Leadership Roles


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Dr. Lewandrowski was appointed member of the North American Spine Society's Section on Minimally Invasive Procedures



Speaking Engagements



Our founder gave an invited keynote speech at the 11th International Congress of the Chinese Orthopaedic Association


Image by Tom Hermans

Books Published

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Selected Publications


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Difficulties, Challenges, and the Learning Curve of Avoiding Complications in Lumbar Endoscopic Spine Surgery


Spinal endoscopy has the stigma of being reserved for only a few surgeons who can figure out how to master the steep learning curve and develop clinical practice settings where endoscopic spine surgery can thrive. In essence, endoscopic treatment of herniated discs specifically and nerve root compression in the lumbar spine in general amounts to replacing traditional open spine surgery protocols with spinal endoscopic surgery techniques. In doing so, the endoscopic spine surgeon must be confident that the degenerative spine's common painful problems can be handled with endoscopic spinal surgery techniques with at least comparable clinical results and complication rates. In this review article, the authors illustrate the difficulties and challenges of the endoscopic lumbar decompression procedure. In addition, they shed light on how to master the learning curve by systematically looking at all sides of the problem, ranging from the ergonomic aspects of the endoscopic platform and its instruments, surgical access planning, challenging clinical scenarios, complications, and sequelae, as well as the training gaps after postgraduate residency and fellowship programs.

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Editors' Commentary: The Effect of Vitamin D Deficiency on Outcomes of Patients Undergoing Elective Spinal Fusion Surgery: A Systematic Review and Meta-Analysis by Khalooeifard et al.

The meta-analysis by Khalooeifard et al on the association of vitamin d deficiency and spinal fusion surgery functional outcomes assessed using the visual analog scale and oswestry disability index was received with mixed evaluations by IJSS editors and reviewers. it prompted a thoughtful internal discus- sion regarding whether the article contained sufficient evidence to warrant publication. in the end, the editors decided to publish the authors’ meta-analysis for the following reasons.

The authors’ meta-analysis implies that the many adverse effects of vitamin d deficiency may directly or indirectly affect spinal fusion outcomes. due to the paucity of literature, the authors were unable to estab- lish a clear, strong causal association between vitamin d levels and radiographic fusion outcomes, although they have demonstrated the validity of their findings by functional outcomes with their methodology. Fusion by definition is first and foremost evaluated radiographi- cally for the presence of fusion (bridging bone) and the absence of motion at a motion segment. The inherent limitations of this meta-analysis would not, however, negate the encouragement of vitamin d supplementa- tion in select spine patients as directed by concomitant endocrine consultation.

Ultimately, original research is required to more plausibly explain whether vitamin d levels should be routinely monitored and corrected preoperatively in high-risk patients, similar to hemoglobin a1C in patients with diabetes. The authors appropriately suggest higher-grade clinical studies with longer fol- low-up employing multivariate logistic regression analysis to substantiate further whether vitamin d defi- ciency can be validated as an independent predictor of pseudarthrosis. This team of editors hopes that the authors will follow through with that proposal to fill the knowledge gap in this underinvestigated area of spinal fusion surgery

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A Differential Clinical Benefit Examination of Full Lumbar Endoscopy vs Interspinous Process Spacers in the Treatment of Spinal Stenosis: An Effect Size Meta-Analysis of Clinical Outcomes


Study Design: A design-agnostic standardized effect meta-analysis of 48 randomized, prospective, and retrospective studies on clinical outcomes with spinal endoscopic and interspinous process spacer (IPS) surgery.

Objective: The study aimed to provide reference set of Oswestry Disability Index (ODI) and visual analog scale (VAS) effect size data for back and leg pain following endoscopic and IPS decompression for lumbar herniated disc, foraminal, or lateral recess spinal stenosis.

Background: Mechanical low back pain following endoscopic transforaminal decompression may be more reliably reduced by simultaneous posterior column stabilization with IPS.

Methods A systematic search of the PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials from 1 January 2000 to 2 April 2020, identified 880 eligible endoscopy and 362 IPS studies varying in design and metrics. The authors compared calculated standardized effect sizes (Cohen’s d) for extracted ODI, VAS-back, and VAS-leg data.

Results: The pooled standardized effect size combining the ODI, VAS-back, and VAS-leg data for the total sample of 19862 data sets from the 30 endoscopy and 18 IPS was 0.877 (95% CI = 0.857–0.898). When stratified by surgery, the combined effect sizes were 0.877 (95% CI = 0.849–0.905) for endoscopic decompression and 0.863 (95% CI = 0.796–0.930; P = 0.056) for IPS implantation. The ODI effect sizes calculated on 6462 samples with directly visualized endoscopic decompression were 0.917 (95% CI = 0.891–0.943) versus 0.798 (95% CI = 0.713–0.883; P < 0.001) with indirect IPS decompression (P < 0.001). The VAS-back effect sizes calculated on 3672 samples were 0.661 (95% CI = 0.585–0.738) for endoscopy and 0.784 (95% CI: 0.644–0.923; P = 0.187) for IPS. The VAS-leg effect sizes calculated on 7890 samples were 0.885 (95% CI = 0.852–0.917) for endoscopic decompression and 0.851 (95% CI = 0.767–0.935; P = 0.427).

Conclusion: Lumbar IPS implantation produces larger reduction in low back pain than spinal endoscopy. On the basis of this meta-analysis, the combination of lumbar transforaminal endoscopy with simultaneous IPS has merits and should be formally investigated in higher grade clinical studies.

Clinical Relevance: Meta-analysis on the added clinical benefit of combining lumbar endoscopic decompression with an interspinous process spacer.

Level of Evidence 2.

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Patient selection criteria for percutaneous anterior cervical laser versus endoscopic discectomy

Background: Percutaneous anterior laser and anterior endoscopic cervical spine surgery are associated with less approach trauma than conventional open cervical spine surgery. The literature illustrating their appropriate use corroborated with objective outcome evidence is scarce. The authors were interested in comparing the clinical outcomes following percutaneous laser disc decompression (PLDD) versus percutaneous endoscopic disc decompression (PEDD). © 2021 Wiley Periodicals LLC.

Materials and Methods: Thirty patients with soft contained symptomatic cervical disc herniations and an average age of 50.5 years (range 26 - 68 years; 16 males and 14 females) were prospectively enrolled in 2 groups of 15 patients to be either treated with PLDD or PEDD. All patients underwent PLDD or PEDD under local anesthesia and sedation. Clinical outcomes were assessed with the Macnab criteria VAS score for arm pain. Complications and reoperations were recorded.

Results: There were significant reductions in the VAS score for arm pain from preoperative 8.4 ± 2.5 to 3.1 ± 1.2 in the PLDD group (P < 0.03), and from preoperative 8.6 ± 2.7 to 2.4 ± 1.1 (P < 0.01) in the PEDD group. In the PLDD group, Macnab outcomes were excellent in 21% of patients, good in 44%, fair in 21%, and poor in 14%. In the PEDD group, Macnab outcomes were excellent in 14% of patients, good in 32%, fair in 12%, and poor in the remaining 12%. There were no statistically significant differences in clinical outcomes between the PLDD and the PEDD group. There were no approach-related or surgical complications.

Conclusions: Tissue trauma is significantly reduced with laser and endoscopic surgery techniques. PLDD and PEDD are both suitable for the specific indication of soft, symptomatic contained cervical disc herniations. The authors’ small prospective cohort study indicates that PLDD and PEDD are options for cervical decompression surgery when medical comorbidities or preferences by patients and surgeons dictate more minimally invasive strategies.

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Minimally Invasive Posterior Tubular Microsurgical Approach for the Management of Symptomatic Synovial Cysts of the Lumbar and Cervical Spine

Background: Synovial cysts are commonly associated with instability. Whether to fuse patients is a matter of controversy. Simple resection may offer favorable clinical outcomes but may come at the expense of recurrence rate. We describe our experience with the minimally invasive management of these lesions using microsurgical dissection through a tubular retractor system.

Materials: A retrospective cohort study of symptomatic patients with synovial cysts treated by a minimally invasive tubular approach from 2001 to 2018 was performed. We evaluated variables such as preexisting spinal pathology, previous surgery, radiological findings, comorbidities, and secondary surgery requiring fusion. We used the visual analog scale (VAS), the Oswestry disability index (ODI), and the Macnab scale for clinical evaluation.

Results: There were 35 patients with a mean age of 63 years. The mean duration of symptoms before surgery was 195 weeks. Axial pain was present in 77.1% of cases; radiculopathy was the main symptom in 94.3% of cases. The most frequent site was L4-L5 (62.8%). Presenting comorbidities were lumbar stenosis (28.6% of patients), spondylolisthesis (8.6%), and facet hypertrophy (31.4%). Mean surgical time was 143 minutes (range, 55-360 minutes). The mean hospital stay was 2 days, ranging from 1 to 5 days. No complications were encountered as a consequence of the surgical procedure. All patients showed neurophysiological improvement after surgical intervention. A total of 34 patients (97.14%) showed clinical improvement at the end of follow-up, averaging 17 months and ranging from 1 to 60 months, 28 patients (80%) had good to excellent Macnab outcomes, 6 patients (17.14%) were rated as fair, and 1 (2.86%) patient had a poor Macnab outcome. Radicular VAS significantly changed (P < .05) from a preoperative mean of 8.23 ± 1.24 to a postoperative mean of 2.23 ± 1.94. ODI significantly decreased (P < .05) from a preoperative of mean of 41.02 ± 12.56 to a postoperative of mean of 11.82 ± 10.56. We performed fusion at initial surgery in 37.1% of cases; however, 3 more patients required secondary fusion at follow-up.

Conclusion: Our series corroborates the prior literature with a low incidence of synovial cysts in the cervical spine and none in the thoracic spine. The present work shows the efficacy of minimally invasive surgery in the treatment of these lesions. Synovial cysts were associated with instability, ultimately requiring fusion in the majority of patients. The authors' study includes a large patient series with minimally invasive microsurgical decompression performed through a tubular retractor to date.

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Full-Endoscopic Oblique Lateral Lumbar Interbody Fusion: A Technical Note With 1-Year Follow-Up

Background: Oblique lateral lumbar interbody fusion (OLLIF) is a minimally invasive lumbar interbody fusion procedure using a bullet-shaped polyetheretherketone (PEEK) nonexpandable fusion cage modified to diminish risk to the exiting nerve root during posterolateral implantation through the Kambin safe zone under fluoroscopic guidance. The objective of this study was to present feasibility of this procedure and 1-year clinical outcome data.

Methods: The authors present a prospective cohort study of 20 patients who underwent fluoroscopy-guided and full-endoscopic OLLIF in 22 segments allowing protection of the exiting nerve root from January 2018 to March 2019. The foraminoplasty, discectomy, endplate preparation, placement of bone graft and insertion of the fusion cage was done under continuous full-endoscopic visualization. The OLLIF fusion was backed up with bilateral percutaneous posterior supplemental pedicle screw fixation. Primary clinical outcome measures were the visual analog scale (VAS) of low back and leg pain, and Oswestry disability index (ODI) at 1 week, 3 months, 6 months, and 1 year after the operation. At final follow-up, the Macnab score was also evaluated. Secondary outcome measures were computed tomography (CT) assessment fusion using the Mannion classification of spinal fusion and adverse events related to the device as well as magnetic resonance imaging (MRI) assessment of nerve root decompression.

Results: All patients had significant relief of low back pain and leg pain, by VAS and ODI scores that improved significantly (P < .01). There were no complications. Postoperative lumbar MRI of all patients showed sufficient direct nerve decompression. At 1-year follow-up, excellent Macnab outcomes were obtained 13 patients, good in six, and fair in one. Impaired sensation and muscle strength of the involved nerve root significantly recovered in all but 2 patients (P < .05). According to the Mannion CT-based classification of spinal fusion, CT showed complete interbody fusion achieved in all 22 segments.

Conclusions: Full-endoscopic OLLIF is a safe, effective, minimally invasive, economical, practical, and widely applicable minimally invasive interbody fusion technique in the lumbar spine.

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Dural Tears During Lumbar Spinal Endoscopy: Surgeon Skill, Training, Incidence, Risk Factors, and Management

Background: Incidental dural tears during lumbar endoscopy can be challenging to manage. There is limited literature on their appropriate management, risk factors, and the clinical consequences of this typically uncommon complication.

Materials and methods: To improve the statistical power of studying durotomy with lumbar endoscopy, we performed a retrospective survey study among endoscopic spine surgeons by email and chat groups on social media networks, including WhatsApp and WeChat. Descriptive and correlative statistics were done on the surgeons' recorded responses to multiple-choice questions. Surgeons were asked about their clinical experience with spinal endoscopy, training background, the types of lumbar endoscopic decompression they perform by approach, the decompression instruments they use, and incidental durotomy incidence with routine lumbar endoscopy.

Results: There were 689 dural tears in 64 470 lumbar endoscopies, resulting in an incidental durotomy incidence of 1.07%. Seventy percent of the durotomies were reported by 20.4% of the surgeons. Eliminating these 19 outlier surgeons yielded an adjusted durotomy rate of 0.32. Endoscopic stenosis decompression (54.8%; P < .0001), rather than endoscopic discectomy (44.1%; 41/93), was significantly more associated with durotomy. Medium-sized dural tears (1-10 mm) were the most common (52.2%; 48/93). Small pinhole durotomies (less than 1 mm) were the second most common type (46.7%; 43/93). Rootlet herniations were seen by 46.2% (43/93) of responding surgeons. The posterior dural sac injury during the interlaminar approach (57%; 53/93) occurred more frequently than traversing nerve-root injuries (31.2%) or anterior dural sac (23.7%; 22/93). Exiting nerve-root injuries (10.8%;10/93) were less common. Over half of surgeons did not attempt any repair or closure (52.2%; 47/90). Forty percent (36/90) used sealants. Only 7.8% (7/90) of surgeons attempted an endoscopic repair or sutures (11.1%; 10/90). DuralSeal was the most commonly used brand of commercially available sealant used (42.7%; 35/82). However, other sealants such as Tisseal (15.9%; 13/82), Evicel (2.4%2/82), and additional no-brand sealants (38; 32/82) were also used. Nearly half of the patients (48.3%; 43/89) were treated with 24-48 hours of bed rest. The majority of participating surgeons (64%; 57/89) reported that the long-term outcome was unaffected. Only 18% of surgeons reported having seen the development of a postoperative cerebrospinal fluid (CSF)-fistula (18%;16/89). However, the absolute incidence of CSF fistula was only 0.025% (16/64 470). Severe radiculopathy with dysesthesia; sensory loss; and motor weakness in association with an incidental durotomy were reported by 12.4% (11/89), 3.4% (3/89), and 2.2% (2/89) of surgeons, respectively.

Conclusions: The incidence of dural tears with lumbar endoscopy is about 1%. The incidence of durotomy is higher with the use of power drills and the interlaminar approach. Stenosis decompression that typically requires the more aggressive use of these power instruments has a slightly higher incidence of dural tears than does endoscopic decompression for a herniated disc. Most dural tears are small and can be successfully managed with mechanical compression with Gelfoam and sealants. Two-thirds of patients with incidental dural tears had an entirely uneventful postoperative course. The remaining one-third of patients may develop a persistent CSF leak, radiculopathy with dysesthesia, sensory loss, or motor function loss. Patients should be educated preoperatively and reassured.

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Artificial Intelligence Comparison of the Radiologist Report With Endoscopic Predictors of Successful Transforaminal Decompression for Painful Conditions of the Lumber Spine: Application of Deep Learning Algorithm Interpretation of Routine Lumbar Magnetic Resonance Imaging Scan

Background: Identifying pain generators in multilevel lumbar degenerative disc disease is not trivial but is crucial for lasting symptom relief with the targeted endoscopic spinal decompression surgery. Artificial intelligence (AI) applications of deep learning neural networks to the analysis of routine lumbar MRI scans could help the primary care and endoscopic specialist physician to compare the radiologist's report with a review of endoscopic clinical outcomes.

Objective: To analyze and compare the probability of predicting successful outcome with lumbar spinal endoscopy by using the radiologist's MRI grading and interpretation of the radiologic image with a novel AI deep learning neural network (Multus Radbot™) as independent prognosticators.

Methods: The location and severity of foraminal stenosis were analyzed using comparative ordinal grading by the radiologist, and a contiguous grading by the AI network in patients suffering from lateral recess and foraminal stenosis due to lumbar herniated disc. The compressive pathology definitions were extracted from the radiologist lumbar MRI reports from 65 patients with a total of 383 levels for the central canal - (0) no disc bulge/protrusion/canal stenosis, (1) disc bulge without canal stenosis, (2) disc bulge resulting in canal stenosis, and (3) disc herniation/protrusion/extrusion resulting in canal stenosis. Both neural foramina were assessed with either - (0) neural foraminal stenosis absent, or (1) neural foramina are stenosis present. Reporting criteria for the pathologies at each disc level and, when available, the grading of severity were extracted and assigned into two categories: "Normal," and "Stenosis." Clinical outcomes were graded using dichotomized modified Macnab criteria considering Excellent and Good results as "Improved," and Fair and Poor outcomes as "Not Improved." Binary logistic regression analysis was used to predict the probability of the AI- and radiologist grading of stenosis at the 88 foraminal decompression sites to result in "Improved" outcomes.

Results: The average age of the 65 patients was 62.7 +/- 12.7 years. They consisted of 51 (54.3%) males and 43 (45.7%) females. At an average final follow-up of 57.4 +/- 12.57, Macnab outcome analysis showed that 86.4% of the 88 foraminal decompressions resulted in Excellent and Good(Improved) clinical outcomes. The stenosis grading by the radiologist showed an average severity score of 4.71 +/- 2.626, and the average AI severity grading was 5.65 +/- 3.73. Logit regression probability analysis of the two independent prognosticators showed that both the grading by the radiologist (86.2%; odds ratio 1.264) and the AI grading (86.4%; odds ratio 1.267) were nearly equally predictive of a successful outcome with the endoscopic decompression.

Conclusions: Deep learning algorithms are capable of identifying lumbar foraminal compression due to herniated disc. The treatment outcome was correlated to the decompression of the directly visualized corresponding pathology during the lumbar endoscopy. This research should be extended to other validated pain generators in the lumbar spine.

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Transforaminal Endoscopic Discectomy Combined With an Interspinous Process Distraction System for Spinal Stenosis

Background: The combination of the percutaneous transforaminal endoscopic decompression (PTED) with an interspinous process distraction system (IPS) may offer additional benefit in the treatment of spinal stenosis in patients who have failed nonsurgical treatment.

Methods: We retrospectively reviewed the medical records of 33 patients diagnosed with lumbar stenosis and radiculopathy and treated them with transforaminal endoscopic lumbar decompression between 2013 and 2017. Primary outcome measures were modified Macnab as well as preoperative and postoperative visual analog scale (VAS) criteria and the Oswestry Disability Index (ODI). Only patients with a minimum follow-up of 2 years were included.

Results: A total of 28 patients were treated with a combination of PTED and percutaneous IPS (group A), and 5 patients were treated with PTED and mini-open IPS (group B). In group A patients, there was a 4.48 reduction in the VAS score. The ODI changed from 50.25 preoperatively to 18.2 postoperatively, and excellent and good Macnab outcomes were obtained in 78% of patients. In group B patients, the mean VAS reduction was 5.2 points. The ODI changed from 44.34 preoperatively to 14.62 postoperatively, and 80% of group B patients achieved excellent and good Macnab outcomes. No complications related to PTED or IPS were observed throughout the 2-year follow-up.

Conclusions: The addition of IPS to the PTED procedure in select patients may offer additional benefits to patients being treated for lumbar lateral stenosis and foraminal stenosis with low-grade spondylolisthesis.

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Feasibility of Using Intraoperative Neuromonitoring in the Prophylaxis of Dysesthesia in Transforaminal Endoscopic Discectomies of the Lumbar Spine

(1) Background: Postoperative nerve root injury with dysesthesia is the most frequent sequela following lumbar endoscopic transforaminal discectomy. At times, it may be accompanied by transient and rarely by permanent motor weakness. The authors hypothesized that direct compression of the exiting nerve root and its dorsal root ganglion (DRG) by manipulating the working cannula or endoscopic instruments may play a role. (2) Objective: To assess whether intraoperative neurophysiological monitoring can help prevent nerve root injury by identifying neurophysiological events during the initial placement of the endoscopic working cannula and the directly visualized video endoscopic procedure. (3) Methods: The authors performed a retrospective chart review of 65 (35 female and 30 male) patients who underwent transforaminal endoscopic decompression for failed non-operative treatment of lumbar disc herniation from 2012 to 2020. The patients' age ranged from 22 to 86 years, with an average of 51.75 years. Patients in the experimental group (32 patients) had intraoperative neurophysiological monitoring recordings using sensory evoked (SSEP), and transcranial motor evoked potentials (TCEP), those in the control group (32 patients) did not. The SSEP and TCMEP data were analyzed and correlated to the postoperative course, including dysesthesia and clinical outcomes using modified Macnab criteria, Oswestry disability index (ODI), visual analog scale (VAS) for leg and back pain. (4) Results: The surgical levels were L4/L5 in 44.6%, L5/S1 in 23.1%, and L3/L4 in 9.2%. Of the 65 patients, 56.9% (37/65) had surgery on the left, 36.9% (24/65) on the right, and the remaining 6.2% (4/65) underwent bilateral decompression. Postoperative dysesthesia occurred in 2 patients in the experimental and six patients in the control group. In the experimental neuromonitoring group, there was electrodiagnostic evidence of compression of the exiting nerve root's DRG in 24 (72.7%) of the 32 patients after initial transforaminal placement of the working cannula. A 5% or more decrease and a 50% or more decrease in amplitude of SSEPs and TCEPs recordings of the exiting nerve root were resolved by repositioning the working cannula or by pausing the root manipulation until recovery to baseline, which typically occurred within an average of 1.15 min. In 15 of the 24 patients with such latency and amplitude changes, a foraminoplasty was performed before advancing the endoscopic working cannula via the transforaminal approach into the neuroforamen to avoid an impeding nerve root injury and postoperative dysesthesia. (5) Conclusion: Neuromonitoring enabled the intraoperative diagnosis of DRG compression during the initial transforaminal placement of the endoscopic working cannula. Future studies with more statistical power will have to investigate whether employing neuromonitoring to avoid intraoperative compression of the exiting nerve root is predictive of lower postoperative dysesthesia rates in patients undergoing videoendoscopic transforaminal discectomy.

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Lumbar Endoscopic Bony and Soft Tissue Decompression With the Hybridized Inside-Out Approach: A Review And Technical Note

This study aimed to showcase the authors' preferred technique of a hybrid of modern "inside-out" and "outside-in" endoscopic decompression. A case series of 411 patients consisting of 192 females (46.7%) and 219 males (53.3%) with an average age of 54.84 ± 16.32 years and an average of 43.2 ± 26.53 months are presented. Patients underwent surgery for low-grade spondylolisthesis (13 of 411, 3.2%), herniated disc (135 of 411, 32.8%), foraminal spinal stenosis (101 of 411, 24.6%), or a combination of the latter 2 conditions (162 of 411, 39.4%). The preoperative Oswestry Disability Index (ODI) and visual analogue scale (VAS) for leg pain were 49.8 ± 17.65 and 7.9 ± 1.55, respectively. Postoperative ODI and VAS leg were 12.2 ± 9.34 and 2.41 ± 5 1.55 at final follow-up (p < 0.0001). MacNab outcomes were excellent in 134 (32.6%), good in 228 (55.5%), fair in 40 (9.7%), and poor in 9 patients (2.2%), respectively. There was end-stage degenerative vacuum disc disease in 304 of the 411 patients (74%) of which had 37.5% had excellent and 50% good MacNab outcomes. Patients without vacuum discs had excellent and good 18.7% and 71.0% of the time. Direct visualization of pain generators in the epidural- and intradiscal space is the authors' preferred transforaminal decompression technique and is supported by their reliable clinical outcomes.

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Dysethesia due to irritation of the dorsal root ganglion following lumbar transforaminal endoscopy: Analysis of frequency and contributing factors

Background: New onset of acute dysethetic leg pain due to irritation of the dorsal root ganglion (DRG) following uneventful recovery from an expertly executed lumbar transforaminal endoscopic decompression is a common problem. Its incidence and relation to any risk factors that could be mitigated preoperatively are not well understood.

Methods: We performed a multicenter frequency analysis of DRG irritation dysesthesia in 451 patients who underwent lumbar transforaminal endoscopic decompression for herniated disc and foraminal stenosis. The 451 patients consisted of 250 men and 201 women with an average age of 55.77 ± 15.6 years. The average follow-up of 47.16 months. The primary clinical outcome measures were the modified Macnab criteria. Chi-square testing was employed to analyze statistically significant associations between increased dysesthesia rates, preoperative diagnosis, the surgical level(s), and surgeon technique.

Results: At final follow-up, Excellent (183/451; 40.6 %) and Good (195/451; 43.2 %) Macnab outcomes were observed in the majority of patients (378/451; 83.8 %). The majority of study patients (354; 78.5 %) had an entirely uneventful postoperative recovery without any DRG irritation, but 21.5 % of patients were treated for it in the immediate postoperative recovery period with supportive care measures including activity modification, transforaminal epidural steroid injections, non-steroidal anti-inflammatories, gabapentin, or pregabalin. There was no statistically significant difference in dysesthesia rates between lumbar levels from L1 to S1, or between single (DRG rate 21.8 %) or two-level (DRG rate 20.2 %) endoscopic decompression (p = 0.742). A statistically significantly higher incidence of postoperative dysesthesia was observed in patients who underwent decompression for foraminal stenosis (38/103; 27 %), and recurrent herniated disc (7/10; 41.2 %; p = 0.039). There were also statistically significant variations in dysesthesia rates between the seven participating clinical study sites ranging from 11.6%-33% (p = 0.002). Unrelenting postoperative dysesthetic leg pain due to DRG irritation was statistically associated with less favorable long-term clinical outcomes with DRG rates as high as 45 % in patients with a Fair and 61.3 % in patients with Poor Macnab outcomes (p < 0.0001).

Conclusions: Postoperative dysesthesia following transforaminal endoscopic decompression should be expected in one-fifth of patients. There was no predilection for any lumbar level. Foraminal stenosis and recurrent herniated disc surgery are risk factors for higher dysesthesia rates. There was a statistically significant variation of dysesthesia rates between participating centers suggesting that the surgeon skill level is of significance. Severe postoperative dysesthesia may be a predictor of Fair of Poor long-term Macnab outcomes.

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Minimal Clinically Important Difference in Patient-Reported Outcome Measures with the Transforaminal Endoscopic Decompression for Lateral Recess and Foraminal Stenosis

Background: Patient-reported outcome measures (PROMs) have become widely used to better measure patients' judgment of treatment benefits from surgical spine care. The concept of determining the minimal clinically important differences (MCIDs) of PROMs is aimed at assessing the benefits of lumbar spine care that are meaningful to the patient. The goal of this study was to validate the utility of MCIDs of the visual analog score (VAS) and Oswestry Disability Index (ODI) in patients with sciatica-type low back and leg pain due to lateral recess and foraminal stenosis who were treated with directly visualized transforaminal outpatient endoscopic decompression.

Methods: The retrospective study population consisted of 406 patients on whom PROMs were obtained preoperatively, and again postoperatively at final follow-up. Employing an anchor-based approach with a patient satisfaction index based on the modified Macnab criteria, a receiver operating characteristics (ROC) and area under the curve (AUC) analysis was performed using IBM SPSS 25.0 to define the optimal MCID in VAS and ODI with the transforaminal endoscopy using the top-left-corner criteria and the Youden index. Improvements in walking endurance were recorded as an additional parameter of patient functioning and correlated with PROMs to test for statistical significance.

Results: The patients' average age was 41.08 years, ranging from 30 to 84 years. The mean follow-up was 33.59 months, ranging from 24 to 85 months, with a standard deviation of 12.79. The MCIDs for VAS and ODI were 2.5 to 3.5 and 15 to 16.5, respectively. Patients were dichotomized as improved (377/406; 92.9%) if they reported excellent (224/406; 55.2%), good (112/406; 27.6%), and fair (41/406; 10.1%) Macnab outcomes. Patients were dichotomized as failed if they reported poor (29/406; 7.1%) Macnab outcomes. Preoperatively, only 32.5% (132/406) of patients had unlimited walking endurance compared to 77.6% (315/406) of patients postoperatively. The ROC and AUC analysis showed better accuracy with the single-integer VAS score (0.926) than with the 10-item ODI score (0.751).

Conclusions: Transforaminal outpatient endoscopic decompression for symptomatic foraminal and lateral recess stenosis is an effective surgical treatment to alleviate sciatica-type and back symptoms in 92.9% of patients. Of the PROMs analyzed, the VAS provided a more meaningful and accurate reflection of patients' interpretation of outcome with the transforaminal endoscopic spinal decompression procedure than ODI. Understanding which patient expectations drive these MCIDs may aid in replacing open surgeries for sciatica-type low back and leg pain currently preferred by traditional spine surgeons with a personalized early-staged transforaminal endoscopic hybrid decompressive/ablative procedures favored by the authors. These may prove more cost effective by focusing on significant pain generators validated with a diagnostic interventional workup instead of employing image-based indication criteria for surgery.

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Indication and Contraindication of Endoscopic Transforaminal Lumbar Decompression

Background: The indications and contraindications to the endoscopic transforaminal approach for lumbar spinal stenosis are not well defined.

Methods: We performed a Kaplan-Meier durability survival analysis of patients with the following types of spinal stenosis: type I, central canal; type II, lateral recess; type III, foraminal; and type IV, extraforaminal. The 304 patients comprised 140 men and 164 women, with an average age of 51.68 ± 15.78 years. The average follow-up was 45.3 years (range, 18-90 years). The primary clinical outcome measures were the Oswestry Disability Index, visual analog scale, and the modified Macnab criteria.

Results: Of 304 study patients, 70 had type I (23.0%) stenosis, 42 type II (13.7%), 151 type III (49.7%), and 41 type IV (13.5%). Excellent outcomes were obtained in 114 patients (37.5%), good in 152 (50.0%), fair in 33 (10.9%), and poor in 5 (1.6%). Kaplan-Meier durability analysis of the clinical treatment benefit with the endoscopic transforaminal decompression surgery showed statistically significance differences (P < 0.0001) on log-rank (Mantel-Cox) χ2 testing between the estimated median (50% percentile) survival times of type I (28 months), type II (53 months), type III (32 months), and type IV (66 months).

Conclusions: We recommend stratifying patients based on the underlying compressive disease and the skill level of the endoscopic spine surgeon to decide preoperatively whether more difficult central or complex foraminal stenotic lesions should be considered for alternative endoscopic approaches.

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Standalone lordotic endoscopic wedge lumbar interbody fusion (LEW-LIF™) with a threaded cylindrical peek cage: report of two cases

We report two cases of a standalone lordotic endoscopic wedge lumbar interbody fusion (LEW-LIF™) with a stress-neutral non-expandable cylindrical threaded polyether ether ketone (PEEK) interbody fusion implant. Patients underwent full-endoscopic transforaminal decompression and fusion for symptomatic lateral recess stenosis due to disc herniation, and hypertrophy of the facet joint complex and ligamentum flavum and no more than grade I spondylolisthesis. Lumbar interbody fusion with cages traditionally calls for posterior supplemental fixation with pedicle screws for added stability. A more simplified version of lumbar decompression and fusion without pedicle screws would allow treating patients suffering from stenosis and instability induced sciatica-type low back and leg pain in an outpatient ambulatory surgery center setting (ASC). This would realize a significant reduction in cost as well as the burden to the patient with decreased postoperative pain and earlier return to function. A 62-year-old female patient had surgery at L4/5 for a 6-year history of worsening right sided sciatica-type leg- and low back pain. Another 79-year-old female had the same surgical management at L4/5 for a 5-year history of unrelenting left-sided spondylolisthesis-related symptoms. Both patients had an uneventful postoperative course until the last available follow-up of 24 weeks with greater than 60% VAS and Oswestry disability index (ODI) reductions. There was no evidence of implant expulsion, subsidence, or postoperative instability. We concluded that standalone outpatient lumbar transforaminal endoscopic interbody fusion with a non-expandable threaded cylindrical cage is feasible, and favorable clinical outcomes provide proof of concept to study long-term clinical outcomes in larger groups of patients.

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Comparative study of curative effect of spinal endoscopic surgery and anterior cervical decompression for cervical spondylotic myelopathy

Background: The aim of this study was to compare the clinical efficacy of endoscopic cervical spinal surgery with anterior cervical decompression and fusion (ACDF) in the treatment of cervical spondylotic myelopathy (CSM).

Methods: A total of forty-six CSM patients who were admitted to the Medical School of Chinese PLA and treated with endoscopic spine surgery or ACDF from January 2015 to June 2017 were collected. The patients were divided into the spinal endoscopy group and the ACDF group, according to the operation methods. The operation time, intraoperative blood loss and hospitalization stay of the two groups were recorded and compared. Japanese Orthopaedic Association (JOA) score before operation, three months, and one year after operation were recorded for intra-group and inter-group comparison. The improvement rates of JOA were compared between the two groups to evaluate the clinical efficacy.

Results: There were twenty-two cases in the spinal endoscopy group and twenty-four cases in the ACDF group. The mean operation lasting time, intraoperative blood loss and hospitalization stay in the spinal endoscopy group were significantly lower than those in the ACDF group (P<0.05). The postoperative JOA score of the two groups were significantly higher than those before the operation (P<0.05). There were no significant differences in the JOA score before operation, three months and one year after operation between the two groups (P>0.05). The improvement rates in the spinal endoscopy group were not significantly different compared to those in the ACDF group (P>0.05). There was no significant difference in the excellent rate (81.8% vs. 83.3%) between the spinal endoscopy group and the ACDF group (P>0.05).

Conclusions: The short-term efficacy of spinal endoscopic surgery and ACDF was equal in the treatment of CSM. The spinal endoscopic surgery was significantly superior to ACDF in reducing the operation time, the intraoperative blood loss and the hospitalization stay.

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Clinical outcomes with endoscopic resection of lumbar extradural cysts

Background: Lumbar extradural cysts may be associated with sciatica-type back and leg pain. The symptoms of clinical pain syndrome from synovial cysts are sometimes difficult to differentiate from those of lumbar disc herniation or spinal canal stenosis and may be identified to be a pain source when visualized endoscopically. The authors analyzed the clinical outcomes with their endoscopic resection to better establish clinical indications and prognosticators of favorable results.

Methods: wo-year Macnab outcomes, VAS scores, and complications were analyzed in a series of 48 patients treated with the endoscopic removal of extradural cyst encountered during routine transforaminal and interlaminar decompression for foraminal and lateral recess stenosis causing lumbar radiculopathy.

Results: There were 26 female and 22 male patients. The extradural cysts were most commonly encountered at L4/5 level in 26 patients (72.2%) followed by the L5/S1 level in 8 patients (22.2%), and in 2 patients (5.6%) at the L3/4 level, respectively. One patient underwent T9/10 decompression. At minimum 2-year follow-up, all patients were improved. Excellent results according to the Macnab criteria were obtained in 19/48 (39.6%) patients, good in 18/48 (37.5%), and fair in 11/48 (22.9%), respectively. The average preoperative VAS score for leg pain was 8.06±1.57 and reduced at a statistically significant level (P<0.000) postoperatively to 1.92±1.49, and 1.77±1.32 at final follow-up, respectively. The percentage of patients with unlimited walking endurance had improved at a statistically significant level (P<0.0001) from 33.3% preoperatively (16/48) to 81.3% (39/48) postoperatively. One patient had a recurrent disc herniation, and another patient did not improve. Two patients underwent fusion during the follow-up period. Patients with Fair outcomes had a statistically significant association (P<0.001) with facet instability as suggested by axial T2-weighted magnetic resonance imaging (MRI) findings of thickened ligamentum flavum, facet joint hypertrophy, and bright white fluid-filled joint gap of >2 mm.

Conclusions: Endoscopic resection of extradural spinal cysts during routine decompression for symptomatic foraminal and lateral recess stenosis is feasible with favorable clinical outcomes in the majority of patients. Fair outcomes were associated with advanced instability of the involved lumbar facet joint complex.

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Return to work and recovery time analysis after outpatient endoscopic lumbar transforaminal decompression surgery

Background: This study aimed to analyze the return to work (RTW) and recovery time (RT) to narcotic independence following outpatient endoscopic decompression for contained lumbar herniated disc causing sciatica-type low back and leg pain.

Methods: A retrospective study of 442 patients with symptomatic contained lumbar herniated disc was treated with the transforaminal endoscopic decompression surgery. The mean follow-up was 33.5 months, ranging from 24 to 85 months. The patients' age ranged from 30 to 85 years, with a mean age of 40.9 years. Statistical analysis of pre- and postoperative VAS, Macnab outcomes, improvement of postoperative walking endurance was performed. RTW rates were correlated with the type of work as classified according to energy consumption per minute (Kcal/min) as Light, Medium, and Heavy using guidelines adopted from the U.S. Department of Labor. Kaplan-Meier (KM) survival tables were calculated, and curves were plotted using IBM SPSS 25.0 to graphically illustrate the diverse RTW and RT dynamic when analyzed by the clinical outcome and the type of work performed by the patient preoperatively.

Results: Excellent (237/442) and Good (133/442) results were obtained in 83.7% (370/442) of patients. Fair results were reported by 43 patients (9.7%), and Poor results by 29 (6.6%), respectively. The mean preoperative VAS was 8.08. The mean postoperative VAS was significantly reduced to 2.55 (P<0.0001). The overall RTW rate was 92.5% (409/442). Patients performing Heavy (RTW rate =87.5%) and Medium (RTW rate =86.0%) work had a lower RTW rate than patients who were performing Light jobs (370/442; RTW rate =95.8%). Preoperatively, only 31.7% (140/442) had unlimited walking endurance. Postoperative walking endurance was unlimited in 77.4% (342/442; P<0.0001). Another 20.4% (90/442) of patients had pain-free walking endurance up to one mile. K-M analysis showed an estimated median RTW of 6 days for Excellent, 9 days for Good, 17 days for Fair, and 18 days for Poor Macnab outcomes. RTW analysis by the type of work showed estimated median RTW of 20 days for patients in the Heavy, 13 days in the Medium, and 6 days in the Light workgroup. The mean RT was 33.52 days in the Heavy, 19.17 days in the Medium, and 9.86 days in the Light workgroup (P<0.0001). The mean RTW was 22.27 days (P=0.008) in the Heavy, 13.97 days (P=0.004) in the Medium, and 7.58 days (P=0.004) in the Light workgroup. Postoperative irritation of the dorsal root ganglion (DRG) occurred in 68 of the 442 study patients (15.38%). DRG irritation delayed RTW to a mean of 18.94 days (P<0.0001) and RT to 15.31 days (P<0.001).

Conclusions: Patient RTW and RT data are "real-world" economic indicators of successful clinical outcomes with the lumbar endoscopic transforaminal decompression procedure and compare favorably to previously reported benchmarks for other types of translaminar surgeries. These median postoperative RTW and RT times with narcotic independence were on the order of 10 days or less in the vast majority of patients Excellent and Good outcomes (83.7%). The most relevant surgical predictor of delayed RTW and RT is a postoperative DRG irritation which predominantly affected patients adversely in the Medium and Heavy workgroups. These RTW and RT data may assist in the management of return-to-work expectations with the spinal endoscopy procedure.

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Outcomes with transforaminal endoscopic versus percutaneous laser decompression for contained lumbar herniated disc: a survival analysis of treatment benefit

Background: Contained lumbar disc herniations frequently cause back- and leg pain. Clinical outcomes with surgical treatment may be affected by the size and location of the disc herniation. The surgical directly visualized transforaminal endoscopic decompression has gained acceptance and popularity, while the simplified percutaneous laser disc decompression has fallen out of favor in spite of its initial success as a minimally invasive intervention. In an attempt to better understand the durability of both procedures, the authors performed a comparative analysis of clinical outcomes in patients with contained lumbar disc herniations.

Methods: The study population was comprised 248 patients consisting of 162 patients in the endoscopy group (group 1) and 86 patients in the laser group (group 2). Primary outcome measures were Macnab criteria. Herniations were classified as large or small. Additional parameters of advanced degeneration of the lumbar motion segment including posterior disc- and lateral recess height of <3 mm were recorded. IBM SPSS 25.0 was used for Kaplan-Meier survival analysis and cross-tabulation of these variables with statistical testing for significant associations.

Results: The mean follow-up was 43.5 months. The serial time recorded for Kaplan-Meier analysis ranged from 1.5 to 84 months. The mean age was 53.37 years (standard deviation =14.65 years). The majority of patients had Excellent and Good Macnab outcomes (212/248; 85.5%) regardless of treatment. Fair and Poor results were achieved in another 36 patients (14.5%). There was a higher percentage of Excellent Macnab outcomes in the endoscopy group (94/162; 58.0%) than in the laser group (38/86; 44.2%) at a statistical significant level (P<0.0001). There was a statistically significantly higher percentage of Excellent and Good Macnab outcomes with endoscopic decompression of small paracentral herniations (97.1%; P<0.0001). Percutaneous laser decompression of large central disc herniations was not statistically better than endoscopic surgical decompression (P=0.125). Endoscopic bony and soft tissue decompression was also better than laser at alleviating symptoms in patients with reduced posterior disc- and lateral recess height with 96.7% in patients with reduced disc height of <3 mm and 94% in patients with reduced lateral recess height of <3 mm (P=0.001). Kaplan-Meier (K-M) Survival time showed longer median survival of the treatment benefit for patients who underwent visualized endoscopic surgical decompression (66.0 months) compared to median K-M survival time for percutaneous laser decompression of 17 months (P<0.0001).

Conclusions: Transforaminal endoscopic decompression for symptomatic herniated disc is an effective and durable surgical treatment to alleviate sciatica-type and back symptoms in the vast majority of patients with good long-term survival of pain relief for up to six years. Interventional percutaneous non-visualized laser decompression for the same condition may provide favorable outcomes in the short-term with soft protrusions. However, the treatment effect deteriorates much faster with a median survival of 17 months.

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Five-year clinical outcomes with endoscopic transforaminal outside-in foraminoplasty techniques for symptomatic degenerative conditions of the lumbar spine

Background: Lumbar foraminal stenosis in the extraforaminal zone is best directly visualized with the outside-in transforaminal endoscopic technique. Stenosis in that area is often missed with traditional translaminar surgery. The authors analyzed the long-term 5-year clinical results, reoperation rates, and unintended after care with the outside-in endoscopic transforaminal foraminoplasty for symptoms from lumbar foraminal stenosis to better establish clinical indications and prognosticators of favorable outcomes.

Methods: Long-term 5-year Macnab outcomes, visual analog scale (VAS) scores, complications, and unintended aftercare were analyzed in a series of 90 patients treated with the transforaminal outside-in selective endoscopic discectomy (SED™) with foraminoplasty for foraminal and lateral recess stenosis.

Results: At minimum 5-year follow-up, excellent results according to the Macnab criteria were obtained in 61 (67.8%) patients, good in 23 (25.6%), fair in 6 (6.7%), respectively. The mean preoperative VAS 7.55. The mean postoperative VAS was 2.87 and at last follow-up 2.53. Both postoperative VAS and last follow-up VAS were statistically reduced at a significance level of P<0.0001. Postoperative dysesthesia occurred in 8 patients (8.9%). While most of the 32 follow-up surgeries following SED™ were additional endoscopic decompressions and rhizotomies (24/32; 75%) were non-fusion procedures, only 8 of the whole study series of 90 patients (8.9%) underwent fusion at the index SED™ level within the minimum 5-year follow-up period. One patient opted for an open laminectomy (1.1%).

Conclusions: Patients with symptomatic foraminal stenosis may be treated successfully in a staged manner with outside-in transforaminal endoscopic decompression while maintaining favorable long-term outcomes without the excessive need for fusion in the vast majority of patients. The reoperation fusion rate at 5-year follow-up was approximately 3 times lower when compared to recently reported reoperation rates following traditional translaminar decompression/fusion.

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Five-year clinical outcomes with endoscopic transforaminal foraminoplasty for symptomatic degenerative conditions of the lumbar spine: a comparative study of inside-out versus outside-intechniques

Background: Foraminal stenosis is a condition that is underappreciated by traditionally trained surgeons because the entire foraminal zone is not adequately visualized with the translaminar approach unless extensive removal of the facet is performed to expose the extraforaminal zone. Its direct endoscopic visualization is feasible with the inside-out and outside-in endoscopic transforaminal technique. The authors analyzed the differences in long-term 5-year clinical outcomes of endoscopic transforaminal foraminoplasty for symptoms from lumbar foraminal stenosis to better establish clinical indications for each technique.

Methods: Long-term 5-year MacNab outcomes, VAS scores, complications, and unintended aftercare were analyzed in a series of 176 patients consisting of 86 inside-out (group 1) and 90 outside-in (group 2) patients treated for sciatica-type back and leg pain due to lumbar foraminal stenosis.

Results: At minimum 5-year follow-up, excellent results according to the MacNab criteria were obtained in 93 (52.8%) patients, good in 63 (35.8%), fair in 17 (9.7%), and poor in 3 (1.7%), respectively. The mean preoperative VAS was 6.87±1.96. The mean postoperative VAS was 3.15±1.59 and 2.98±1.75 at last follow-up, respectively. Both postoperative VAS and final follow-up VAS were statistically reduced at a significance level of P<0001. There were no major approach-, surgical- or anesthesia-related complications in this series. The vast majority of patients (112/176; 63.6% of the study population) did not require any additional interventional or surgical treatment following the index transforaminal endoscopic decompression. Postoperative dysesthesia due to irritation of the dorsal root ganglion (DRG) as a consequence of operation next to the DRG occurred in 17 patients (9.7%) and was the most common benign postoperative sequelae. There was a higher reoperation rate in the outside-in group (35.6%) than in the inside-out group (8.1%). The secondary fusion rate was also higher with the outside-in (8.9%) than with the inside-out technique (2.3%). Ultimately, the long-term clinical outcomes with the endoscopic transforaminal decompression procedure were favorable regardless of whether the inside-out or outside-intechnique was used. These numbers were generated by two experienced endoscopic surgeons with thousands of case experience.

Conclusions: Patients with symptomatic foraminal stenosis may be treated successfully with either the inside-out or the outside-in selective endoscopic discectomy (SED™) method while maintaining favorable long-term outcomes with a 3.2× decreased need for secondary fusion at 5-year follow-up when compared to recently reported reoperation rates for traditional decompression/fusion. Long-term clinical outcomes with the inside-out technique were presumably better because of the ability to visualize and decompress underneath the dural sac, the ventral facet and the axilla known as the hidden zone of MacNab.

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Use of "Inside-Out" Technique for Direct Visualization of a Vacuum Vertically Unstable Intervertebral Disc During Routine Lumbar Endoscopic Transforaminal Decompression-A Correlative Study of Clinical Outcomes and the Prognostic Value of Lumbar Radiographs

Background: The purpose of this study was to record the frequency of lumbar intervertebral disc vacuum phenomenon on routine lumbar plain films taken prior to transforaminal endoscopic decompression surgery for sciatica-type leg and back pain and to correlate it with visualized intradiscal pathology and clinical outcomes.

Methods: A prospective case series study of 200 consecutive patients with an average mean follow-up of 41.85 months who underwent lumbar endoscopic transforaminal decompression at 236 lumbar levels was conducted. The sensitivity, specificity, and accuracy of vacuum phenomenon on preoperative x-ray to predict the presence of an empty vacuum disc found during transforaminal microdiscectomy using the "inside-out" approach were calculated using the YESS™ technique. Clinical outcomes were assessed by both Macnab criteria and visual analog score (VAS) reduction.

Results: Of the 200 patients evaluated, 124 (62%) were deemed to have a vacuum disc on intraoperative probing using the "inside-out" technique. During needle insertion the more severely degenerative discs are met with negative pressures manifested by an air discogram. According to Macnab criteria, all patients who also had extruded disc herniations had excellent results (8 of 200), with the mean VAS decreasing from 6.1 ± 2.6 preoperatively to 1.9 ± 1.4 at the final follow-up (P < .01). This indicates a more severely degenerative disc causing nonspecific back pain due to lack of anterior column support from the intervertebral disc, accentuating foraminal stenosis. Patients with contained disc herniations (62 of 200) had excellent and good results 82.2% of the time. The mean VAS decreased from 6.9 ± 1.7 preoperatively to 2.2 ± 1.1 at final follow-up (P < .01). This identifies the disc as a contributing factor in low back pain. It can also identify the disc and annulus in combination with foraminal stenosis as a contributing factor. In the spinal stenosis group (130 of 200), 81.5% of patients had excellent to good results, and the mean VAS decreased from 6.3 ± 1.5 preoperatively to 2.1 ± 1.2 at final follow-up (P < .01). An analysis of lumbar x-ray vacuum phenomenon in patients with visualized vacuum disc showed true-positive (35 patients) and false-negative (89 patients), compared with an x-ray negative grading in patients without intraoperatively visualized vacuum disc of false-positive (2 patients); and true-negative (74 patients); this allowed for calculation of sensitivity (28.2%), specificity (97.4%), and positive predictive value (94.6%) of preoperative diagnostic x-ray in relation to intraoperatively visualized presence of the vacuum disc during subsequent endoscopic decompression surgery. Direct endoscopic visualization of the inside of the vacuum disc revealed longitudinal fissuring of the intervertebral disc as the most common finding in 77 of the 124 patients (62.1%) with a vacuum disc. Cavitation with delamination was the second most common observation (21 patients). Fair outcomes were associated with cavitation and delamination of the intervertebral disc from the endplates (P < .0001).

Conclusions: A vacuum phenomenon seen on lumbar x-rays is highly specific for a source of one component that is actually a multiple source of nonspecific common back pain. A vacuum disc being found during "inside-out" transforaminal discectomy actually encompasses the disc, annulus, and foraminal stenosis as a multifactorial source of nonspecific common back pain. Further studies of better prognosticators of failed endoscopic transforaminal discectomy are required and are underway by the coauthors.

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The Concept for A Standalone Lordotic Endoscopic Wedge Lumbar Interbody Fusion: The LEW-LIF

Objective: To review concepts of a standalone endoscopically assisted lumbar interbody fusion as a simplified method to treat spinal instability.

Methods: MacNab outcomes and complications were analyzed in a series of 48 consecutive patients who underwent standalone lordotic endoscopic wedge lumbar interbody fusion (LEW-LIF) for advanced lumbar disc degeneration, spinal stenosis, and spondylolisthesis.

Results: Forty-two of the 48 patients (77.8%) did well with excellent and good outcomes with a follow up of up to 20 months. Fair outcomes were reported by 4, and poor by another 2 patients, respectively. Six patients had endoscopic decompression procedures at another level. Four patients underwent open transforaminal lumbar interbody fusion revision surgery including the index level between 2 to 6 months postoperatively. An L5 vertebral body fracture was noted in 1 of these 4 patients. Another patient underwent removal of the extruded L3/4 cage. The cage fractured in one additional asymptomatic patient not requiring any intervention. No patient had a wound infection, or permanent sensory, or motor dysfunction. However, 29 patients developed a postoperative irritation of the dorsal root ganglion with burning leg pain typically between postoperative weeks 2 and 6. Symptoms were treated with activity modification, gabapentin, and transforaminal epidural steroid injections in 12 patients (25%).

Conclusion: Standalone LEW-LIF was associated with favorable clinical outcomes in the majority of patients. Patient-related predictors of less favorable outcomes considering normal variations as well as patho-anatomy may aid in the development of next-generation implants.

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Retrospective analysis of accuracy and positive predictive value of preoperative lumbar MRI grading after successful outcome following outpatient endoscopic decompression for lumbar foraminal and lateral recess stenosis


Objectives: The aim of this study was to analyze the accuracy and positive predictive value (PPV) of preoperative lumbar MRI grading for successful outcome after outpatient endoscopic decompression for lumbar foraminal and lateral recess stenosis. Lumbar MRI is commonly employed in preoperative decision making to identify symptomatic pain generators amenable to surgical decompression. However, its accuracy and positive predictive value for successful postoperative pain relief after endoscopic transforaminal decompression for sciatica-type back and leg pain has not been reported.

Patients and methods: A retrospective study of 1839 consecutive patients with a mean follow-up of 33 months that underwent lumbar endoscopic transforaminal decompression at 2076 lumbar levels was conducted. The sensitivity, specificity, accuracy, and positive predictive value of preoperative MRI grading correctly identifying the symptomatic surgical level were calculated based on the recorded intraoperatively visualized pathology and clinical outcomes assessed by both Macnab criteria and VAS score reduction.

Results: Of the 1839 patients evaluated, 1750 had intraoperatively visualized stenosis in the lateral recess at the surgical level whereas 89 patients did not. Analysis of radiologist grading of exiting nerve root compression in the lumbar MRI reports in patients with visualized compressive pathology: true positive (1196), false negative (554); as compared with patients without visualized compressive pathology showed: false positive (30), and true negative (59); and allowed for calculation of sensitivity (68.34%), specificity (68.29%), accuracy (68.24%) and the positive predictive value (97.38%) in relation to successful clinical outcome of the subsequent endoscopic decompression surgery. Sensitivity (87.2%), specificity (73.03%), and accuracy (86.51%) improved when the treating surgeon graded same MRI scan for traversing nerve root compression. Taking different spinal stenosis classification systems by the radiologist and surgeon into consideration, Kappa statistic assessment of agreement between radiology and surgeon reporting of stenosis showed different degrees of concordance for extruded herniated disc (κ = 0.42; 331 patients), contained disc herniation (κ = -0.01; 648 patients), and stenosis (κ = 0.25; 860 patients). Disagreement (κ = 0.216; 440 patients) predominantly existed in grading the relevance of foraminal stenosis in the entry- (κ = 0.18; 278/440 patients), mid- (κ = -0.036; 121/440 patients), and less so in the exit zone (κ = -0.036; 41/440 patients) associated with contained (κ = -0.10; 178/440 patients), extruded disc herniations (κ = 0.4; 62/440 patients), and stenosis (κ = 0.25; 200/440 patients).

Conclusion: The grading of a preoperative MRI scan for lumbar foraminal and lateral recess stenosis may significantly differ between radiologist and surgeon. The endoscopic spine surgeon should read and grade the lumbar MRI scan independently to aid in appropriate patient selection for successful transforaminal endoscopic decompression surgery. More contemporary MRI reporting criteria are needed to describe the surgical anatomy in the neuroforamen and lateral recess relevant during the minimally invasive endoscopic transforaminal decompression.

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Incidence, Management, and Cost of Complications After Transforaminal Endoscopic Decompression Surgery for Lumbar Foraminal and Lateral Recess Stenosis: A Value Proposition for Outpatient Ambulatory Surgery


Objective: The objective of this study is to analyze incidence, estimate cost savings, and evaluate best management practices of complications resulting from outpatient transforaminal endoscopic decompression surgery for lumbar foraminal and lateral recess stenosis performed in an ambulatory surgery center.

Background: Endoscopic spinal surgery is gaining popularity for the treatment of lumbar disc herniations. Recent advances in surgical techniques allow for endoscopically assisted bony decompression for neurogenic claudication symptoms due to spinal stenosis. Postoperative complications from dural tears, recurrent disc herniations, nerve root injuries, foot drop, and facet and pedicle fractures, and postoperative sequelae such as dysesthetic leg pain and infiltration of the surgical access and spinal canal with irrigation fluid causing spinal headaches and painful wound swelling, as well as failure to cure, have been reported.

Methods: A retrospective study of 1839 consecutive patients with an average mean follow up of 33 months (range: 24 to 85 months) that underwent transforaminal endoscopic decompression surgery at 2076 levels between 2006 and 2015 was conducted to analyze incidence, and estimate the cost savings of postoperative adverse events following endoscopic foraminotomy and microdiscectomy. Complications were stratified using Dindo's 7-category grading system, distinguishing them from procedure-inherent sequelae as well as failure to cure. Only patients with unilateral radiculopathy due to either herniated disc or lateral recess stenosis were included in this study. Preoperatively, disc migration was graded by direction and distance from the disc space according to Lee's radiologic 4-zone classification. The type of disc herniation was classified either as contained or extruded. Contained herniations were further subclassified as disc protrusions versus disc bulges. In addition, the preoperative disc height was recorded. Bony spinal foraminal stenosis and lateral recess stenosis were graded on preoperative magnetic resonance imaging and computed tomography scans into mild, moderate, and severe by dividing the lumbar neuroforamen into 3 zones: (1) entry zone, (2) midzone, and (3) exit zone. Surgical outcomes were classified according to the Macnab criteria. In addition, reduction in the visual analog scale (VAS) scores were assessed.

Results: According to the Macnab criteria, excellent and good results were obtained in 82.2% of patients with extruded disc fragment (331/1839). In this group, the mean VAS score decreased from 5.9 ± 2.5 preoperatively to 2.4 ± 1.8 at final follow-up (P < .01). Patients with contained disc herniations (648/1839) had excellent and good results 72.7% of the time. In this group, the mean VAS score decreased from 7.2 ± 1.6 preoperatively to 3.1 ± 1.5 at final follow-up (P < .01). In the spinal stenosis group (860/1839), 75% of patients had excellent to good results. Postoperative grade I complications (any deviation from normal postoperative course treated with observation) occurred in 2 patients who immediately developed foot drop postoperatively on the surgical side (0.11%) and in another 2 patients (0.11%) with incidental durotomy. Grade II complications (any deviation with pharmacological interventions) occurred in 11 patients due to chronic obstructive pulmonary disease exacerbation, and in another 2 patients due to infections as the latter were successfully treated with antibiotics. Grade IIIb complications (any deviation requiring surgical, endoscopic, or radiological intervention under general anesthesia) occurred in 9 patients with reherniations of extruded discs within the first 3 postoperative months (recurrence rate 2.7%). Reherniations were associated with preserved disc height of > 6 mm (P < .02). Grade IV (organ failure), and grade V (death) complications did not occur. Procedure-inherent sequelae from adverse operative side effects were noted in 8 patients with spinal headaches (0.44%), and in 69 patients (3.75%), who had extravasations of irrigation fluid into the subcutaneous tissues causing wound swelling. Another 229 patients developed postoperative dysesthetic leg pain due to irritation of the dorsal root ganglion (12.45%), which was associated with severe foraminal stenosis (P < .01) and improved with supportive care in all cases. Failure to cure occurred in 39 patients (2.12%) with bony stenosis in the central canal, and lateral recess involving the entry zone of the neuroforamen and in 41 patients (2.23%) with contained disc herniations.

Conclusions: Complications after outpatient transforaminal endoscopic decompression surgery with respect to reherniation, wound infections, durotomy, and nerve root injury are approximately 1 magnitude lower than equivalent reported complication rates with microdiscectomy while delivering comparable clinical outcomes and lower readmission rates to an emergency room or hospital. Postoperative sequelae are typically self-limiting and successfully managed with supportive care measures. Significant cost savings are realized due to a considerably lower rate of decompensated postoperative medical problems.

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Differential Agnostic Effect Size Analysis of Lumbar Stenosis Surgeries


Study Design: A meta-analysis of 89 randomized prospective, prospective, and retrospective studies on spinal endoscopic surgery outcomes.

Objective: The study aimed to provide familiar Oswestry Disability Index (ODI), visual analog scale (VAS) back, and VAS leg effect size (ES) data following endoscopic decompression for sciatica-type back and leg pain due to lumbar herniated disc, foraminal, or lateral recess spinal stenosis.

Background: Higher-grade objective clinical outcome ES data are more suitable than lower-grade clinical evidence, including cross-sectional retrospective study outcomes or expert opinion to underpin the ongoing debate on whether or not to replace some of the traditional open and with other forms of minimally invasive spinal decompression surgeries such as the endoscopic technique.

Methods: A systematic search of PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials from 1 January 2000 to 31 December 2019 identified 89 eligible studies on lumbar endoscopic decompression surgery enrolling 23,290 patient samples using the ODI and VAS for back and leg pain used for the ES calculation.

Results: There was an overall mean overall reduction of ODI of 46.25 (SD 6.10), VAS back decrease of 3.29 (SD 0.65), and VAS leg reduction of 5.77 (SD 0.66), respectively. Reference tables of familiar ODI, VAS back, and VAS leg show no significant impact of study design, follow-up, or patients’ age on ES observed with these outcome instruments. There was no correlation of ES with long-term follow-up (P = 0.091). Spinal endoscopy produced an overall ODI ES of 0.92 extrapolated from 81 studies totaling 12,710 patient samples. Provided study comparisons to tubular retractor microdiscectomy and open laminectomy showed an ODI ES of 0.9 (2895 patients pooled from 16 studies) and 0.93 (1188 patients pooled from 5 studies). The corresponding VAS leg ES were 0.92 (12,631 endoscopy patients pooled from 81 studies), 0.92 (2348 microdiscectomy patients pooled from 15 studies), and 0.89 (1188 open laminectomy patients pooled from 5 studies).

Conclusion: Successful clinical outcomes can be achieved with various lumbar surgeries. ESs with endoscopic spinal surgery are on par with those found with open laminectomy and microsurgical decompression.

Level of Evidence: 2

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