Ossification Of Ligamentum Flavum Research Articles

Incremental regression of localization context for automatic segmentation of ossified ligamentum flavum from CT data.

Segmentation of ossified ligamentum flavum (OLF) plays a crucial role in developing computer-assisted, image-guided systems for decompressive thoracic laminectomy. Manual segmentation is time-consuming, tedious, and label-intensive. It also suffers from inter- and intra-observer variability. Automatic segmentation is highly desired. A two-stage, localization context-aware framework is developed for automatic segmentation of ossified ligamentum flavum. In the first stage, localization heatmaps of OLFs are obtained via incremental regression. In the second stage, the obtained heatmaps are then treated as the localization context for a segmentation U-Net. Our framework can directly map a whole volumetic data to its volume-wise labels. We designed and conducted comprehensive experiments on datasets of 100 patients to evaluate the performance of the proposed method. Our method achieved an average Dice similarity coefficient of 61.2±7.6%, an average surface distance of 1.1±0.5mm, and an average positive predictive value of 62.0±12.8%. To the best knowledge of the authors, this is the first study aiming for automatic segmentation of ossified ligamentum flavum. Results from the comprehensive experiments demonstrate the superior performance of the proposed method over the state-of-the-art methods.

CT imaging features of calcium pyrophosphate dihydrate crystal deposition involving spine

PurposeTo explore the computed tomography (CT) imaging features of the spine involved by calcium pyrophosphate dihydrate crystal deposition disease (CPPD-CDD) in order to improve the understanding of this disease. Materials and methodsAmong 79 patients diagnosed with CPPD-CDD in our hospital, 51 patients with spinal involvement were selected, 9 patients without CT examination were excluded, and 42 patients were finally included as research objects. The CT images of the 42 patients were retrospectively analyzed. The analysis contents mainly included the distribution of lesions and the characteristic imaging findings of intervertebral disc, posterior ligament complex, sacroiliac joint and atlantoaxial joint. ResultsIn this paper, 42 patients with 11 males and 31 females were studied. The onset age ranged from 62 to 95 years. There were 264 lesions in 42 patients with spinal involvement, including 177 lumbar vertebrae, 43 cervical vertebrae, 27 thoracic vertebrae and 17 sacroiliac joints (14 bilateral and 3 unilateral). Characteristic imaging findings include: disc calcification (129 cases), posterior ligament complex calcification (107 cases), sacroiliac articular cartilage calcification (17 cases), and ligaments around the odontoid process calcification (11 cases). ConclusionsThe characteristic images of CPPD-CDD involving the spine are calcification of intervertebral disc, posterior ligament complex, sacroiliac joint surface and ligaments around odontoid process, and the lesions are frequent and coexisting, so it should be differentiated from gout, rheumatoid arthritis, ankylosing spondylitis, ossification of ligamentum flavum, basic calcium phosphate and infectious spondylodiscitis.

Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension.

Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance.This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.

Multilevel Spinal Canal Stenosis with Ossification of the Ligamentum Flavum in an Achondroplastic Patient : A Case Report

Achondroplasia is the most common form of dwarfism in humans. There are abnormalities of intracartilaginous ossification caused by mutation of FGFR 3 gene resulting in a narrow spinal canal accompanied by neurological impairements in some patients. The neurological impairements could be caused by ossification of ligamentum flavum, disc degeneration, kyphosis of lumbar spine, bony spurs, thickened laminae and facet joints. We reported a case of 23-year-old Indonesian male with achondroplasia, spinal canal stenosis accompanied by ossification of ligamentum flavum presented with progressive myelopathy and neurogenic claudication. Spinal canal stenosis with OLF was observed at L2-L5 level of lumbar spine. Laminectomy with decompression and removal of the OLF was performed at L2-L5. There was an improvement on patient's neurological symptoms and function after the surgery. In this report, we describe a rare case of achondroplasia with OLF presenting with neurological symptoms from multiple level of spinal canal stenosis. We perfromed decompressive wide laminectomy and resection of adherent OLF followed by fusion with instrumentation resulted in the improvement of patient's neurological symptoms and function.

Evolution of sagittal spinal shape for the development of thoracic ossification of ligamentum flavum.

Thoracic ossification of the ligamentum flavum (TOLF) is a rare pathology for which limited research exists. While it is known that mechanical factors play a role in the development of TOLF, little is currently understood about the sagittal alignment and related mechanical stress involved in its development. This study aims to describe the sagittal alignment of patients with TOLF based on the pathologic evolution of the Roussouly classification. The current study evaluated the preoperative Roussouly type in consecutive patients who underwent posterior decompressive laminectomy with or without posterior screw fixation for TOLF between January 2015 and December 2021. The post-evolution sagittal alignments were analyzed using the classic Roussouly classification based on sacral slope (SS). To determine the pre-evolution Roussouly type, the patients were retrospectively classified using their individual PI and PT values. Lumbopelvic parameters and morphological index including inflection point (IP), lumbar apex (LA), and lordosis distribution index (LDI) were also evaluated. Forty-three patients (21 women and 22 men) were included; their mean age was 64.21 ± 11.01 years (range 43-81). The most affected level was T10-11 (48.83%). The mean PI was 50.81 ± 9.56°, the mean SS was 33.11 ± 8.61°and the mean PT was 17.69 ± 7.89°. According to the post-evolution Roussouly classification, type 2 shape was the most frequently observed type (n = 23, 53.5%) in the post-evolution classification while type 3 was the most common type observed in the pre-evolution classification (n = 22, 51.5% and P = .00). The level of IP and LA in type 3 moved caudally (around L2 and L4/5 level, respectively) and the LDI increased (77.98 ± 8.08%) than the normal standard value. The authors found that the majority of the patients had a false type 2 spine, which had evolved pathologically from Roussouly type 3 and exhibited increased LDI, a lowered level of IP, and a lowered level of LA. These changes of spinal shape, including the transition to long hypolordosis and increased length of the thoracic kyphosis, may have accentuated tensile stress at the lower thoracic spine and contributed to the development of TOLF.

Safety and Efficacy Outcomes Following Spinal Endoscopic Procedures for Thoracic Ligamentous Ossification: A Systematic Review and Meta-Analysis.

A systematic review and meta-analysis. This study systematically reviewed and evaluated the safety and efficacy of spinal endoscopic techniques as a treatment for thoracic ligamentum flavum ossification (TOLF). The use of spinal endoscopic techniques for the treatment of TOLF has increased in recent years. The present study is the first comprehensive systematic review and meta-analysis focused on the use of spinal endoscopic techniques for TOLF. The Cochrane Central, PubMed, Web of Science, and Embase databases were systematically searched for studies focused on patients undergoing spinal endoscopic techniques to treat symptomatic TOLF. This meta-analysis included 23 studies. We included 323 patients (177 males, 146 females) with a mean age of 58.40±10.06 years, with 304 total recorded lesion locations of which 245 were located in the lower thoracic spine. Complications affected 35/323 patients, and the mean operative duration for 305 patients was 108.15±47.34 minutes. For 187 patients, the mean operative bleeding was 25.13±12.54 mL,while for 87 patients the mean duration of hospitalization was 4.59±1.93 days. At last follow-up, functional assessment was performed for 260 patients, of whom 200 were in excellent condition, visual analog scale (VAS) scores were assessed for 160 patients, with a mean improvement of 4.40 (3.95, 4.86) Japanese Orthopedic Association (JOA) scores were recorded for 115 patients, with a mean improvement of 3.49 (2.79,4.18), and modified Japanese Orthopedic Association (mJOA) scores were recorded for 208 patients, with a mean improvement of 3.62 (2.89,4.35). These results support several advantages of spinal endoscopic techniques for the treatment of symptomatic TOLF. These include low complication rates, rapid postoperative recovery, and good functional recovery when used for single-segment, non-nodular ossification and no combined dural ossification.

Single-level ossified ligamentum flavum causing a holocord syrinx: illustrative case.

Syringomyelia is a neurological disorder that is caused by abnormal cerebrospinal fluid flow or circulation. It is an incidental finding in most cases, predominantly presenting with sensory symptoms of insensitivity to pain and temperature. Spinal ossified ligamentum flavum (OLF) leading to syringomyelia is one of the rare causes. The authors report an unusual case of syringomyelia due to a thoracic OLF. A 54-year-old female presented with backache, difficulty walking, spasticity in the bilateral lower limbs, tingling sensation in the bilateral lower limbs, and paraparesis for 5 years. Her radiological investigations were suggestive of an OLF causing a syrinx. She underwent laminectomy, and her syrinx resolved on subsequent follow-up. A syrinx due to a single-level OLF is rare, and this uncommon cause should be kept in mind while formulating treatment plans.

Complications of Endoscopic Thoracic Spine Surgery: Overview and Complication Avoidance

In endoscopic thoracic spine surgery, adaptations of thoracic surgical techniques such as full endoscopic uniportal and biportal surgical techniques have been developed. Full endoscopic uniportal surgery for thoracic disc herniation or thoracic ossified ligamentum flavum (OLF) has been performed via transforaminal and interlaminar approaches. In the case of thoracic OLF or thoracic spinal stenosis, the uniportal interlaminar approach is appropriate. The uniportal interlaminar approach has been used to treat thoracic OLF and has shown good surgical results. Thoracic OLF removal via a biportal endoscopic technique has been developed recently and is described in a few studies. Although endoscopic thoracic spine surgery has significant advantages, complications often occur with this approach. We reviewed the literature to date on the complications associated with endoscopic spine surgery in thoracic pathology. This review emphasizes how to avoid and manage complications. Based on the results of several previous studies, endoscopic thoracic spine surgery could be associated with fewer potential complications than conventional surgery. Endoscopic spine surgery has remarkable advantages; however, endoscopic thoracic surgery is technically challenging and is potentially associated with serious complications. To minimize the risk of avoidable complications, surgeons should be familiar with prevention methods and pitfalls.

Uniportal Thoracic Endoscopic Unilateral Laminotomy with Bilateral Decompression of Thoracic Ossification of Ligamentum Flavum: A Systematic Review of Current Literature

Thoracic ossification of ligamentum flavum (TOLF) is a rare disease that often results in worsening neurologic sequelae if left untreated. Although the gold standard treatment for TOLF is open posterior laminectomy, it is often accompanied by high rates of complications and perioperative morbidity. There have been studies looking into feasibility of endoscopic posterior decompression for TOLF, citing potential for lower perioperative morbidity and achieving similar functional outcomes to its open laminectomy counterparts. We provide an up-to-date systematic review of clinical outcomes after endoscopic posterior decompression for TOLF from the latest assemblage of evidence. A systematic review of the technique was conducted from May 2000 to May 2023. Articles were selected based on PRISMA guidelines. Eligibility of studies was independently by 2 reviewers, with disagreements resolved by a third author. Nineteen primary references comprising 337 patients with TOLF who underwent endoscopic posterior decompression were included in the systematic review. Mean follow-up time across all studies ranged from 8.9 to 65.3 months. Mean age ranged from 51.2 to 63 years, with mean intraoperative blood loss ranging from 15 to 62 mL. There is significant improvement in visual analog scale (VAS) score, VAS back, VAS leg, modified Japanese Orthopaedic Association score, and Oswestry Disability Index compared with preoperative recorded values across all studies, with low rates of complications reported. Endoscopic posterior spinal decompression is a safe and effective technique for treatment of TOLF, with a low rate of complications and improvement in pain and function.

Posterior Cervical Unilateral Biportal Endoscopic One-Block Resection Technique for Cervical Ossified Ligamentum Flavum

Background: There is sparse literature on the technique of single-stage anterior discectomy fusion and posterior decompression and flavectomy using the biportal endoscopic technique. Methods: Single-stage anterior discectomy fusion and posterior biportal endoscopic decompression and flavectomy apply to cervical myelopathy at a single level with an anterior disc and posterior ossified ligamentum flavum complex. Anterior discectomy and fusion were performed in the usual fashion in the supine position, and subsequently, posterior biportal endoscopic decompression was carried out after turning the patient prone. Conclusion: Single-stage anterior discectomy fusion and posterior biportal endoscopic decompression and flavectomy are good alternatives for circumferential decompression with myelopathy

Clinical Results and Review of Techniques of Thoracic Endoscopic Unilateral Laminotomy with Bilateral Decompression (TE-ULBD) Using the Outside-In Technique for Thoracic Ossified Ligamentum Flavum

Objective: Uniportal full endoscopic thoracic endoscopic surgery can be performed through transforaminal and interlaminar approaches. The interlaminar approach is commonly described as thoracic endoscopic unilateral laminotomy for bilateral decompression (TE-ULBD), which is typically indicated for pathologies such as ossified ligamentum flavum and other posteriorly based compressive pathologies. TE-ULBD decompresses the central and lateral recesses of the thoracic spinal canal. Both the outside-in (over the top of ligamentum flavum) and inside-out (under the ligamentum flavum) approaches can decompress the thoracic spinal canal through the uniportal interlaminar endoscopic route.Methods: A retrospective clinical cohort evaluation of patients who underwent TE-ULBD was performed from January 2018 to December 2021 Results: A cohort of 50 cases of TE-ULBD with a mean age of 65 years old were evaluated. The complication rate was 5.4% and the reoperation rate was 2%. Statistically significant mean VAS improvements were found at 1 week, 6 months, and the final follow-up, with changes of 3.95 ± 1.49, 4.95 ± 1.7, and 5.2 ± 1.8 points, respectively. Likewise, the mean Oswestry Disability Index improvements at 1 week, 3 months, and the final follow-up were 33.8 ± 9.05, 40.12 ± 10.38, and 41.92 ± 11.26, respectively (p < 0.001). Significant improvements were found in the cross-sectional area of the spinal canal in the upper endplate, mid-disc, and lower endplate (57.62 ± 50.6, 89.86 ± 55.93, and 64.93 ± 60.91 mm<sup>2</sup>, respectively; p < 0.001). Conclusion: TE-ULBD using the outside-in technique could achieve good clinical outcomes and a low rate of complications in our cohort of patients.

Unilateral Biportal Endoscopic Decompression for Thoracic Spinal Stenosis

In conventional thoracic laminectomy, postoperative complications such as dural tears, cerebrospinal fluid leakage, postoperative infection, and iatrogenic spinal cord injury are relatively common. To address these issues, unilateral biportal endoscopy (UBE) techniques for thoracic laminectomy have been developed and published, demonstrating various advantages over conventional thoracic laminectomy with satisfactory clinical results. In comparison to conventional thoracic laminectomy, the UBE decompression technique with the unilateral approach and bilateral decompression (ULBD) appears to be safe and effective for treating thoracic ossified ligamentum flavum (OLF) or thoracic spinal stenosis. Thoracic ULBD by UBE preserves the paraspinal muscle and ligament that would otherwise be resected during the conventional posterior approach, and it has the added benefit of reducing back pain and muscle atrophy. This manuscript covers the technical aspects of UBE implementation using thoracic ULBD in patients with thoracic OLF or thoracic spinal stenosis, the indications and benefits of this procedure, and tips for preventing complications. With a review of previously published articles on thoracic laminectomy by UBE, we also summarize whether the procedure is safe and can prevent cord injuries.

Piezo1 involves in intracellular osteogenic transformation signal to promote the ossification of ligamentum flavum

Ectopic osteogenesis refers to the occurrence of osteoblasts in soft tissues other than bone tissue and the formation of bone tissue. The ligamentum flavum is an essential connecting structure between adjacent vertebral lamina, which participates in the formation of the vertebral canal's posterior wall and maintains the vertebral body's stability. Ossification of the ligamentum flavum (OLF) is one of the manifestations of systemic ossification of the spinal ligaments and one of the degenerative diseases related to the spine. However, there is a lack of research on the expression and biological function of Piezo1 in ligamentum flavum. Whether Piezo1 participates in the development of OLF is still unclear. The FX-5000C cell or tissue pressure culture and real-time observation and analysis system was applied to stretch ligamentum flavum cells to detect the expression of mechanical stress channel and osteogenic markers after the effect of different stretching durations. The results showed elevated expression of mechanical stress channel Piezo1 and osteogenic markers with the effect of tensile time duration. In conclusion, Piezo1 involves in intracellular osteogenic transformation signal to promote the ossification of ligamentum flavum. An approved explanatory model and further research will be required in the future.

CT-based radiographic measurements and effectiveness estimates of full-endoscopic surgery in thoracic myelopathy caused by ossification of ligamentum flavum

BackgroundEvaluate the effectiveness of posterior percutaneous full-endoscopic technique for patients with thoracic myelopathy caused by ossification of ligamentum flavum (TOLF).MethodsA prospective study was conducted for 16 patients with TOLF, who were treated with posterior endoscopic technique from 2017 to 2019. The sagittal and cross-sectional CT images are used to measure the area of ossified ligamentum and evaluate the decompression of surgery, respectively. The effectiveness was evaluated with visual analog scale (VAS), modified Japanese Orthopedic Association scale (mJOA), The Oswestry Disability Index (ODI), and Macnab efficacy evaluation.ResultsThe average area of TOLF on sagittal and cross-sectional CT images in the 16 patients was (116.62 ± 32.72) mm2 and (141.59 ± 27.25) mm2 preoperatively, (15.99 ± 12.54) mm2 and (11.72 ± 8.64) mm2 at 3 days after the operation, (16.78 ± 11.49) mm2 and (10.82 ± 7.57) mm2 postoperative 1 year, respectively. The invasive proportion of spinal canal at preoperative sagittal and cross-sectional CT images was (48.10 ± 10.04) % and (57.58 ± 11.37) %, which decreased to (6.83 ± 4.48) % and (4.40 ± 3.01) % at the final follow-up. The average score of mJOA, VAS and ODI improved. The excellent and good rate was 87.50% according to Macnab evaluation. Compared with preoperative, differences in areas of TOLF, proportions of spinal canal, and clinical assessments of postoperative 3 days and 1 year were all statistically significant. Two cases of dural tear were observed.ConclusionEndoscopic surgery has a good clinical effect on TOLF, which has the advantage of less trauma to the paraspinal muscles and no impact on the spinal structure. The CT-based radiographic measurements can quantitatively evaluate the degree of spinal canal stenosis in TOLF.

Thoracic spondylotic myelopathy in diffuse idiopathic skeletal hyperostosis: a comparative study

BackgroundTo explore the characteristics and clinical management of thoracic spinal stenosis with diffuse idiopathic skeletal hyperostosis (DISH).MethodsThe patients diagnosed with thoracic spondylotic myelopathy who underwent spinal decompression and fusion surgery in a single center between 2012 and 2020 were retrospectively analyzed. All the patients were followed up for at least 2 years. Patients were classified into DISH and non-DISH groups. Demographic, radiographic and clinical parameters were compared between the two groups.ResultsA total of 100 thoracic spondylotic myelopathy patients were included in the study. 22 patients were diagnosed with DISH. The proportion of male patients in the DISH group was higher, and the average BMI was larger. The incidence of upper thoracic vertebrae with ossification of posterior longitudinal ligament (OPLL) (P < 0.05) and lumbar spine with ossification of ligamentum flavum (OLF) was higher (P < 0.05) in DISH the group. The proportion of patients received staged surgery is higher in the DISH group (P < 0.1). There were no significant differences between the two groups in the amount of surgical bleeding, the ratio of cerebrospinal fluid leakage, the time duration of drainage tube placement and the JOA scores.ConclusionThoracic spinal stenosis with DISH occurred more in male patients with larger BMI. The posterior decompression and fusion surgery could achieve comparable satisfying clinical outcomes between DISH and non-DISH patients. More proportion of patients received staged surgery in the DISH group; the underline mechanism may be DISH caused more OPLL in the upper thoracic spine and more OLF in the lumbar spine because of mechanical stress.

Schmorl's nodes are associated with prevalent osteoporotic vertebral fracture and low bone mineral density: a population-based thoracic spine MRI study in older men and women.

Schmorl's node (SN) corresponds to nucleus pulposus herniation into the vertebral spongy bone with thickened trabeculae around the formed node. We hypothesize that a pathway may exist that: osteoporosis → weakened endplate → SN development ↔ endplate fracture of an osteoporotic vertebra. For osteoporotic fractures in men (MrOS) and in women (MsOS) Hong Kong studies, at 14-year follow-up, thoracic spine magnetic resonance imaging (MRI) was sampled in 270 males (mean: 82.9±3.7 years) and 150 females (mean: 81.5±4.3 years). SN and Modic change were assessed as existed or not existed. For posterior disc protrusion, ligamentum flavum ossification, and spinal canal stenosis, semi-quantitative gradings were applied. For each vertebra in women, a score of 0, 0.5, 1, 1.5, 2, 2.5, 3 was assigned for no osteoporotic vertebral fracture (OVF) or OVF of <1/5, ≥1/5-1/4, ≥1/4-1/3, ≥1/3-2/5, ≥2/5-2/3, and ≥2/3 vertebral height loss, respectively, and a summed score was calculated by summing up the scores of vertebrae T1 to T12. For men, those of minimal grade were not considered as OVF and assigned a '0' score. SN prevalence in women (55.5%) almost doubled that in men (25.9%). SN was statistically significantly correlated with lower bone mineral density (BMD) derived femoral neck T-score, while the other four spine degeneration changes were not statistically significantly correlated with the T-score. SN were statistically significantly correlated with OVF score. Subjects with SN were more likely to have OVF, with odds ratio for men of 4.32 [95% confidence interval (CI): 1.70-11.00, P=0.002] and odds ratio for women of 3.28 (95% CI: 1.23-8.74, P=0.018). Among older population, many features of SN parallel those of OVF.

Application of unilateral biportal endoscopy technique in single-segment thoracic ossification of ligamentum flavum

To investigate the safety and effectiveness of unilateral biportal endoscopy (UBE) technique in the treatment of single-segment thoracic ossification of ligamentum flavum (TOLF). Between August 2020 and December 2021, 11 patients with single-segment TOLF were treated with UBE technique. There were 6 males and 5 females, with an average of 58.2 years (range, 49-72 years). The responsible segment was T 6, 7 in 1 case, T 7, 8 in 1 case, T 8, 9 in 2 cases, T 9, 10 in 2 cases, T 10, 11 in 2 cases, and T 11, 12 in 3 cases. Imaging examination showed that the ossification were located on the left side in 4 cases, on the right side in 3 cases, and on bilateral sides in 4 cases. The main clinical symptoms were chest and back pain or lower limb pain, all accompanied by lower limb numbness and fatigue. The disease duration ranged from 2 to 28 months (median, 17 months). The operation time, postoperative hospital stay, and complications were recorded. Visual analogue scale (VAS) score was used to evaluate the chest and back pain and low limb pain, and Oswestry disability index (ODI) and Japanese Orthopedic Association (JOA) score were used to evaluate functional recovery before operation and at 3 days, 1 month, 3 months after operation, and last follow-up. The anteroposterior diameter of the coronal spinal canal was measured by CT before and after operation to evaluate the effect of surgical decompression. All operations were successfully completed. The operation time was 50-105 minutes, with an average of 80.0 minutes. No postoperative complication such as dural sac tear, cerebrospinal fluid leakage, spinal nerve injury, or infection occurred. The postoperative hospital stay was 2-5 days, with an average of 3.1 days. All incisions healed by first intention. All patients were followed up 6-22 months, with an average of 14.8 months. CT measurement at 3 days after operation showed that the anteroposterior diameter of the spinal canal was (8.63±1.61) mm, which was significantly larger than that before operation [(3.67±1.37) mm] ( t=-12.181, P<0.001). The VAS score of chest and back pain and lower limb pain and ODI at each time point after operation were significantly lower than those before operation ( P<0.05). The above indexes were further improved after operation, except that there was no significant difference between at 3 months after operation and at last follow-up ( P>0.05), the differences between other time points were significant ( P<0.05). There was no recurrence during the follow-up period. UBE technique is a safe and effective method to treat single-segment TOLF, but its long-term effectiveness needs to be further studied.

Artificial lamina after laminectomy: Progress, applications, and future perspectives.

In clinical practice, laminectomy is a commonly used procedure for spinal decompression in patients suffering from spinal disorders such as ossification of ligamentum flavum, lumbar stenosis, severe spinal fracture, and intraspinal tumors. However, the loss of posterior column bony support, the extensive proliferation of fibroblasts and scar formation after laminectomy, and other complications (such as postoperative epidural fibrosis and iatrogenic instability) may cause new symptoms requiring revision surgery. Implantation of an artificial lamina prosthesis is one of the most important methods to avoid post-laminectomy complications. Artificial lamina is a type of synthetic lamina tissue made of various materials and shapes designed to replace the resected autologous lamina. Artificial laminae can provide a barrier between the dural sac and posterior soft tissues to prevent postoperative epidural fibrosis and paravertebral muscle compression and provide mechanical support to maintain spinal alignment. In this paper, we briefly review the complications of laminectomy and the necessity of artificial lamina, then we review various artificial laminae from clinical practice and laboratory research perspectives. Based on a combination of additive manufacturing technology and finite element analysis for spine surgery, we propose a new designing perspective of artificial lamina for potential use in clinical practice.

Novel therapeutic strategy in the treatment of ossification of the ligamentum flavum associated with dural ossification.

To investigate the imaging characteristics of thoracic ossification of ligamentum flavum (OLF) combined with dural ossification (DO) and the clinical efficacy of zoning laminectomy. The clinical data of 48 patients with thoracic OLF combined with DO who underwent zoning laminectomy between June 2016 and May 2020 were retrospectively analyzed. The modified Japanese Orthopedic Association (mJOA) score was used to evaluate neurological function before and after surgery, and the clinical efficacy was evaluated according to the improvement rate. The symptoms of all patients significantly improved after the operation, and the average follow-up time was 27.8 (10-47) months. In addition, the average mJOA score had increased from 5.0 (2-8) preoperatively to 8.7 (6-11) postoperatively (t = 18.880, P < 0.05). The average improvement rate was 62.6% (25-100%), with 16 patients graded as excellent, 21 as good, and 11 as fair. Cerebrospinal fluid leakage occurred in 12 cases (25.0%), and all of them healed well after treatment. No postoperative aggravation of neurological dysfunction, wound infection or hematoma occurred. At the last follow-up, there was no recurrence of symptoms and kyphosis. The Zoning laminectomy described here is both safe and effective.

Surgical Management of Cervical Myelopathy: Current Algorithm

Cervical myelopathy (CM) is a progressive disorder associated with a varied spectrum of etiological factors. Cervical spondylotic myelopathy (CSM) encompasses two-thirds of the cases of CM, while ossified posterior longitudinal ligament (OPLL) and ossified ligamentum flavum (OLF) are significant regional etiological factors. Microvascular disruption, resulting from repetitive dynamic compression or static pressure to the spinal cord, is attributed as a primary pathophysiological mechanism for CM. Magnetic resonance imaging (MRI) is the investigation of choice to assess the spinal cord. Lateral cervical radiographs are crucial for lordosis assessment, and tomographic scans (CT) can delineate the extent of OPLL and OLF. Non-surgical treatment is usually not successful once the patient develops progressive myelopathy. Anterior cervical procedures are ideal for one or two level disc-osteophytes complexes or in patients with kyphotic cervical alignment. Laminoplasty is an effective motion-preserving option in patients with adequate cervical lordosis. Laminectomy or laminoplasty and fusion are optimal for patients with significant preoperative neck pain. Posterior surgery is preferred over anterior surgery for CM involving three or more levels. Older age at presentation, longer duration of symptoms, and severity of pre-operative symptoms are adverse prognostic factors. Progressive cervical myelopathy is a surgical disease, and early intervention is rewarded with better outcomes. Keywords: Cervical myelopathy, Cervical spondylotic myelopathy, OPLL, OLF, Laminoplasty, Laminectomy, ACDF, Cervical corpectomy.