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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).)

Introduction: Ligamentum flavum haematoma (LFH) is an extremely rare entity, found mostly in the lumbar and thoracic ligamentum flavum and seldom in the cervical ligamentum flavum. Cervical LFH can cause paralysis in patients. We describe a case of LFH in the cervical spine that accepted surgical treatment., Case Presentation: A 70-year-old man with incomplete spinal cord injury presented with sudden paralysis of his left limbs for 10 days and hemi-hypaesthesia below the level of the right clavicle. Magnetic resonance imaging (MRI) showed a space-occupying lesion in the left ligamentum flavum between the C4 and C5 laminae. The preliminary diagnoses were concluded to be incomplete spinal cord injury, spinal epidural lesions, and cervical spinal stenosis. After a posterior C3-C6 laminectomy with lateral mass screw instrumentation, the muscle strength and sensation recovered partially. The lesion was greyish black and located in the ligamentum flavum. A pathological examination identified it as a haematoma of the ligamentum flavum. The patient was discharged 15 days after the operation and commenced rehabilitation., Discussion: The LFH was mainly caused by slight trauma during gentle activities and contributed by many factors. MRI is an essential tool but pathological diagnosis is the gold standard. Most LFH patients can be treated surgically., (© 2024. The Author(s), under exclusive licence to International Spinal Cord Society.)

Obejective: To perform a magnetic resonance imaging T2-mapping of the ligamentum flavum in healthy individuals and patients with lumbar spinal stenosis scheduled for surgery and compare the T2 relaxation times., Subjects and Methods: The T2 relaxation time of the ligamentum flavum was compared among 3 groups, healthy young individuals (H group (age< 50)), healthy middle-aged and older individuals (H group (age≥50)), and patients with lumbar spinal stenosis (L group). Additionally, the thickness of the ligament was measured in the axial image plane, and the occupied area ratio of each fiber was measured by staining the surgically obtained ligament, and each was correlated with the T2 relaxation time. We also evaluated the adhesion of the ligamentum flavum with the dura mater during the surgery., Results: The T2 relaxation times were significantly prolonged in H group (age ≥50) and L group (P < 0.001) compared to H group (age<50). The relationship between collagen fiber and T2 relaxation times was significantly positive (r = 0.720, P < 0.001). Moreover, the relaxation times were significantly prolonged in those with adhesion of the ligamentum flavum with the dura mater (P < 0.05). The cut-off for the relaxation time was 50 ms (sensitivity: 62.50%, false positive rate: 10.8%)., Conclusion: Healthy middle-aged and older individuals and patients with lumbar spinal stenosis and adhesion of the ligamentum flavum with the dura mater have prolonged T2 relaxation times. Hence, the adhesion between the ligamentum flavum and dura mater should be considered in cases with a relaxation time ≥50 ms., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Thickening of the cervical ligamentum flavum (CLF) has been considered as a main cause of cervical spinal stenosis (CSS). A previous study reported that cervical ligamentum flavum thickness (CLFT) is correlated with CSS. However, the whole hypertrophy is different from focal thickness. Therefore, to analyze hypertrophy of the CLF, we created a new morphological parameter, called the cervical ligamentum flavum area (CLFA). We hypothesized that the CLFA is an important morphological parameter in the diagnosis of CSS. CLF samples were acquired from 83 patients with CSS, and from 84 controls who underwent cervical magnetic resonance imaging (C-MRI). T2-weighted axial C-MRI images were acquired. We measured the CLFA and CLFT at the C6-C7 intervertebral level on C-MRI using appropriate image analysis software. The CLFA was measured as the cross-sectional area of the entire CLF at the level of C6-C7 stenosis. The CLFT was measured by drawing a straight line along the ligament side towards the spinal canal at the C6-C7 level. Mean CLFA was 25.24 ± 6.43 mm2 in the control group and 45.34 ± 9.09 mm2 in the CSS group. The average CLFT was 1.48 ± 0.28 mm in the control group and 2.09 ± 0.35 mm in the CSS group. CSS patients had significantly higher CLFA (P < .01) and CLFT (P < .01). For the validity of both CLFA and CLFT as predictors of CSS, a receiver operating characteristic curve analysis revealed an optimal cutoff point for the CLFA was 31.66 mm2, a sensitivity of 92.8%, specificity of 88.4%, and an area under the curve of 0.97 (95% CI, 0.94-0.99). The optimal cut off-point of the CLFT was 1.79 mm, with a sensitivity of 83.5%, specificity of 84.5%, and an area under the curve of 0.92 (95% CI, 0.87-0.96). Both CLFT and CLFA were significantly related to CSS, but CLFA was the more sensitive measurement parameter. Therefore, to evaluate patients with CSS, treating physicians should test for CLFA., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Thickened ligamentum flavum has been considered as a major cause of central lumbar spinal canal stenosis (CLSCS). Previous studies have demonstrated that ligamentum flavum thickness (LFT) is correlated with aging, degenerative spinal stenosis, and disc degeneration. Thus, hypertrophy of the ligamentum flavum is a major cause of CLSCS, and measurement of LFT has been considered a morphologic parameter in the diagnosis of CLSCS. To our knowledge, comparison of LFT between central and lateral lesions has not been reported. In addition, no research has analyzed best clinical cutoff values of central ligament flavum thickness (CLFT) and lateral ligament flavum thickness (LLFT). This study aimed to compare CLFT with LLFT in patients with CLSCS and further compare the CLFT and LLFT findings between the 2 groups to analyze LFT variation. Both CLFT and LLFT samples were collected from 101 participants with CLSCS and from 103 participants in the control group who underwent lumbar magnetic resonance imaging without evidence of CLSCS. Axial T2-weighted lumbar magnetic resonance scans were acquired at the L4 to 5 facet joint level from each participant. Average CLFT value was 2.25 ± 0.51 mm in the control group and 4.02 ± 0.74 mm in the CLSCS group. Average LLFT value was 2.50 ± 0.51 mm in the control group and 3.38 ± 0.66 mm in the CLSCS group. CLSCS patients had significantly higher CLFT and LLFT (both P < .001). Regarding the validity of both CLFT and LLFT as predictors of CLSCS, a receiver operating characteristic estimation revealed that the most suitable cutoff value for CLFT was 3.10 mm, with sensitivity of 95.0%, specificity of 94.2%, and an area under the curve of 0.97. The best cut-off value of LLFT was 2.92 mm, with sensitivity of 78.2%, specificity of 77.7%, and area under the curve of 0.87. We have 4 important new findings: The mean CLFT is significantly lower than that of the mean LLFT in the normal control group; CLFT and LLFT are both significantly associated with CLSCS; Increase rate of CLFT is faster than that of LLFT in the CLSCS group; and CLFT is a more sensitive measurement parameter to predict CLSCS than LLFT., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background and Objectives: Lumbar ligamentum flavum cyst is a rare spinal condition that can cause significant morbidity and neurological deficits. Traditional surgical treatment involves open surgery, which can be associated with prolonged recovery time and significant morbidity. In recent years, endoscopic treatment of lumbar ligamentum flavum cyst has emerged as a minimally invasive and effective alternative to open surgery, but only a few cases have been reported in the literature. This paper describes our experience with endoscopic resection of an L4/5 ligamentum flavum cyst through an interlaminar approach and reviews the literature on the treatment of lumbar ligamentum flavum cyst., Methods: An 87-year-old man presented with lameness in the left leg, and magnetic resonance imaging (MRI) showed nerve compression by a ligamentum flavum cyst at the L4/5 intervertebral plane. The patient underwent endoscopic resection of the ligamentum flavum cyst through a left interlaminar approach with the facet joint preserved. The present study was approved by the Ethics Committee of our hospital. The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Text regarding patient consent is not applicable for this case., Results: Postoperative clinical results improved significantly, and postoperative MRI showed complete cyst resection., Conclusion: Total endoscopic resection via an interlaminar approach provides a new minimally invasive approach for the surgical treatment of lumbar ligamentum flavum cyst, which can be used as a reference by clinicians., (© 2023. The Author(s).)

Introduction: The occurrence of concurrent hypertrophied posterior longitudinal ligament (HPLL) and hypertrophied ligamentum flavum (HLF) in the thoracic spine is a very rare presentation. This case report describes a young female who developed thoracic myelopathy secondary to a combination of both thoracic HPLL and HLF., Case Presentation: A 30-year-old previously well female was referred for an MRI scan of the thoraco-lumbar spine. She was having lower limb weakness and difficulty in walking, which had progressed over 3 months. On examination, she was found to have spastic lower limbs with associated motor weakness. Her biochemical investigations were unremarkable. The MRI scan showed HPLL, which was uniformly hypointense on T2W images and was isointense on T1W images. The hypertrophied segment was extending from T2 level to T7 level. Similarly, the ligamentum flavum was hypertrophied from T1 level to T8 level. The thoracic spinal cord was seen compressed between the hypertrophied ligaments. The compressed cord showed central hyperintense signal pattern in T2W images. CT scan of the thoracic spine did not show any calcifications or ossifications along the ligaments. Patient underwent posterior decompressive surgery and she had an uneventful recovery., Discussion: Although few cases of HPLL and HLF were reported in older patients in literature, both these conditions were found in this patient at a younger age. HPLL and HLF are thought to be precursors of ossification of these ligaments and these patients need long-term follow-up., (© 2023. The Author(s), under exclusive licence to International Spinal Cord Society.)

Patients with ossification of the ligamentum flavum (OLF) in the lumbar spine may be at high risk of developing concomitant ossification of the entire spinal ligament, but the etiology remains unclear. We investigated the propensity for spinal ligament ossification in asymptomatic subjects with lumbar OLF using the data of 595 Japanese individuals receiving medical check-ups, including computed tomography (CT) scanning. The severity of OLF (total number of intervertebral segments with OLF) of the entire spine on CT was quantified using an OLF index. Subjects with OLF were grouped according to this index: localized OLF (n = 138), intermediate OLF (n = 70), and extensive OLF (n = 31). The proportion of subjects with lumbar OLF increased with increasing OLF index (localized 13.7%, intermediate 41.4%, and extensive 70.9%). Multiple regression analysis found that lumbar OLF index was associated with thoracic OLF index, and co-existence of ossification of the posterior longitudinal ligament (OPLL) of the thoracic and lumbar spine. This study showed that subjects with more multilevel lumbar OLF were more likely to develop multilevel thoracic OLF and to have coexisting OPLL. Patients with lumbar OLF may be a distinctive subgroup with a strong tendency to ossification of the entire spinal ligament., (© 2023. The Author(s).)

Objective: A CSF leak is a potential complication in a lumbar laminectomy. An analysis of the author's surgical experience identified inadvertent durotomies that occurred when resecting the ligamentum flavum at its insertion into the superior aspect of the caudal lamina. Anatomical analyses of the lumbar canal diameter demonstrate that the insertion point of the caudal ligamentum flavum is the most constrained area of the canal. The surgical technique was modified to eliminate the need for direct action in that anatomical region after the author compared the efficacy of piecemeal resection of the ligamentum flavum with en bloc resection with a laminotomy of the caudal lamina beyond the insertion point of the ligamentum flavum in the lumbar laminectomy., Methods: An analysis of a single surgeon's experience managing 147 consecutive patients with lumbar stenosis who underwent single-level lumbar hemilaminectomies over a 4-year period was performed. Patients were managed with either piecemeal resection (cohort 1) or en bloc resection with a laminotomy beyond the caudal insertion (cohort 2) of the ligamentum flavum., Results: Seventy-seven patients underwent piecemeal resection (cohort 1), and 70 underwent en bloc resection (cohort 2). There were 5 CSF leaks (6.4%) in cohort 1. There were no CSF leaks in cohort 2. There was a statistically significant difference in operative times between the two groups (p = 0.04), but there was no statistically significant difference in patient-reported outcomes at 6 months between the groups., Conclusions: En bloc resection of the ligamentum flavum with a laminotomy below the caudal insertion point appears to decrease the risk of a CSF leak by working beyond the most constrained diameter of the lumbar canal to release the caudal insertion of the ligamentum flavum.

Obesity and metabolic disturbances are prevalent in ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF); however, the involvement of dyslipidemia (DL) in OPLL/OLF remains uncertain. We investigated the association between dyslipidemia and OPLL/OLF using a dataset of 458 individuals receiving health screening tests, including computed tomography. Subjects were grouped according to the presence or location of OPLL/OLF: controls (no OPLL/OLF, n = 230), OLF (n = 167), cervical OPLL (n = 28), and thoracic OPLL (n = 33). They were also grouped according to the presence of dyslipidemia (DL[+], n = 215; DL[-], n = 243). The proportion of dyslipidemia in the OLF and OPLL groups was 1.6-2.2 times higher than that in the control group. The proportion of OLF and OPLL in the DL(+) group was significantly higher than that in the DL(-) group (OLF, 43% vs. 29%; cervical OPLL, 14.4% vs. 3.2%; thoracic OPLL, 11.1% vs. 3.7%). Multivariate logistic regression analysis showed an association between all ossification types and dyslipidemia. This study demonstrated an association of dyslipidemia with OPLL/OLF; further investigation on the causal relationship between dyslipidemia and ectopic spinal ligament ossification is warranted to develop a therapeutic intervention for OPLL/OLF., (© 2022. The Author(s).)

Background: Facet cysts in the thoracic spine are a rare cause of thoracic myelopathy. We aimed to investigate the clinical/radiological features and surgical results of these lesions., Methods: Nine thoracic facet cysts in eight patients (seven men, one woman) were diagnosed based on magnetic resonance imaging (MRI) and computed tomography (CT) with facet arthrography findings and surgically treated. The mean patient age was 71 (59-83) years. The cysts were distributed as follows: one each at T8-9 and T9-10, two each at T1-2 and T11-12, and three at T10-11. The mean follow-up period was 1.8 (1-5) years. Clinical and radiological features were retrospectively investigated, and surgical outcomes were evaluated according to modified Japanese Orthopaedic Association (JOA) scores for thoracic myelopathy (full score: 11)., Results: Neurological examination revealed progressive thoracic transverse myelopathy in all patients with a mean disease duration of 1.2 months (2 weeks-2 months). MRI revealed a total of nine cysts across the eight patients: four in the median region and five in the paramedian portion of the spinal canal. CT revealed degeneration in all involved facet joints. All the cysts were in communication with the neighboring facet joint confirmed by CT facet arthrography. All patients underwent bilateral fenestration, and the cysts were resected with the ligamentum flavum. The mean preoperative and postoperative modified JOA scores were 4.5 and 8.8, respectively. The mean recovery rate was 67.5%. Differences in the degree of local kyphosis were 2° or less between before and after surgery. On histopathology, synovial lining cells were not noted in any case., Conclusions: Decompression surgery is recommended for treating progressive myelopathy in patients with cystic lesions. Our study suggests that thoracic facet cyst resection with satisfactory surgical outcomes would be possible through fenestration., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Objective: To evaluate the rate of increase in thickness and cross-section area (CSA) of the ossification in thoracic myelopathy with or without cervical and lumbar spinal ligament ossification., Methods: A total of 24 patients with 170 segments (47 ligamentum flavum [OLF] and 123 cases of ossification of the posterior longitudinal ligament [OPLL]) of spinal ligament ossification between January 2012 and March 2019 at a single institution were retrospectively reviewed. Demographic data, classification of OPLL, Sato classification of OLF, pre- and postoperative neurological function and complications were recorded. The thickness and CSA at the segment of maximum compression were measured with Image J software on the axial CT image., Results: Twelve female and 12 male patients with thoracic myelopathy and spinal ligament ossification were enrolled in the study. The mean age of the patients was 54.0 ± 11.9 years with an average follow-up of 22.2 ± 23.5 months. Overall, the mean rate of progression in thickness and CSA was 1.2 ± 1.6 and 18.4 ± 50.6 mm 2 /year, respectively. Being female, aging (≥45 years), and lower BMI (<28 kg/m 2 ) predisposed patients to have faster ossification growth in thickness and CSA. The difference between the rate of OPLL and OLF progression in thickness and CSA was not significant. However, the rate of OPLL progression in the thoracic spine was significantly higher than that in the cervical spine regarding thickness (1.4 ± 1.9 vs. 0.6 ± 0.7 mm/year) and CSA (27.7 ± 72.0 vs. 7.3 ± 10.3 mm 2 /year)., Conclusion: This is the first study to investigate ligament ossification progression in patients with thoracic myelopathy. The difference between the rate of OPLL and OLF progression in thickness and CSA was not significant. However, the rate of thoracic OPLL progression in thickness and CSA was significantly higher than that in the cervical spine., (© 2022 The Authors. Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

Brown-Séquard syndrome (BSS) has many etiologies, including penetrating trauma, extramedullary tumors, and disc herniation. However, thoracic ossification of the ligamentum flavum (OLF) is an extremely rare cause of this syndrome. A 46-year-old woman with motor weakness in her right lower extremity and urinary retention was admitted to our department. Based on the results of physical examination, computed tomography, and magnetic resonance imaging, a diagnosis of BSS with OLF was considered. The patient underwent urgent conservative treatment. BSS is a rare condition characterized by hemisection or hemicompression of the spinal marrow. The herein-described case of incomplete BSS due to OLF responded to conservative treatment. However, the successful nonoperative management of this case is insufficient evidence to consider it as the standard of care. Therefore, emergency laminectomy decompression remains the standard of care for BSS.

Background: To determine whether there is a correlation between the type of ossification and radiological parameters, modified thoracic JOA scores, and complications in patients with thoracic ossification of ligamentum flavum treated by posterior thoracic surgery., Methods: This retrospective cohort study included 48 patients with thoracic myelopathy caused by single-level thoracic ossification of ligamentum flavum who underwent thoracic posterior approach surgery in our Hospital o between December 2013 to December 2018. Patients were divided into unilateral, bilateral, and bridged groups in axial position, and beak and round groups in sagittal position. The differences were analyzed according to the ossification morphology., Results: In axial myelopathy, there was no significant difference in preop and postop JOA scores and RR among the three groups in axial position (P = 0.884). In sagittal view, there was no significant difference in preoperative JOA score between the two groups (P = 0.710), while the postop JOA score and the recovery rate in the beak group were significantly lower than that of the round group (P = 0.010, P = 0.034). Two-way ANOVA showed that sagittal morphology had a significant effect on postop JOA score (P = 0.028), but axial morphology don't (P = 0.431); there was no interaction between them (P = 0.444). For the recovery rate, sagittal morphology also had a significant effect (P = 0.043), but axial ossification don't (P = 0.998); there was no interaction between them (P = 0.479)., Conclusion: Sagittal morphology had a significant adverse effect on postop JOA score and surgical outcome, while axial morphology had no effect on surgical outcome, and there was no interaction between sagittal morphology and axial morphology., (© 2022. The Author(s).)

Objectives: To explore the influencing factors of satisfaction with postoperative treatment in patients diagnosed with thoracic ossification of the ligamentum flavum during different follow-up periods., Methods: This was a retrospective study of 57 patients who were diagnosed with thoracic ossification of ligamentum flavum (TOLF) and treated with laminectomy in the Spine Surgery Department of the Third Hospital of Hebei Medical University from January 2010 to January 2017. The Patient Satisfaction Index (PSI) was collected at discharge and at 6-month, 1-year, and the last follow-up. According to the evaluation results, the patients could be divided into a satisfied group and a dissatisfied group. The patient's Japanese Orthopaedic Association (JOA) score improvement rate was evaluated at the last follow-up. Possible influencing factors of the two groups of patients were compared and the related influencing factors of satisfaction with postoperative treatment in patients during different follow-up periods were summarized., Results: At the time of discharge, the dissatisfied and satisfied groups had significant differences in variables of diabetes mellitus, duration of preoperative symptoms, urination disorder, intramedullary signal change on MRI, dural ossification, residual rate of cross-sectional spinal canal area on CT, shape on the sagittal MRI, hospital stay, hospitalization expenses, postoperative pain in LE VAS, delayed wound healing, postoperative depression, and intercostal pain ( P < 0.05). There were also significant differences in urination disorder, postoperative pain according to the LE VAS, JOA score, and postoperative depression during the 6-month follow-up ( P < 0.05). There were no significant differences in other variables between the two groups ( P > 0.05). One year after the operation, there were significant differences between the dissatisfied group and the satisfied group in urination disorder, JOA score, and symptom recurrence ( P < 0.05). There were also significant differences in the JOA score and symptom recurrence at the final follow-up ( P < 0.05). For further analysis, the duration of preoperative symptoms in the satisfied group was less than 24 months and the duration of preoperative symptoms in the dissatisfied group was more than 24 months. The JOA scores of patients in the satisfied group and the dissatisfied group increased gradually with the improvement of neurological function in different follow-up periods, but, at the last follow-up, the JOA scores of patients in the satisfied group were significantly higher than those in the dissatisfied group., Conclusions: In conclusion, for thoracic ossification of ligamentum flavum patients who received laminectomy, dissatisfaction with the early and medium-term postoperative results may be related to diabetes, the duration of preoperative symptoms, hospitalization expenses, delayed wound healing, intercostal pain, and urination disorder, and dissatisfaction with the long-term postoperative results might be related to the low JOA score improvement rate and symptom recurrence., Competing Interests: All the authors declare no conflicts of interest regarding this study., (Copyright © 2021 Zhiwei Wang et al.)

Background: This study aimed to assess the effects of anterior cervical discectomy and fusion (ACDF) on distraction of the posterior ligamentum flavum (LF) by increasing the intervertebral disc height and positioning a graft in patients with degenerative cervical spine disease., Methods: Sixty-eight patients with degenerative cervical diseases who underwent single-level ACDF were included in the analysis. The intervertebral disc height, Cobb angle, and transverse thickness of the LF were measured, and magnetic resonance imaging was performed both preoperatively and 6 weeks postoperatively on each patient. Correlation analyses were performed to evaluate the relationships between age, sex, change in intervertebral disc height, Cobb angle, and position of the intervertebral implant according to the postoperative change in LF thickness. The position of the intervertebral implant was categorized as anterior, middle, or posterior. We also evaluated radiological effects according to the implant position., Results: The mean intervertebral disc height increased from 5.88 mm preoperatively to 7.49 mm postoperatively. The Cobb angle was 0.88° preoperatively and 1.43° postoperatively. Age ( p = 0.551), sex ( p = 0.348), position of cage ( p = 0.312), pre- and postoperative intervertebral disc height ( p = 0.850, p = 0.900), Cobb angle ( p = 0.977, p = 0.460), and LF thickness ( p = 0.060, p = 1.00) were not related to changes in postoperative LF thickness. Postoperative increase in disc height was related to Cobb angle ( r = 0.351, p = 0.038). No other factors were significantly related. The position of the cage was not related with the change of Cobb angle ( p = 0.91), LF thickness ( p = 0.31), or disc height ( p = 0.54)., Conclusions: Change in the intervertebral disc height and the position of the intervertebral implant after ACDF did not affect the thickness of the LF after surgery in patients with degenerative cervical spine disease., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2021 by The Korean Orthopaedic Association.)

Background: Involvement in cervical ligamentum flavum is a rare manifestation of the calcium pyrophosphate dihydrate deposition disease. Only few cases of this condition have been reported. We revealed eighteen cases of CPPD in cervical ligamentum flavum that diagnosed at a single medical center. In our case series, clinical characteristics and magnetic resonance imaging findings of patients are described., Methods: We retrospectively reviewed the medical charts and imaging studies of the eighteen patients with pseudogout attack of the cervical ligamentum flavum. In addition, we discussed the differences between this disease and ossification of ligamentum flavum in image manifestations., Results: There were fourteen men and four women aged between 59 and 87 years. Diabetes mellitus and hypertension were the most common comorbidities. Myelopathy and neck pain were presented in most patients. C4-5 and C5-6 were attacked most frequently, and multiple- rather than single-level involvement could be observed in our series. "Acute on chronic phenomenon" was a specific magnetic resonance image finding in patients whose symptom durations were between 2 to 5 months. Compared to ossification of ligamentum flavum, calcium pyrophosphate dihydrate crystal deposition had different image signs, including morphology, side of the involved ligament, no continuity with the lamina, acute on chronic phenomenon, and presence of retro-odontoid mass., Conclusions: Nodular calcifications in cervical ligamentum flavum raise highly suspicion for calcium pyrophosphate dihydrate deposition and must be diagnosed by histological examination and polarized light microscopy. This disease is different from ossification of ligamentum flavum, and it could be recognized by specific image features., (© 2021. The Author(s).)

Both systemic and local factors might influence the development of ossification of the ligamentum flavum (OLF); however, whether specific physical activities play a role in the development of OLF remains unclear. This report presents two cases of thoracic radiculopathy owing to progressive enlargement of thoracic OLF within a few years in Japanese professional baseball pitchers. Two left-handed, Japanese, professional baseball pitchers in their 20s experienced thoracic radiating pain. Mild hypesthesia of the lower thoracic vertebral levels was observed, and an increase in the size of the OLF within a few years was identified in the lower thoracic spine using computed tomography and magnetic resonance imaging. Neither patient exhibited myelopathy and were, therefore, treated conservatively. Both patients were able to return to playing in top condition within 4 months after onset. The findings in these cases suggest that thoracic OLF might increase in size and become exacerbated in certain individuals, such as professional pitchers, who experience repeated, localized, mechanical stress on the thoracic spine, irrespective of age.

Background: It is imperative to preoperatively distinguish dural ossification (DO) and thus anticipate the risks and outcome of the surgery for patients with ossification of ligamentum flavum (OLF). However, studies have disagreed as to the efficacy of the radiographic signs or factors to predict DO and surgical outcome. In additon, the association between the cerebrospinal fluid cross-section area ratio (CCAR) and DO or clinical outcome had not been reported. The purpose of this study was to analyse CCAR and its role in prediction of DO and neurological function recovery rate in patients with OLF., Methods: Fifty-two consecutive patients with OLF, who underwent posterior thoracic decompression and fusion between September 2012 and March 2019 at a single institution, were retrospectively reviewed. Demographic data, radiographic signs of DO, CCAR, pre- and postoperative modified Japanese Orthopedic Association (mJOA) score were recorded., Results: There were 27 patients in the DO group and 25 patients in the non-DO group, with a mean age at surgery of 57.4 years and 53.9 years, respectively. No significant differences were found in sex, age, segment of maximum compression and preoperative mJOA score between the two groups. The receiver operating characteristic curve showed that the value of CCAR had a relatively high value for diagnosis of DO and prediction of neurological function recovery rate (P = .000). According to the value of CCAR, three zones were defined as DO zone (≤14.3%), non-DO zone (≥44.5%), and gray zone (14.3 to 44.5%). When the value of CCAR≤14.3%, the recovery rate was poor or fair, while it had good or excellent recovery when CCAR≥45.2%., Conclusion: The value of CCAR had a high diagnostic value for prediction of DO and neurological function recovery rate in patients with OLF., (© 2021. The Author(s).)

Introduction: Acute spinal cord injury without tomographic evidence of vertebral fracture or dislocation in patients post trauma can represent a diagnostic challenge for the treating physician. The ossification of thoracic ligamentum flavum has been widely published as a cause of thoracic myelopathy, however its association with acute traumatic spinal cord injury is limited to isolated cases., Case Presentation: we report a Caucasian 37-year-old man who suffered a high-energy thoracolumbar spine trauma in a motorcycle accident with acute paraplegia. He presented ossification of the ligamentum flavum between the thoracic vertebrae T10 and T11 with a decrease in the diameter of the vertebral canal as the only pathological finding. We treated the patient with early surgical release before 72 h of trauma. We performed a posterior approach with hemilaminectomy and T10-T11 flavectomy. Arthrodesis was done with T10-T11 pedicle screws. Postoperative neurological status improved from ASIA Impairment Scale (AIS) A to C with severe functional dependence., Discussion: Ossification of the ligamentum flavum should be considered in the differential diagnosis in patients presenting with acute traumatic spinal cord injury without tomographic evidence of trauma. A proper diagnosis in time is the key to decision making and treatment of spinal cord injury. Especially in adult patients, we must consider nontraumatic associated factors that could be involved in the spinal cord injury mechanism, such as ossification of the ligamentum flavum., (© 2021. The Author(s), under exclusive licence to International Spinal Cord Society.)

Background: Although several causes of ligamentum flavum (LF) hypertrophy have been identified, the pathomechanisms underlying LF hypertrophy are not fully understood. Because collagen fibers are essential for the maintenance of LF tissues, characterization of the collagen composition of hypertrophied LF may help to elucidate the pathology of lumbar spinal canal stenosis (LCS). This study aimed to determine the association between the collagen composition and LF hypertrophy., Methods: LF tissues were collected from 23 patients who underwent spinal decompression surgery for lumbar disorders. The cross-sectional area of LF was measured using the axial images of lumbar MRI. The expression of each collagen in human surgical samples was evaluated by real-time RT-PCR and immunohistochemical analysis. To investigate the impact of inflammatory cytokines on the expression of each collagen, we treated primary human LF cells with TNF-α or IL-1β., Results: Real-time RT-PCR analysis and immunohistochemistry showed that of the 28 types of collagen, collagen type I, III, V, VI, VIII were highly expressed regardless of LF hypertrophy. In addition, we found the moderate correlation between the cross-sectional area of LF and the mRNA expression level of collagen type I, III, and VI. In vitro analysis showed that the mRNA expression of collagen type I, III, V, VI, and VIII was up-regulated by treatment with TNF-α and with IL-1β., Conclusion: Our results suggested that collagen type I, III, V, VI, and VIII were the main components of the LF extracellular matrix and that collagen type I, III, and VI may serve as useful markers of LF hypertrophy. These findings may contribute to the future development of diagnostic and treatment modalities for LF hypertrophy and even LCS., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: Cervical ossification of ligamentum flavum (COLF) is a rare clinical entity which can occasionally contribute to severe myeloradiculopathy. Many orthopedists are unfamiliar with or underestimate this pathology. Therefore, a comprehensive research is obligatory to reappraise the epidemiological, radiological, clinical and histopathological characteristics of COLF-myeloradiculopathy based on synthesis of individual patient data., Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed, EMBASE, Scopus and Web of Science databases were searched for studies discussing COLF-myeloradiculopathy from the inception to December 2020., Results: A total of 94 cases from 54 studies were identified. The annual publications demonstrated a steady increase, and most reports were from Japan and China. The mean age was 58.76±13.39 years and nearly 60% of cases occurred in the 55-64 and 65-74 years age group. The male-female ratio was 1.4:1. Most cases belonged to East Asian population (60.64%). COLF predominately appeared in the lower cervical and cervicothoracic spine (76.60%) and mainly affected C4-5 (23.29%) and C5-6 (21.23%). Single-segment type ossification accounted for 62.76 and 45.45% of ossification lesions distributed bilaterally. The majority of COLF (81.1%) were spontaneous, and motor disturbance (76.4%), spinal ataxia (62.5%) and sensory disturbance (58.9%) were the most common manifestations. Histopathologically, it's a metaplastic process of endochondral ossification with the formation of mature lamellar bone which was distinguished from calcification of ligamentum flavum. About 21.28% of concurrent COLF and COPLL cases were identified as a separated group, with unique characteristics., Conclusion: COLF is an underappreciated but potentially growing pathogeny of myeloradiculopathy in aging population, though its distinct epidemiological, radiological, clinical and histopathological features are not fully supported by current evidence. However, our findings will provide several referential data for future researches to shed light on COLF., Competing Interests: The authors have declared no conflicts of interest., (© 2021 Zhang et al.)

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.

Background: The purpose of this study was to establish a novel rat model for ligamentum flavum (LF) hypertrophy using increased motion of lumbar and to elucidate the etiology of (LFH)., Methods: A total number of 30 male rats were used. The increased motion of lumbar was induced by surgical resection of L5/6 posterior elements (n = 15). The other rats underwent a sham operation (n = 15). After 8 weeks, all rats were taken lateral plain X-rays. The LF from L5/6 in both groups were harvested to investigate histological, immunohistological, and real-time PCR analysis., Results: According to radiological results, the disc height ratio, flexion ratio, and extension ratio were larger in the rats in the experimental group than that of in the sham group. The HE staining showed that the LF thickness in the experimental group significantly increased in comparison to the sham group. The Masson trichrome staining showed that the ratio of elastic fibers to collagen fibers in experimental group was lower than that in the sham group. The protein and gene expression of TGF-β1, TNF-α, IL-1β, and Col 1 were significantly higher in the experimental group than that in the sham group., Conclusion: A relatively safe, simple, and rapid rat model of LFH using increased motion of lumbar was established. The increased motion of lumbar could lead to high expression of inflammatory and fibrotic factors in LF, causing the accumulation of collagen fibers and decreasing of elastic fibers.

Background: Conventional open laminectomy is considered to be the standard procedure for the treatment of thoracic ossified ligamentum flavum, but multi-segment thoracic laminectomy extensively removes the facet joints and ligamentous tissue, destroying the thoracic spine biomechanics and stability, may lead to delayed thoracic spine kyphosis deformities, which in turn can lead to potential neurological deterioration and local intractable pain., Objective: To introduce the technical notes and clinical outcome of ultrasonic osteotome assisted full-endoscopic en block resection of thoracic ossified ligamentum flavum., Study Design: A prospective cohort study., Setting: Hospital and outpatient surgery center., Methods: From January 2017 to March 2018, 15 patients with 1 - 2 segment thoracic ossified ligamentum flavum were treated with ultrasonic osteotome assisted full-endoscopic en block resection of thoracic ossified ligamentum flavum under local anesthesia. The magnetic resonance imaging and computed tomography of the thoracic spine was reexamined after the operation to evaluate the completeness of ossified ligamentum flavum resection and spinal cord decompression. The patients were followed up on the visual analog scale of back pain and radicular pain, Nurick score and mJOA score of neurological function, and Oswestry Disability Index at 1 week, 3 months, 6 months, one year, and 2 years after operation., Results: All operations of 17 segments thoracic ossified ligamentum flavum in 15 patients were successfully completed without intraoperative conversion to open surgery. There were no intraoperative spinal cord injuries, dura tears, postoperative cerebrospinal fluid leakage, postoperative infections, and postoperative spinal cord injury aggravated symptoms. Postoperative thoracic spine magnetic resonance imaging and computed tomography examinations of all patients showed that the spinal cord was fully decompressed without any residual pressure. Back pain and radicular pain were relieved significantly, and spinal cord function (Nurick, mJOA, and Oswestry Disability Index scores) was obviously restored. The mJOA recovery rate at the 2-year follow-up was 78.3% in average., Limitations: This is an observational cohort study with relative small sample and short-term follow-up., Conclusions: Ultrasonic assisted full-endoscopic en block resection of ossified ligamentum flavum is a safe and effective minimally invasive spine surgery for thoracic myelography caused by thoracic ossified ligamentum flavum.

Background: Thoracic ossification of ligamentum flavum (T-OLF), as one of the causes of thoracic myelopathy, is often combined with other spinal disorders. Concurrent lumbar spinal canal stenosis (LCS) is often obscured by symptoms due to T-OLF, leading to difficulty in identifying the origin of these neurological findings. It is common to be misdiagnosed or delayed diagnosis due to the complicated nature. We evaluated the prevalence, distribution, and clinical characteristics of OLF, especially in patients with LCS., Methods: The authors performed a retrospective analysis of the outcomes of 61 patients who underwent thoracic surgeries performed for symptomatic T-OLF. In all the patients, whole spine lesions were evaluated preoperatively. We examined the factors related to poor outcomes (the recovery rate of the Japanese Orthopedic Association score for thoracic myelopathy is less than 40%) following OLF surgeries. We compared the clinical outcomes according to whether there was concurrent LCS, and determined the optimal surgical approach., Results: The occurrence of T-OLF increased with age. Forty-six cases (75.4%) were considered to be tandem T-OLF and LCS (LCS group). An advanced age, and concurrent LCS were associated with a poor outcome after the surgery. The LCS group significantly included a greater number of elderly, and more light-weighted patients with Modic change in thoracic spine and a greater sagittal vertical axis, resulting in the lower neurological recovery. Additional lumbar surgery (13cases) effectively improved both the T-JOA and L-JOA scores (from 6.5 ± 2.0 points to 8.0 ± 1.8 points, p = 0.0406, and from 14.5 ± 4.7 points to 20.7 ± 2.6 points, p = 0.001, respectively) in OLF patients with LCS., Conclusions: T-OLF was highly associated with other spinal disorders. Poor outcomes in T-OLF surgery could be associated with age and concurrent LCS, and an additional surgery for another lumbar lesion significantly improved neurological findings in T-OLF patients.

Objective: This study was performed to evaluate the role of posterior suspension of the laminae-ossification of the ligamentum flavum complex combined with miniplate fixation (modified expansive thoracic laminoplasty) in treating thoracic ossification of the ligamentum flavum (TOLF)., Methods: Eight patients with TOLF treated by modified expansive thoracic laminoplasty were retrospectively analyzed. Their general information, operative time, intraoperative blood loss, and postoperative complications were recorded. Neurological functional recovery was evaluated by the modified Japanese Orthopaedic Association (mJOA) score and Hirabayashi recovery rate preoperatively, postoperatively, and at the final follow-up. Preoperative and postoperative imaging was performed, and the decompression range and internal fixation positioning were evaluated., Results: The mJOA score significantly improved from 4.63 points preoperatively to 9.0 points at the final follow-up (Hirabayashi recovery rate of 77.75%). Postoperative computed tomography and magnetic resonance imaging revealed sufficient decompression of the surgical segment. At the final follow-up, the internal implants were well-placed, the lamina-ligamentum flavum complex showed no significant displacement, and neurological functional recovery was satisfactory., Conclusion: Surgical treatment of TOLF is complicated and high-risk. Characterized by simplicity and sufficient decompression, modified expansive thoracic laminoplasty can reduce the risk of cerebrospinal fluid leakage and nerve injury with satisfactory neurological functional recovery.

Pseudogout, also known as calcium pyrophosphate deposition disease, is an inflammatory arthropathy that primarily occurs in the peripheral joints, such as the knee or elbow. Spinal pseudogout is uncommon, and neck pain is its most common clinical manifestation. However, cervical myeloradiculopathy as an initial presentation of pseudogout attack of the ligamentum flavum has rarely been reported in the literature. We report a case of a 65-year-old woman who presented with neck pain, bilateral finger numbness, and left-sided upper extremity weakness. Magnetic resonance images showed an epidural mass at the C4-5 level, compressing the spinal cord. Following laminectomy with removal of the calcified mass, the profound neurologic deficits gradually recovered. A pathological examination confirmed the diagnosis of cervical pseudogout., (Copyright: © Neurosciences.)

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Introduction: Calcification of the ligamentum flavum can cause acute neck pain and compression of the spinal cord, which can induce myelopathy. However, there are very few reports of acute exacerbation of myelopathy due to a pseudogout attack of the cervical ligamentum flavum, and there are no reports of that after a cervical spinal cord injury. Here, we report the case of a patient with acute neck pain and tetraplegia caused by pseudogout attack of the cervical ligamentum flavum after cervical central spinal cord injury., Case Presentation: A 78-year-old man experienced mild tetraplegia after falling. He was diagnosed with cervical spinal cord injury without radiographic abnormality. Four days after the injury, he developed fever and his paralysis worsened. Magnetic resonance imaging revealed increasing of spinal stenosis at the C4-5 level. Computed tomography revealed calcification of the ligamentum flavum at the same level. C3 laminectomy and C4-5 laminoplasty were performed. A collection of turbid yellow fluid was found in the ligamentum flavum. A histopathological examination revealed evidence of calcium pyrophosphate dihydrate crystals in the fluid., Discussion: With increase in the aging population in Japan, the patients with acute exacerbation of myelopathy due to pseudogout in the cervical spine following spinal cord injury without radiographic abnormality may increase in the future. Computed tomography is useful for the diagnosis of such cases.

Background: Lumbar spinal stenosis (LSS) is a common degenerative disease, which can lead to neurological dysfunction and requires surgical treatment. In the previous study, we used H&E staining and immunohistochemistry to qualitatively analyze the expression of S100 and P16 in the pathological process of ligamentum flavum (LF) hypertrophy in patients with LSS. To further explore the relationship between P16, S100 and LF hypertrophy in patients with LSS, we quantitatively detected S100 and P16 and their expressed products based on molecular biology techniques, and analyzed their imaging correlation., Methods: Before posterior lumbar surgery, LF thickness was measured by Magnetic Resonance Imaging (MRI). Through the operation, we obtained the specimens of LF from 120 patients, all of whom were L4/5 LF. They were designated: simple lumbar disc herniation (LDH), single-segment spinal stenosis (SLSS), and double-segment LSS (DLSS). The detection of each side of LF was assessed. S100 and P16 and their expression products were detected by western blot and quantitative polymerase chain reaction (qPCR)., Results: The dorsal mRNA expression of P16 in DLSS group was significantly higher than that in SLSS group. On the dorsal and dural side of LF, the expression of P16 mRNA and proteins in the LDH group was significantly lower than that in SLSS and DLSS groups. We found a correlation between the thickness of LF and the expression of P16. However, there was no significant difference in the expression of S100 mRNA and S100 protein on both sides of the ligament and among the three groups, and no significant correlation between the expression of S100 and the thickness of LF., Conclusions: P16 is involved in the process of LF hypertrophy in patients with LSS, and the imaging thickness of LF is related to the expression of P16. No obvious evidence proves that S100 may be related to the hypertrophy of LF in patients with LSS.

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: The objective of our study was to compare clinical outcome and postoperative complications between patients with thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) treated with and without intraoperative methylprednisolone (MP)., Methods: This retrospective study enrolled 101 patients who underwent posterior approach surgery for OLF and were followed up at least 1 year. Patients were divided into two groups according to MP use in the operation: MP group (n = 47) and non-MP group (n = 54). Clinical outcomes and complications were evaluated before and after operation and at the last follow-up., Results: Significant differences were found in modified Japanese Orthopedics Association (mJOA) scores and proportion of Frankel grade (A-C) between the two groups immediately after surgery and at 2-week follow-up. No significant differences were found between the two groups in mJOA score before operation and at the final follow-up. Moreover, no significant differences were observed in recovery rate according to mJOA score at any time points, and there was no significant difference in the proportion of Frankel grade (A-C) between the two groups at final follow-up. There were 13 documented infections: 10 in the MP group and 3 in the non-MP group (P = 0.034)., Conclusion: Management therapy with intraoperative 500 mg MP showed better recovery of nerve function within 2 weeks in patients with thoracic myelopathy caused by OLF compared with those did not receive MP. However, long-term follow-up results showed that there was no significant difference in neurological recovery between patients with intraoperative MP or not. Moreover, intraoperative MP increased the rate of wound infection.

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.

BACKGROUND The bridge crane technique is a novel surgical technique for the treatment of thoracic ossification of the ligamentum flavum (TOLF), but its preoperative planning has not been studied well, which limits the safety and efficacy of surgery to some extent. The purpose of this study was to investigate the method of application and effect of computer-aided preoperative planning (CAPP) on the bridge crane technique for TOLF. MATERIAL AND METHODS This retrospective multi-center included 40 patients with TOLF who underwent the bridge crane technique from 2016 to 2018. According to the utilization of CAPP, patients were divided into Group A (with CAPP, n=21) and Group B (without CAPP, n=19). Comparisons of clinical and radiological outcomes were carried out between the 2 groups. RESULTS The patients in Group A had higher post-mJOA scores and IR of neurological function than those in Group B (p<0.05). Group A had shorter surgery time, fewer fluoroscopic images, and lower incidence of complications than Group B. In Group A, there was a high consistency of all the anatomical parameters between preoperative simulation and postoperative CT (p>0.05). In Group B, there were significant differences in 3 anatomical parameters between postoperative simulation and postoperative CT (p<0.05). In Group B, the patients with no complications had higher post-SVOR and lower SVRR and height of posterior suspension of LOC in postoperative CT than those in postoperative simulation (p<0.05). CONCLUSIONS CAPP can enable surgeons to control the decompression effect accurately and reduce the risk of related complications, which improves the safety and efficacy of surgery.

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: One of the characteristics of lumbar spinal stenosis (LSS) is elastin degradation and fibrosis in the ligamentum flavum (LF). However, the biochemical factors that cause these histologic changes is unclear. P16 and S100 participate in scar formation and collagen development in wound healing and fibrosis diseases. In this study, we investigate the association between P16 and S100 expression and the fibrosis of the hypertrophic LF in LSS., Methods: The LF specimens were surgically obtained from 30 patients with single-segment LSS (SLSS), 30 patients with double-segment LSS (DLSS) and 30 patients with L4/5 lumbar disc herniation (LDH). The LF thickness was measured by axial T1-weighted MRI. The extent of LF elastin degradation and fibrosis were graded based on hematoxylin-eosin (HE) and Verhoff's Van Gieson's (VVG) stain, respectively. The localization of P16 and S100 was determined by immunohistochemistry., Results: The Absolute and relative LF thickness were greater in the DLSS group compared with the SLSS and LDH groups (p <  0.05). The elastic tissue from the dorsal aspect to the dural aspect in SLSS and DLSS groups was significantly increased. The amount of collagen deposition and elastic tissue is significantly higher in the DLSS group compared with the SLSS and LDH groups (p <  0.05). The specimens in the DLSS group showed positive staining of P16, especially in the dorsal layer. Almost all samples in the SLSS group were partially positive for P16. The LDH group showed negative staining of P16 in both the dural and dorsal layers. All the three groups were stained with S100 in the dorsal layer of the LF. On the contrary, S100 staining was absent in the dural layer of the LF in the three groups., Conclusions: Elastin degradation and fibrosis of the LF in the DLSS patients is more severe compared with the SLSS and LDH patients. Increased expression of P16 associated with LF fibrosis and thickness, suggested that the expression of P16 may related to LF hypertrophy in the patients who suffer with LSS. LF hypertrophy process may not be associated with high expression of S100.

Thoracic ossification of the ligamentum flavum (TOLF) is heterotopic ossification of spinal ligaments, which may cause serious thoracic spinal canal stenosis and myelopathy. However, the underlying etiology remains inadequately understood. In this study, the ossification patterns of TOLF were analyzed by micro-computer tomography (micro-CT). The expression profile of genes associated with angiogenesis was analyzed in thoracic ligamentum flavum cells at sites of different patterns of ossification using RNA sequencing. Significant differences in the expression profile of several genes were identified from Gene Ontology (GO) analysis. Angiopoietin-2 (ANGPT2) was significantly up-regulated in primary thoracic ligamentum flavum cells during osteogenic differentiation. To address the effect of ANGPT2 on Notch signaling and osteogenesis, ANGPT2 stimulation increased the expression of Notch2 and osteogenic markers of primary thoracic ligamentum flavum cells of immature ossification, while inhibition of ANGPT2 exhibited opposite effect on Notch pathway and osteogenesis of cells of mature ossification. These findings provide the first evidence for positive regulation of ANGPT2 on osteogenic differentiation in human thoracic ligamentum flavum cells via modulating the Notch signaling pathway., Competing Interests: The authors have declared that no competing interests exist.

Background: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by ossification of the enthesis. The diagnosis has been mainly based on the chest or whole spine lateral plain film. Recently, chest or thoracolumbar computed tomography (CT) has been reported to be more reliable for the diagnosis of DISH. The purposes of this study were to investigate the prevalence and location of DISH and evaluate the prevalence of comorbidities, such as ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF), using whole spine CT., Methods: Whole spine CT scans of patients over 16 years of age who were examined at Cheju Halla General Hospital between February 2011 and December 2016 were reviewed for this study. The diagnosis of DISH was made according to the modified Resnick criteria. The prevalence of DISH in each age decade and its location were evaluated. Also, the prevalence of OPLL and OLF in DISH patients was investigated., Results: The overall incidence of DISH was 24.4% (40 of 164 cases). There was no case of DISH in patients in their 40s and younger. The percentile incidences of DISH in patients in their fifth, sixth, seventh, eighth, and ninth decades were 20.0% (4 of 20 cases), 32.3% (10 of 31 cases), 40.0% (10 of 25 cases), 34.5% (10 of 29 cases), and 27.3% (6 of 22 cases), respectively. A strong positive correlation between the age decade and the incidence of DISH was noted (r = 0.853, p = 0.007). DISH patients had higher incidences of OLF (22.5%) and OPLL (37.5%). The most common location of DISH was the middle thoracic spine (90.0%) followed by the lower thoracic spine (87.5%). There was one case of DISH involving only the cervical spine., Conclusions: The incidence of DISH diagnosed by CT was higher than we expected. Whole spine CT can be a valuable modality to evaluate the location of DISH in the cervical and lumbar spine and the comorbidity rates of OLF and OPLL., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.

Background/aims: Narrowing of the lumbar spinal canal is a condition called lumbar spinal stenosis (LSS) and is a high-morbidity problem in the elderly. LSS is commonly caused by hypertrophy of the ligamentum flavum (HLF). Previous studies showed that fibrosis of the ligamentum flavum (LF) largely contributed to HLF. However, the underlying pathomechanism remains unclear. Insulin-like growth factor-1 (IGF-1) is known to have an intimate relationship with fibrosis in various tissues. Nevertheless, currently, there are few studies regarding IGF-1 in HLF. In this study, we investigated the role of IGF-1 in HLF and its potential molecular mechanism of action., Methods: First, the IGF-1, phosphorylation of IGF-1 receptor (pIGF-1R), phosphorylation of AKT (pAKT), phosphorylation of S6(pS6), collagen I and collagen III expression levels were examined via immunohistochemistry and Western blotting in LF tissues from patients with LSS or Non-LSS. Second, primary LF cells were isolated from adults with a normal LF thickness and were cultured with different concentrations of IGF-1 with or without NVP-AEW541/rapamycin., Results: The results showed that IGF-1, pIGF-1R, pAKT, pS6, collagen I and collagen III protein expression in the LSS group was significantly higher than that in the Non-LSS group. Meanwhile, pIGF-1R, pAKT, pS6, collagen I and collagen III protein expression was significantly enhanced in LF cells after IGF-1 exposure, which can be notably blocked by NVP-AEW541. In addition, pS6, collagen I and collagen III protein expression was blocked by rapamycin., Conclusions: Enhanced IGF-1 promotes the synthesis of collagen I and collagen III via the mTORC1 signaling pathway, which eventually contributes to hypertrophy of the ligamentum flavum., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background: Posterior decompression surgeries of cervical spine such as laminoplasty and laminoforaminotomy are well established and increasing in aging population. The anatomical knowledge of cervical ligamentum flavum (LF) is critical to perform posterior spinal surgeries, however, few studies have evaluated it, especially the relation of LF and neural foramen., Methods: The whole spine was removed en bloc from 15 formalin-embalmed human cadavers and then divided into two segments along the pedicle bases. A total of 90 LFs from C2-C3 to C7-T1 were measured manually from the ventral side before being painted with iron powder containing contrast agent and scanned by computed tomography. We recorded dimensions, coverage of adjacent laminae, and the relationships between LF and neural foramen or facet joints. Three-dimensional CT data was used to evaluate manually limited areas and make reconstructed images., Results: LF height gradually increased from C2-C3 to C7-T1, and gradually decreased from medial to lateral within each level. LF width and thickness were relatively constant from cranial to caudal. The laminar surface covered by LF gradually increased from 33% in para midline and 30% laterally at C2, and increased to 70% in para midline and 47% laterally at C6, this trend was not completed at C7. The empty zone of the laminar surface (without LF coverage) was located at the upper half of each lamina; this zone gradually decreased from cranial to caudal. The craniomedial side of the cervical facet joint was covered by a mean 4.6 ± 0.7 mm of LF, however, LF did not enter the cervical neural foramen., Conclusions: LF did not enter the neural foramen in cervical spine unlike lumbar spine. This information might be critical to avoid neurological deterioration after cervical laminoplasty or laminoforaminotomy. Surgeons would imagine the attachments and coverage of LF and its relation to posterior bony structures to perform safe posterior cervical surgeries., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Thoracic ossification of the ligamentum flavum (TOLF) complicated with dural ossification (DO) is a severe clinical disease. The diagnosis of DO preoperatively remains challenging. The current study retrospectively analyzed imaging features of 102 segments with TOLF from 39 patients and proposed a grading system for evaluating DO risk. Logistic regression results showed that unilateral spinal canal occupational rate (UCOR), tram track signs, and C-signs were all risk factors for DO (odds ratios of 5.393, 19.734 and 72.594, respectively). In validation analyses for the TOLF-DO grading system, sensitivity was 76.0% (19/25), specificity was 91.0% (70/77), and Youden's index was 0.66. Thus, implementation of the TOLF-DO grading system has the potential to improve the diagnosis of DO.

Objective: To evaluate neurologic findings caused by a single ossification of ligamentum fravum (OLF) and identify the level of the lumbar segment of spinal cord., Design: Retrospective study., Methods: Subjects were 28 patients with a single OLF at T10-11 level (15 patients), T11-12 (11), and T12-L1 (2). The tip of the conus medullaris was assessed using computed tomographic myelography or magnetic resonance imaging. Neurologic evaluations were performed for patellar tendon reflex (PTR), sensory disturbance, and motor weakness., Results: The tip of the conus medullaris was located at the L1 vertebral body level. At the T10-11 level, all patients showed hyperreflexia of PTR. Sensory disturbance was observed for L1 dermatome and weakness of the iliopsoas was noted. At the T11-12 level, 8 of 11 patients didn't show hyperreflexia of PTR. Sensory disturbance was observed for L5 dermatome and weakness of the tibialis anterior was noted. At the T12-L1 level, all patients showed normal reflex of PTR, sensory disturbance of L5 dermatome, and weakness of the tibialis anterior., Conclusion: With regard to the relationship between PTR and OLF level, all patients at the T10-11 level showed involvement of the L3 segment of spinal cord proximally. On the other hand, most patients at the T11-12 level showed involvement of the L4 segment of spinal cord distally. From all neurologic findings, we confirmed the presence of the L4 segment of spinal cord from the lower third of T11 vertebral body to the T11-12 intervertebral disc level.