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Hard or calcified discs are often adherent to surrounding nerve tissue. The whole herniated disc is difficult to remove by pulling part of the hernia mass, which makes obtaining good results through endoscopic treatment difficult. The purpose of this study was to describe the details of the transforaminal endoscopic lumbar discectomy technique for a hard or calcified disc and report the clinical results.From October 2016 to June 2019, 43 consecutive cases diagnosed as hard or calcified lumbar disc herniation at our institution and treated with transforaminal endoscopic discectomy were evaluated. Endoscopic decompression was performed in patients with hard or calcified lumbar disc herniation.The preoperative visual analog scale score for leg pain (mean ± standard deviation) was 7.09 ± 1.74. The score improved to 2.55 ± 1.35 at 1 week postoperatively, 1.88 ± 1.29 at 4 weeks postoperatively, and 1.58 ± 1.0 at 26 weeks postoperatively (P0.01 for all). The preoperative Oswestry Disability Index (mean ± standard deviation) was 55.4 ± 23.04, which improved to 30.89 ± 13.64 at 1 week postoperatively, 23.08 ± 11.64 at 4 weeks postoperatively, and 16.42 ± 9.76 at 26 weeks postoperatively (P0.01 for all). Two patients developed a dural laceration. Both patients were discharged after several hours of observation. None of the patients had postoperative infection, epidural hematoma, or delayed neurological deterioration.Transforaminal endoscopic discectomy could be an effective treatment method for a selected group of patients with hard or calcified lumbar disc herniation.

Introduction Presently, programmed death ligand 1 is the most commonly used biomarker to predict response to immune checkpoint inhibitors (ICIs) in NSCLC. Owing to its several limitations, there is continuous search for more precise and reliable markers. Frameshift mutations by insertion or deletion (fsindels) are suggested to induce more immunogenic tumor-specific neoantigens, conferring better response to ICIs. Positive correlation of fsindels with ICI response has been studied in melanoma and renal cell carcinoma. We investigated the implication of fsindels in the clinical outcomes and immune landscape of patients with NSCLC treated with ICIs. Methods We utilized The Cancer Genome Atlas data set to analyze tumor mutational burden, neoantigen burden, and immune landscape in relation to fsindel status. In addition, utilizing the clinical data from 122 patients treated with ICIs, we evaluated the influence of fsindels on disease response rates and survival outcomes. Results A positive correlation between fsindel burden and tumor mutational burden and activated CD4/CD8 T-cell infiltration was shown. Presence of fsindels was also associated with significant prolongation of progression-free survival in patients treated with ICIs (median 6.2 versus 2.7 months [p = 0.01]). In addition, significant differences in the overall response rates (26% versus 12% [p = 0.04]) and disease control rates (68% versus 48% [p = 0.02]) were observed in patients with fsindels. Conclusion Our findings suggest that fsindels may have a predictive role for ICI response in NSCLC.

Background Minimally invasive oblique lumbar interbody fusion (OLIF) techniques generally rely on deformity correction to achieve indirect neural decompression. However, indirect neural decompression will not always be sufficient. Thus, a second procedure, such as posterior direct decompression, will be added for full decompression, increasing the surgical morbidity and healthcare costs. We have described a technique of direct anterior microscopic neural decompression combined with OLIF. Methods We report our surgical technique of anterior lumbar neural microscopic decompression with OLIF with patients in the lateral position. We also report the cases of 3 patients treated from March 2018 to June 2018. Results Three patients underwent anterior microscopic neural decompression combined with OLIF in the lateral position. All 3 patients achieved clinically and radiologically significant neural decompression and deformity correction. No perioperative complications developed. Conclusion Direct anterior microscopic neural decompression is feasible and safe in selected patients undergoing OLIF.

Background Despite its growing popularity, no comparative studies have explored the minimum clinically important difference (MCID) of health-related quality of life scores following lumbar interbody fusion (LIF) performed on a single-level adult low-grade isthmic spondylolisthesis (LGIS). Objective The purpose of this study is to investigate factors related to MCID of health-related quality of life scores following instrumented LIF performed on a single-level adult LGIS. Methods Consecutive patients who underwent instrumented LIF for single-level LGIS were reviewed. The inclusion criteria were adult patients who underwent L4-5 or L5-S1, underwent anterior lumbar interbody fusion or transforaminal lumbar interbody fusion with a posterior screw fixation, and had a minimum 36-month postoperative follow-up period. MCID was defined as having an improved score of visual analog scale (VAS) back and leg pain >3 and Oswestry Disability Index (ODI) >12. Patients were subdivided into groups named “achievement” (A) and “nonachievement” (N) depending on their postoperative MCID for each health-related quality of life score category. Results One-hundred and five patients met the inclusion criteria. The overall achievement of MCID for VAS back, leg, and ODI was 80%, 73.3%, and 82.9%. MCID-VAS leg and ODI were less achieved at the L5-S1 level than at the L4-5 level. Postoperatively, disk height was higher and segmental lordosis (SL) was lower in group A of MCID-VAS leg. SL was lower in group A of MCID-ODI. Conclusions We postulate that excessive SL does not affect lumbar lordosis; rather, it can result in lowering posterior disk height. The decrease in posterior DH may lead to a decreased foraminal height that, in turn, can lead to nerve root compression. Proper restoration of disk height and bone fusion is more important than restoration of more segmental lordosis or slip reduction for isthmic spondylolisthesis.

Transforaminal endoscopic treatment has been reported to be an effective treatment option in patients with lumbar disc herniation. However, it is rarely performed for spinal stenosis because of the limitation of endoscopic working mobility caused by the exiting nerve root and foraminous bony structure. The objective of this study was to describe a novel transforaminal endoscopic decompression technique for spinal stenosis and report the clinical results.From October 2015 to October 2016, 30 consecutive cases were diagnosed as lateral recess stenosis in our institution and underwent transforaminal endoscopic decompression. Visual analog scale (VAS) of back and leg pain and the Oswestry Disability Index (ODI) were measured preoperatively and at follow-up.The mean ± SD value of preoperative VAS leg pain score was 7.6 ± 1.17. The score improved to 2.2 ± 1.11 at 1 week postoperatively, 1.73 ± 0.96 at 4 weeks postoperatively, and 1.63 ± 0.95 at 26 weeks postoperatively (P0.01). The mean ± SD value of the preoperative ODI score was 65.69 ± 14.22. The score improved to 24.29 ± 11.89 at 1 week postoperatively, 21.25 ± 9.25 at 4 weeks postoperatively, and 15.62 ± 10.49 at 26 weeks postoperatively (P0.01). There were no patients with postoperative infection, dural tear, delayed neurologic deterioration, or conversion to open surgery.Transforaminal endoscopic decompression under local anesthesia could be an effective treatment method for the selected group of patients with spinal stenosis.

Objective Chronic low back pain (CLBP) often causes disabling pain that impairs a patient's quality of life. Surgical treatment is recommended for patients who do not respond to conservative treatments lasting more than 6 months. The purpose of this study is to present results after the use of an interlaminar dynamic spacer for CLBP. Methods We enrolled consecutive patients with CLBP irresponsive to more than 6 months of conservative treatment into the present study. Included patients underwent an interlaminar dynamic spacer insertion without direct decompression. We assessed radiographic parameters and health-related quality of life (HRQoL) data included visual analog scale back/leg pain and Oswestry Disability Index scores. Substantial clinical benefit achievement was assessed. Results Thirty-five patients (average age, 47.8 years; 21 female) were included. The mean preoperative symptom duration was 29.6 months. Surgeries involved 1-level (n = 18) and 2-levels (n = 17) procedures. Operative levels included L4-5 (n = 8), L5-S1 (n = 10), L3-4-5 (n-2), and L4-5-S1 (n = 15). The average follow-up period was 16.6 months. After the procedure, all radiographic parameters (including disc height, segmental extension angle, and foraminal area) improved significantly. All preoperative HRQoL parameters improved significantly at the final follow-up. Substantial clinical benefit achievement was observed in 75.8% of the cases on the Oswestry Disability Index, and in 72.7% and 84.8% of the cases on the visual analog scale back and leg pain, respectively. Conclusions An interlaminar dynamic spacer significantly improves HRQoL scores in patients with CLBP who do not respond to conservative treatment. Although encouraging, these results should be confirmed with studies assessing a larger cohort and a longer follow-up.

Background: Lumbosacral junction (L5-S1) with its distinctive anatomical features, presents a unique challenge to endoscopic spine surgeons.1–7 The choice between interlaminar and postero-lateral (transforaminal) routes for L5-S1 endoscopic discectomy remains controversial. Purpose: Describe a novel isthmic approach for postero-lateral endoscopic lumbar discectomy (PELD) at L5-S1 level and critically analyze the surgical results. Study Design: Technical note. Case series. Patient Sample: 25 patients with symptomatic L5-S1 disc herniation. Outcome Measure: Demographics, radiological features, bony anatomy, and clinical outcomes. Methods: Each patient underwent postero-lateral endoscopic lumbar discectomy utilizing isthmic approach. The patient data was prospectively collected and retrospectively analyzed. Results: Average pain score for back pain and leg pain significantly improved from pre-op level of 3.09 and 7.81 to 2.17 and 2.15, respectively. Statistically significant improvement was also observed in post-op ODI score (pre-op = 58, post-op 33.85, p ≤ 0.00001). There were no intra-op complications of nerve or thecal sac injury. Conclusion: Combining isthmus trajectory to L5-S1 postero-lateral endoscopic discectomy adds to the applicability of this already well established surgical procedure. Isthmic approach offers a safe and effective anatomical corridor for performing endoscopic discectomy via transforaminal route, even in individuals with high iliac crest. Keywords: Endoscopic discectomy, Lumbosacral junction, Postero-lateral approach

Background context Anterior lumbar interbody fusion (ALIF) with percutaneous pedicle screw fixation (PPF) provides successful surgical outcomes to isthmic spondylolisthesis patients with indirect decompression through foraminal volume expansion. However, indirect decompression through ALIF followed by PPF may not obtain a successful surgical outcome in patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by a posterior osteophyte or foraminal sequestrated disc herniation. Thus far, there has been no report of foraminal decompression through anterior direct access in the lumbar spine. Purpose This study aims to describe the new surgical technique of microscopic anterior foraminal decompression and to analyze the clinical outcomes and radiologic results of the microscopic anterior decompression during ALIF followed by PPF. Study design/Setting We conducted a multisurgeon, retrospective, clinical series from a single institution. Patient sample This study was carried out from March 2007 to July 2010 and included 40 consecutive patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by posterior osteophyte or foraminal sequestrated disc herniation undergoing microscopic anterior foraminal decompression during ALIF followed by PPF. Outcome measures The visual analog scales (VAS) of back and leg pain and the Oswestry disability index were measured preoperatively and at the last follow-up. Methods Postoperative computed tomography and magnetic resonance imaging measured whether decompression of neural structure had been made and morphometric change of the foramen and the amount of resected bone. Moreover, segmental lordosis, whole lumbar lordosis, disc height, and degree of listhesis were measured through X-ray examination before the operation and at the last follow-up; we also verified whether fusion had been achieved. Results Successful decompression was confirmed in both patients with foraminal stenosis caused by posterior osteophyte and those with foraminal sequestrated disc herniation. Clinically, compared with before the surgery, the VAS (leg and back) and the Oswestry disability index significantly decreased at the last follow-up (p=.000). With regard to radiology, at the last follow-up all patients had bone fusion on X-ray examination, and an increase in disc height, a reduction in the degree of listhesis, an increase in segmental lordosis, and an increase in whole lumbar lordosis were significant in both groups (p=.000) compared with before the surgery. Foraminal volume, foraminal width, and foraminal height also significantly increased postoperatively compared with before the operation (p=.000). The height, width, and dimension of resected body were 4.61±1.05 mm, 7.92±1.42 mm, 17.15±4.96 mm 2 , respectively, in patients with foraminal stenosis caused by a posterior osteophyte, and 3.88±0.92 mm, 6.8±1.29 mm, and 13.12±2.25 mm 2 , respectively, in patients with foraminal sequestrated disc. Conclusions The microscopic anterior foraminal approach provides successful foraminal decompression. Combined with ALIF and PPF, this approach shows a good surgical outcome in patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by a posterior osteophyte or those with foraminal sequestrated disc herniation.

A modeling method for the flapwise bending vibration analysis of a rotating multi-layered composite beam is presented in this paper. For the modeling method, the shear and the rotary inertia effects are considered based on Timoshenko beam theory and hybrid deformation variables are employed to derive the equations of motion. Dimensionless parameters are identified from the equations of motion and the combined effects of the dimensionless parameters on the modal characteristics of the rotating composite beams are investigated through numerical study.

Equations of motion of a rotating cantilever beam are derived based on a new dynamic modelling method in this paper. The derived equations (governing stretching and bending motions), which are coupled through gyroscopic coupling terms, are all linear, so they can be directly used for the vibration analysis including the coupling effect, which could not be considered in the conventional modelling method. With the coupling effect ignored, the analysis results are consistent with the results obtained by the conventional modelling method. With the coupling effect considered, eigenvalue loci veerings and mode shape variations could be observed through numerical study. Generally, when the rotating speed increases up to a certain value, the analysis results including the coupling effect show significant difference compared to the results ignoring the coupling effect. A modal formulation method is also introduced in this study to calculate the tuned angular speed of a rotating beam at which resonance occurs.