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.

Limited discectomy versus aggressive discectomy by spinal endoscopy with the transforaminal approach for lumbar disc herniation: a retrospective study.

OBJECTIVE: To compare the clinical and radiological outcomes of limited discectomy (LD) and aggressive discectomy (AD) performed via spinal endoscopy using the transforaminal approach in patients with lumbar disc herniation(LDH) METHODS: We conducted a retrospective review of patients who underwent percutaneous endoscopic transforaminal discectomy (PETD) at the L4-L5 lumbar spine segments in our department from January 2017 to December 2020. The follow-up period extended to 24 months postoperatively. Patients were categorized into the LD and AD groups based on the extent of intraoperative disc removal. We retrospectively collected and analyzed clinical and radiological data. RESULTS: The study followed 65 patients, with 36 in the LD group and 29 in the AD group. No statistically significant differences were noted in recurrence rates, the excellent and good Macnab rates, preoperative Disc Height Index (DHI), and preoperative Modic changes between the groups (P >0.05). However, significant differences were observed in operation duration, postoperative DHI and postoperative Modic change (P<0.05). No significant differences in Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores were detected between the groups preoperatively, or one and two years postoperatively (P>0.05). Nevertheless, notable differences in VAS and ODI scores were present one month postoperatively (P<0.05). CONCLUSION: As a conventional surgical method for treating LDH, PETD can achieve satisfactory clinical results in both LD and AD, with no significant variance in recurrence rates. However, AD is associated with longer operation times, and greater postoperative reductions in DHI and greater postoperative Modic changes compared to LD.

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.

Necessity of routinely performing foraminoplasty during percutaneous endoscopic transforaminal discectomy (PETD) for lumbar disc herniation.

OBJECTIVE: To assess the role of foraminoplasty during percutaneous endoscopic transforaminal discectomy (PETD) and compared the 2-year clinical results of patients underwent PETD w/o foraminoplasty. METHODS: A total of 412 patients, who underwent PETD at L3-S1 by the same surgical group, were enrolled in this study. The MRI was used to determine the height (H1) and width (W1) of the intervertebral foramen of L3-S1, the distance between the exiting nerve root and the upper edge of the lower vertebral pedicle (H2), and the distance (W2) between the point with 3 mm to the ventral side of the intervertebral space and superior articular process. The intervertebral foramen widths in the flexion (W3) and extension positions (W4) were also measured. A VAS of low back pain (LBP) and leg pain, ODI and JOA scores of LBP were used to assess the clinical results. RESULTS: Intraoperative verification showed that 347 cases (group A) did not need foraminoplasty, while the other 65 patients (group B) needed foraminoplasty, including 31 at L4-5 and 34 at L5-S1. The H1 and H2 of L3-S1 were reduced gradually without significant difference between two groups. The W1, W2, W3 and W4 were higher in group A (p < 0.05). The W3 was higher than W4 in both groups (p < 0.05). At 2-year follow-up, there was no significant difference of ODI and JOA score between two groups (p > 0.05). The VAS score of LBP was better in group A (p < 0.05). CONCLUSIONS: Most of PETD procedure at L3-S1 levels could reach the therapeutic target without foraminoplasty. Due to anatomic characteristics of L5-S1, the foraminoplasty rate was much higher at L5-S1.

A comparative study of percutaneous endoscopic interlaminar discectomy and transforaminal discectomy for L5-S1 calcified lumbar disc herniation.

BACKGROUND: Percutaneous endoscopic lumbar discectomy (PELD) is a relatively safe and effective minimally invasive surgery in the treatment of calcified lumbar disc herniation (CLDH). However, studies on percutaneous endoscopic interlaminar discectomy (PEID) and percutaneous endoscopic transforaminal discectomy (PETD) for CLDH have rarely been reported. This research aimed to compare the clinical efficacy of PEID and PETD for L5-S1 CLDH. METHODS: We retrospectively analyzed 54 consecutive patients with L5-S1 CLDH treated with PELD at our institution from August 2016 to August 2020. Patients were divided into PEID group (n = 28) and PETD (n = 26) group according to the surgical methods. The demographic characteristics and surgical results of the two groups were compared. Clinical outcomes were estimated by the visual analog scale (VAS) for leg pain, Oswestry disability index (ODI) and modified MacNab criteria. RESULTS: All patients were successfully operated on by PEID or PETD. No significant differences in the demographic characteristics, intraoperative blood loss, postoperative hospital stay and complication rate were noted between the PEID and PETD groups. The excellent and good rates in the PEID group were similar to those in the PETD group (89.29% vs 88.46%, P = 1.000), whereas the PEID group exhibited superior results for operative time (min) (64.61 ± 5.60 vs 85.58 ± 8.52, P < 0.001) and fluoroscopy times (n) (2.93 ± 0.90 vs 13.35 ± 2.30, P < 0.001) compared with the PETD group. CONCLUSIONS: PEID has achieved good clinical efficacy as PETD for L5-S1 CLDH. Compared with PETD, PEID has the advantages of shorter operative time and a reduced number of fluoroscopy times in the treatment of CLDH.

Comparing oblique lumbar interbody fusion with lateral screw fixation and percutaneous endoscopic transforaminal discectomy (OLIF-PETD) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for the treatment of lumbar disc herniation complicated with lumbar instability.

OBJECTIVE: To evaluate the early clinical effect of oblique lumbar interbody fusion with lateral screw fixation and percutaneous endoscopic transforaminal discectomy (OLIF-PETD) in the treatment of lumbar disc herniation with lumbar instability. METHODS: A total of 22 patients with lumbar disc herniation and lumbar instability from August 2017 to August 2019 were enrolled in this retrospective study. The general information, perioperative indicators and complications were recorded. The clinical outcomes and radiological outcomes were evaluated before the operation, seven days after the operation, and at the last follow-up. Vertebral fusion and degree of multifidus muscle injury were evaluated at the last follow-up. RESULTS: In this study, OLIF + PETD showed shorter incision length compared to the MIS-TLIF (P < 0.001). In the two groups, the clinical outcomes and radiological outcomes were significantly improved compared with the preoperative (P < 0.001). At the seven days after the operation and the last follow-up, the VAS of OLIF + PETD group was lower than that of MIS-TLIF group (P < 0.05). OLIF + PETD could give superior outcome in restoring disc height (P < 0.001), but the fusion segment angle of OLIF + PETD group was larger compared to the MIS-TLIF group seven days after the operation and at the last follow-up (P < 0.05). In addition, the fusion rate was not significantly different between the two groups (P > 0.05), but OLIF + PETD could avoid the multifidus injury (P < 0.001). CONCLUSION: Compared to MIS-TLIF, OLIF-PETD can achieve satisfactory decompression effects and fusion rates with less multifidus injury and postoperative low back pain, which may be an alternative choice for the treatment of lumbar disc herniation combined with lumbar instability.

Complications and risk factors of percutaneous endoscopic transforaminal discectomy in the treatment of lumbar spinal stenosis.

BACKGROUND: With the advancements in surgical methods, optical designs, and surgical instruments, percutaneous endoscopic transforaminal discectomy (PETD) has become an effective and minimally invasive procedure to treat lumbar spinal stenosis (LSS) in recent years. Few studies have focused on the complications associated with the treatment of LSS using percutaneous endoscopic lumbar discectomy (PELD). This study aimed to summarize the complications of PETD and identify the associated risk factors. METHODS: Complications in a total of 738 consecutive LSS patients who underwent single-level PETD were retrospectively recorded and analyzed between January 2016 and July 2020. In addition, a matched case-control study was designed, and according to the date of operation, the control group was matched with patients without complications, with a matching ratio of 1:3. Demographic parameters included age, sex, BMI, smoking and drinking status, comorbidity, and surgical level. The radiological parameters included grade of surgical-level disc degeneration, number of degenerative lumbar discs, grade of lumbar spinal stenosis, degenerative lumbar scoliosis, lumbar lordosis, disc angle, and disc height index. Univariate analysis was performed using independent samples t-test and chi-squared test. RESULTS: The incidence of different types of complications was 9.76% (72/738). The complications and occurrence rates were as follows: recurrence of LSS (rLSS), 2.30% (17/738); persistent lumbosacral or lower extremity pain, 3.79% (28/738); dural tear, 1.90% (14/738); incomplete decompression, 0.81% (6/738); surgical site infection, 0.41% (3/738); epidural hematoma, 0.27% (2/738); and intraoperative posterior neck pain, 0.27% (2/738). Univariate analysis demonstrated that age, the grade of surgical-level disc degeneration (P < 0.001) and the number of disc degeneration levels (P = 0.004) were significantly related to the complications. CONCLUSION: Complications in the treatment of LSS using PELD included rLSS, persistent pain of the lumbosacral or lower extremity, dural tear, incomplete decompression, surgical site infection, epidural hematoma, and intraoperative posterior neck pain. In addition, old age, severe grade of surgical-level disc degeneration and more disc degeneration levels significantly increased the incidence of complications.

Different approaches to percutaneous endoscopic lumbar discectomy for L5/S1 lumbar disc herniation: a retrospective study.

OBJECTIVE: To observe the surgical procedure and outcome of percutaneous endoscopic lumbar discectomy for L5/S1 lumbar disc herniation (LDH) by the interlaminar and transforaminal approach. METHODS: A total of 153 patients with L5/S1 LDH who were treated using percutaneous endoscopic transforaminal discectomy (PETD, n = 84) or percutaneous endoscopic interlaminar discectomy (PEID, n = 69) from January 2016 to January 2018 were enrolled in this retrospective study. The time of puncture, operation under the endoscope, total operation and number of fluoroscopy of the two groups were compared. All groups were followed up for two years by using the Oswestry disability index (ODI) and the Visual Analogue Scale (VAS). Additionally, the incidence of complications, reoperation and postoperative low back pain were compared between the two groups. RESULTS: There were no significant difference in general information between the two groups. Compared to the PEID group, the PETD group had a decreased operation time under the endoscope and an increased puncture time, total operation time, and the number of fluoroscopy (p < 0.05). The preoperative VAS and ODI scores of the PETD and PEID group were decreased at the last follow-up (p < 0.05). There were no difference in the preoperative or last follow-up VAS and ODI scores, as well as complications, reoperation between the two groups (p > 0.05). The incidence of postoperative low back pain in the PETD group was lower than that in the PEID group (p > 0.05). CONCLUSIONS: The two-year clinical outcome of PETD is equal to that of PEID for L5/S1 LDH. Compared to those with PETD, the puncture time, total operation time and radiation exposure are lower with PEID, but the incidence of postoperative low back pain is higher.

[Percutaneous endoscopic transforaminal discectomy for L5~S1 disc herniation].

Objective: To evaluate the clinical results of percutaneous endoscopic transforaminal discectomy (PETD) for L5~S1 lumbar disc herniation (LDH). Methods: One hundred and two cases of L5~S1 LDH from April 2016 to June 2018 were retrospectively analyzed, including 13 patients with high iliac crest. Pre-and postoperative pain was measured by Visual Analog Scale (VAS) and functional status was assessed by Oswestry Disability Index (ODI). Results: All the operations were successful and no severe complications occurred such as hemorrhages, infections, injury of nerves. The operation time was (87.6±21.0) min; the frequencies of intraoperative fluoroscopy were 29.1±11.7; the postoperative bedridden time was (4.6±1.1) hours and the hospital stay was (3.6±0.5) days. The mean VAS and ODI scores were significantly improved (P<0.01) postoperatively. The efficiency of 102 cases were excellent in 89 cases (87.3%), good in 8 cases (7.8%), fair in 4 cases (3.9%) and poor in 1 cases (1.0%). One patient (1.0%) relapsed at 6 months after surgery. Conclusions: PETD is a safe and effective method for treatment of L5~S1 LDH. The "transverse process localization method" might be an effective technique for patient with high iliac crest and/or hypertrophic transverse process.

Nomogram Development and Validation for Predicting Postoperative Recurrent Lumbar Disc Herniation Based on Paraspinal Muscle Parameters.

Purpose: Previous studies highlight paraspinal muscles' significance in spinal stability. This study aims to assess paraspinal muscle predictiveness for postoperative recurrent lumbar disc herniation (PRLDH) after lumbar disc herniation patients undergo percutaneous endoscopic transforaminal discectomy (PETD). Patients and Methods: Retrospectively collected data from 232 patients undergoing PETD treatment at our institution between January 2020 and January 2023, randomly allocated into training (60%) and validation (40%) groups. Utilizing Lasso regression and multivariable logistic regression, independent risk factors were identified in the training set to construct a Nomogram model. Internal validation employed Enhanced Bootstrap, with Area Under the ROC Curve (AUC) assessing accuracy. Calibration was evaluated through calibration curves and the Hosmer-Lemeshow goodness-of-fit test. Decision curve analysis (DCA) and clinical impact curve (CIC) were employed for clinical utility analysis. Results: Diabetes, Modic changes, and ipsilesional multifidus muscle skeletal muscle index (SMI) were independent predictive factors for PRLDH following PETD (P<0.05). Developed Nomogram model based on selected predictors, uploaded to a web page. AUC for training: 0.921 (95% CI 0.872-0.970), validation: 0.900 (95% CI 0.828-0.972), respectively. The Hosmer-Lemeshow test yielded χ 2=5.638/6.259, P=0.688/0.618, and calibration curves exhibited good fit between observed and predicted values. DCA and CIC demonstrate clinical net benefit for both models at risk thresholds of 0.02-1.00 and 0.02-0.80. Conclusion: The Nomogram predictive model developed based on paraspinal muscle parameters in this study demonstrates excellent predictive capability and aids in personalized risk assessment for PRLDH following PETD.

Hidden blood loss in three different endoscopic spinal procedures for lumbar disc herniation.

Purpose: This study compared hidden blood loss (HBL) among three different endoscopic spinal procedures and investigated its risk factors. Patients and methods: This single-centre retrospective analysis collected data from consecutive hospitalized patients with single-segment lumbar disc herniation (LDH) undergoing unilateral biportal endoscopic discectomy (UBE), percutaneous endoscopic transforaminal discectomy (PETD), or percutaneous endoscopic interlaminar discectomy (PEID) from December 2020 to October 2022. HBL was calculated using Nadler's and Gross's formulas. The authors used Pearson's or Spearman's correlation analysis to explore the relationship between patient characteristics and HBL. Multivariate linear regression analysis was used to identify independent risk factors for HBL. Results: In total, 122 consecutive patients (68 females and 54 males) were enroled in this study. The average HBL was 381.87±218.01 ml in the UBE group, 252.05±118.44 ml in the PETD group and 229.63±143.9 ml in the PEID group (P<0.05). Pearson's or Spearman's correlation analysis showed that operative time, preoperative haemoglobin, preoperative haematocrit, and preoperative Albumin (ALB) were correlated with HBL in the UBE group, while sex, age, operative time, postoperative ALB, and patients' blood volume (PBV) were related to HBL in the PETD group (P<0.05). Operative time and preoperative activated partial thromboplastin time were related to HBL in the PEID group (P<0.05). Multiple linear regression analysis showed a positive correlation between HBL and operative time in all three groups (P<0.001, P<0.001, P<0.05). Conclusion: HBL was higher in the UBE group than in the PETD and PEID groups, and operative time may be a common risk factor for the three groups.

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

Background: The learning curve for percutaneous endoscopic transforaminal discectomy (PETD) is steep, especially for the puncturing and localization procedures. The implementation of 3D printing technology may solve this problem. Methods: A novel individualized 3D-printing template (3D-PT) was designed and utilized in PETD. A prospective randomized controlled trial was performed. A total of 28 patients with lumbar disc herniation treated with PETD were analyzed. Of these, 14 patients were treated with the assistance of 3D printing technology (3D-PT group) in conjunction with fluoroscopy, while the remaining 14 patients were treated exclusively under the guidance of C-arm fluoroscopy (control group). Results: The number of puncture attempts in the 3D-PT group was significantly less than in the control group (1.36 ± 0.63 vs. 6.07 ± 3.08, p = 0.000). The 3D-PT group exhibited a significant reduction in both intraoperative puncture fluoroscopies (2.71 ± 1.27 vs. 12.14 ± 6.15, p = 0.000) and the overall number of fluoroscopies (2.71 ± 1.27 vs. 17.43 ± 6.27, p = 0.000). In the 3D-PT group, there was a significant reduction in both the puncture time (5.77 ± 1.82 vs. 13.99 ± 4.36, p = 0.000) and the total operation time (60.39 ± 9.78 vs. 76.25 ± 17.78, p = 0.007). Complications were not observed in either group. Conclusion: The application of the novel individualized 3D-PT for PETD is effective and safe. The technique has substantial potential and is worth widely promoting.

Development and Validation of a Nomogram Predicting Postoperative Recurrent Lumbar Disc Herniation Based on Activity Factors.

Purpose: To develop an individualized predictive model for postoperative recurrent lumbar disc herniation (PRLDH) in patients undergoing percutaneous endoscopic transforaminal discectomy (PETD) by considering postoperative activity factors. Patients and Methods: Retrospectively collected data from 612 LDH patients who underwent PETD in our institution from January 2017 to June 2023. They were divided into a training group (429 cases) and a validation group (183 cases). Lasso regression (Model 1) and random forest (Model 2) were applied for variable selection in the training group. The two models were compared in terms of discrimination (the area under curve, AUC), calibration (calibration curve), and clinical utility (decision curve analysis, DCA). Akaike information criterion (AIC) was used for model comparison, and internal validation employed 1000 times Bootstrap + 10-fold cross-validation. Finally, a Nomogram was constructed to display the results and uploaded to the web version. Results: Among 612 treated LDH patients, 66 (10.78%) developed PRLDH. Model 1, superior in AUC, calibration, DCA, and AIC over Model 2, was chosen as the predictive model. Logistic regression in the training group identified BMI, smoking, activity level score, time to first ambulation, diabetes, Modic change, and Pfirrmann grade as independent predictors of PRLDH. Model 1 exhibited a training group AUC of 0.813 (95% CI 0.753-0.872) and a validation group AUC of 0.868 (95% CI 0.773-0.962). At a Youden index of 0.50, sensitivity was 0.73, specificity was 0.77. Internal validation (1000 times Bootstrap + 10-fold cross-validation) for the training group showed accuracy of 0.889, kappa consistency of 0.112, and AUC of 0.757. The Hosmer-Lemeshow goodness-of-fit tests indicated good discriminative ability for Model 1 in both the training (χ2=2.895, P=0.941) and validation groups (χ2=8.197, P=0.414). The DCA and Nomogram are accessible at https://sofarnomogram.shinyapps.io/PRLDHNom/. Conclusion: The Nomogram predictive model, developed based on postoperative activity factors in this study, demonstrates excellent predictive capability, facilitating risk assessment for the occurrence of PRLDH after PETD.

Modified Percutaneous Endoscopic Interlaminar Discectomy through the Near-spinous Process Approach for L4/5 Disc Herniation: A Retrospective Clinical Study.

OBJECTIVE: Compared with traditional open surgery, percutaneous endoscopic lumbar discectomy (PELD) has the advantages of less trauma, faster recovery, and less postoperative pain, so it has been widely used in the field of spinal surgery. However, it still has the defect of intraoperative fluoroscopy occurrences, complications, and even the risk of damage to the spinal cord and nerve. This study aims to compare the clinical efficacy of modified percutaneous endoscopic interlaminar discectomy (MPEID) with percutaneous endoscopic transforaminal discectomy (PETD) in treating L4/5 lumbar disc herniation (LDH) and to evaluate the effectiveness and safety of MPEID. METHODS: Thirty-four L4/5 LDH patients treated at the Second Affiliated Hospital of Nanchang University from June 2020 to June 2021 were studied retrospectively. Seventeen underwent MPEID and seventeen PETD. Variables analyzed included demographics, operative duration, intraoperative fluoroscopy occurrences, and surgical outcomes. Effectiveness was evaluated using the visual analogue scale (VAS), Oswestry disability index (ODI), and modified MacNab criteria. Lumbar Magnetic Resonance Imaging (MRI) was used to assess radiological outcomes. A paired t-test was performed to compare intragroup pre- and postoperative clinical data, VAS, and ODI scores. RESULTS: The average operative time in PETD group was 91.65 ± 14.04 min, and the average operative time in MPEID group was 65.41 ± 12.61 min (p < 0.001). In PETD group, the fluoroscopy occurrences averaged 9.71 ± 1.05 times, with fluoroscopy occurrences averaging 6.47 ± 1.00 times (p < 0.001) in MPEID group. At 12 months follow-up, the clinical effect showed significant improvement in both two groups. The MPEID group showed a decrease in average VAS-back score from 5.41 ± 2.18 to 1.76 ± 1.09 (p < 0.001) and VAS-leg score from 6.53 ± 1.66 to 0.82 ± 0.64 (p < 0.001). The ODI scores decreased from 51.35 ± 10.65 to 11.71 ± 2.91 (p < 0.001). In the PETD group, the VAS-back score decreased from 4.94 ± 1.98 to 2.06 ± 1.25 (p < 0.001), VAS-leg score from 7.12 ± 1.73 to 1.12 ± 0.60 (p < 0.001), and ODI scores from 48.00 ± 11.62 to 12.24 ± 2.56 (p < 0.001). According to the modified MacNab criteria, MPEID had 15 excellent and two good results; PETD had 12 excellent and 5 good (p = 0.23). No nerve root injuries, dural tears, or significant complications were reported. CONCLUSION: MPEID and PETD effectively treat L4/5 LDH, with MPEID showing shorter operative times and fewer fluoroscopies. Furthermore, the MPEID group can provide excellent clinical efficacy as the PETD group in the short term.

Development and Validation of a Prognostic Model for the Risk of Recurrent Lumbar Disc Herniation After Percutaneous Endoscopic Transforaminal Discectomy.

BACKGROUND: Recurrence of lumbar disc herniation (LDH) is an adverse event after percutaneous endoscopic transforaminal discectomy (PETD). Accurate prediction of the risk of recurrent LDH (rLDH) after surgery remains a major challenge for spine surgeons. OBJECTIVES: To develop and validate a prognostic model based on risk factors for rLDH after PETD. STUDY DESIGN: Retrospective study. SETTING: Inpatient surgery center. METHODS: Clinical data were retrospectively collected from 645 patients with LDH who underwent PETD at the Affiliated Hospital of Xuzhou Medical University from January 1, 2017 to January 1, 2021. Predictors significantly associated with rLBH were screened according to least absolute shrinkage and selection operator (LASSO) regression, and a prognostic model was established, followed by internal model validation using the enhanced bootstrap method. The performance of the model was assessed using receiver operating characteristic (ROC) curves and calibration curves. Finally, the clinical usefulness of the model was analyzed using decision curve analysis (DCA) and clinical impact curves (CICs). RESULTS: Among the 645 patients included in this study, 56 experienced recurrence of LDH after PETD (8.7%). Seven factors significantly associated with rLDH were selected by LASSO regression, including age, type of herniation, level of herniation, Modic changes, Pfirrmann classification, smoking, and history of high-intensity physical work. The bias-corrected curve of the model fit well with the apparent curve, and the area under the ROC curve was 0.822 (95% confidence interval, 0.76-0.88). The DCA and CIC confirmed that the prognostic model had good clinical utility. LIMITATIONS: This is a single-center study, and we used internal validation only. CONCLUSIONS: The prognostic model developed in this study had excellent comprehensive performance and could well predict the risk of rLDH after PETD. This model could be used to identify patients at high risk for rLDH at an early stage to individualize the patient's treatment modality and postoperative rehabilitation plan.

Visible trephine-based foraminoplasty in PTED leads to asymmetrical stress changes and instability in the surgical and adjacent segments: a finite element analysis.

This study aimed to construct a multi-segment lumbar finite element model (FEM) of PTED surgery to analyze the changes in stress and ROM after visible trephine-based foraminoplasty. The CT scans of a 35-year-old healthy male were used to develop a multi-segment lumbar FEM with Mimic, Geomagic Studio, Hypermesh and MSC.Patran. Different foraminoplasty was performed on the model, and these were grouped into normal group (A), the ventral resection group (B), the apex resection group (C), the ventral + apex + isthmus resection group (D), and the SAP + isthmus + lateral recess resection group (E). A vertical load of 500N and a torque of 10N·M were applied to the upper surface of the L3 vertebral body to simulate the biomechanical characteristics under the motion of flexion, extension, lateral bending, and rotation. The von Mises stress maps of the intervertebral f, vertebral body, facet joints, and the ROM of the L3-S1 intervertebral disk were calculated and analyzed. The changes of peak stress on the vertebral body for each group were not significant in the same motion state. Significant stress differences were observed in the L4/5 intervertebral disks, while no obvious stress changes were observed for the L3/4 and L5/S1 intervertebral disks. The stress of the L3/4 and L5/S1 facet joints decreased after L4/5 foraminoplasty, while the stress of L4/5 facet joints displayed an overall increasing trend. Significant asymmetrical stress changes of bilateral facet joints were observed in all three segments, particularly during bilateral rotation movements. The ROM of L3-S1 gradually increased from Group A to Group E, especially during flexion, left lateral bending, and right rotation, with the highest elevation observed for the L45 ROM. Our FEM indicated that enlarged resection and exposure of the articular surface could lead to significant asymmetrical stress changes in the bilateral facet joints and ROM instability of the surgical and adjacent segments. These findings suggested that unnecessary and excessive resection should be avoided in PTED to reduce the incidence of low back pain and the risk of postsurgical degeneration.

Nomogram for predicting the unfavourable outcomes of percutaneous endoscopic transforaminal discectomy for lumbar disc herniation: a retrospective study.

Objective: To investigate and integrate multiple independent risk factors to establish a nomogram for predicting the unfavourable outcomes of percutaneous endoscopic transforaminal discectomy (PETD) for lumbar disc herniation (LDH). Methods: From January 2018 to December 2019, a total of 425 patients with LDH undergoing PETD were included in this retrospective study. All patients were divided into the development and validation cohort at a ratio of 4:1. Univariate and multivariate logistic regression analyses were used to investigate the independent risk factors associated with the clinical outcomes of PETD for LDH in the development cohort, and a prediction model (nomogram) was established to predict the unfavourable outcomes of PETD for LDH. In the validation cohort, the nomogram was validated by the concordance index (C-index), calibration curve, and decision curve analysis (DCA). Results: 29 of 340 patients showed unfavourable outcomes in the development cohort, and 7 of 85 patients showed unfavourable outcomes in the validation cohort. Body mass index (BMI), course of disease (COD), protrusion calcification (PC), and preoperative lumbar epidural steroid injection (LI) were independent risk factors associated with the unfavourable outcomes of PETD for LDH and were identified as predictors for the nomogram. The nomogram was validated by the validation cohort and showed high consistency (C-index = 0.674), good calibration and high clinical value. Conclusions: The nomogram based on patients' preoperative clinical characteristics, including BMI, COD, LI and PC, can be used to accurately predict the unfavourable outcomes of PETD for LDH.

Cave-in decompression technique in percutaneous endoscopic transforaminal discectomy for ossification occupation in lumbar spinal canal: A retrospective analysis of 23 cases.

OBJECTIVE: Percutaneous endoscopic transforaminal discectomy (PETD) for the treatment of ossification occupation of the lumbar spinal canal is technically demanding. The purpose of this study was to describe an endoscopic cave-in decompression technique in PETD for ossification occupation of the lumbar spinal canal and to report the clinical results. METHODS: From May 2018 to June 2020, 23 consecutive cases, diagnosed in our institution as ventral ossification in the lumbar spinal canal and treated with PETD, were evaluated. The endoscopic cave-in decompression technique was performed. We analyzed the clinical outcomes on a visual analogue scale (VAS) and the Oswestry Disability Index (ODI). Perioperative data and complications rate were also recorded. RESULTS: Mean follow-up was 15.7±2.8months. Mean preoperative VAS score for low-back pain was 5.65±1.43, and decreased to 0.57±0.5 at final follow-up. Mean preoperative VAS score for leg pain was 5.48±1.38, and decreased to 0.56±0.5 at final follow-up. Mean preoperative ODI score decreased from 33.04±5.28 preoperatively to 8.7±2.54 at last follow-up. One patient experienced transient postoperative hypoesthesia, and one developed a mild transient decline in muscle strength; both recovered progressively. Postoperative CT and MRI showed that the ossification was effectively removed and the nerve root and dural mater was completely decompressed in all cases. CONCLUSION: The endoscopic cave-in decompression technique in PETD is a safe and effective treatment method for selected patients with ossification occupation of the lumbar spinal canal.

Treatment of Upper Lumbar Disc Herniation with a Transforaminal Endoscopic Technique.

Background: To investigate the clinical efficacy of percutaneous endoscopic transforaminal discectomy (PETD) in the treatment of upper lumbar disc herniation (LDH). Methods: Twenty-two patients, 14 males and 8 females with ages ranging from 23 to 76 years, who had upper LDH and were treated with PETD from April 2015 to April 2020 in the Department of Neurosurgery of Xuanwu Hospital, were selected to evaluate the surgical efficacy by the visual analog scale (VAS) and Oswestry Disability Index (ODI). Results: All patients underwent successful completion of PETD surgery. The operation time was 80.4 ± 18.0 min; intraoperative fluoroscopy was used 17.1 ± 8.7 times; and the hospital stay was 3.2 ± 0.6 days. The VAS scores were 7.9 ± 1.2, 2.3 ± 1.5, 2.2 ± 1.3, and 2.1 ± 1.0 before the operation, 1 day and 3 months after the operation, and during the last follow-up, respectively. The postoperative VAS score was significantly lower than that before the operation (P < 0.01). The ODI scores before and 3 months after the operation were 59.8 ± 16.8 and 15.3 ± 8.2, respectively; thus, the postoperative score was decreased (P < 0.01). Conclusion: Upper lumbar discs have unique anatomical structures, and PETD is a safe and effective surgical method for the treatment of upper LDH.

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.