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This study aimed to determine the prevalence of lumbar ligamentum flavum lesions and identify correlations between radiological and pathological findings. We conducted an observational cross-sectional study of 349 patients (lumbar: n = 296, thoracic: n = 39, lumbar and thoracic: n = 14, mean age: 69 ± 12 years, male: 74%) who underwent posterior surgery for thoracolumbar spinal canal stenosis between January 2008 and April 2023 at our hospital.Computed tomography (CT) revealed that the prevalence of ligamentum flavum lesions defined as a high-density area with a CT value of 200 Hounsfield Unit or higher in the lumbar and thoracic spine was 47% (147/310) and 85% (45/53), respectively. CT showed that most patients had radiologically suspected ossification in the lumbar (90%) and thoracic spine (98%) than radiologically suspected calcification. Lumbar lesions were thinner than the thoracic lesions (2.5 vs 3.7 mm, p < 0.01). Pathological examinations were performed in specimens collected from 34 cases (lumbar: n = 13, thoracic: n = 21), and ossification was found in 62% (8/13) and 95% (20/21) of lumbar and thoracic lesions (p = 0.02), respectively. Lastly, ossification was confirmed pathologically in 72% (8/11) and 95% (19/20) of lumbar and thoracic lesions that showed ossification on imaging (p = 0.13), respectively. The literature review revealed that the prevalence of the lumbar ligamentum flavum lesions varied from 1.5 to 35% and the patient population was mostly asymptomatic.Collectively, we found that the prevalence of lumbar ligamentum flavum lesions in symptomatic patients was greater than previously reported. Histologically confirmed ossification was less common in lumbar lesions than in thoracic lesions.

Rationale: Lumbar disc herniation (LDH) manifests in diverse forms. If the nucleus pulposus or endplate tissues protrudes, the location of annular tears also varies, which poses various challenges for the annular suture technique. Tears at the annular attachment area at the edge of the vertebral body (cephalad or caudad) are considered a prohibitively challenging area for annular suturing., Patient Concerns: A 37-year-old woman presented with a gradual onset of symptoms, experiencing leg pain and numbness over the left leg for 1 year before presentation. The pain radiated to the left S1 dermatome. Despite undergoing continuous medical therapy for more than 6 months, her symptoms showed no improvement. The strength of the left plantar flexion in the ankle and great toe was rated at 4 out of 5. The straight leg-raising and strengthening tests were positive for the left sides. Lumbar computed tomography and magnetic resonance imaging revealed left-sided disc herniation at the L5-S1 level, and nerve root compression, confirming the diagnosis of LDH., Diagnoses: The preoperative impression was LDH, intraoperative confirmation of a tear in the annular attachment area at the vertebral body edge., Interventions: This patient was treated with an arthroscopic-assisted uniportal spinal surgery (AUSS) technique focusing on ligament flavum (LF) preservation, protruding nucleus pulposus removal, nerve root decompression, and vertebral edge tear was then sutured using a bone anchoring annular suture with the Smile suture device., Outcomes: This technique was performed successfully in a patient with LDH. Significant improvements were observed in postoperative pain and numbness, Visual Analog Scale, and Japanese Orthopaedic Association scores. No postoperative instability or complications were observed, with computed tomography and magnetic resonance imaging confirming complete decompression. To the best of our knowledge, this is the first used AUSS with LF preservation and bone anchoring annular suture technique for LDH., Lessons: This case study demonstrates the AUSS combined with LF preservation and the bone anchoring annular suture technique provides favorable clinical and imaging outcomes and is a safe and effective technique for the treatment of LDH., Competing Interests: The authors have no conflicts of interest to disclose, (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: To analyze the characteristics of an unnamed interlaminar ligaments(ILL) through magnetic resonance image (MRI), endoscopy and pathological examination., Method: A retrospective study was conducted to analyze the clinical data of patients who underwent posterior endoscopic surgery for lumbar disc herniation or lumbar spinal stenosis from January 2021 to February 2022 at our medical center. The height, width and cross-sectional thickness of the ligament was analyzed using T2 weighted MRI. Meanwhile, the morphological and pathological characteristics were also compared with those of the ligamentum flavum to highlight the differences between above mentioned ligaments., Result: Forty-three patients were included in this study, including 27 males and 16 females, with an average age of 46.6 ± 12.1y. There were 20 cases of lumbar disc herniation and 23 cases of lumbar spinal stenosis. The width, length, thickness of the ILL, the thickness of LF and surgical time in the lumbar disc group were 17.7 ± 3.5 mm, 4.3 ± 1.3 mm, 18.3 ± 3.5 mm, 5.3 ± 1.9 mm, 53.2 ± 14.5 min, respectively. In the lumbar spinal stenosis group, the corresponding parameters were 16.0 ± 3.1 mm, 4.1 ± 1.6 mm, 17.6 ± 4.8 mm, 6.3 ± 0.8 mm, 61.8 ± 12.4 min, respectively. The intergroup difference in thickness of the ligamentum flavum was statistically significant (P = 0.02). The difference in surgical time was also established(P = 0.04). Endoscopic differences were identified as to the location of the anchor points and appearances among the two ligaments. Significant differences in the density and direction of fibrous structures were also observed under biopsy. Under endoscopy, significant difference as to the grade of ILL thickness was established when compared regarding disease spectrum (P = 0.09.) CONCLUSION: The interlaminar ligament is a structure that has not yet been officially named, which has significant structural differences from those of the ligamentum flavum. For posterior endoscopic procedure, its clinical significance lies in its ability to serve as the endpoint of soft tissue channel establishment. The thickness of the ligamentum flavum in MRI and the thickness of ILL under endoscopy vary according to the disease spectrum., (© 2024. The Author(s).)

Study Design: Experimental study., Objective: We sought to elucidate the association between ligamentum flavum thickening and tissue buckling, and the clinical and imaging factors related to buckling by comparing the ligamentum flavum thickness on MRI images and within the actual tissue., Summary of Background Data: Ligamentum flavum thickening is a main contributor to lumbar spinal canal stenosis. Buckling of the tissue may contribute to ligamentum flavum thickening along with tissue hypertrophy; however, this association has not been established conclusively., Materials and Methods: Ligamentum flavum samples (135 ligament samples) from 70 patients with lumbar spinal canal stenosis were evaluated. The ligamentum flavum thicknesses on magnetic resonance imaging (MRI) and in the tissue samples were compared to assess for the presence of buckling. The ligamentum flavum samples were divided into groups with or without buckling based on the difference between their thicknesses on MRI and in the tissues. The Pearson correlation coefficient test was used to assess the relationships between the LF thicknesses on MRI and in the tissues, MRI-tissue difference and LF thickness in the tissues, and MRI-tissue difference and LF thickness on MRI. Further, differences between the buckling+ and buckling- groups were compared using the unpaired t-test (LF thickness on MRI, LF thickness in the tissues, age, disc angle, and disc height) and χ2 (disc level, disc degeneration, and receival/nonreceival of dialysis) test., Results: The ligamentum flavum thickness on MRI and in the tissues had a positive linear relationship, although the thickness was estimated to be significantly larger on MRI than in the tissues themselves. The ligamentum flavum with buckling had a larger thickness on MRI, less tissue hypertrophy, more severe disc degeneration, and was present in patients with a higher rate of dialysis. There were no differences in age and disc height, angle, or level between the two groups., Conclusions: Buckling of the ligamentum flavum coexists with tissue hypertrophy and contributes to perceived ligamentum thickening on imaging. Buckling of the ligamentum flavum tends to occur in less hypertrophied tissues and is associated with the grade of disc degeneration and the presence of other characteristics associated with spinal degeneration., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: We assessed the sequential magnetic resonance imaging changes of indirect neural decompression after minimally invasive lumbar lateral interbody fusion (LIF) combined with posterior percutaneous pedicle screw (PPS) fixation for degenerative spondylolisthesis (DS) according to the severity of preoperative lumbar spinal stenosis., Methods: A total of 43 patients (mean age, 68.7 years; 16 men and 27 women) with DS who had undergone LIF and closed reduction with PPS fixation were enrolled. The intervertebral levels were divided into the moderate stenosis (MS) group (preoperative cross-sectional area [CSA] of the thecal sac >50 mm 2 ) and severe stenosis (SS) group (CSA ≤50 mm 2 ). The CSA, ligamentum flavum thickness, and diameter of the thecal sac at the affected level were measured on cross-sectional magnetic resonance images at baseline, immediately postoperatively, and 2 years postoperatively., Results: For the 31 and 29 intervertebral levels in the MS and SS groups, the mean CSA at baseline, immediately postoperatively, and 2 years postoperatively was 76.9 mm 2 and 35.8 mm 2 , 104.3 mm 2 and 81.4 mm 2 , and 130.9 mm 2 and 105.7 mm 2 , respectively. The mean ligamentum flavum thicknesses at 2 years postoperatively became thinner than that immediately after surgery in both groups (P < 0.01). The mean diameter of the thecal sac at 2 years was longer than that immediately after surgery in both groups (MS group, P < 0.05; SS group, P < 0.01) The expansion ratio of the CSA at 2 years postoperatively was significantly greater in the SS group than that in the MS group (P < 0.01)., Conclusions: Sequential enlargement of the spinal canal was obtained by the thinning of the ligamentum flavum after LIF and PPS fixation in patients with DS with both mild and severe stenosis. The effect of indirect neural decompression was equivalent even in those with severe lumbar spinal stenosis., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: This study was designed to investigate the relationship between the laminar slope angle (LSA) and the lumbar disc degenerative grade, the cross-section area (CSA) of multifidus muscle, the muscle-fat index, and the thickness of the ligamentum flavum., Methods: Retrospective analysis of 122 patients who were scheduled to undergo a lumbar operation for diagnoses associated with degenerative lumbar disease between January and December 2017. The L4-L5 disc grade was evaluated from preoperative sagittal T2-weighed magnetic resonance imaging of the lumber region; the CSA of the multifidus and muscle-fat index were measured at the L4 level, while the thickness of the ligamentum flavum was measured at the L4-L5 facet level from axis T2-weighed magnetic resonance imaging. The slope of the laminar was evaluated from preoperative three-dimensional computer tomography at the tip level of the facet joints and selected by the axis plane. Independent-sample T-tests were used to assess the association between age and measurement indices., Results: Our results showed that age was positively connected with the LSA of L4 and L5 in different patients, although there was no significant difference between age and the difference of the two segment LSA. Partial correlation analysis, excluding the interference of age, revealed a strong negative relationship between the LSA of L4 and the thickness of the ligamentum flavum, irrespective of whether we considered the left or right. However, there was no correlation with lumbar disc degenerative grade, the CSA of the multifidus, and the muscle-fat index., Conclusion: The thickness of the ligamentum flavum showed changes with anatomical differences in the LSA, but not the lumbar disc degenerative grade, the CSA of the multifidus, and the muscle-fat index. A small change in LSA may cause large mechanical stress; this may be one of the causative factors responsible for lumbar spinal stenosis.

Objective: A prospective, randomized, controlled clinical study was conducted with surgery performed by the same surgeon. The aim was to present a new technique for preserving the ligament flavum during lumbar microdiscectomy, and to evaluate whether this helps prevent postoperative fibrosis and improve outcome., Methods: From January to December 2017, 251 patients with indication for microdiscectomy were randomly divided into test group using ligament flavum preservation technique and control group using conventional procedures. Visual analogue scale (VAS) scores and Oswestry Disability Index (ODI) were assessed before the surgery, and 3 days, 1 month, 6 months, 1 year and 2 years after the operation respectively. The grade of epidural fibrosis on MRI after 6 months was evaluated by two radiologists independently and double-blindly., Results: Both groups' VAS and ODI were significantly improved after surgery, but there was no significant difference between two groups at 3d and 1 month after operation. The grade of epidural fibrosis in test group was significantly lower than that in control group at 6 months postoperative. The VAS and ODI were significantly lower in test group than that in control group at 6 months,1 year and 2 years after operation., Conclusion: Preservation of more ligament flavum is practicable during the procedure of microdiscectomy. It can prevent postoperative epidural fibrosis, and is helpful to achieve a better clinical outcome., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Study Design: A retrospective study (level of evidence: level 4)., Objective: To evaluate the radiographic outcomes after extreme lateral lumbar interbody fusion (XLIF) and oblique lateral lumbar interbody fusion (OLIF) procedures especially the effect of indirect decompression to the ligamentum flavum and to evaluate the effect of facet degeneration to the radiographic outcomes of these procedures., Summary of Background Data: Indirect decompression via lateral lumbar interbody fusion provides spinal canal area expansion. However, the effect to the ligamentum flavum area and thickness at the operated spinal level is unclear., Methods: Thirty-five patients (57 lumbar levels) underwent XLIF or OLIF with percutaneous pedicle screw fixation (PPS) without direct posterior decompression were retrospectively studied. Radiographic parameters including ligamentum flavum area (LFA), ligamentum flavum thickness (LFT), cross-sectional area (CSA) of thecal sac, posterior disc height, foraminal height, cage alignment, and facet degeneration were measured on magnetic resonance image (MRI). Cage position was assessed with plain radiography., Results: All of the radiographic parameters were significantly improved. Comparing pre- and postoperative value, mean LFA decreased from 78.9 ± 24.9 mm to 66.9 ± 26.8 mm (-14.2%; P-value < 0.00625). Mean right LFT decreased from 2.9 ± 0.9 mm to 2.3 ± 0.7 (-17.0%; P-value < 0.00625). Mean left LFT decreased from 3.3 ± 1.6 mm to 2.6 ± 0.9 mm (-17.6%; P-value < 0.00625). Mean CSA of thecal sac increased from 93.1 ± 43.0 mm to 127.3 ± 52.5 mm (50.8%; P-value < 0.00625). All radiographic outcomes were not significant difference between lumbar levels that have grade 0-1 and grade 2-3 or between grade 2 and grade 3 facet degeneration., Conclusion: Ligamentum flavum area and thickness were significantly reduced after lateral lumbar interbody fusion through both XLIF and OLIF. Unbuckling of the ligamentum flavum played an important role for improvement of spinal canal area after the indirect decompression., Level of Evidence: 4.

Purpose: Ligamentum flavum is one of the structures that could compress the spinal canal. Few studies have reported atrophy of ligamentum flavum after spinal fusion. The purpose of this study was to demonstrate the reduction of ligamentum flavum size after oblique lumbar interbody fusion (OLIF) using magnetic resonance imaging (MRI)., Method: Seventeen patients who underwent OLIF without direct decompression were included. The MRI was obtained at the preoperative period, immediate postoperative period, and the follow-up period. Disc height (DH) was measured in plain radiograph. MRI measurements were spinal canal cross-sectional area (SCSA), ligamentum flavum thickness (LFT), ligamentum flavum area (LFA), and foraminal area (FA)., Results: Mean age of the patients was 68.5 ± 10.8. Mean times between postoperative MRI and follow-up MRI were 20.2 ± 11.9 months. Mean disc height increased from 7.6 ± 1.6 to 11.6 ± 1.7 mm at an immediate postoperative period but decreased to 10.1 ± 1.6 mm during follow-up (p < 0.001). SCSA increased from 96.9 ± 54.9 to 136.0 ± 72.7 mm 2 and 171.4 ± 76.10 mm 2 during follow-up (p < 0.001). LFT decreased from 3.9 ± 1.2 to 3.2 ± 0.8 mm (17.9%) and further decreased to 2.9 ± 0.7 mm during follow-up (9.4%) (p < 0.001). LFA decreased from 97.4 ± 36.9 to 86.1 ± 36.9 mm2 (11.6%) and further decreased to 77.2 ± 32.5 mm 2 during follow-up (10.3%) (p = 0.001). FA increased from 69.2 ± 26.6 to 96.1 ± 23.0 mm 2 and increased to 112.9 ± 23.0 mm 2 during follow-up (p < 0.001)., Conclusion: OLIF could decompress the spinal canal and foraminal canal indirectly. Despite the diminishing disc height during the follow-up period, the spinal canal was further increased in size from the remodeling of the ligamentum flavum.

The aim of this study was to take ultrasonographic measurements of the length of the ligamentum flavum (LF), the LF-skin distance and the interspinous distance, which are critical for the application of neuraxial anaesthesia, with volunteers in the sitting position and with lateral tilt of the operating table at different angles to evaluate whether the target structures in neuraxial anaesthesia can be better visualised with the lateral tilt position and to determine whether or not these measurements change at different angles. The study included 29 volunteers. For the measurements, the operation table was first set into the neutral position and the length of the LF, the skin-LF distance and the interlaminar distance were measured at between L1-S1 spaces with a paramedian oblique sagittal approach with a linear ultrasound probe. Then the table was moved into 5°, 10° and 15° lateral tilt positions and the LF, LF-skin distance and the interlaminar distance were measured at the L1-S1 interspaces and recorded. At L2-3, L3-4, L4-5 and L5-S1 intervertebral interspaces, as the lateral tilt angle increased, so the measured LF length and interlaminar distance was determined to increase, this increase was statistically significant. In the ultrasonographic measurements of the skin-LF distance, at L3-4 and L4-5 intervertebral interspaces, there was a statistically significant increase. With lateral tilt applied to the table, there was determined to be an increase in ultrasonographic measurements of the LF length in the lumbar intervertebral interspaces. Therefore, for neuraxial blocks applied in the sitting position, the procedure may be facilitated with lateral tilt of the operating table.

Objective: To quantitatively describe the stress of the ligamentum flavum (LF) using the finite element method and to compare the stress at different parts of the healthy LF., Methods: Based on the high resolution computed tomography imaging data of a healthy 22-year-old man, three-dimensional nonlinear L 4-5 lumbar finite element model (FEM) representing intact condition was developed. The LF, as the object of the present research, was incorporated into the spinal model in the form of solid three-dimensional structure. The model's validity is verified by comparing its biomechanical indices, such as range of motion and axial compression pressure displacement, with published results under specific loading conditions. To authenticate the accuracy of the solid LF, the lamina attachments, the central cross-section, and other anatomy indicators were compared with figures in the published literature. After the average and maximum von Mises stress on the surface of LF under various working conditions were measured using ANSYS and AutoCAD software, the surface stress difference in the LF between the ventral and dorsal sides as well as the lateral and lamina parts were determined., Results: The FEM predicted a similar tendency for biomechanical indices as shown in previous studies. The lamina attachments, the central cross-section, and the height as well as the width of the LF in the healthy FEM were in accordance with published results. In the healthy model, the average and maximum von Mises stress in the shallow layer of the LF were, respectively, 1.40, 2.28, 1.76, 1.48, 1.38 and 1.79, 2.41, 1.46, 1.42, 1.71 times that in the deep layer under a compressive preload of 500 N incorporated with flexion, extension, and lateral and rotational moments (10 Nm). The most conspicuous difference in surface stress was observed with the flexion motion, with a nearly 241% difference in the maximum stress and a 228% difference in the average stress compared to those in other states. As far as the whole dorsal side of the LF was concerned, the maximum surface stress was almost all concentrated in the dorsal neighboring facet joint portion. In addition, the maximum and average stress were, respectively, 77%, 72%, 15%, 11%, 71% and 153%, 39%, 54%, 200%, 212% higher in the lateral part than in the lamina part., Conclusion: Based on the predisposition of LF hypertrophy in the human spine and the stress distribution of this study, the positive correlation between LF hypertrophy and its stress was confirmed., (© 2020 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Background: During lumbar epidural injection (LEI) using a midline approach, we might encounter failure of identifying the epidural space owing to an equivocal or absent loss of resistance (LOR) sensation. The reason for such absence of LOR sensation has been suggested as paucity of midline ligamentum flavum, paravertebral muscle, and cyst in the interspinous ligament of the lumbar spine. Despite its low specificity, LOR is the most commonly used method to identify the epidural space., Objectives: The purpose of this study was to analyze lumbar epidural pressure decrease patterns and identify factors contributing to this pressure decrease., Study Design: Prospective randomized trial., Setting: An interventional pain management practice in South Korea., Methods: This prospective study included 104 patients receiving LEI due to lumbar radiculopathy. A midline or paramedian approach of LEI was determined with randomization. Among various factors, gender, age, body mass index (BMI), and diagnosis were analyzed using a subgroup that included 60 cases of only a paramedian approach., Results: Grades I, II (abrupt decrease), and III (gradual decrease) were found as patterns of epidural pressure decrease. Abrupt pressure decrease was more frequently observed in the paramedian group (P < 0.001). Age, gender, BMI, and diagnosis did not show any significant difference in frequencies between abrupt and gradual pressure decrease., Limitations: We could not match LOR sensation with epidural pressure decrease shown in the monitor., Conclusions: This study demonstrates that abrupt pressure decrease occurs more frequently with the paramedian approach. However, age, gender, BMI, or diagnosis did not affect the incidence of epidural pressure decrease., Key Words: Epidural, paramedian, midline, pressure decrease.

Objectives: To investigate the correlation between fatty infiltration in the multifidus muscle related to the involved nerve root and structural parameters associated with stenosis in patients with degenerative lumbar spinal stenosis (DLSS)., Patients and Methods: Sixty-four patients with single-segment DLSS at L4-5 were retrospectively enrolled. The fatty infiltration rate (FIR) of the multifidus muscle at L5-S1, lumbar lordosis and the cross-sectional area (CSA) of the structural parameters at L4-5, such as dural sac, disc bulge, ligamentum flava and vertebral body of L5 were measured on magnetic resonance images using ImageJ software. All enrolled patients were divided into an FIR < 25 % group and an FIR ≥ 25 % group according to the FIR of the multifidus muscle at L5-S1. The propensity scores matching and adjustment of potential covariates were performed to reduce the confounding bias between the two groups., Results: Lumbar lordosis in the FIR ≥ 25 % group was significantly lower than that in the FIR＜25 % group in both cohorts. The mean differences in lumbar lordosis of 14.16 degrees between the two groups in the complete cohort and of 14.23 degrees in the matched cohort remained significant after adjustment. The disc bulge CSA/ vertebral body CSA in the FIR ≥ 25 % group was greater than that in the FIR＜25 % group in both cohorts. The mean differences in the disc bulge CSA/ vertebral body CSA between the two groups of 0.67 in the complete cohort and 0.96 in the matched cohort were statistically significant after adjustment. There was no significant difference in the dural sac CSA/ vertebral body CSA and ligamentum flava CSA/ vertebral body CSA between the two groups in either cohort regardless of adjustment. Logistic regression analysis for FIR ≥ 25 % in the multifidus muscle at L5-S1 exhibited that the disc bulge CSA/ vertebral body CSA were independent risk factors with odds ratio (OR) of 8.52, while lumbar lordosis were independent protective factors (OR = 0.72)., Conclusions: The disc bulge at the stenosis segment and lumbar lordosis reduction may be correlated with fatty infiltration in the multifidus muscles at L5-S1 in patients with L4-5 single-segment DLSS., Competing Interests: Declaration of Competing Interest None of the authors has any potential conflict of interest. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript. And we state that we have full control of all primary data and that we agree to allow the journal to review our data if requested, (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Symptomatic calcification of the ligamentum flavum (CLF) is common in the cervical spine but rare in the thoracic spine. Rapidly progressing CLF in the thoracic spine has not been reported in the literature., Case Description: A 76-year-old Asian male experienced back pain after a fall and was diagnosed with osteoporotic vertebral fractures at T11 and L1. He was treated conservatively because of the lack of neurologic deficits. Nine months after the initial visit, he complained of progressive incomplete paraplegia. Magnetic resonance imaging and computed tomography of the thoracic spine showed CLF at T11-T12 severely compressing the spinal cord. This finding had not been seen on imaging studies at the initial visit. The patient underwent surgical resection of CLF and posterior instrumented spine fusion. Symptoms of muscle weakness recovered postoperatively., Conclusions: In this case, sequential imaging studies with a 9-month interval showed evidence of rapidly progressing thoracic CLF. The preceding osteoporotic vertebral fracture may have triggered the development of CLF., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Lumbar stenosis is characterized by a narrowing of the spinal canal in association with progressive degenerative changes in the lumbar spine and surrounding structures, including hypertrophy of the ligamentum flavum (LF)., Objectives: The aim of this study was to examine the usefulness of endoscope-assisted interlaminar lumbar decompression (EILD) for patients with lumbar stenosis and hypertrophy of the LF., Study Design: Retrospective study., Setting: Department of Anesthesiology and Pain Medicine, Neurosurgery at Wooridul Spine Hospital., Methods: A total of 51 patients were enrolled in this study. Outcomes were evaluated at baseline and at 2 weeks and 6 months postprocedure via the Numeric Rating Scale, Oswestry Disability Index (ODI), and Zurich Claudication Questionnaire (ZCQ)., Results: Mean posttreatment pain scores at 2 weeks and 6 months were significantly lower, and ODI scores were significantly decreased compared with baseline. ZCQ scores were also significantly decreased compared with pretreatment surveys. Two patients required reoperation within one month. At postprocedure 6 months, a>/= 50% reduction in pain score was recorded in 26 (80%) of 51 patients, and there was >/= 40% reduction in ODI score in 82% of patients. No serious complications including epidural bleeding, dural or neural injuries, or infection were recorded., Limitations: This study lacked secondary outcome substantiation. In addition, the follow-up period was short (< 6 months), and no patients had postprocedure magnetic resonance imaging. The number of patients was also small., Conclusions: EILD provided good outcomes and may be a reasonable treatment option for carefully selected patients with hypertrophy of the LF., Key Words: Spinal stenosis, ligamentum flavus, hypertrophy, decompression, endoxcope, minimally.

Background: Transthyretin wild-type (ATTRwt) amyloidosis is a systemic process resulting in deposition of misfolded transthyretin protein in several different tissues throughout the body. It is known to be a cause of progressive, life-threatening cardiomyopathy and lumbar spinal stenosis and carpal tunnel syndrome., Case Description: Here we present the case of a 71-year-old man who has clinical manifestations of all 3 entities over several years, providing a picture of the natural history of ATTRwt amyloidosis. This patient eventually underwent a heart transplant because of progressive cardiac amyloidosis (CA) resulting in end-stage heart failure. However, symptoms in carpal tunnel and lumbar spine manifested years before the symptoms of heart failure. ATTRwt amyloidosis may present as a clinical triad of lumbar stenosis, carpal tunnel syndrome, and heart failure. Recently developed medications have shown efficacy in slowing the progress of systemic and cardiac amyloidosis., Conclusions: Knowing that extracardiac symptoms may occur first, we propose that sending ligamentum flavum and flexor tenosynovium for pathologic evaluation may be a unique opportunity to screen and treat a population of patients at risk for developing CA and heart failure., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background and Objectives: This study evaluated the long-term durability of the minimally invasive lumbar decompression (MILD) procedure in terms of functional improvement and pain reduction for patients with lumbar spinal stenosis and neurogenic claudication due to hypertrophic ligamentum flavum. This is a report of 2-year follow-up for MILD study patients., Methods: This prospective, multicenter, randomized controlled clinical study compared outcomes for 143 patients treated with MILD versus 131 treated with epidural steroid injections. Follow-up occurred at 6 months and at 1 year for the randomized phase and at 2 years for MILD subjects only. Oswestry Disability Index, Numeric Pain Rating Scale, and Zurich Claudication Questionnaire were used to evaluate function and pain. Safety was evaluated by assessing incidence of device-/procedure-related adverse events., Results: All outcome measures demonstrated clinically meaningful and statistically significant improvement from baseline through 6-month, 1-year, and 2-year follow-ups. At 2 years, Oswestry Disability Index improved by 22.7 points, Numeric Pain Rating Scale improved by 3.6 points, and Zurich Claudication Questionnaire symptom severity and physical function domains improved by 1.0 and 0.8 points, respectively. There were no serious device-/procedure-related adverse events, and 1.3% experienced a device-/procedure-related adverse event., Conclusions: MILD showed excellent long-term durability, and there was no evidence of spinal instability through 2-year follow-up. Reoperation and spinal fracture rates are lower, and safety is higher for MILD versus other lumbar spine interventions, including interspinous spacers, surgical decompression, and spinal fusion. Given the minimally invasive nature of this procedure, its robust success rate, and durability of outcomes, MILD is an excellent choice for first-line therapy for select patients with central spinal stenosis suffering from neurogenic claudication symptoms with hypertrophic ligamentum flavum., Clinical Trial Registration: This study was registered at ClinicalTrials.gov, identifier NCT02093520.

Objective: To evaluate clinical feasibility and safety of percutaneous endoscopic decompression by a uniportal, unilateral approach for lumbar canal or lateral recess stenosis., Methods: In this retrospective study, the procedure was performed with endoscopic instruments in the same way as conventional microscopic laminotomy and flavectomy. Clinical outcomes (visual analog scale, Oswestry Disability Index, modified MacNab criteria) were evaluated. Surgical outcomes, including operative time, hospital stay, and complications, were recorded., Results: Decompression was performed in 213 patients (232 lumbar levels) for spinal canal or lateral recess stenosis (unilateral laminotomy, n = 80; bilateral laminotomy, n = 152). Mean follow-up period was 26.45 months. Mean visual analog scale for leg pain, and back pain and mean Oswestry Disability Index improved from 8.24%, 5.35%, and 67.8% at baseline to 1.93% (P < 0.001), 2.05% (P < 0.001), and 17.14% (P < 0.001) at final follow-up. Based on modified MacNab criteria, excellent or good results were obtained in 93.8% of patients. Average operative time was 105.3 ± 56 minutes. In the late period of the learning curve, mean operative time was shortened by two thirds, and mean hospital stay was 2.45 days. There were 12 cases of transient postoperative dysesthesia, 3 cases of motor weakness, and 6 cases of dural tear. No patient had postoperative infection, hematoma, or need for revision surgery for incomplete decompression., Conclusions: Percutaneous endoscopic decompression by a uniportal, unilateral approach is a safe, clinically feasible, and effective surgical technique for treatment of lumbar stenosis., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background and Objectives: Unintentional dural puncture is one of the most frequent complications of the epidural technique. One previous study suggested that atypical sonoanatomy of the ligamentum flavum/dura mater unit may be a risk factor for this complication. In this study, we describe the anatomy of the lumbar spine, assessed by magnetic resonance imaging (MRI) and ultrasound, in women sustaining unintentional dural puncture during epidural catheter placement for labor analgesia., Methods: We approached women who sustained a recognized unintentional dural puncture. Following consent, technical aspects of the epidural catheter placement were documented. Postpartum MRI of the lumbar spine and bedside spinal ultrasound were performed. Ultrasound images of the ligamentum flavum/dura mater unit in the transverse view were classified as typical, atypical, or inconclusive. Magnetic resonance imaging images were reviewed by a neuroradiologist, who was blinded to the level of the puncture., Results: We included 10 women with unintentional dural punctures in the study. In 5 of the 10 women, these dural punctures occurred despite epidural catheter insertion by experienced practitioners. These women had a mean body mass index of 28.5 kg/m (range, 24-38 kg/m). Two women suffered dural punctures twice. Ultrasound imaging in the paramedian view produced typical images in all patients. In the transverse view, 7 of 10 women showed atypical or inconclusive images, with atypical images seen at either L4/5 or L5/S1. Magnetic resonance imaging results revealed no anatomical abnormalities, with the exception of 1 woman who showed a ligamentum flavum gap away from the puncture site., Conclusions: Our results suggest that unintentional dural punctures occur in likely anatomically normal women. Furthermore, the transverse ultrasound views may fail to demonstrate typical ligamentum flavum/dura mater unit at the lower lumbar levels despite its confirmed presence by MRI.

Posterior decompression surgery which enlarges the spinal canal in cases with lumbar spinal stenosis is the most fundamental technique in spine surgery, but controversy still remains for the exact technique. Because nerve roots run under the ventral side on the superior articular process (SAP), achieving both facet joint preservation and nerve root decompression is problematic. In conventional laminotomies or laminectomies, medial facetectomies are performed to decompress the nerve root, but it is ideal to preserve the facet joints completely for preserving joint stability. We handle this problem with an original decompression technique, called "semicircumferential decompression." The main features of this procedure are an en bloc flavectomy and total preservation of facet joints. The procedure is performed under the microscope with a midline approach. The flavum is detached from the ventral surface of the SAP using a currete without disturbing the SAP. The facet joints are preserved completely. The advantage of an en bloc flavectomy is that we can remove the flavum attachment to the ventral surface of SAP totally without a medial facetectomy. Since 1991, we have performed this technique in more than 5000 cases. In this paper, we will explain the tips, pitfalls, and advantages of this technique.

Background: Posterior spinal bony prominences are commonly used as landmarks during posterior spinal surgery; however, the exact relationship of these structures with ligamentum flavum (LF) borders and attachments has not been clarified., Materials and Methods: Whole spines were removed en bloc from 20 embalmed human cadavers. Plain radiographs and computed tomography (CT) scans of each whole spine were taken, and then the spine was divided in two parts along the pedicle bases. The LFs were painted with contrast dye, and second radiographs and CT scans were taken again. Radiographic data were analyzed using CT image analyzer., Results: The craniolateral border of LF at four upper lumbar levels (from L1/2 to L4/5) located cranial to isthmus in both sides (3.5 mm), meanwhile, it located at or below isthmus in both sides at L5-S1 level (0.5 mm). In the midline, LF attached below the isthmus levels at four upper lumbar levels (4 mm), though it located in the same level of isthmus at L5-S1 (1 mm). The mean distance between medial border of pedicles and lateral border of LF increased from upper to the lower lumbar levels (6.5 mm at L1/2 - 11.4 mm at L5-S1). Distance between interlaminar space and cranial border of LF at the midline gradually increased from 8.2 mm at L1 toward 11.1 mm at L4, it was 9.3 mm in L5., Conclusions: From the data of new analytical method using contrasted LF and reconstructed CT, the detailed relations between bony prominence and the border of LF were uncovered. Based on these findings and reconstructed LF images superimposed on lamina, surgeons would design safe and adequate lumbar spinal decompression with imagination of overall pictures of the LF from the dorsal side., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Lumbar spinal canal stenosis (LSCS) is one of the most common spinal disorders in elderly people, with the number of LSCS patients increasing due to the aging of the population. The ligamentum flavum (LF) is a spinal ligament located in the interior of the vertebral canal, and hypertrophy of the LF, which causes the direct compression of the nerve roots and/or cauda equine, is a major cause of LSCS. Although there have been previous studies on LF hypertrophy, its pathomechanism remains unclear. The purpose of this study is to establish a relevant mouse model of LF hypertrophy and to examine disease-related factors. First, we focused on mechanical stress and developed a loading device for applying consecutive mechanical flexion-extension stress to the mouse LF. After 12 weeks of mechanical stress loading, we found that the LF thickness in the stress group was significantly increased in comparison to the control group. In addition, there were significant increases in the area of collagen fibers, the number of LF cells, and the gene expression of several fibrosis-related factors. However, in this mecnanical stress model, there was no macrophage infiltration, angiogenesis, or increase in the expression of transforming growth factor-β1 (TGF-β1), which are characteristic features of LF hypertrophy in LSCS patients. We therefore examined the influence of infiltrating macrophages on LF hypertrophy. After inducing macrophage infiltration by micro-injury to the mouse LF, we found excessive collagen synthesis in the injured site with the increased TGF-β1 expression at 2 weeks after injury, and further confirmed LF hypertrophy at 6 weeks after injury. Our findings demonstrate that mechanical stress is a causative factor for LF hypertrophy and strongly suggest the importance of macrophage infiltration in the progression of LF hypertrophy via the stimulation of collagen production., Competing Interests: There are no conflicts of interest concerning this manuscript.

Introduction: The purpose of this study was to determine whether radiographic findings associated with thoracolumbar burst fractures could also indicate the presence of posterior ligamentous complex (PLC) injuries, which were identified through short-tau inversion-recovery (STIR)-weighted MRI., Patients and Method: Sixty-four patients were surgically treated for thoracolumbar burst fractures between April 2007 and February 2014 at our institution. Twenty-four patients were excluded from this study because of the lack of STIR-weighted MRIs, and therefore 40 patients were included in this study. The patients were divided into two groups based upon the integrity of the PLC, which was evaluated using STIR-weighted MRI: a P group with a PLC injury and a C group without such injury. The following radiographic parameters were evaluated: loss of vertebral body height (LOVBH), local kyphosis (LK), vertebral body translation, canal compromise (sagittal transverse ratio, STR), interlaminar distance (ISD), supraspinous distance (SSD) and interspinous distance (ISD). Frankel scale score and total severity score (load sharing and thoracolumbar injury classification systems, respectively) were also evaluated., Results: Preoperative STIR-weighted MRI showed that 25 patients had a PLC injury (P group: 15 men and 10 women), and 15 patients did not have a PLC injury (C group: 8 men and 7 women). More patients in the P group had an LK>20°: 14 patients in the P group and 1 patient in the C group (p<0.01). The % SSD differed between the P and C groups (118.8%±53.4% and 88.0%±24.3%, respectively; p<0.05). Multivariate logistic analysis showed that an LK>20° was a risk factor for PLC injury in patients with thoracolumbar burst fractures (odds ratio, 55.5 [95% confidence interval, 1.30-2360.1]; p<0.05)., Conclusions: These results demonstrate that while LOVBH, vertebral body translation, and canal compromise do not correlate significantly with the presence of a PLC injury in patients with thoracolumbar fractures, an LK>20° and increased % SSD are associated with a PLC injury., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Study Design: A retrospective study of medium-term results., Objective: To describe a technique for posterior decompression using microsurgical lumbar flavectomy (MLF) without facetectomy, which is based on the anatomic features of the ligamentum flavum, and to examine the clinical outcomes of patients with lumbar spinal spondylolisthesis with lower extremity symptoms rather than low back pain, who underwent this procedure by 2 different approaches., Summary of Background Data: Posterior decompression with fusion has been the optimal and standard operative treatment for lumbar degenerative spondylolisthesis. Alternatively, minimally invasive procedures have been used for the treatment of lumbar degenerative spondylolisthesis with favorable outcomes., Methods: A bilateral laminotomy (BL group) was performed on 44 consecutive patients, and bilateral decompression by a unilateral approach (BDU group) was performed on 23 consecutive patients. The mean follow-up period was 7.0 years. The Japanese Orthopaedic Association score and recovery rate were obtained, and radiographic assessment was performed using plain radiograms on the lateral view while standing in flexion, neutral, and extension postures before surgery and at the final follow-up., Results: The Japanese Orthopaedic Association score at the final follow-up was improved in the BL and BDU groups, compared with that before MLF. The mean recovery rate was 72.4% and 68.4%, respectively. The mean % slip increased at the final follow-up, compared with that before surgery in both groups, except for the % slip in the extension posture in the BDU group. However, there was no significant difference in the dynamic % slip in the flexion-extension posture between before surgery and at the final follow-up., Conclusions: Clinical and radiologic parameters were not significantly different between the 2 groups. This technique of MLF using either approach did not increase the dynamic % slip and showed favorable medium-term clinical results in cases of lumbar degenerative spondylolisthesis.

Study Design: Retrospective, case-control study., Objective: The purpose of this study was to determine if thoracolumbar vertebral body collapse, translation, or canal compromise (CC) is associated with injury to the posterior ligamentous complex (PLC) or neurological elements., Summary of Background Data: Radiographical parameters, including loss of vertebral body height (LOVBH), vertebral body translation, local kyphosis (LK), and CC, are often used as indicators of spinal instability. The hypothesis of this study was that LOVBH greater than 50%, LK greater than 20°, translation greater than 3.5 mm, or CC greater than 50% is associated with ligamentous and neurological injury., Methods: Retrospective review of prospectively collected spinal cord injury database was performed. Inclusion criteria include consecutive patients with thoracolumbar burst fractures. Exclusion criteria include flexion-distraction injuries and pathological fractures. Computed tomographic scan measurements of the spine were performed by 2 experienced spine surgeons blinded to magnetic resonance imaging results. On magnetic resonance imaging, the supraspinous ligament, interspinous ligament, ligamentum flavum, facet joints, and disc were graded as intact, indeterminate, or disrupted. American Spinal Injury Association (ASIA) score and Frankel Scale score were recorded. Spearman correlation coefficients were calculated to evaluate relationships between vertebral body measurements, ligamentous injury, and neurological injury., Results: Forty-six patients were included in the study. Ten patients had kyphosis greater than 20°, 1 patient had kyphosis greater than 30°, and 9 patients had LOVBH greater than 50%. There were 34 patients with vertebral body translation greater than 3.5 mm and 15 patients with CC greater than 50%. Sixteen patients had ligamentous injury. There was a significant correlation between subjacent segment translation greater than 3.5 mm and ligamentous injury (R = 0.323, P = 0.029) and ASIA motor score (R = -0.379, P = 0.009). There was no significant correlation between ligamentous injury or neurological injury and the following threshold parameters: LOVBH greater than 50%, vertebral body kyphosis greater than 20°, caudal or cephalad interspinous widening greater than 7 mm, CC greater than 50%, and sagittal transverse ratio less than 0.48., Conclusion: The results of this study indicate that LOVBH greater than 50% and LK greater than 20° are not predictive of PLC injury in thoracolumbar burst fractures. Translation greater than 3.5 mm was associated with PLC injury. The PLC and neural elements should be directly assessed with magnetic resonance imaging if there is clinical concern.

Objective: To determine the prevalence of anatomic impediments to interlaminar lumbar epidural steroid injection (LESI) in a community-based population., Design: Cross-sectional observational study., Setting: Community-based., Participants: Older adults (N=333) sampled irrespective of back pain status., Interventions: Not applicable., Main Outcome Measures: Computed tomography evaluation of 5 potential anatomic impediments to interlaminar LESI at the L2-S1 spinal levels, including (1) ligamentum flavum (LF) calcification, (2) interspinous ligament (ISL) calcification, (3) spinous process (SP) contact, (4) the absence of epidural fat in the posterior epidural space, and (5) the presence of fat density superficial to the LF in the midsagittal plane. Independent variables included age, sex, body mass index (BMI), and current smoking., Results: LF and ISL calcifications were prevalent in 3% to 7% and 2% to 3% of spinal levels, respectively, without significant differences by spinal level. SP contact was most common at the L4-5 level (22%). Absence of posterior epidural fat was very common at L5-S1 (65%), but infrequent at other levels. The presence of midline fat density superficial to LF was most common at L5-S1 (55%). The prevalence of LF calcification, ISL calcification, and SP contact increased with age, but the prevalence of absence of posterior epidural fat and the presence of a midline fat density superficial to LF did not. Sex and smoking status were not associated with the prevalence of anatomic impediments, but higher BMI was associated with a lower prevalence of absence of posterior epidural fat., Conclusions: Anatomic impediments to interlaminar LESI were common in this community-based population, particularly at the L5-S1 spinal level. Because of the high overall prevalence of anatomic impediments, and differences in prevalence by spinal level, knowledge of the distribution and frequency of these impediments may aid in aspects of decision-making for the interventional spine physician., (Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

We report the case of a 72-year-old man who underwent surgery for a mobile spondylolisthesis L4-L5. Six months later, magnetic resonance imaging revealed an extradural cyst of the ligamentum flavum at L5-S1, which was then removed. Histological examination revealed a ganglion cyst of the ligamentum flavum. Cyst formation could be explained primarily according to the natural history of chronic degenerative disease of spine elements. Nevertheless, we could also consider the cyst formation as demonstrative of an adjacent segment syndrome: hypermobility of the L5-S1 segment just below three fixed vertebral segments would have triggered the mechanical stress necessary for L5-S1 ligamentum flavum degeneration.

Ultrasound has been proposed for aiding epidural needle insertion, but challenges remain in differentiating spinal structures due to noise, artifacts, and inexperience by anesthesiologists in ultrasound interpretation. Moreover, the anesthesiologist needs to measure relevant distances while preserving sterile conditions; therefore, interaction with the ultrasound controls must be minimal. Automated measurement is needed. Beam-steered ultrasound images are captured and spatial compounding is used to improve image quality. Phase symmetry is used to enhance bone (lamina) and ligamentum flavum (LF) ridges. A lamina template is matched to this ridge map using Pearson's cross-correlation, and the most likely lamina positions are found. Then, the lamina is traversed using a LF template with the Pearson's cross-correlation, and the location of the LF is obtained. Tests are performed on 39 sets of compounded ultrasound images in the L2-3 and L3-4 levels of the spine in the paramedian plane. The proposed algorithm can detect the laminas in 38 of the 39 images, and the LF in 34 of the 39 images. In successful detections, the automatic detections versus manual segmentation has an rms error of 0.64 mm and average error 0.04 mm, versus independent sonographer-measured depth has a root-mean-squared error of 3.7 mm and average error 2.5 mm, and versus the actual needle insertion depth has a root-mean-squared of 5.1 mm and average error -2.8 mm. The computational time is 4.3 s on a typical personal computer. The accuracy, reliability, and speed suggest this method may be valuable for helping guide epidurals in conjunction with the traditional loss-of-resistance method.

Study Design: A descriptive computed tomography (CT) study of the ligamentum flavum (LF) thickness in individuals with normal and stenotic lumbar spines., Objective: To establish standards for normal and pathologic range of LF thickness and its asymmetry as indicated in CT images and to examine its association with vertebral body size, age, and gender., Summary of Background Data: LF lines a considerable part of the posterior and lateral walls of the spinal canal and is a major role contributor to spinal canal stenosis. Due to methodologic deficiencies (e.g., small sample size, lack of control for vertebral body size, gender, and age), the normal range of LF thickness is still controversial. Furthermore, data on important aspect of LF thickness such as left-right differences are missing., Methods: Two groups of individuals were studied. The first group included 65 individuals with lumbar spinal stenosis (LSS) (mean age: 66 +/- 9.7 years) and the second, 150 individuals (mean age: 52 +/- 19 years) without LSS-related symptoms. LF thickness was measured on CT images (Philips Brilliance 64), obtained from axial plane scan at the intervertebral disc level. Measurements were performed at the levels of L3-L4, L4-L5, and L5-S1. Analysis of variance and t test were carried out to evaluate the association between LF thickness and demographic factors., Results: Absolute and relative LF thickness were significantly greater in the LSS group at the levels of L3-L4 and L4-L5 on both sides, compared to control group (P < 0.05). LF thickness was independent of gender (absolute and relative thickness). Even though LF thickness at all levels significantly increases with age, significant changes after the age of 60 occurred only at L3-L4. Significant asymmetry in LF thickness was found at L3-L4 (2.9 +/- 0.90 mm on the right vs. 2.76 +/- 0.90 mm on the left) and L5-S1 (3.42 +/- 1.1 mm on the right vs. 3.22 +/- 1.22 mm on the left) (P < 0.05)., Conclusion: LF thickness is an age-dependent and gender-independent phenomenon. LF is significantly thicker on the right side. The borderline between normal and pathologic LF thickness should not be set at 4 mm.

Spinal anesthesia may be challenging in patients with poorly palpable surface landmarks or abnormal spinal anatomy. Pre-procedural ultrasound imaging of the lumbar spine can help by providing additional anatomical information, thus permitting a more accurate estimation of the appropriate needle insertion site and trajectory. However, actual needle insertion in the pre-puncture ultrasound-assisted technique remains a 'blind' procedure. We describe two patients with an abnormal spinal anatomy in whom ultrasound-assisted spinal anesthesia was unsuccessful. Successful dural puncture was subsequently achieved using a technique of real-time ultrasound-guided spinal anesthesia. This may be a useful option in patients in whom landmark-guided and ultrasound-assisted techniques have failed.

Background and Objectives: Lumbar canal stenosis is a common source of chronic low back and leg pain. Minimally Invasive Lumbar Decompression (mild(R)) is a new minimally invasive treatment for pain relief from symptomatic central lumbar canal stenosis. The procedure involves limited percutaneous laminotomy and thinning of the ligamentum flavum in order to increase the critical diameter of the stenosed spinal canal. The objective of this technical report is to evaluate the acute safety of the mild procedure., Methods: Manual and electronic chart survey was conducted by 14 treating physicians located in 9 U.S. states on 90 consecutive patients who underwent the mild procedure. Patients within local geographical practice areas were selected in keeping with product Instructions For Use. Those patients requiring lumbar decompression via tissue resection at the perilaminar space, within the interlaminar space and at the ventral aspect of the lamina were treated. Data collected included any complications and/or adverse events occurring during or immediately following the procedure prior to discharge., Results: Of 90 procedures reviewed, there were no major adverse events or complications related to the devices or procedure. No incidents of dural puncture or tear, blood transfusion, nerve injury, epidural bleeding, or hematoma were observed., Limitations: Data were not specifically collected; however, regardless of difficulty, in this series none of the procedures were aborted and none resulted in adverse events. Efficacy parameters were not collected in this safety survey., Conclusions: This review demonstrates the acute safety of the mild procedure with no report of significant or unusual patient complications. To establish complication frequency and longer-term safety profile associated with the treatment, additional studies are currently being conducted. Survey data on file at Vertos Medical, Inc.

Background and Objectives: Spinal ultrasound offers valuable information to facilitate the placement of lumbar neuraxial anesthesia. Lumbar spine sonograms are unique, and aspects may appear atypical at times, particularly the ligamentum flavum (LF). The objective of this study was to describe the sonoanatomy of the lumbar spine and to determine the frequency of atypical images of the LF in pregnant women at term., Methods: Using a 2-5 MHz curvilinear transducer, we imaged all the lumbar interspaces in the left and right paramedian longitudinal and transverse planes. The images were categorized as typical, atypical or inconclusive. The primary outcome was the presence of an atypical image of the LF in the transverse plane. The distance from the skin to the epidural space, and the dural sac width, were also measured., Results: One hundred subjects were studied. All the images in the longitudinal planes were conclusive and typical, whereas the number of inconclusive images in the transverse plane increased from L1-L2 to L5-S1 (1, 0, 4, 9, and 34, respectively). The incidence of atypical LF images in the transverse plane was 2.0% at L1-L2, 1.0% at L2-L3, 3.1% at L3-L4, 19.8% at L4-L5, and 28.8% at L5-S1., Conclusions: The paramedian longitudinal sonograms of the lumbar spine are of superior quality to those obtained in the transverse plane. When using the transverse approach, a high incidence of inconclusive sonograms should be expected in the lower segments. The incidence of atypical LF images, especially in the upper lumbar segments, warrants further investigation because it can have implications for the epidural technique.

Background and Objectives: Preprocedural lumbar ultrasound is a valuable tool to assess anatomical landmarks and predict the depth of the epidural space. Variations of the ligamentum flavum sonoanatomy are occasionally observed; however, no literature is available as to their incidence or clinical significance. We hypothesize that abnormal sonoanatomy of the lumbar spine detected by ultrasound can be associated with an increase in unintentional dural punctures. This study was undertaken to determine if the sonoanatomy of the lumbar spine of patients who had documented unintentional dural punctures differs from that of patients with a history of uneventful epidural placement for labor analgesia., Methods: Ultrasound of the entire lumbar spine was performed on 18 patients with a documented history of unintentional dural punctures, and 18 volunteers with a history of uneventful labor epidurals. At each interspace, we studied the quality of the ligamentum flavum (normal or abnormal), the symmetry of the bony structures (symmetric or asymmetric), and the distance from the skin to the ligamentum flavum. These parameters were compared in both groups., Results: The incidence of asymmetric sonoanatomy and the distance from the skin to the ligamentum flavum was similar in both groups. The incidence of abnormal ligamentum flavum sonoanatomy was higher in the dural puncture group (overall odds ratio for the 5 interspaces was 8.21, 95% confidence interval 3.07-22.0, P < .0001)., Conclusions: Abnormal sonoanatomy of the ligamentum flavum may represent anatomical variations of this structure, which may be related to an increased incidence of unintentional dural punctures during epidural placements.

Background and Objectives: Epidural cannulation is technically difficult in children who have small anatomic structures. Ultrasound information regarding the distance of skin-to-ligament flavum may be useful, leading to an increase in success rate without dural puncture. This study was performed to assess whether ultrasound-measured, skin-to-ligament flavum distance would reflect the needle depth during epidural puncture in infants and children., Methods: The study compromised 180 children, aged 2 to 84 months, undergoing urologic surgery. After induction of anesthesia, ultrasound images of the longitudinal median and transverse views were acquired from L4-L5 in lateral decubitus position. Measured distance of skin-to-ligament flavum in each view was compared with the perpendicular skin-to-epidural depth, which was obtained from needle depth and angle by use of a trigonometric ratio equation. Additionally, we evaluated the ultrasound visibility of the ligament flavum and dura mater, number of puncture attempts, and complications., Results: The correlation coefficient between measured distance and perpendicular epidural depth was slightly higher in longitudinal median view (R2 = 0.848) than in transverse view (R2 = 0.788). The visibility of ligament flavum and dura mater was "good" in 91 and 170 of 180 patients, respectively, and "sufficient" in the remaining subjects. The epidural space was located on first puncture attempt in 179 of 180 cases (99.4%). No incidents of dural puncture or bloody tap occurred., Conclusions: Ultrasound, particularly in the longitudinal median view, provides accurate information on the distance of skin-to-ligament flavum in infants and children. With reference to the measured distance, epidural puncture can be performed with minimal risk of dural puncture (upper limit of 95% CI = 1.67%).

A newly designed technique for preservation of the ligamentum flavum (LF) during the lumbar discectomy is presented. This technique allows the evacuation of the lumbar herniated disk, without removal or laminar disinsertion of the LF. This ligament is smoothly dissected longitudinally in its more lateral portion, obtaining, after discectomy, the contact of the 2 margins with restoration of its functional integrity. Forty-five patients were operated on with this technique. We feel that this technique could offer advantages in reduction of epidural fibrosis and of decreased risk of dural injury, and is helpful to the surgeon in the case of recurrence of discal herniation.

Background: Cysts of the ligamentum flavum are rare and unusual causes of spinal compression., Methods: We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the possible etiologies and pathophysiologic mechanisms according to the available literature., Conclusion: This entity is clearly different from the synovial facet-joints or ganglion cysts.

The ligamentum flavum is considered to be one of the important causes of radiculopathy in lumbar degenerative disease. Although there have been several reports anatomically examining the positional relationship between the ligamentum flavum and nerve root, there are few reports on ventral observation. The purpose of this study is to clarify the shape of the ligamentum flavum seen ventrally, and to obtain anatomic findings related to nerve root compression. The subjects were 18 adult embalmed cadavers, with an average age of 78 years at the time of death. The ventral shapes of the ligamentum flavum were observed. The relationships between the morphological change of the ligamentum flavum and nerve root compression or radiographic findings were statistically evaluated. Among the shapes of the ligamentum flavum, bulging of the ligament was most frequently observed. Proximal bulging indicates the type with the cranial portion bulging from the subarticular zone to the foraminal zone of the ligamentum flavum. In this type associated with a decrease in disc height, nerve root compression was frequently observed. Thus, we could more realistically grasp the relationship between bulging morphology of the ligamentum flavum and nerve root compression.

Purpose: Comparison of metric analysis of spinal structures, exemplarily of the ligamentum flavum, obtained with computed tomography (CT) (soft tissue window and bone window) and magnetic resonance imaging (MRI) (T1 and T2 weighted images)., Material and Methods: Forty-six lumbar ligamenta flava of 46 patients (25 women and 21 men) were examined at a Somatom Plus 4 (Siemens, Erlangen, FRG) and at a 1.5 T clinical scanner (Magnetom Vision, Siemens, Erlangen, FRG). Two independent neuroradiologists measured the thickness of the ligamenta flava in mm. Statistics included Pearson's correlation coefficient and the intra-class correlation coefficient., Results: Mean values did not differ significantly. The correlation coefficients varied between 0.69 and 0.98. The best correlation occurred comparing the same techniques in different windowing and weighting (CT: r = 0.98; MRI: r = 0.95). Correlating different techniques the combination of CT bone window and T1 weighted images presented the best result (r = 0.75)., Conclusions: Because of the excellent correlation between the examined techniques CT as well as MRI can equally be used to measure distances of spinal structures.

Objective: The objective of this work was to investigate the clinical and histologic features of patients with pseudocystic lesions of the ligamentum flavum in the lumbar region of the spinal canal and ascertain the existence of genuine ligamentum flavum pseudocysts., Methods: Retrospective chart and histologic study of a patient cohort with lumbar radiculopathy due to a cystic intraspinal lesion and who had undergone decompressive surgery was conducted. Intraoperatively, the stenosing process had been found to be different from common etiologic entities and had been submitted for histologic examination., Results: The 33 patients with symptoms and signs of lumbar radiculopathy were between 48 and 85 years of age (mean 63.5 years). Twenty (61%) of them were women. All patients showed degenerative changes of the bony structures of the spine by conventional radiography. Segmental instability due to degeneration of the lumbar spine was present in 45%. Computed tomography and/or magnetic resonance imaging showed a cystic lesion. Clinical and histologic examination confirmed their origin from within the severely degenerated ligamentum flavum., Conclusions: Radiologic, surgical, and histologic findings suggest that the pseudocystic degeneration of the ligamentum flavum represents a genuine entity that is associated with degenerative changes of the structures of the respective lumbar spine segment. These pseudocystic lesions may compress the adjacent nerve roots, provoking symptoms and signs of radiculopathy. The findings suggest that the surgical treatment not only must consist of removal of the pseudocyst but must also include a radical extirpation of the ligamentum flavum surrounding the pseudocyst to avoid recurrence of such a lesion.

Study Design: A prospective study of 12 patients with thoracolumbar spinal fractures was conducted., Objective: To assess the feasibility of ultrasound examination for posterior ligament complex injury in thoracolumbar spinal fractures., Summary of Background Data: In posterior ligament complex injury of thoracolumbar spine fracture, the reliability of magnetic resonance imaging (MRI) for diagnosis has been reported. Nevertheless the usefulness of ultrasound for diagnosis has not been studied, whereas diagnostic ultrasound has been applied in the musculoskeletal system., Methods: Two healthy volunteers without a history of spinal trauma were recruited for pilot examination of the ultrasound procedure to access normal findings of the posterior ligament complex. This study investigated 12 thoracolumbar spine fractures. Four were flexion distraction injury; six were stable or unstable burst fractures; and two were simple compression fractures. Osteoporotic spine fractures were excluded from this study. Ultrasound was performed over the injured area by an experienced musculoskeletal radiologist in addition to radiography and MRI. Five patients underwent operative procedures to stabilize the fractured spine. Imaging data and operative findings were correlated with ultrasound examination., Results: In the patients who did not undergo surgery, agreement in diagnosis between MRI and ultrasound was moderate (5 of 7). Difficulty evaluating ligament status was encountered when the region of interest was the lower thoracic level (T10, T11, T12) because of long overlapping spinous processes. In the patients who underwent surgery, correlation between MRI, ultrasound, and operative findings was excellent, especially in diagnosing the status of the supraspinous and interspinous ligaments. Nevertheless, it is impossible to visualize deep-seated structures (i.e., ligamentum flavum, deep muscles of the spine, and facet joint) with ultrasound., Conclusions: This study demonstrated the excellent diagnostic ability of ultrasound to detect the status of the supraspinous and interspinous ligaments, especially in patients who undergo surgery. Although ultrasound examination appears to be less sensitive than MRI in predicting ligament status, the cost effectiveness of ultrasound and its use as an alternative to MRI in special situations (i.e., patients with pacemaker, ferromagnetic implant, or severe claustrophobia) should be emphasized. More clinical data concerning the sensitivity, specificity, and accuracy of ultrasound examination should be addressed in future studies.

Epidural anaesthesia is an important analgesia technique for obstetric delivery. During pregnancy, however, obesity and oedema frequently obscure anatomical landmarks. Using ultrasonography, we investigated the influence of these changes on spinal and epidural anatomy. We examined 53 pregnant women who were to receive epidural block for vaginal delivery or Caesarean section. The first ultrasound imaging was performed immediately before epidural puncture; the follow-up scan was done 9 months later. The ultrasound scan of the spinal column was performed at the L3/4 interspace in transverse and longitudinal planes, using a Sonoace 6000 ultrasonograph (Kretz, Marl, Germany) equipped with a 5.0-MHz curved array probe. We measured two distances from the skin to the epidural space: the minimum (perpendicular) and the maximum (oblique) needle trajectory. The quality of ultrasonic depiction was analysed by a numerical scoring system. An average weight reduction of 12.5 kg had occurred by the follow-up examination. During pregnancy, the optimum puncture site available on the skin for epidural space cannulation was smaller, the soft-tissue channel between the spinal processes was narrower, and the skin-epidural space distance was greater. The epidural space was narrower and deformed by the tissue changes. The visibility of the ligamentum flavum, of the dura mater and of the epidural space decreased significantly during pregnancy. Nevertheless, ultrasonography offered useful pre-puncture information. Thus far, palpation has been the only available technique to facilitate epidural puncture. Ultrasound imaging enabled us to assess the structures to be perforated. We anticipate that this technique will become valuable clinically.

Degenerative spinal stenosis of the lumbar spine is caused by many factors, some of which include: disc herniation, ligamentum flavum and facet hypertrophy, spondylolisthesis, and compression fracture. Most often the stenosis is caused by a combination of these factors. The imaging modalities in routine use to evaluate these conditions are computed tomography, magnetic resonance imaging and computed tomography-myelogram. They each have their advantages and disadvantages although any one of these modalities can adequately diagnose lumbar stenosis. The overall accuracy rate of computed tomography, magnetic resonance imaging, and computed tomography-myelogram has been reported to be similar and even complimentary. It is recommended that the least invasive modality be performed first. Magnetic resonance imaging should be the first choice because it does not require ionizing radiation or contrast injection. The aim of the current study is to present the common causes of lumbar stenosis. Where appropriate, each case is shown with images from each modality so that their similarities and differences can be highlighted.

We report two very rare cases of bilateral synovial cyst of the lumbar spine arising at the L4-L5 level. The diagnosis was made by CT without any ambiguity. The reported lesions illustrate almost the complete panel of CT findings in synovial cyst of the spine including gas formation, marginal calcifications, bone erosion of the adjacent lamina, and in one case the original development of an intracystic calcified nodule. The symptoms of the two patients improved with medical treatment only and spontaneous regression of the calcified cysts was confirmed in one case.