Percutaneous endoscopic transforaminal discectomy and unilateral biportal endoscopic discectomy for lumbar disc herniation: a comparative analysis of learning curves.

OBJECTIVE: The purpose of this study was to investigate the learning curve of percutaneous endoscopic transforaminal discectomy (PETD) and interlaminar unilateral biportal endoscopic discectomy (UBED) in the treatment of lumbar disc herniation (LDH). METHODS: Between 2018 and 2023, 120 consecutive patients with lumbar disc herniation (LDH) treated by endoscopic lumbar discectomy were retrospectively included. The PETD group comprised 87 cases, and the UBED group comprised 33 cases. Cumulative sum analysis was used to evaluate the learning curve, with the occurrence of complications or unresolved symptoms defined as surgical failure, and variables of different phases of the learning curve being compared. RESULTS: The learning curve analysis identified the cutoff point at 40 cases in the PETD group and 15 cases in the UBED group. In the mastery phase, both PETD and UBED demonstrated a significant reduction in operation times (approximately 38 min for PTED and 49 min for UBED). In both PETD and UBED groups, the surgical failure rates during the learning and mastery phases showed no statistically significant differences. The visual analogue scale at the last follow-up was significantly lower than before surgery in both the PETD and UBED groups. CONCLUSION: PETD and UBED surgery are effective in the treatment of LDH with a low incidence of complications. However, achieving mastery in PETD necessitates a learning curve of 40 cases, while UBED requires a minimum of 15 cases to reach proficiency.

Validity of A Novel Simulator for Percutaneous Transforaminal Endoscopic Discectomy.

BACKGROUND: Percutaneous transforaminal endoscopic discectomy (PTED) has steep learning curves and a high incidence of complications, but currently, efficient and economical training methods are lacking. This study aimed to validate a novel simulator for PTED. METHODS: The simulated PTED included puncturing and establishing the working channel (PEWC) and endoscopic discectomy, with the PEWC being the tested module. Eleven experts and 21 novices were included and introduced to the simulator and tasks; all participants completed the PEWC. Outcomes included: total operation time, number of fluoroscopy for positioning the working sheath, number of spinal risk region invasion, Global Rating Scale (GRS) and a modified GRS, etc. The Mann-Whitney U test was used to compare 2 groups. Spearman's correlation coefficient analyzed continuous variables. RESULTS: Experts outperformed novices in total operation time (P = 0.001), requiring fewer number of fluoroscopies for positioning the working sheath (P = 0.003). Additionally, experts had a lower number of spinal risk region invasions (P = 0.016) and higher scores on both the GRS (P < 0.001) and modified GRS (P < 0.001). PTED experience correlated with GRS scores (P = 0.001) and modified GRS (P < 0.001). The overall realism scored a median of 4 (3.75-5), and educational value had a median of 4 (range 3-5). CONCLUSIONS: This study demonstrates the validity of the novel simulator, revealing significant associations between PTED experience and performance metrics in a simulated PEWC setting. Furthermore, the PEWC module also offers a good realistic design and high education value according to experts.

Learning Curve for Interlaminar Endoscopic Lumbar Discectomy: A Systematic Review.

BACKGROUND: Interlaminar endoscopic lumbar discectomy (IELD) is an efficient surgical treatment for lumbar disc herniation. However, this minimally invasive procedure requires a considerable learning curve that has not yet been standardized. This review aimed to evaluate the learning curve's characteristics, including the cutoff point required to achieve technical proficiency and to discuss appropriate training methods. METHODS: We systematically searched the core databases (PubMed, Embase, and Cochrane Library) for clinical studies that evaluated the learning curve using quantitative data. We performed a quality assessment using the Newcastle-Ottawa scale. We also compared descriptive statistics, including operative time and other variables before and after the cutoff point. RESULTS: Six studies reporting 302 cases of IELD were selected from 7188 screened articles. The cutoff point was randomly set in 3 studies and determined as the curve's asymptote in 3 studies. The mean value for the cutoff point was 22.17 ± 12.40 cases (range: 10-43 cases) and mainly determined based on the operative time, which was shorter in the late group than that in the early group (P < 0.05). The cutoff points were not significant for patient outcome parameters such as pain score, functional result, surgical failure, or complications. CONCLUSIONS: The evidence of published studies regarding the learning curve for the IELD technique is insufficient. The reported cutoff points may be significant only for task efficiency. Moreover, they may not represent the asymptote of the curve. Future studies should evaluate the actual plateau points using patient outcome data.

Learning curve of percutaneous endoscopic transforaminal lumbar discectomy by a single surgeon.

ABSTRACT: To evaluate the learning curve of percutaneous endoscopic transforaminal lumbar discectomy (PETLD) from the novice stage to the proficient stage, we performed retrospective study for patients with lumbar disc herniation who underwent PETLD performed by a single surgeon and evaluated the surgeon's learning curve and the effect of surgical proficiency on outcomes.A total of 48 patients who underwent PETLD at the lower lumbar level (L3-S1) with a minimum 1-year follow-up were enrolled. The learning curve of the surgeon was assessed using cumulative study of operation time and linear regression analyses to reveal the correlation between operation time and case series number.Because the cutoff of familiarity was 25 cases according to the cumulative study of operation time, the patients were allocated into two groups: early group (n = 25) and late group (n = 23). The clinical, surgical, and radiological outcomes were retrospectively evaluated and compared between the two groups.According to linear regression analyses, the operation time was obtained using the following formula: operation time (minutes) = 69.925-(0.503 × [case number]) (P < .001).As expected, the operation time was significantly different between the two groups (mean 66.00 ±â€Š11.37 min in the early group vs 50.43 ±â€Š7.52 min in the late group, P < .001). No differences were found between the two groups in demographic data and baseline characteristics. Almost all clinical outcomes (including pain improvement and patient satisfaction), surgical outcomes (including failure, recurrence, and additional procedure rates), and radiological outcomes (including change of disc height and sagittal angles) did not differ between the two groups.However, the late group demonstrated a more favorable postoperative volume index of the remnant disc (362.91 mm3 [95% confidence interval, 272.81-453.02] in the early group vs 161.14 mm3 [95% confidence interval, 124.31-197.97] in the late group, P < .001), and a lower complication rate related to exiting nerve root (16.0% in the early group vs 0% in the late group, P = .045).The learning curve of PETLD is not as difficult as that of other minimally invasive spine surgery technique. Although the overall outcomes were not different between the groups, the risks of incomplete decompression and exiting root injury-related complication were higher in the novice stage.

Learning curve of percutaneous endoscopic interlaminar lumbar discectomy versus open lumbar microdiscectomy at the L5-S1 level.

OBJECTIVE: Many studies on the clinical outcome of full endoscopic spine surgery versus open spine surgery have been published. However, only a few studies have compared the learning curves of percutaneous endoscopic interlaminar lumbar discectomy (PEILD) and open lumbar microdiscectomy (OLM) at the L5-S1 level. This study included patients with disc herniation at the L5-S1 level, who underwent PEILD or OLM performed by a single novice surgeon and compared the learning curves. METHODS: Fifty-six patients who underwent PEILD or OLM at the L5-S1 level and completed a minimum 1-year follow-up were enrolled in the study. The patients were allocated to the PEILD group (n = 27, September 2014 to August 2016) or an OLM group (n = 29, September 2012 to August 2014). The learning curves were retrospectively compared based on operation time and surgical outcomes, including complication, failure, and recurrence rates were retrospectively compared. RESULTS: Significant intergroup differences were not noted with respect to the baseline characteristics, including age, sex, body mass index, preoperative symptoms, or preoperative radiological findings. The mean operation time was significantly shorter in the PEILD group than in the OLM group (63.89±17.99 min versus 78.03±19.01 min, p = 0.006). Based on the operation time according to the number of cases, the learning curve was more difficult in the PEILD group according to the cumulative analysis (case number cut-off for proficiency was 18 in the PEILD group versus 10 in the OLM group) and linear regression analysis (proportionality constant for decrease in the operation time was -0.922 in the PEILD group versus -1.738 in the OLM group) than that in the OLM group. However, the surgical outcomes, including failure, surgical efficacy based on nerve root decompression, complication, and recurrence rates did not differ between the two groups. CONCLUSION: Although the learning curve of PEILD was more difficult than that of OLM, the mean operation time was shorter in the PEILD group than that in the OLM group. Moreover, based on the surgical outcomes, PEILD showed efficacy and safety similar to those of OLM.

Indications Selection for Surgeons Training in the Translaminar Percutaneous Endoscopic Discectomy Based on Finite Element Analysis.

BACKGROUND: Translaminar percutaneous endoscopic discectomy (PED) was used widely in the treatment of lumbar disc herniation (LDH), especially for the training of novice surgeons. A larger range of osteotomy was a suitable method to get enough operation space and reduce intraoperative risks. But osteotomy, especially facetectomy, may be associated with the biomechanical deterioration and resulting adjacent segment diseases (ASD). Hence, the objects of this study were to investigate whether different levels of surgical experience in performing different ranges of osteotomy (especially facetectomy) affected the risk for ASD and to identify the safe indications for the training of PED novice surgeons. Study Design. In this study, a three-dimensional lumbosacral model was constructed and validated. Corresponding translaminar PED models with different ranges of osteotomy for armpit, periradicular, and shoulder types of LDH were constructed. The von Mises stress on the endplates, the shear stress on the annulus, the intradiscal pressure, and the range of motion (ROM) in the L3-L4 segment disc were computed. RESULTS: Computational results in our well-validated model indicated that large ranges of osteotomy led to deterioration in most of the biomechanical indicators, and this trend was most significant in the shoulder-type LDH model. CONCLUSIONS: To ensure the appropriateness of the surgical prognosis, armpit and periradicular types of LDH can be seen as suitable indications for the training of novice PED surgeons, and shoulder-type LDH should be excluded from such indications until novices can perform PED within a relatively small range of osteotomy. Mini Abstract. Based on biomechanical variations in our finite element analysis, armpit and periradicular types of LDH can be seen as suitable indications for the training of novice PED surgeons, and shoulder-type LDH should be excluded until novices can perform PED within a relatively small range of osteotomy.

Learning Curve for Percutaneous Endoscopic Lumbar Diskectomy in Bi-needle Technique Using Cumulative Summation Test for Learning Curve.

BACKGROUND: The purpose of this study was to determine the number of cases needed to achieve the level of competence for percutaneous endoscopic lumbar diskectomy (PELD) via the bi-needle technique using the cumulative summation test for learning curve (LC-CUSUM). METHODS: A retrospective design was used. We included 60 patients who underwent a single-level PELD via the bi-needle technique performed by a single surgeon. The surgeon had 5 years of experience in open surgery including the transforaminal endoscopic spine system and Yeung endoscopic spine system but no experience in the bi-needle technique. Surgery success was defined as an operative time <60 minutes, and the acceptable procedure was completed within 3 times of C-arm fluoroscopies. The LC-CUSUM was used to analyze the data. RESULTS: The average operative time for PELD via the bi-needle technique was 58.3 ± 12.4 minutes. The mean operative time was 65.7 ± 12.1 minutes in the early learning period (30 cases) and 51.0 ± 7.5 minutes in the late learning period (30 cases) (P < 0.05). On the basis of the evaluation indexes of the operative time and radioactive exposure, the LC-CUSUM signaled proficiency for the bi-needle technique at the 50th-54th operation. Seven cases of complications were observed during the whole learning process, with 6 in the early period and 1 in the late period (P < 0.05). CONCLUSIONS: The novel bi-needle technique is safe and effective for PELD with appropriate patients, and the learning curve is acceptable. A substantial learning period (50-54 cases) is needed before a spine surgeon can master the bi-needle technique.

Mixed Reality-Based Preoperative Planning for Training of Percutaneous Transforaminal Endoscopic Discectomy: A Feasibility Study.

OBJECTIVE: To explore the effect of preoperative planning using mixed reality (MR) on training of percutaneous transforaminal endoscopic discectomy (PTED). METHODS: Before the training, we invited an experienced chief physician to plan the puncture path of PTED on the X-ray films of the lumbar spine model and the 3D Slicer platform, respectively, and used this as the standard to guide trainees. In the aggregate, 60 young residents were randomly divided into Group A (N = 30) and Group B (N = 30). Group A learned the 2-dimensional standard planning route, whereas Group B learned the standard route planning based on MR through the 3D Slicer platform. Then, trainees were asked to conduct PTED puncture on a lumbar spine model. Questionnaires were distributed to trainees before and after the training. During the training, puncture times, operating time (minutes), and fluoroscopy times were recorded. RESULTS: After the training, it was obvious that more trainees showed their recognition of MR, believing that MR could help preoperative planning and training of PTED. Their high satisfaction with the training indicated the success of our training. Moreover, puncture times, operating time (minutes), and fluoroscopy times of Group B were significantly lower than those of Group A. CONCLUSIONS: MR technology contributes to preoperative planning of PTED and is beneficial in the training of PTED. It significantly reduces puncture times and fluoroscopy times, providing a standardized method for the training of PTED.

Experimental model for transforaminal endoscopic spine

Abstract Purpose: To validate the porcine spine as a model for learning and practicing transforaminal percutaneous endoscopic lumbar procedures (TF-PELP). Methods: TF-PELP was performed in three porcine cadaver lumbar spine levels. Anatomical features of the current cadaver were compared to human and porcine spines. Performance and documentation of endoscopic procedures were described. Results: This study shows that this representative animal model reflects anatomical characteristics of the human spine. Transforaminal approaches were successfully completed. Although lower disc heights make disc puncture more difficult, the outside-in technique is feasible and more useful to identify anatomical parameters and to practice different surgical steps and maneuvers. Conclusion: This is an effective and representative model for learning and practicing this procedure. Difficulties of the procedure, as well as the differences compared to the human spine, were described.

Experimental model for transforaminal endoscopic spine.

PURPOSE: To validate the porcine spine as a model for learning and practicing transforaminal percutaneous endoscopic lumbar procedures (TF-PELP). METHODS: TF-PELP was performed in three porcine cadaver lumbar spine levels. Anatomical features of the current cadaver were compared to human and porcine spines. Performance and documentation of endoscopic procedures were described. RESULTS: This study shows that this representative animal model reflects anatomical characteristics of the human spine. Transforaminal approaches were successfully completed. Although lower disc heights make disc puncture more difficult, the outside-in technique is feasible and more useful to identify anatomical parameters and to practice different surgical steps and maneuvers. CONCLUSION: This is an effective and representative model for learning and practicing this procedure. Difficulties of the procedure, as well as the differences compared to the human spine, were described.

Increased Volume of Lumbar Surgeries for Herniated Intervertebral Disc Disease and Cost-Effectiveness Analysis: A Nationwide Cohort Study.

STUDY DESIGN: Retrospective cohort study of a nationwide database. OBJECTIVE: The primary objective was to summarize the use of surgical methods for lumbar herniated intervertebral disc disease (HIVD) at two different time periods under the national health insurance system. The secondary objective was to perform a cost-effectiveness analysis by utilizing incremental cost-effectiveness ratio (ICER). SUMMARY OF BACKGROUND DATA: The selection of surgical method for HIVD may or may not be consistent with cost effectiveness under national health insurance system, but this issue has rarely been analyzed. METHODS: The data of all patients who underwent surgeries for HIVD in 2003 (n = 17,997) and 2008 (n = 38,264) were retrieved. The surgical methods included open discectomy (OD), fusion surgery, laminectomy, and percutaneous endoscopic lumbar discectomy (PELD). The hospitals were classified as tertiary-referral hospitals (≥300 beds), medium-sized hospitals (30-300 beds), or clinics (<30 beds). ICER showed the difference in the mean total cost per 1% decrease in the reoperation probability among surgical methods. The total cost included the costs of the index surgery and the reoperation. RESULTS: In 2008, the number of surgeries increased by 2.13-fold. The number of hospitals increased by 34.75% (731 in 2003 and 985 in 2008). The proportion of medium-sized hospitals increased from 62.79% to 70.86%, but the proportion of surgeries performed at those hospitals increased from 61.31% to 85.08%. The probability of reoperation was highest after laminectomy (10.77%), followed by OD (10.50%), PELD (9.20%), and fusion surgery (7.56%). The ICERs indicated that PELD was a cost-effective surgical method. The proportion of OD increased from 71.21% to 84.12%, but that of PELD decreased from 16.68% to 4.57%. CONCLUSION: The choice of surgical method might not always be consistent with cost-effectiveness strategies, and a high proportion of medium-sized hospitals may be responsible for this change. LEVEL OF EVIDENCE: 4.

Learning curves of percutaneous endoscopic lumbar discectomy in transforaminal approach at the L4/5 and L5/S1 levels: a comparative study.

OBJECTIVES: This study aimed to compare the learning curves of percutaneous endoscopic lumbar discectomy (PELD) in a transforaminal approach at the L4/5 and L5/S1 levels. METHODS: We retrospectively reviewed the first 60 cases at the L4/5 level (Group I) and the first 60 cases at the L5/S1 level (Group II) of PELD performed by one spine surgeon. The patients were divided into subgroups A, B, and C (Group I: A cases 1-20, B cases 21-40, C cases 41-60; Group II: A cases 1-20, B cases 21-40, C cases 41-60). Operation time was thoroughly analyzed. RESULTS: Compared with the L4/5 level, the learning curve of transforaminal PELD at the L5/S1 level was flatter. The mean operation times of Groups IA, IB, and IC were (88.75±17.02), (67.75±6.16), and (64.85±7.82) min, respectively. There was a significant difference between Groups A and B (P<0.05), but no significant difference between Groups B and C (P=0.20). The mean operation times of Groups IIA, IIB, and IIC were (117.25±13.62), (109.50±11.20), and (92.15±11.94) min, respectively. There was no significant difference between Groups A and B (P=0.06), but there was a significant difference between Groups B and C (P<0.05). There were 6 cases of postoperative dysesthesia (POD) in Group I and 2 cases in Group IIA (P=0.27). There were 2 cases of residual disc in Group I, and 4 cases in Group II (P=0.67). There were 3 cases of recurrence in Group I, and 2 cases in Group II (P>0.05). CONCLUSIONS: Compared with the L5/S1 level, the learning curve of PELD in a transforaminal approach at the L4/5 level was steeper, suggesting that the L4/5 level might be easier to master after short-term professional training.

Complications of endoscopic microdiscectomy using the EASYGO! system: is there any difference with conventional discectomy during the learning-curve period?

BACKGROUND: Microendoscopic discectomy (MED) is emerging as a minimally invasive alternative to conventional microsurgical discectomy (MSD). EASYGO! is a new system for spinal endoscopy that claims smooth transition from MSD to MED, with a reduced learning curve period. The aims of this study were to describe the complications that appeared during the learning curve period of MED and to compare their incidence with the rate and type of complications that occurred during a simultaneous non-randomised series of standard MSDs. METHODS: Between July 2009 and December 2010, 138 patients underwent scheduled first-time discectomy in our institution, 37 using an MED approach and 101 by a conventional MSD. A MED learning curve was obtained by plotting every case with its respective operative time. Complications, length of hospital stay, need of further surgery and outcome were prospectively recorded in both groups. RESULTS: The mean operative time was 66 min for the MSD group and 100 min for the MED group, although for the last 14 cases of the latter group the time was reduced. Curve-fitting techniques showed that the inverse equation, ƒ(x) = 122.12/x + 73.05, had the best correlation between case number and operative time. The learning curve was overcome after the 30th case. Complications occurred in 9.8 % of the MSD group and 8.1 % of the MED group (P = 0.49). Average length of hospital stay was 2.36 days for the MED group and 3.36 days for the MSD group (P = 0.01). The procedure successfully relieved patient symptoms in 68.63 % of the MSD group and 89.92 % of the MED group. No revision surgery was required in the MED group, but it was necessary in ten patients of the MSD group. CONCLUSIONS: Between 25 and 30 cases are needed to reach the learning curve's asymptote of MED. Even during this initial learning period MED is a safe procedure, with comparable results to those obtained with conventional MSD and with a similar complication rate. The key points for reducing intraoperative complications are an adequate expertise in MSD, a precise selection of initial cases, a proper surgical planning and a careful technique, which are mandatory to avoid unnecessary neurological injury in an otherwise secure surgical approach.

Learning curve for percutaneous endoscopic lumbar discectomy.

Percutaneous endoscopic lumbar discectomy (PELD) is one of the surgical options for soft lumbar disk herniation, but the learning curve is perceived to be steep. The first 51 PELD cases performed for single-level intracanalicular lumbar disk herniation causing radiculopathy by the same surgeon were prospectively studied. The patients were divided into 3 groups of 17 patients, and the PELD learning curve was assessed by evaluating operating time, failure rate, complication rate, and 1-year reherniation rate. One-year clinical success rate was assessed by telephone interviews. The herniated disk was successfully removed by PELD in 47 patients. Four patients required subsequent open discectomy due to PELD failure. There were 2 minor complications. One year after surgery, clinical success was achieved in 42 of the 47 patients in whom PELD was initially successful, and reherniation developed in 5 patients. A significant reduction in operating time was observed after 17 patients had been treated (p = 0.0004). No significant differences were observed in terms of either failure rate or complication rate between the 3 groups. No significant differences were observed in terms of either the clinical success rate or the reherniation rate at 1 year after surgery. The PELD learning curve seems to be stable and acceptable with proper pre-PELD training.