients with symptoms of radiculopathy, and for those who have not responded to conventional rehabilitation treatment or chronic pain management. Few complications arose as a result of this approach, and most of them were treated clinically.

Comparison of full-endoscopic foraminoplasty and lumbar discectomy (FEFLD), unilateral biportal endoscopic (UBE) discectomy, and microdiscectomy (MD) for symptomatic lumbar disc herniation

PURPOSE

This study aimed to evaluate the clinical outcomes of full-endoscopic foraminoplasty and lumbar discectomy (FEFLD), unilateral biportal endoscopic (UBE) discectomy, and microdiscectomy (MD) in the treatment of symptomatic lumbar disc herniation (LDH).

METHODS

From January 2020 and May 2021, 128 patients with single-level LDH at L4-5 or L5-S1 received FEFLD, UBE discectomy or MD. Patients were divided into three groups according to surgical method: the FEFLD group (n = 43), the UBE group (n = 42), and the MD group (n = 43). Operative time, fluoroscopy frequency, in-bed time, length of hospital stays, total expenses, complications, visual analogue scale (VAS, 0-10), and Oswestry Disability Index (ODI, 0-100%) were assessed and compared among three groups.

RESULTS

There were no significant differences in VAS or ODI scores at 12 months after surgery among three groups. In comparison with the MD group, the FEFLD and UBE group yield better VAS scores for back pain on the first day following surgery (P < 0.05). The FEFLD group was superior to the UBE group or MD group with less time in bed and shorter hospital stay (P < 0.05). The operation time and total expenses in the UBE group were significantly longer and higher than those in the FEFLD group or MD group (P < 0.05).

CONCLUSIONS

FEFLD and UBE discectomy yield comparable results to conventional MD concerning pain relief and functional outcomes. In addition, FEFLD and UBE discectomy enable less back pain in the immediate postoperative period. FEFLD offers advantages in rapid recovery. Conventional MD is still an efficient and cost-effective surgical procedure.

Clinical efficacy of general anesthesia versus local anesthesia for percutaneous transforaminal endoscopic discectomy

Objective

Local anesthesia (LA) is recommended for percutaneous transforaminal endoscopic discectomy(PTED), but satisfactory pain management is not mostly achieved. The goal of this study was to examine the clinical efficacy of PTED for lumbar disc herniation when performed under local anaesthetic vs. general anesthesia (GA).

Methods

From August 2018 to August 2020, the clinical data of 108 patients treated with PTED were retrospectively evaluated and separated into two groups: LA and GA based on the anesthesia method. General information and clinical outcomes of patients were included. Visual analog scale (VAS) and Oswestry disability index (ODI) were recorded before operation, 1 week after operation, and 1 year after operation. In addition, VAS for back pain and leg pain on the second postoperative day were also recorded.

Results

We divided the patients into two groups: 72 in LA and 36 in GA. There were no significant differences in gender, age, course of disease, body mass index, surgical segment, duration of operation, intraoperative bleeding, time of fluoroscopy, length of hospital stay, total hospitalization cost reoperation, surgical satisfaction, Macnab satisfaction, complications, preoperative and 1 year postoperatively VAS for back pain and leg pain and ODI, VAS for leg pain on the second day and 1 week postoperatively between the two groups (P > 0.05). VAS for back pain in GA group on the second day postoperatively, as well as the VAS for back pain and ODI at one week postoperatively, were better than those in LA group (P < 0.05). However, the total hospitalization cost in LA group was significantly lower than that in GA group (P < 0.05). Further analysis of different ages in the two groups showed that there were significant differences in the VAS for back pain on the second day postoperatively and ODI at 1 week postoperatively in the middle-aged group (45 ≤ Y ≤ 59), as well as the VAS for back pain on the second day postoperatively in the senior group (Y ≥ 60) (P < 0.05). However, there were no significant difference among other groups (P > 0.05).

Conclusion

Long-term outcomes were similar for both PTED under LA and GA, while GA group had better short-term outcomes, especially in middle-aged and elderly patients.

Size matters - From the working channel to the wavelength of light: Optimizing visualization in endoscopic spine surgery

BACKGROUND

Minimally invasive surgery bases many of its benefits on decreasing tissue disruption. Endoscopic spine surgery has continued to push the boundaries to accomplish successful clinical outcomes through the evolution of the endoscope and working channel. As the indications for endoscopic spine surgery increase, a more profound discussion of cannula size selection for endoscopic spine surgery is required. The intimate relationship between the working channel, the endoscope and how these choices affect workflow and visualization are paramount to maximize outcomes.

METHODS

The authors review the nuances of the endoscopic approaches to the various regions of the spine as it relates to the selection of the working channel. The advantages and limitations of various endoscopic working channels were analyzed as to how they address anatomic regional considerations as well as ultimate goals of surgery.

RESULTS

In addition to anatomic regional differences and the goals of the surgery other key elements in endoscopic working channel selection included the amount of tissue disruption, regional risk to the neural elements, impact on visualization, optical physics, and the implications for surgical maneuverability/dexterity.

CONCLUSION

Understanding the role and use of the endoscope-working channel combination with its effects on visualization is essential for any surgeon aspiring to perform safe and efficient full endoscopic spine surgery.

Clinical Application of Large Channel Endoscopic Systems with Full Endoscopic Visualization Technique in Lumbar Central Spinal Stenosis: A Retrospective Cohort Study

INTRODUCTION

Recently, large channel endoscopic systems and full endoscopic visualization technique have been used to perform unilateral laminotomy for bilateral decompression (ULBD) treatment for lumbar central spinal stenosis (LCSS). However, various endoscopic systems possess different design parameters, which may affect the technical points and treatment outcomes. The object of this retrospective study was to compare the efficiency, safety, and effectiveness of ULBD under the iLESSYS Delta system versus the Endo-Surgi Plus system.

METHODS

In the period from October 2020 to April 2021, ULBD was performed using the iLESSYS Delta system or Endo-Surgi Plus system to treat LCSS. Patients were classified into two groups based on the endoscopy system employed. Patient demographics, perioperative indexes, complications, and imaging characteristics were reviewed. Clinical outcomes were quantified using back and leg visual analog scale (VAS) scores and Oswestry Disability Index (ODI) at the time points of follow-up.

RESULTS

Thirty-two patients were assigned to the iLESSYS Delta system group and 37 to the Endo-Surgi Plus system group. In the comparison between the two groups, the Endo-Surgi Plus system possessed a shorter incision length and operation time (p < 0.005), and no statistical differences in other aspects were observed. The dural sacs of both groups were significantly expanded postoperatively compared to preoperatively (p < 0.001). Both groups experienced improvements in VAS and ODI scores at all time points (p < 0.001) and equally low frequency of complications.

CONCLUSIONS

Current research suggests that both the Endo-Surgi Plus system and iLESSYS Delta system achieved favorable high safety and clinical outcomes in ULBD for treatment of LCSS. The use of a fully visualized trephine may have increased the efficiency of the Endo-Surgi Plus system. Moreover, the Endo-Surgi Plus system may be associated with a wider decompression range and indications.

Full-endoscopic foraminoplasty for highly down-migrated lumbar disc herniation

BACKGROUND AND STUDY AIMS

Multiple surgical approaches have been studied and accepted for the removal of highly downward migrated lumbar disc herniation (LDH). Here, we investigated the efficacy and safety of full-endoscopic foraminoplasty for highly downward migrated LDH.

PATIENTS AND METHODS

Thirty-seven patients with highly down-migrated LDH treated by the full-endoscopic foraminoplasty between January 2018 and January 2020 were retrospectively investigated. Clinical parameters were evaluated preoperatively and 1, 6, and 12 months postoperatively, using pre- and post-operative Oswestry Disability Index (ODI) scores for functional improvement, visual analog scale (VAS) for leg and back pain, and modified MacNab criteria for patients satisfactory.

RESULTS

Thirty-seven patients with highly downward migrated LDH were successfully removed via the transforaminal full-endoscopic discectomy. The average VAS back and leg pain scores were significantly reduced from 7.41 ± 1.17 and 8.68 ± 1.06 before operation to 3.14 ± 0.89 and 2.70 ± 0.46 at postoperative 1 month, and 1.76 ± 0.59 and 0.92 ± 0.28 at postoperative 12 months, respectively (P < 0.05). The average ODI scores were reduced from 92.86 ± 6.41 to 15.30 ± 4.43 at postoperative 1 month, and 9.81 ± 3.24 at postoperative 12 months (P < 0.05). Based on the modifed MacNab criteria, 36 out of 37 patients (97.30%) were rated as excellent or good outcomes.

CONCLUSION

The full-endoscopic foraminoplasty can be used successfully for surgical removal of high grade down-migrated LDH, and it could serve as an efficient alternative technique for patients with highly downward migrated LDH.

Comparison of the Clinical Outcomes of Full-Endoscopic Visualized Foraminoplasty and Discectomy Versus Microdiscectomy for Lumbar Disc Herniation

OBJECTIVE

This retrospective case-control study aimed to evaluate and compare the clinical outcomes of full-endoscopic visualized foraminoplasty and discectomy (FEVFD) with microdiscectomy (MD) for lumbar disc herniation (LDH).

METHODS

Data from 198 patients who presented with LDH between January 2016 and December 2017 treated by either FEVFD or MD were retrospectively analyzed. The inclusion criteria were single-level LDH, unilateral radiating leg pain with or without positive Lasegue's sign, and failure of standard conservative treatment for at least 12 weeks. The patients were categorized into an FEVFD group (n = 102) or an MD group (n = 96), according to the surgical procedure performed. Operative time, time in bed after surgery, postoperative hospitalization time, complications, and reoperations were recorded. Visual analog scales (VAS) for leg and back pain, Oswestry Disability index (ODI), 36-Item Short-Form Health Survey physical function (SF36-PF), and bodily pain (SF36-BP) scores were assessed and compared between the two groups.

RESULTS

The demographic data and baseline characteristics of the two groups were not significantly different. Operative time for the FEVFD group (73.82 ± 20.73 min) was longer than that for the MD group (64.74 ± 17.37 min) (P = 0.003), and fluoroscopy time for the FEVFD group (1.71 ± 0.58s) was longer than that for the MD group (1.30 ± 0.33s) (P < 0.001). However, time in bed experienced in the FEVFD group (8.51 ± 2.10 h) was less than that in the MD group (9.24 ± 2.01 h) (P = 0.014), and postoperative hospitalization time experienced in the FEVFD group (2.89 ± 0.83d) was also shorter than that in the MD group (4.94 ± 1.35d) (P < 0.001). All patients completed 24 months of follow-up. Postoperative scores at each follow-up for the VAS for leg and back pain, ODI, SF36-PF, and SF36-BP all improved significantly for both groups, as compared to the preoperative data (P < 0.05). The mean preoperative and postoperative scores for the VAS for leg and back pain, ODI, SF36-PF, and SF36-BP were not significantly different between the two groups. According to the modified MacNab criteria, the outcomes of the procedures were rated as excellent or good by 92.16% and 93.75% of the patients in the FEVFD and MD groups, respectively. One patient suffered a nerve root injury during the discectomy, one patient suffered from a dural tear, and two patients suffered from a residual herniation in the FEVFD group. One patient in the MD group suffered from poor wound healing. Moreover, recurrence happened in two cases in the FEVFD group, and in one case in the MD group.

CONCLUSION

FEVFD and MD are both reliable techniques for the treatment of symptomatic LDH. FEVFD resulted in a more rapid recovery and equivalent clinical outcomes after 24 months of follow-up.

Full-Endoscopic Transforaminal Ventral Decompression for Symptomatic Thoracic Disc Herniation with or without Calcification: Technical Notes and Case Series

Background

Symptomatic thoracic disc herniation is a challenge in spinal surgery, especially for cases with calcification. Traditional open operation has a high complication rate. The authors introduced a modified full-endoscopic transforaminal ventral decompression technique in this study and evaluated its imaging and clinical outcomes.

Materials and Methods

Eleven patients with symptomatic thoracic disc herniation who underwent full-endoscopic transforaminal ventral decompression in a single medical center were enrolled. The surgical technique was performed as described in detail. Dilator sliding punching, endoscope-monitored foraminoplasty, and base cutting through the “safe triangle zone” are the key points of the technique. Clinical outcomes were assessed by the modified Japanese Orthopedic Association (mJOA) score for neurological improvement and the visual analogy score (VAS) for thoracic and leg pain. The operation time, hospital stay, and complications were also analyzed.

Results

Postoperative magnetic resonance imaging (MRI) revealed good decompression of the spinal cord. The mJOA improved from 7.4 (range: 5–10) to 10.2 (range: 9–11). Axial thoracic pain improved in 8 of 9 patients. Leg pain and thoracic radicular pain improved in all patients. No complications were observed. The average operation time was 136 minutes (range: 70–180 minutes). The average length of hospital stay was 5.3 days (range: 2–8 days).

Conclusion

Minimally invasive full-endoscopic transforaminal ventral decompression for the treatment of symptomatic thoracic disc herniation with or without calcification is feasible and may be another option for this challenging spine disease.

A novel vertebral trench technique (VTT) involving transforaminal endoscopic lumbar foraminotomy (TELF) for very highly up-migrated lumbar disc herniation above L5

BACKGROUND

Percutaneous endoscopic lumbar discectomy (PELD) has become popular for the treatment of symptomatic lumbar disc herniation (LDH). The very highly up-migrated lumbar disc herniation (VHUM-LDH) is difficult to remove under PELD. The purpose of this research is to investigate the feasibility, clinical efficacy and operative nuances of a novel VTT involving TELF for this type of herniation.

METHODS

Eleven patients with very highly up-migrated LDH who underwent VTT involving TELF discectomy from May 2016 to May 2019 were included in this study. The operative time, length of hospital stay, and postoperative complications were recorded. Pre-and postoperative radiologic findings were investigated. All the patients were followed more than 1 year. The visual analogue score (VAS), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) scores and modified MacNab criteria were used to assess surgical efficacy.

RESULTS

All the 11 patients underwent successful surgery. We compared the VAS, ODI, and JOA scores before and after surgery. The differences were statistically significant (P < 0.05). According to the modified MacNab criteria, 10 patients were assessed as "excellent", 1 patient was assessed as "good" at the last follow up.

CONCLUSION

The novel VTT involving TELF discectomy is a supplement to the traditional PELD. This technique enables the endoscope with working cannula to get closer the sequestrated nucleus pulposus without irritating the exiting nerve root, and facilitates the nucleus pulposus be removed successfully under direct visualization. The VTT involving TELF discectomy can be a safe, effective and feasible surgical procedure for the treatment of LDH with very highly up-migrated.

Nerve recognition in percutaneous transforaminal endoscopic discectomy using convolutional neural network

PURPOSE

Percutaneous transforaminal endoscopic discectomy (PTED) is one of the most common minimally invasive surgery methods used in clinic in recent years. In this study, we developed a computer-aided detection system (CADS) based on convolutional neural network (CNN) to automatically recognize nerve and dura mater images under PTED surgery.

METHODS

We collected surgical videos from 65 patients with lumbar disc herniation who underwent PTED; we then converted the videos into images, and randomly divided some images into a training dataset, a validation dataset, test dataset. The training dataset and validation dataset were composed of 10 454 images containing nerve and dura mater from 50 randomly selected patients; test dataset contained 12 000 images from the remaining 15 patients.

RESULTS

The results showed that sensitivity, specificity, and accuracy reached 90.90%, 93.68%, and 92.29%, respectively. CADS could recognize the nerve and dura mater with no significant difference (P > 0.05) between each patient in test dataset. In comparison with clinicians of different levels, the performance of CADS was lower than that of a spinal endoscopist, but significantly higher than that of general surgeons. With the assistance of CADS, the performance of the general surgeons approached that of the spinal endoscopist.

CONCLUSIONS

CNN can recognize well nerve and dura mater images in PTED surgery, and can help general surgeons to improve their ability to recognize tissues during the operation.

Full-Endoscopic Foraminoplasty Using a Visualized Bone Reamer in the Treatment of Lumbar Disc Herniation: A Retrospective Study of 80 Cases

BACKGROUND

Percutaneous endoscopic lumbar discectomy (PELD) has been widely used, before which foraminoplasty is necessary to widen the foramen for subsequent procedures. However, the learning curve of this technology is high, as the use of traditional reamers requires repeated intraoperative fluoroscopy. We sought to compare the clinical outcomes by using the visualized and traditional reamers in PELD foraminoplasty for the treatment of lumbar disc herniation.

METHODS

Eighty patients with lumbar disc herniation who were treated with PELD between 1 January 2017 and 1 January 2019 were retrospectively reviewed. The patients were randomly divided into 2 groups (40 patients in the Visualized Bone Reamer group) and (40 patients in the Traditional Bone Reamer group). Intraoperative fluoroscopy time, cannulation introduction time, visual analog scale, and Macnab criteria score were compared between the 2 groups.

RESULTS

The mean follow-up durations were 17.41 ± 1.47 and 18.37 ± 1.69 months in the visualized and traditional groups, respectively. The average cannulation introduction time and intraoperative fluoroscopy times in the visualized group is significantly lower than those in traditional group (29.20 ± 3.31 vs. 39.85 ± 3.98 minutes, P < 0.001; and 12.30 ± 2.38 vs. 20.65 ±3.51 seconds, P < 0.001, respectively). One patient in the traditional group required reoperation, and no complications occurred in the visualized group. There were no severe durotomies or vascular or visceral injuries.

CONCLUSIONS

Full-endoscopic foraminoplasty using a visualized reamer is safe and effective and can decrease intraoperative fluoroscopy time in PELD.

Learning curve and clinical outcomes of percutaneous endoscopic transforaminal decompression for lumbar spinal stenosis

PURPOSE

To define and analyze the learning curve of percutaneous endoscopic transforaminal decompression (PETD) for lumbar spinal stenosis (LSS).

METHODS

From July 2015 to September 2016, 78 patients underwent PETD; one of whom was converted to open surgery, two were lost, and 75 were included in this study. Clinical results were assessed by using the Oswestry Disability Index (ODI) and visual analog scale (VAS). The learning curve was assessed by a logarithmic curve-fitting regression analysis. Of these 75 patients, 35 were defined as the "early" group, and 40 were defined as the "late" group for comparison.

RESULTS

The mean follow-up was 25.37 ± 4.71 months. The median operative time gradually decreased from 95 (interquartile range, IQR, 85-110) minutes for the early group to 70 (IQR, 60-80) minutes for the late group (P < .000), and an asymptote was reached after approximately 35 cases. After surgery, the VAS for leg pain (LP) and ODI decreased significantly and remained constant during the follow-up. However, the VAS of low back pain (LBP) increased mildly. The total complication rate was 6.6%. ODI, VAS of LP and of LBP, and complication rate did not significantly differ between two groups. Early ambulation and short hospital stay after surgery were achieved.

CONCLUSION

The learning curve of PETD for LSS was assessed and good clinical results were achieved. The surgeon's experience with this technique correlated with reduced operation time. Proper patient selection, familiarity with pathological anatomy, and manipulation under endoscopic view may shorten the learning curve and decrease complications.