Ligamentum Flavum Research Articles

Abstract 4115801: Assessing Prevalence of Cardiac Amyloidosis at the Time of Spinal Laminectomy for Spinal Stenosis

Introduction: Cardiac amyloidosis (CA) involves deposition of amyloid fibrils within cardiac myocardium, resulting in heart failure. Recent studies have shown an association between amyloid deposition in the ligamentum flavum (LF) and development of CA. Our study aims to investigate the prevalence of CA in patients identified with amyloid deposition in their LF at the time of spinal laminectomy for spinal stenosis, employing a comprehensive approach integrating multi-modality imaging and laboratory testing. Methods: This is a retrospective study of patients age >50 years old who underwent spinal laminectomy for non-congenital spinal stenosis or spondyloarthropathy. LF tissue samples obtained during surgery were examined histologically for amyloid deposition. Patients with positive findings underwent testing, including serum markers, echocardiography, and 99mtechnetium pyrophosphate (99mTcPYP) scintigraphy. Additionally, cardiac magnetic resonance imaging (cMRI) was obtained when clinically appropriate to assess for CA. Results: Among the 197 enrolled patients, 39 (19.3%) exhibited amyloid deposition in LF tissue. Patient demographics and clinical characteristics did not significantly differ between the positive and negative groups (Table 1). Of the 39 amyloid positive specimens, subtyping using mass spectrometry identified 1 (3%) light-chain, 28 (72%) transthyretin (TTR), and 10 (25%) were unable to be subtyped. Of the 28 TTR positive patients, 8 were of the wild type genotype. Furthermore, 18 of the 28 TTR patients underwent 99mTcPYP scintigraphy, of which none had cardiac uptake consistent with TTR amyloidosis; the other 10 declined work up. Of the 10 untyped patients, 6 had 99mTcPYP scintigraphy with none of the patients having cardiac uptake. Adjunctive cMRI in select positive patients showed findings inconsistent with amyloid deposition. Serum NT-proBNP, Troponin T, and serum pre-albumin levels were similar between groups. Conclusion: Amyloid deposition in LF tissue did not correlate with cardiac manifestations of amyloidosis at the time of surgery. Longitudinal investigation is ongoing to better understand the relationship between amyloid deposition in LF tissue and the development of CA over time.

Pathogenesis of thoracic ossification of the ligamentum flavum.

Thoracic ossification of the ligamentum flavum (TOLF) is characterized by ectopic ossification of the ligamentum flavum in the thoracic spine and is considered the main cause of thoracic spinal stenosis and spinal cord disease. Osteoblast specific transcription factor Osterix (Osx) is required for bone formation, and there is no bone formation or ossification without Osx. Surgical intervention is recognized as the only effective method for TOLF treatment with set of complications. However, underlying mechanisms of TOLF are not well understood. This paper summarizes the pathogenesis of TOLF. Some relevant factors have been discussed, such as mechanical stress, genetic susceptibility genes, endocrine and trace element metabolism abnormalities, which may associate with TOLF. More recent studies using proteomics technology and RNA sequencing approach have discovered that some new factors participate in TOLF by upregulation of Osx gene expression including inflammatory factors. TOLF is a unique disease involving multiple factors. On the other hand, studies on TOLF pathogenic mechanism may provide new ideas for finding possible upstream regulatory factors of Osx and further developing novel drugs to stimulate new bone formation to treat osteoporosis.

Contralateral Sublaminar Approach in Lumbar Spine With Unilateral Biportal Endoscopy

Unilateral biportal endoscopy (UBE) can be used to treat common lumbar pathologies, such as synovial facet cysts, foraminal disc herniations, and foraminal stenosis via a contralateral sublaminar approach. Due to the ultra-minimally invasive technique, UBE can reduce damage to anatomical structures, thereby reducing postoperative pain and allowing faster recovery. The patient is placed prone on a Wilson frame or bolsters. Fluoroscopy is used to identify the midline and medial pedicle line in the anterior-posterior projection. Spinal needles can aid to identifying portals’ trajectory in the lateral fluoroscopic projection. The procedure is performed via 2 separate portal incisions. The endoscope is introduced through the viewing portal and the surgical instruments through the working portal. Soft tissue dissector is used to create a working area over the spinous process-lamina junction. Bony shaving and drilling start at the target area and continue medially underneath the base of the spinous process until the midline and contralateral ligamentum flavum are identified. Contralateral ligamentum flavum is excised, exposing thecontralateral thecal sac, traversing nerve root, and lateral recess. The contralateral disc space, annulus, and superior articulating process are then identified and the offending pathology can be addressed under direct visualization. Meticulous hemostasis and close attention to outflow should be maintained to reduce the risk of complications. The steps of this procedure closely resemble those of traditional microscopic “over-the-top” techniques, including the surgical instruments used through the working portal. In this video, authors present the surgical technique of the contralateral sublaminar approach in the lumbar spine with UBE.

Unilateral Biportal Endoscopic Decompression for Thoracic Spinal Stenosis Secondary to Ossification of the Ligamentum Flavum

Ossification of the ligamentum flavum (OLF) in the thoracic spine is a cause of thoracic myelopathy that is more commonly found in East Asian populations (Koreans, Japanese, Chinese) than in others. Early diagnosis and sufficient surgical decompression can improve the functional prognosis for thoracic OLF. Surgical decompression is necessary and should be done as soon as the symptoms develop. There is a wide range of possible treatments, from standard open laminectomy to endoscopic decompression surgery. This video demonstrates the least invasive technique of decompressive laminectomy with bilateral decompression and removal of thoracic OLF through unilateral biportal endoscopic spinal surgery. The authors present the case of an 81-year-old male patient who presented with bilateral lower extremity weakness, numbness, pain, and ataxia. Magnetic resonance imaging and computed tomography scans of the whole spine showed the presence of OLF with severe spinal canal stenosis and a cord signal change at the T9–10 level. He underwent biportal endoscopic decompression and removal of thoracic OLF at T9–10. On the discharge day (postoperative day 7), motor power and pain had significantly improved. He could stand and independently ambulate with a walker.

ATTR cardiac amyloidosis after lumbar spinal stenosis- a prospective cohort study

Abstract Background Systemic wild type transthyretin (ATTRwt) amyloidosis is underdiagnosed and generally diagnosed in manifest cardiac disease. Lumbar spinal stenosis (LSS) might be an early sign of ATTRwt and a possible screening target for early diagnosis. Aim To characterize patients with transthyretin amyloid deposits in ligamentum flavum six years after surgery for lumbar spinal stenosis, and assess prevalence of undiagnosed cardiac amyloidosis. Materials and methods In this prospective cohort study, 21 patients who had surgery for LSS in 2016-2018 and grade 3-4 ATTR deposits in ligamentum flavum, without manifest cardiac amyloidosis (CA) were followed up in 2022-2023, including biomarkers and multimodality cardiac imaging. Results Median age at follow-up was 79 years and 62% were male; 16% (3/19) of patients had DPD-scintigraphy and were diagnosed with ATTRwt cardiac amyloidosis. 48% (10/21) had a history of other tenosynovial conditions that associate to ATTRwt amyloidosis. on echocardiography. Conclusion In this prospective cohort study, 16% of patients were diagnosed with ATTRwt cardiomyopathy after a median of six years following surgery for lumbar spinal stenosis. These findings strengthen the hypothesis that LSS is a possible manifestation of ATTRwt amyloidosis and that analysis for amyloid in connective tissue and subsequent cardiac follow-up is of value.

Thoracic hypertrophied ligamentum flavum: A retrospective study of pre-operative factors and surgical outcome

Objectives: Thoracic hypertrophied ligamentum flavum (HLF) is a rare cause of thoracic myelopathy which requires surgical treatment. The study aims to analyze the pre-operative factors and surgical outcomes in patients with thoracic myelopathy secondary to HLF. Materials and Methods: This is a retrospective study of patients who underwent surgery for thoracic myelopathy due to HLF at a single center from December 2015 to November 2023. We included patient’s demographic data, clinical symptoms, radiological details, operative details, and outcome. We used Nurick’s grading system for outcome evaluation in pre-operative, post-operative, and follow-up. Relationship of various pre-operative parameters was evaluated with surgical outcomes on binary scale (favorable group [Nurick’s grade 1 and 2] and unfavorable outcome [Nurick’s grade 3–5]) using univariate and multivariate analysis. Results: A total of 57 patients were included in the study. On analyzing various prognostic factors with respect to favorable and unfavorable outcomes using univariate analysis, four factors came out to be statistically significant which were segments involved (multi vs. single segment involvement) (P < 0.05), walking difficulty (P < 0.05), intramedullary signal changes on T2-weighted magnetic resonance imaging (MRI) (P < 0.001), and pre-operative Nurick’s grade (P < 0.001). On multivariate analysis, only one factor, pre-operative Nurick’s grade came out statistically significant. Conclusion: Various factors are important in predicting the outcome of a patient with thoracic myelopathy secondary to HLF. The most important of which is pre-operative Nurick’s grade. Other factors that also affect the outcome are the presence of multisegmented disease and intramedullary T2 signal changes on MRI.

Evaluating the efficacy of a cost-effective, fully three-dimensional-printed vertebra model for endoscopic spine surgery training for neurosurgical residents.

A fused deposition modeling three-dimensional (3D)-printed model of the L4-5 vertebra for lumbar discectomy was designed. The model included separately printed dura mater, spinal cord, ligamentum flavum, intervertebral disc (from thermoplastic polyurethane), and bony structures (from polylactic acid), and the material cost approximately US$ 1 per model. A simple plumbing endoscope was used for visualization. Dura mater injury was assessed by painting two layers on the dura mater, which peeled off with trauma. Endoscopic spine surgery is a subject of high interest in neurosurgery given its minimally invasive nature; however, it has a steep learning curve. This study evaluated the effectiveness of a cost-efficient 3D-printed model when teaching this technique to neurosurgery residents. Only a few studies have investigated the efficacy of such a model. Eight residents with >2 years of training participated. Residents performed the procedure bilaterally and twice at 1-week intervals. From the 32 surgeries, four were excluded because of facet removal (as it widened the surgical corridor), leaving 28 surgeries for analysis. Initial surgeries demonstrated a mean operation time of 21 minutes 18 seconds (standard deviation [SD], 2 minutes 32 seconds), which improved to a mean of 6 minutes 45 seconds (SD, 37 seconds) in the fourth surgery (F(3, 17)=19.18, p <0.0001), demonstrating a significant reduction in surgical time over successive surgeries. The median area with the paint removed decreased, from 161.80 (85.55-217.83) to 95.13 mm2 (12.62-160.54), (F(2.072, Inf)=2.04, p =0.128); however, this was not significant. Resident feedback indicated high satisfaction with the educational value of the model. The developed fully 3D-printed model provides a viable and scalable option for neurosurgical training programs, enhancing the learning experience while maintaining low costs. This model may be an excellent stepping stone for learning lumbar spine endoscopy, acclimating to the two-dimensional view, progressing to cadaver models, and, eventually, independent surgery.

Laminoplasty and In-Site Regrafting for the Treatment of Thoracic Ossification of the Ligamentum Flavum: A Surgical Technique.

Current surgical strategies for thoracic ossification of the ligamentum flavum (TOLF) are denounced by thoracic kyphosis, loss of spinal motion range, etc. A new surgical technique, laminoplasty and in-site regrafting (LPIR), was modified to address the problems. This study aimed to report the safety and feasibility of LPIR for TOLF treatment. This retrospective study reported the outcome of eight consecutive patients (3 males and 5 females, mean age 52.87 years) with TOLF who underwent LPIR surgery from January 2019 to March 2024. Pre- and post-operative data including x-ray, computerized tomography (CT), magnetic resonance imaging (MRI), the modified Japanese Orthopedic Association score (mJOA), the visual analog scale (VAS), and complications were collected to evaluate the outcome. All surgeries were performed successfully, significantly alleviating symptoms postoperatively. During an average follow-up period of 28.63 months, the VAS score reduced from 4.50 ± 1.00 pre-operatively to 1.63 ± 0.48 on the third post-operative day and further reduced to 0.50 ± 0.70 during the last follow-up. The mJOA score increased from 3.63 ± 0.70 pre-operatively to 6.13 ± 0.78 on the third postoperative day and further increased to 8.88 ± 1.27 during the last follow-up. No severe complications were observed. LPIR exhibited significant safety and feasibility for treating TOLF, offering a novel strategy for managing this problem.

N6-methyladenosine-modified circCDK14 promotes ossification of the ligamentum flavum via epigenetic modulation by targeting AFF4

BackgroundThe ligamentum flavum (LF) is an important anatomical structure of the spine. Ossification of the LF (OLF) has become the leading cause of thoracic spinal stenosis. Circular RNAs (circRNAs) and N6-methyladenosine (m6A) modification are reported to be associated with several human diseases. However, the role of circRNAs and m6A modification in the pathogenesis of OLF has not been fully investigated. Here, we aimed to explore the vital function of circRNAs and m6A modification in OLF.Materials and methodsWe analysed the circRNA expression of 4 OLF tissues and 4 normal LF tissues using bioinformatic analysis and identified circCDK14 for further analysis. We investigated the effects of circCDK14 on the osteogenic differentiation of LF cells. We observed that circCDK14 regulated its target genes by binding to miRNAs as a miRNA sponge. Moreover, the circRNA pull-down assay indicated that RNA-binding proteins might regulate the expression of circCDK14 via m6A modification.ResultsCircCDK14 was significantly upregulated in OLF tissues compared to normal LF tissues. Overexpression of circCDK14 promoted the osteogenic differentiation of LF cells. Mechanistically, CircCDK14 promoted the expression of ALF transcription elongation Factor 4 (AFF4) by serving as a sponge for miR-93-5p. Moreover, Wilms tumour 1-associated protein (WTAP) increased the stability of circCDK14 via N6-methyladenosine modification.ConclusionThe m6A-modified CircCDK14 binding to miR-93-5p played an important role in the osteogenesis of LF cells by targeting AFF4, providing a promising therapeutic target for OLF.

Prevalence, Radiological, and Pathological Findings of Ossification and Calcification of the Lumbar Spinal Ligamentum Flavum: A Comparative Study with Thoracic Lesions.

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.

Multilevel thoracic myelopathy: full-endoscopic solution. Illustrative case.

Thoracic myelopathy is relatively uncommon but, when present, causes significant disability. Early surgical intervention is often recommended for patients with myelopathy with compression at multiple levels. Surgical approaches and techniques for thoracic myelopathy have evolved from traditional open spine surgery to less invasive full-endoscopic spine surgery. This article reports an unusual presentation of a 31-year-old male with thoracic myelopathy due to thoracic disc herniation (TDH) at the T8-9 level and ossification of the ligamentum flavum at the T10-11 level that was managed using full-endoscopic spine surgery techniques in a single sitting. The presence of coexisting spinal disorders, that is, TDH and ossification of the posterior longitudinal ligament at noncontiguous spinal levels, makes surgical decision-making more complicated. Uniportal full-endoscopic spine surgery is a safe and effective surgical technique even for thoracic myelopathy. It is less invasive with minimal tissue and bone damage, better access to and visualization of the pathology, and minimal cord handling and is performed through small windows without destabilizing the spine, thus avoiding fusion. Anterior thoracic pathologies are better addressed through the transforaminal approach, whereas the interlaminar approach is preferred for posterior pathologies. Both of these approaches are complementary to each other with their own indications and advantages. https://thejns.org/doi/10.3171/CASE24413.

Cellular and Molecular Mechanisms of Hypertrophy of Ligamentum Flavum.

Hypertrophy of the ligamentum flavum (HLF) is a common contributor to lumbar spinal stenosis (LSS). Fibrosis is a core pathological factor of HLF resulting in degenerative LSS and associated low back pain. Although progress has been made in HLF research, the specific molecular mechanisms that promote HLF remain to be defined. The molecular factors involved in the onset of HLF include increases in inflammatory cytokines such as transforming growth factor (TGF)-β, matrix metalloproteinases, and pro-fibrotic growth factors. In this review, we discuss the current understanding of the mechanisms involved in HLF with a particular emphasis on aging and mechanical stress. We also discuss in detail how several pathomechanisms such as fibrosis, proliferation and apoptosis, macrophage infiltration, and autophagy, in addition to several molecular pathways involving TGF-β1, mitogen-activated protein kinase (MAPKs), and nuclear factor-κB (NF-κB) signaling, PI3K/AKT signaling, Wnt signaling, micro-RNAs, extracellular matrix proteins, reactive oxygen species (ROS), etc. are involved in fibrosis leading to HLF. We also present a summary of the current advancements in preclinical animal models for HLF research. In addition, we update the current and potential therapeutic targets/agents against HLF. An improved understanding of the molecular processes behind HLF and a novel animal model are key to developing effective LSS prevention and treatment strategies.

Transthyretin amyloidosis in patients with spinal stenosis who underwent spinal surgery: a systematic review and meta-analysis.

Accumulation of transthyretin amyloids (ATTR) is detected in ligamentum flavum in about 1/3 of patients underwent surgery for spinal stenosis. However, the significance of this finding is not known. The aim of this systematic review and meta-analysis is to analyze the incidence and importance of ATTR in patients with spinal stenosis who underwent spinal surgery. The primary outcome measure was incidence of ATTR in patients with spinal stenosis. English language observational studies published within 10 years period were searched in Pubmed and Taylor and Francis databases. Nine articles were included in the systematic review. The incidence of positive ATTR among patients who underwent lumbar spinal surgery was 48% (95%CI 38-58%). ATTR deposits were found in the lumbar region the most frequently. Seven studies showed that patients with positive ATTR were older than those with negative. Five studies investigated and found a significant relationship between the ligamentum flavum thickness and positive ATTR. Five studies investigated cardiac involvement among patients with positive ATTR. ATTR deposits are frequently found in older patients with spinal stenosis, especially in the lumbar region. The presence of ATTR deposits is related to ligamentum flavum thickness.

Macrophage polarization and macrophage-related factor expression in hypertrophy of the ligamentum flavum.

Owing to the unknow types of infiltrating macrophages and the corresponded factors, we aimed to investigate the specific types of infiltrating macrophages involved in HLF and the expression of macrophage-related factors. The ligamentum flavum was obtained from patients with lumbar spinal stenosis (HLF group; n = 15) and lumbar disc herniation (non-hypertrophic ligamentum flavum [NLF] group; n = 15). Ligamentum flavum specimens were paraffin embedded, followed by histological and immunohistochemical staining to identify the macrophage type and expression of macrophage-related factors. The HLF group demonstrated CD206 marker expression, while the NLF group did not (P < 0.0001; n = 11). CD68 marker was expressed in both groups (P > 0.05; n = 11). CCR7 was not expressed in either group. The expression levels of the extracellular matrix proteins aggrecan (Agg), type I collagen (Coll1), and type II collagen (Coll2) were higher in the HLF group than in the NLF group (P < 0.0001; n = 11). The aging markers p21, p16, and p53 were expressed in the HLF group, but not in the NLF group (P < 0.0001; n = 11). The expression levels of the inflammatory factors TNF-α and IL-1β were higher in the HLF group than in the NLF group (P < 0.0001; n = 11). Similarly, the expression level of the fibrosis factor TGF-β1 was higher in the HLF group than in the NLF group (P < 0.0001; n = 11). The infiltration of M2 macrophages may be involved in HLF, while involvement of M1 macrophages may only occur early in inflammation. The expression of extracellular matrix proteins and macrophage-related factors was increased. Aging may also be associated with HLF.

Could indirect decompression occur for cord compression by the ligamentum flavum with anterior cervical discectomy and fusion?

Cord compression by the ligamentum flavum (CCLF) has been reported to adversely affect the clinical outcomes of anterior cervical discectomy and fusion (ACDF). While indirect decompression does occur for foraminal stenosis with ACDF, whether ACDF could improve CCLF with the distraction of disc space remains unclear. This study aimed to identify 1) whether indirect decompression occurs for CCLF with ACDF, and 2) risk factors that hinder the improvement of CCLF. This retrospective cohort study included 119 patients who underwent ACDF for the treatment of cervical myelopathy and CCLF was detected on preoperative MRI. Patients who demonstrated improvement in CCLF grade after ACDF were included in the improved group, while those who did not show improvement were classified as the unimproved group. Patient characteristics, cervical sagittal parameters, neck and arm pain visual analog scale score, and Japanese Orthopaedic Association (JOA) score were assessed. A comparison between the improved and unimproved groups was performed. Regression analyses were performed to identify factors associated with CCLF grade improvement. Overall, 58.0% (69/119) of patients showed improvement in CCLF grade after ACDF. CCLF grade did not improve in the remaining 42.0% (50/119) of patients, and 3.4% (4/119) of patients experienced aggravation of CCLF after ACDF. Preoperative spondylolisthesis (OR 0.252, 95% CI 0.090-0.711; p = 0.009) and greater segmental lordosis 3 months postoperatively (OR 0.835, 95% CI 0.731-0.953; p = 0.008) were the factors that hindered the improvement of CCLF after ACDF. Furthermore, patients with higher pre- or postoperative CCLF grades showed significantly less improvement in JOA score 2 years postoperatively. Indirect decompression for CCLF with ACDF is not reliable because 42.0% of patients did not demonstrate improvement in CCLF grade after the operation. Preoperative spondylolisthesis and postoperative increased segmental lordosis were risk factors for failure of CCLF improvement. Both pre- and postoperative higher CCLF grades were associated with poor neurological recovery 2 years postoperatively.

CircTMTC1 Mediates Nucleo-cytoplasmic Translocation of DDX3X to Regulate Osteogenic Differentiation of Human Ligamentum Flavum Cells.

This study was aimed to investigate the potential roles of circTMTC1 in the underlying pathophysiological mechanisms of ossification of the ligamentum flavum (OLF). OLF is the primary contributor to thoracic spinal stenosis, which may cause severe neurological symptoms. There is a lack of effective medical therapy for OLF available so far because the exact underlying mechanism of OLF has not been fully elucidated. CircRNAs are a special class of non-coding RNAs and have attracted a growing interest of research in various human diseases recently. Therefore, we explored the potential roles of circRNAs in the underlying pathophysiological mechanisms of OLF. We performed RNA-seq analysis to investigate the differentially expression profile of circRNAs in osteogenic differentiation of human LF cells, and identified a key circular RNA circTMTC1 functioned in OLF. Subsequently, we performed a series of experiments to investigate the exact molecular and cellular mechanisms in osteogenic differentiation of human ligamentum flavum cells. CircTMTC1 is significantly up-regulated during osteogenic differentiation of human LF cells. Mechanistically, we found that circTMTC1 could interact with the RNA binding protein DDX3X and enhance its nucleo-cytoplasmic translocation. An increased cytoplasmic level of DDX3X activated the NLRP3 inflammasome pathway and thus promoted osteogenic differentiation of human ligamentum flavum cells. Our findings suggested the circTMTC1-DDX3X-NLRP3 inflammasome signaling plays a pivotal role in osteogenic differentiation of human ligamentum flavum cells, which may provide novel diagnostic and therapeutic strategies for OLF.

Inferior-Medial Dry Needling at the Thoracolumbar Junction: A Cadaveric Study.

Dry needling (DN) has emerged as a popular therapeutic intervention for managing musculoskeletal pain. While major adverse events are generally rare, those that have been reported in vulnerable areas such as the spine and thorax can be serious and warrant further investigation regarding safe techniques in and around these areas. The purpose of this study was to reproduce the methods employed by Williams et al.but with an inferior-medial multifidus DN technique to determine if a dry needle can penetrate the ligamentum flavum (LF) and breach the spinal canal at the thoracolumbar junction. Descriptive Cadaveric study. The procedure was performed on a cadaver in the prone position. The needle was advanced under ultrasound guidance to determine if a 0.30 x 40 mm dry needle inserted lateral to the spinous process of T12 and directed inferior-medially could penetrate the LF and enter the spinal canal. A 0.30 x 40 mm dry needle inserted 1.9 cm lateral to the spinous process of T12 was able to traverse the space between the vertebral laminae of T12 and L1, penetrate the LF, and enter the spinal canal with an inferior-medial needle angulation of 33-degrees medial and 18-degrees inferior. The results of this study demonstrate the feasibility of a dry needle entering the spinal canal at the thoracolumbar junction using an inferior-medial technique. These findings support the potential role of ultrasound guidance in the training and clinical practice of DN, especially in regions where safety issues have been documented. Level IV.

Surgery on the C3-4 Level and the Presence of Ligamentum Flavum Hypertrophy Increases the Risk of 30-Day Reoperation Rate After Anterior Cervical Discectomy and Fusion

BACKGROUND AND OBJECTIVES: Cervical myelopathy caused by C3-4 level degeneration often exhibits different characteristics after anterior cervical discectomy and fusion (ACDF) than other cervical levels. This study compared the outcomes of C3-4 ACDF with surgeries at other levels and identified risk factors of 30-day reoperation after ACDF. METHODS: We retrospectively analyzed patients who underwent ACDF for degenerative cervical disease from 2018 to 2023. The patients were divided into 2 groups based on the level of surgery: C3-4 and non–C3-4 groups. Radiological outcomes, including cervical alignment and range of motion (ROM), were analyzed. Clinical outcomes were assessed with patient-reported outcomes and the rates of 30-day reoperation and complications after ACDF. Patient-reported outcomes included visual analog scale for neck pain, visual analog scale for arm pain, and modified Japanese Orthopedic Association scores. Risk factors of 30-day reoperation were assessed. RESULTS: Of 259 patients, 74 (28.6%) and 185 (71.4%) were in the C3-4 and non–C3-4 groups, respectively. The C3-4 group exhibited lower C2-7 ROM (P = .019), higher C3-4 ROM (P = .015), and greater C3-4 %ROM (P = .014). The C3-4 group demonstrated lower preoperative and 1-month postoperative modified Japanese Orthopedic Association scores (P &lt; .001; P &lt; .001, respectively). The rate of 30-day reoperation was significantly higher in the C3-4 group (9.5%) compared with the non–C3-4 group (2.2%) (P = .014). In addition, C3-4 surgical level (odds ratio = 4.99, P = .034) and ligament flavum hypertrophy (odds ratio = 5.84, P = .018) were identified as independent risk factors of 30-day reoperation after ACDF. CONCLUSION: Surgery on C3-4 level showed a higher risk of 30-day reoperation than other levels. It is likely due to C3-4 surgical level, and ligament flavum hypertrophy contributes to cord compression, particularly in the unstable early postoperative period.

Commentary: Surgery on the C3-4 Level and the Presence of Ligamentum Flavum Hypertrophy Increases the Risk of 30-Day Reoperation Rate After Anterior Cervical Discectomy and Fusion

Commentary: Surgery on the C3-4 Level and the Presence of Ligamentum Flavum Hypertrophy Increases the Risk of 30-Day Reoperation Rate After Anterior Cervical Discectomy and Fusion

Distribution of mechanical properties of native human ligamentum flavum depending on histopathological changes

This study aimed to characterize the mechanical properties of native human ligamentum flavum (LF) and correlate them with histopathological changes. Mechanical property gradients across the cranial, medial, and caudal regions of LF were mapped and compared with histological sections. We also compared lumbar spinal stenosis (LSS) samples with disc herniation (DH) samples as reference material to identify differences in mechanical properties and histopathological features. Our results revealed significant heterogeneity in LF mechanical properties, with local variations correlating with specific histopathological changes such as chondroid metaplasia and loss of elastic fibers. These findings underscore the importance of considering LF heterogeneity in mechanical characterization and provide insights into its behavior under pathological conditions.