Ossification Of The Posterior Longitudinal Ligament Patients Research Articles

Prediction of angular kyphosis after cervical laminoplasty using radiologic measurements

Angular kyphosis is an important complication after cervical laminoplasty. Previous reports have suggested that T1 slope (T1s) and extension function (EF) have key roles in kyphosis, and no different radiologic measuments which affects postoperative kyphosis were seen between ossification of the posterior longitudinal ligament (OPLL) or cervical spondylotic myelopathy (CSM). We tried to find preoperative radiologic measurements predicting angular kyphosis after laminoplasty according to disease entities. We retrospectively analyzed 133 patients with OPLL or CSM who underwent expansive laminoplasty. Preoperative neutral and extension C2-7 cobb angle (CA), T1s, C2-7 sagittal vertical axis, and C2-7 slope angle (SA) were measured. EF of C2-7 CA and C2-7 SA was defined as extension CA/SA minus neutral CA/SA. Significant angular kyphosis was defined as LCL less than −10° after surgery. Mean loss of lordosis was −3.23, and 16.5% of patients showed significant kyphosis. Preoperative EF-CA, EF-SA, and T1s were found to be predictive for angular kyphosis by Pearson correlation analysis. The receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of radiologic measurements could not reach 0.7. In patients with OPLL, the AUC of preoperative neutral CA was 0.716. However, in patients with CSM ROC curve analysis revealed that EF-CA and EF-SA could predict the significant angular kyphotic changes. Examining OPLL and CSM separately, preoperative radiologic measurements were found to influence postoperative cervical kyphosis, respectively. However, preoperative C2-7 neutral CA in OPLL patients and both EF-CA and EF-SA in CSM patients could predict significant angular kyphosis after cervical laminoplasty.

Risk factor analysis of surgery-related complications in primary cervical spine surgery for degenerative diseases using a surgeon-maintained database.

This study, using a surgeon-maintained database, aimed to explore the risk factors for surgery-related complications in patients undergoing primary cervical spine surgery for degenerative diseases. We studied 5,015 patients with degenerative cervical diseases who underwent primary cervical spine surgery from 2012 to 2018. We investigated the effects of diseases, surgical procedures, and patient demographics on surgery-related complications. As subcategories, the presence of cervical kyphosis ≥ 10°, the presence of ossification of the posterior longitudinal ligament (OPLL) with a canal-occupying ratio ≥ 50%, and foraminotomy were selected. The surgery-related complications examined were postoperative upper limb palsy (ULP) with a manual muscle test (MMT) grade of 0 to 2 or a reduction of two grade or more in the MMT, neurological deficit except ULP, dural tear, dural leakage, surgical-site infection (SSI), and postoperative haematoma. Multivariate logistic regression analysis was performed. The significant risk factors (p < 0.050) for ULP were OPLL (odds ratio (OR) 1.88, 95% confidence interval (CI) 1.29 to 2.75), foraminotomy (OR 5.38, 95% CI 3.28 to 8.82), old age (per ten years, OR 1.18, 95% CI 1.03 to 1.36), anterior spinal fusion (OR 2.85, 95% CI 1.53 to 5.34), and the number of operated levels (OR 1.25, 95% CI 1.11 to 1.40). OPLL was also a risk factor for neurological deficit except ULP (OR 5.84, 95% CI 2.80 to 12.8), dural tear (OR 1.94, 95% CI 1.11 to 3.39), and dural leakage (OR 3.15, 95% CI 1.48 to 6.68). Among OPLL patients, dural tear and dural leakage were frequently observed in those with a canal-occupying ratio ≥ 50%. Cervical rheumatoid arthritis (RA) was a risk factor for SSI (OR 10.1, 95% CI 2.66 to 38.4). The high risk of ULP, neurological deficit except ULP, dural tear, and dural leak should be acknowledged by clinicians and OPLL patients, especially in those patients with a canal-occupying ratio ≥ 50%. Foraminotomy and RA were dominant risk factors for ULP and SSI, respectively. An awareness of these risks may help surgeons to avoid surgery-related complications in these conditions. Cite this article: Bone Joint J 2021;103-B(1):157-163.

Autophagy in spinal ligament fibroblasts: evidence and possible implications for ossification of the posterior longitudinal ligament

BackgroundThe molecular mechanisms of ossification of the posterior longitudinal ligament (OPLL) remain to be elucidated. The aim of the present study was to investigate the autophagy of spinal ligament fibroblasts derived from patients with OPLL and to examine whether autophagy-associated gene expression was correlated with the expression of osteogenic differentiation genes.MethodsExpression of autophagy-associated genes was detected in 37 samples from 21 OPLL patients and 16 non-OPLL patients. The correlation of autophagy-associated gene expression and the expression of osteogenic differentiation genes was analyzed by Pearson’s correlation. The expression of autophagy-associated genes of ligament fibroblasts was assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting, and immunofluorescence. The incidence of autophagy was assessed by flow cytometry. After knockdown using small interfering RNA targeting Beclin1, the expression of osteogenic differentiation genes were compared in spinal ligament fibroblasts.ResultsIn clinical specimens, mRNA expression levels of microtubule-associated protein 1 light chain 3 and Beclin1 were higher in the OPLL group compared with the non-OPLL group. Pearson correlation analysis demonstrated that Beclin1 expression was positively correlated with expression of osteocalcin (OCN) (r = 0.8233, P < 0.001), alkaline phosphatase, biomineralization associated (ALP) (r = 0.7821, P < 0.001), and collagen type 1 (COL 1) (r = 0.6078, P = 0.001). Consistently, the upregulation of autophagy-associated genes in ligament fibroblasts from patients with OPLL were further confirmed by western blotting and immunofluorescence. The incidence of autophagy was also increased in ligament fibroblasts from patients with OPLL. Furthermore, knockdown of Beclin1 led to a decrease in the expression of OCN, ALP, and COL 1 by 63.2% (P < 0.01), 52% (P < 0.01), and 53.2% (P < 0.01) in ligament fibroblasts from patients with OPLL, respectively.ConclusionsBeclin1-mediated autophagy was involved in the osteogenic differentiation of ligament fibroblasts and promoted the development of OPLL.

New Classification Algorithm Guiding Surgical Decision-making for Posterior Longitudinal Ligament Ossification of the Thoracic Spine: A Study of 108 Patients With Mid-term to Long-term Follow-up.

This is a single-center, retrospective, cohort study. The objective of this study was to propose a surgical classification algorithm guiding the choice of surgical approaches for ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine based on the characteristics of each patient's specific pathology. Surgical decision-making in this OPLL patient population requires balancing a more definitive decompression of the thoracic spinal cord through direct decompression against a higher risk of significant complications. Patients with a primary diagnosis of thoracic OPLL who received surgical decompression in a tertiary spine center between May 2009 and June 2015 were included. Surgical planning was guided by our classification algorithm according to the location and the extent of OPLL in each patient. Patient demographics, neurological function using the 11-point Japanese Orthopaedic Association scale, length of procedure, estimated blood loss, the occurrence of major complications, etc., were extracted from the database of electronic medical record system. The Kruskal-Wallis test and Fisher exact test were used when data were not normally distributed. A total of 115 patients (33 men and 82 women) were included in this study, among whom 108 had a follow-up of at least 12 months (average: 51.7±22.2 mo, range: 12-100 mo). On the basis of our classification algorithm, 11 patients were type I, 26 were type II, 60 were type III, 11 were type IV, and the choice of surgical decompression techniques used in each patient followed that recommended by the algorithm in all cases. On average, the Japanese Orthopaedic Association score improved from 5.0±1.8 preoperatively to 8.7±1.7 postoperatively, with a Hirabayashi improvement rate of 63.6%. A new surgical classification algorithm guiding the choice of approach for decompression of OPLL in the thoracic spine was validated in a series of 108 patients through an analysis of their clinical outcomes and surgical complications. Level III.

Dkk1 acts as a negative regulator in the osteogenic differentiation of the posterior longitudinal ligament cells

Ossification of the posterior longitudinal ligament (OPLL) is a spinal disorder characterized by progressive ectopic bone formation in the PLL of the spine. Dickkopf-1 (Dkk1) is a secreted inhibitor of the Wnt pathway that negatively regulates bone formation during skeletal development. However, whether Dkk1 impacts the pathogenesis of OPLL has not been reported. This study is to investigate the role of Dkk1 in the development of OPLL. Our results show that the serum levels of Dkk1 are decreased in OPLL patients compared with non-OPLL controls. The expression of Dkk1 is also reduced in OPLL ligament cells. Downregulation of Dkk1 in ligament cells is associated with activation of the Wnt/β-catenin signaling, as indicated by stabilized β-catenin and increased T-cell factor-dependent transcriptional activity. Functionally, Dkk1 exerts a growth-inhibitory effect by repressing proliferation but promoting apoptosis of ligament cells. Dkk1 also suppresses bone morphogenetic protein 2-induced entire osteogenic differentiation of ligament cells, and this suppression is mediated via its inhibition of the Wnt pathway. Our results demonstrate for the first time that Dkk1 acts as an important negative regulator in the ossification of the PLL. Targeting the Wnt pathway using Dkk1 may represent a potential therapeutic strategy for the treatment of OPLL.

Aberrantly Expressed lncRNAs and mRNAs of Osteogenically Differentiated Mesenchymal Stem Cells in Ossification of the Posterior Longitudinal Ligament.

Ectopic bone formation is the chief characteristic of ossification of the posterior longitudinal ligament (OPLL). Emerging evidence has revealed that long non-coding RNAs (lncRNAs) can regulate the osteogenic differentiation of mesenchymal stem cells (MSCs), which are the main cells responsible for bone formation. However, the role of lncRNAs in the pathogenesis of OPLL remains unclear. In this study, 725 aberrantly expressed lncRNAs and 664 mRNAs in osteogenically differentiated MSCs from OPLL patients (OPLL MSCs) were identified by microarrays and confirmed by qRT-PCR assays. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the most enriched pathways included the p53, JAK-STAT, and PI3K-Akt signaling pathways. The co-expression network showed the interactions between the aberrantly expressed lncRNAs and mRNAs in OPLL MSCs, and the potential targets and transcription factors of the lncRNAs were predicted. Our research demonstrated the aberrantly expressed lncRNA and mRNA and the potential regulatory networks involved in the ectopic bone formation of OPLL. These findings imply that lncRNAs may play a vital role in OPLL, which provides a new perspective on the pathogenesis of OPLL.

Methylation-mediated down-regulation of microRNA-497-195 cluster confers osteogenic differentiation in ossification of the posterior longitudinal ligament of the spine via ADORA2A.

Aberrant expression of microRNAs (miRNAs) has been associated with spinal ossification of the posterior longitudinal ligament (OPLL). Our initial bioinformatic analysis identified differentially expressed ADORA2A in OPLL and its regulatory miRNAs miR-497 and miR-195. Hence, this study was conducted to clarify the functional relevance of miR-497-195 cluster in OPLL, which may implicate in Adenosine A2A (ADORA2A). PLL tissues were collected from OPLL and non-OPLL patients, followed by quantification of miR-497, miR-195 and ADORA2A expression. The expression of miR-497, miR-195 and/or ADORA2A was altered in posterior longitudinal ligament (PLL) cells, which then were stimulated with cyclic mechanical stress (CMS). We validated that ADORA2A was expressed highly, while miR-497 and miR-195 were down-regulated in PLL tissues of OPLL patients. miR-195 and miR-497 expression in CMS-treated PLL cells was restored by a demethylation reagent 5-aza-2'-deoxycytidine (AZA). Moreover, expression of miR-195 and miR-497 was decreased by promoting promoter CpG island methylation. ADORA2A was verified as the target of miR-195 and miR-497. Overexpression of miR-195 and miR-497 diminished expression of osteogenic factors in PLL cells by inactivating the cAMP/PKA signaling pathway via down-regulation of ADORA2A. Collectively, miR-497-195 cluster augments osteogenic differentiation of PLL cells by inhibiting ADORA2A-dependent cAMP/PKA signaling pathway.

The relationship between preoperative cervical sagittal balance and clinical outcome of laminoplasty treated cervical ossification of the posterior longitudinal ligament patients

Laminoplasty is a common surgical method used to treat patients with cervical ossification of the posterior longitudinal ligament (OPLL). Although laminoplasty is preferred over traditional laminectomy, the factors affecting the complications and outcomes are unclear. Recently, sagittal balance indexes have been revealed to be predictors of clinical outcomes in patients with cervical degenerative diseases, but their relationships with laminoplasty-treated OPLL outcomes remains unknown. The purpose of this study is to evaluate the relationship of preoperative cervical sagittal balance indexes and clinical outcome in laminoplasty treated OPLL patients. This is a retrospective case study. Between January 2015 and January 2017, 181 consecutively included patients who underwent cervical laminoplasty for OPLL were enrolled (male:female ratio=126:75; mean age=60.2 years). Cervical spine lateral radiographs in neutral, flexion, and extension positions were taken before and 2 years after the surgery. The C2-C7 Cobb angle, T1 slope, C1-C7 sagittal vertical axis (SVA), C2-C7 SVA, CGH (center of gravity of the head)-C7 SVA, cervical JOA (Japanese Orthopedic Association) score, and neck VAS (visual analogue scale) score were measured preoperatively and postoperatively at the 2-year follow-up. The patients were divided into two groups according to changes in the lordotic angle or the recovery rate of the JOA score. The relationships between the postoperative lordosis loss or the clinical outcome and the preoperative variables, including the patient's age, JOA score, C2-C7 Cobb angle, T1 slope, C1-C7 SVA, C2-C7 SVA, and CGH-C7 SVA, were investigated. The patients were divided into two groups according to the postoperative change in the C2-C7 Cobb angle. There were no differences in the age, preoperative C2-C7 Cobb angle, C1-C7 SVA, or C2-C7 SVA; there was only a difference in the preoperative CGH-C7 SVA and T1 slope level (p=.038, p=.042). The postoperative JOA and JOA recovery rate were related to the postoperative lordosis loss in cervical alignment (p=.048, p=.031). We again divided the patients into two groups according to the JOA recovery rate and found that only the preoperative CGH-C7 SVA and C1-C7 SVA were related to the neurological outcome (p=.011, p=.047). According to the multivariate logistic regression analysis, higher preoperative CGH-C7 SVA levels were significantly associated with decreases in the lordosis angle postoperatively and the clinical outcome (p=.018, OR=1.225; p=.034, OR=1.654). The ROC (receiver operating characteristic) analysis revealed that the proper cutoff value of preoperative CGH-C7 SVA for predicting the postoperative loss of lordosis and clinical outcomes is 3.8 cm. Preoperative cervical sagittal balance indexes are related to the outcomes of OPLL patients after laminoplasty. Patients with high preoperative CGH-C7 SVA levels have a high probability of developing sagittal imbalances and neurological symptoms of the cervical spine, and this measurement can be used as a predictor of outcomes in laminoplasty-treated cervical OPLL patients.

High incidence of venous thromboembolism after acute cervical spinal cord injury in patients with ossification of the posterior longitudinal ligament

Objective: To determine the incidence of venous thromboembolism (VTE) in patients with acute cervical spinal cord injury (SCI) and ossification of the posterior longitudinal ligament (OPLL). Design: Prospective cohort study. Setting: A department of a university hospital in Japan. Participants: This study included 57 patients (OPLL, n = 10; non-OPLL, n = 47) treated for acute cervical SCI between January 2011 and April 2017. Patients were classified according to motor complete paralysis (MC), motor incomplete paralysis (MIC), or normal motor function, based on American Spinal Injury Association (ASIA) Impairment Scale results. Interventions: N/A. Outcome Measures: All patients were screened for VTE by D-dimer monitoring, and some underwent ultrasonography. If ultrasonography indicated deep venous thrombosis (DVT) or if the D-dimers increased to ≥10 µg/mL, patients underwent contrast venography to detect VTE, including DVT or pulmonary embolism. We compared blood coagulability and VTE incidence in the OPLL and non-OPLL groups. Results: VTE occurred in 11 (19.3%) of 57 patients. The incidence of VTE was higher in the OPLL group than in the non-OPLL group (50% vs. 12.8%; P = 0.017) and higher in the MC group (57.1%) than in the MIC (8.3%; P = 0.002) or normal group (5.3%; P = 0.002). In the MC group, VTE occurred in 50% of OPLL patients and in 62.5% of non-OPLL patients (P = 0.529). In the MIC group, VTE occurred in 50% of OPLL patients and in none of the non-OPLL patients (P = 0.022). Conclusions: Patients with OPLL tended to develop VTE after SCI with motor complete and incomplete paralysis.

Clinical characteristics in patients with ossification of the posterior longitudinal ligament: A prospective multi-institutional cross-sectional study

Ossification of the posterior longitudinal ligament (OPLL) can occur throughout the entire spine and can sometimes lead to spinal disorder. Although patients with OPLL sometimes develop physical limitations because of pain, the characteristics of pain and effects on activities of daily living (ADL) have not been precisely evaluated in OPLL patients. Therefore, we conducted a multi-center prospective study to assess whether the symptoms of cervical OPLL are different from those of cervical spondylosis (CS). A total of 263 patients with a diagnosis of cervical OPLL and 50 patients with a diagnosis of CS were enrolled and provided self-reported outcomes, including responses to the Japanese Orthopaedic Association (JOA) Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), JOA Back Pain Evaluation Questionnaire (JOABPEQ), visual analog scale (VAS), and SF-36 scores. The severity of myelopathy was significantly correlated with each domain of the JOACMEQ and JOABPEQ. There was a negative correlation between the VAS score for each domain and the JOA score. There were significantly positive correlations between the JOA score and the Mental Health, Bodily Pain, Physical Functioning, Role Emotional, and Role Physical domains of the SF-36. One-to-one matching resulted in 50 pairs of patients with OPLL and CS. Although there was no significant between-group difference in scores in any of the domains of the JOACMEQ or JOABPEQ, the VAS scores for pain or numbness in the buttocks or limbs were significantly higher in the CS group; however, there was no marked difference in low back pain, chest tightness, or numbness below the chest between the two study groups. The scores for the Role Physical and Body Pain domains of the SF-36 were significantly higher in the OPLL group than in the CS group, and the mean scores for the other domains was similar between the two groups. The results of this study revealed that patients with OPLL were likely to have neck and low back pain and restriction in ADL. No specific type of pain was found in patients with OPLL when compared with those who had CS.

A novel anterior decompression technique for kyphosis line (K-line) ossification of posterior longitudinal ligament (OPLL): vertebral body sliding osteotomy

Conventional anterior cervical corpectomy and fusion (ACCF) for cervical ossification of the posterior longitudinal ligament (OPLL) is associated with a high incidence of surgery-related complications. A novel anterior decompression technique [vertebral body sliding osteotomy (VBSO)] has been developed to prevent such complications and achieve effective anterior decompression for severe OPLL patients. The purpose of this study was to describe the procedure of novel surgical technique and to evaluate the long-term surgical outcomes. Between 2012 and 2014, 24 patients underwent VBSO for treatment of cervical myelopathy caused by severe OPLL. Operation time, estimated blood loss (EBL), neurologic outcomes and perioperative complications were investigated. Various radiographic parameters such as the preoperative canal occupying ratio, postoperative canal widening, and preoperative and postoperative cervical sagittal alignment were also measured. Minimum follow-up was 24 months. The mean Japanese Orthopaedic Association score for cervical myelopathy (C-JOA score) improved from 12.4±2.9 preoperatively to 16.0±1.4 at the final follow-up (P<0.05). The mean recovery rate of the C-JOA score at the final follow-up was 68.65%±17.80%. The mean operating time was 130.7±21.0 minutes and the EBL was 176.3±38.0 mL. There were no perioperative complications. Pseudarthrosis was detected in two cases at 12 months postoperatively. The average spinal canal compromised ratio by OPLL decreased from 64.0%±15.0% preoperatively to 15.5%±12.2% postoperatively (P<0.05), with an average postoperative canal widening of 5.15±1.39 mm. Novel anterior decompression technique termed VBSO may be an effective and safe surgical option for anterior decompression surgery in patients with severe cervical OPLL. Since, VBSO does not involve a direct manipulation of the OPLL mass or dissection of the interspace between the OPLL and dura mater, this may significantly decrease the incidence of surgery-related complications, operation time, and intraoperative blood loss.

National Trends and Complications in the Surgical Management of Ossification of the Posterior Longitudinal Ligament (OPLL).

A retrospective database analysis. The aim of this study was to analyze US trends in surgical approaches for ossification of the posterior longitudinal ligament (OPLL); and to compare US patient and hospital characteristics, length of stay, total charges, and 30-day complications by surgical approach in OPLL management. A robust literature on surgical management of OPLL in East Asian countries, where OPLL has a higher prevalence, exists. However, there is a paucity of literature evaluating the surgical management of OPLL in non-Asian countries. Using the Nationwide Inpatient Sample (NIS), we identified surgically treated OPLL patients from 2003 to 2014. Data on patient characteristics, surgical approaches, complications, hospital characteristics, length of stay, and hospital charges were extracted and analyzed. Analysis of variance (ANOVA) and Chi-squared tests were used to assess variation across categorical variables. Linear regression was used to evaluate the trend of surgical management for OPLL over the study timeframe. Five thousand two hundred twelve patients fit our inclusion criteria. The overall complication rate was 21.5%, but the highest complication rate was for patients undergoing a combined anterior-posterior decompression/fusion (44.7%). Patients undergoing a combined anterior-posterior decompression/fusion had a longer length of stay and higher total charges (P < 0.01). Overall, surgical OPLL cases significantly increased from 2003 to 2014 (336-920; P < 0.01). To our knowledge, this is the largest study examining the surgical treatment of OPLL in a non-Asian country. OPLL surgical cases increased over the study timeframe and the overall surgical complication rate was 21.5%. The percentage of Asians or Pacific Islanders with OPLL undergoing surgical intervention was 10.8%, which is higher than the prevalence in the US population (4.9%). This suggests a potential genetic component to OPLL. Future work is warranted to determine how best to decrease the high complication rate. 4.

K-line (−) in the neck-flexed position affects surgical outcomes in patients with ossification of the posterior longitudinal ligament after muscle-preserving selective laminectomy

BackgroundPosterior cervical decompression results in favorable outcomes for K-line (+) ossification of the posterior longitudinal ligament (OPLL) patients. However, even for patients with K-line (+) in the neck neutral position, K-line (−) in the neck-flexed position (flexion K-line (−)) may affect surgical outcomes. We investigated the influence of flexion K-line (−) on surgical outcomes after muscle-preserving selective laminectomy using multivariate analysis. MethodsThis study involved 113 OPLL patients with K-line (+) in the neck neutral position who underwent muscle-preserving selective laminectomy. Patients were divided into flexion K-line (+) (n = 90) and flexion K-line (−) (n = 23) groups. We analyzed the influence of a flexion K-line (−) on radiological and surgical outcomes. We conducted a multivariate analysis to analyze the factors affecting surgical outcomes. ResultsThe patients with a flexion K-line (−) had a larger C2–C7 sagittal vertical axis (preoperatively, P = 0.042; postoperatively, P = 0.021), narrower postoperative clearance of the spinal cord (P = 0.003), a smaller proportion of segmental-type OPLL (P < 0.001), and a greater OPLL occupancy ratio (P < 0.001). The recovery rate measured by the Japanese Orthopedic Association (JOA) score was poorer in patients with a flexion K-line (−) (17.6 ± 32.2%) than in those with a flexion K-line (+) (35.3 ± 29.5%) (P = 0.013). Multiple linear regression analysis revealed that the flexion K-line (−) affected the recovery rate of the JOA score (β = −0.233, P = 0.013). ConclusionsEven for patients with K-line (+) OPLL, the flexion K-line (−) affects surgical outcomes. The flexion K-line (−) is a useful predictor of poor surgical outcomes after posterior decompression surgery.

Dynamic Cord Compression Causing Cervical Myelopathy.

Due to the highly mobile nature of the cervical spine, and the fact that most magnetic resonance imagings (MRIs) and computed tomography scans are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve the diagnostic accuracy of cervical stenosis. We performed a literature review on dynamic cord compression in the context of cervical spondylotic myelopathy (CSM), with particular emphasis on the role of dMRI. Cadaveric studies report that the spinal cord lengthens in flexion and the spinal canal dimension increases, whereas the spinal cord relaxes and shortens in extension and the spinal canal decreases. These changes may lead to biomechanical stress in the spinal cord with movement, especially in patients with critical cervical stenosis. The majority of the studies using dMRI in CSM reported that this imaging modality is more sensitive at detecting cervical cord compression compared to routine MRIs done in a neutral position, especially with the neck in extension. Dynamic MRI was also useful to diagnose dynamic cervical cord compression after laminectomies in patients with clinical deterioration without evident cord compression on neutral static MRI. Finally, dMRI is more sensitive in detecting stenosis in patients with CSM than in those with ossification of the posterior longitudinal ligament (OPLL), likely because OPLL patients often have a more limited range of motion than CSM patients. Thus, dMRI is a promising new tool that can help spine surgeons in diagnosing and treating CSM.

Clinical Impact of Ossification of the Posterior Longitudinal Ligament Progression After Cervical Laminoplasty.

This is a retrospective study. (1) To analyze the incidence of second surgery after initial laminoplasty for ossification of the posterior longitudinal ligament (OPLL) due to disease progression, (2) to examine factors associated with poor surgical outcome. Neurological deterioration after laminoplasty is frequently encountered due to OPLL progression. Of 201 OPLL patients treated by laminoplasty at a single-institution, the 153 monitored for >3 years postsurgery were included in this analysis. Neurological findings were graded by the Japanese Orthopaedic Association (JOA) score. We retrospectively examined the incidence of second surgery due to OPLL progression. We also evaluated the clinical characteristics and the surgical outcomes after second operation to identify potential risk factors for poor outcome. Eight patients required a second surgery due to OPLL progression. Neurological recovery was achieved in 5 of these patients, whereas 3 exhibited continued dysfunction. Patients with poor recovery showed kyphotic changes of spinal alignment and high-intensity regions in the spinal cord on T2-weighted magnetic resonance images (T2-MRI). Only a small fraction of OPLL patients required a second surgery due to OPLL progression. Recovery was poor in those with clear high-intensity T2-MRI signals in the spinal cord.

Cervical Ossification of the Posterior Longitudinal Ligament: A Computed Tomography-Based Epidemiological Study of 2917 Patients.

Study Design:Retrospective cohort study.Objectives:To identify prevalence of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine in a large sample, to characterize spinal involvement, and to identify associations with patient characteristics.Methods:Computed tomography (CT) scans of all patients receiving cervical spine CT imaging in a level-1 emergency department from January 1, 2014 to December 31, 2014 were reviewed. Diagnosis and classification of OPLL was performed, and data for associated patients was obtained (age, sex, race, ethnicity, body mass index, diabetes). US Census data was referenced for the sample population. Statistical analysis included t test and chi-square testing, with significance cutoff P < .05.Results:There were no significant differences between the sample and population data. Of 2917 patients reviewed, 74 exhibited OPLL (2.5%). Age distribution between OPLL and non-OPLL cohorts was significantly different (P < .01), with highest prevalence of OPLL between ages 40 to 49 and 50 to 59 years. Comorbid diabetes also differed between groups (27% OPLL, 13% non-OPLL, P < .01). There was no difference in distribution of sex, race, or ethnicity. For OPLL, segmental type is most common (67.6%), involving on average 3.4 levels. OPLL involvement begins at any level, but ends most commonly at C6 (40.5%) or C7 (36.5%). Among OPLL patients, 18 (24.3%) demonstrated concurrent ponticulus posticus.Conclusions:This review of 2917 patients reaffirms previous data, with OPLL prevalence of 2.5%. In asymptomatic patients, incidental diagnosis is frequently seen as early as ages 40 to 49 years. OPLL is better characterized with a significant association with diabetes, segmental type being the most common, and the caudal extent typically involving C6-7 (77%).

Predictors for Development of Symptomatic Myelopathy in Patients with Radiculopathy Caused by Cervical Ossification of Posterior Longitudinal Ligament

To identify clinical factors predicting the development of myelopathy in cervical ossification of the posterior longitudinal ligament (OPLL) patients with radiculopathy. We retrospectively reviewed 83 cervical OPLL patients who presented with radiculopathy. On the basis of the symptoms and physical findings, we divided patients into 2 groups: myelopathy group and nonmyelopathy group. Demographic, clinical, and radiologic characteristics were reviewed and analyzed among the 2 groups. Predictors for the development of myelopathy were assessed via univariate and multivariate analysis. Univariate analysis demonstrated that a high occupying ratio and the presence of an intramedullary high signal were risk factors for development of myelopathy from radiculopathy in OPLL patients. Multivariate analysis further identified that a high occupying ratio was the only independent predictor (odds ratio 1.05, 95% confidence interval 1.003-1.091, P= 0.035). The cervical range of motion and minor trauma were not related to the development of myelopathy in our study. Nonmyelopathic OPLL patients with radiculopathy and a high occupying ratio were at higher risk of developing myelopathy, and surgical intervention should be recommended in these cases. However, for elderly patients with significant comorbid conditions, the risks and benefits of surgery should be carefully considered.

The progression of ossification of the posterior longitudinal ligament of the cervical spine: A follow-up study by CT im-aging after laminoplasty

Objective To evaluate the CT imaging after laminoplasty for the patients with ossification of the posterior lon-gitudinal ligament (OPLL) of the cervical spine. Methods From June 2011 to June 2016, Retrospectively analyzed the data of OPLL patients who underwent posterior cervical open-door laminoplasty. There were 21 patients finally enrolled in this study, which consisted of 11 male and 10 female aging from 55-69, mean(61.48±4.29). The preoperative patients all had severe symp-toms of spinal compression. Collected the Japanese Orthopaedic Association Scores(JOA) Scores of all patients for gender, age, pre-operative and postoperative follow-up.The length, width and thickness of OPLL were measured by CT scan and two-dimensional re-construction of cervical spine during preoperative and follow-up, and the average progress rate was calculated. The relationship be-tween OPLL size before surgery and OPLL progress rate after surgery was analyzed. Results A total of 21 patients were included in this study, with an average age of 61.48±4.29 years-old. The mean follow-up time was 3.36±1.92 years. The JOA score of cervi-cal spine was 11.81±1.75 before operationand 14.43±1.69 at the last follow-up time (t=3.8, P<0.01). The progression rate of OPLL length, width and thickness was 3.54± 2.89 mm/year, 0.49± 0.52 mm/year and 0.34± 0.21 mm/year, respectively. Compared with the width and thickness, the average progress speed of the length was statistically significant (t=3.6, P=0.003; t= 3.8, P=0.002). The progression rate of the rostraland caudal of OPLL was 1.54 ±1.19 mm/year and 1.60±1.33 mm/year (t=0.1, P=0.559). Linear regression showed that OPLL length progression speed (mm)=0.05×preoperative length+1.23, R2=0.26 and P=0.02. Theprogres-sion rate of width and thickness of OPLL had no correlation with preoperative OPLL width and thickness. The progression rates of local, segmental, continuous, and mixed OPLL were 3.02±0.26 mm, 2.97±0.65 mm, 3.65±1.14 mm, and 3.82±1.27 mm per year. Conclusion The JOA score of the posterior open-door laminoplasty of the cervical OPLL patients was significantly improved dur-ing a short-term follow up. CT imaging follow-up showed there was progression of OPLL in length, width and thickness, and the progression rate of length was faster than width and thickness. However, there was no significant difference between the progres-sion of rostral and caudal of OPLL. In addition, short-term follow-up showed a positive correlation between the progression rate of OPLL length and the length of OPLL preoperation.The progress rate of mixed and continuous OPLL may be greater than that of seg-mental and limited OPLL. Key words: Cervical vertebrae; Ossification of posterior longitudinal ligament; Tomography, spiral computed; Follow-up studies

Co-existence of ossification of the nuchal ligament is associated with severity of ossification in the whole spine in patients with cervical ossification of the posterior longitudinal ligament -A multi-center CT study-

BackgroundPrevious studies have shown that patients with cervical ossification of the posterior longitudinal ligament (OPLL) often have co-existing ossification of the nuchal ligament (ONL). However, no studies have focused on ONL and its relevance to the severity of OPLL or ossification of other spinal ligaments, such as anterior longitudinal ligament (OALL), ligamentum flavum (OLF), and supraspinous/interspinous ligament (OSIL). MethodsIn this multicenter study, we investigated ossification of the spinal ligaments in the whole spine computed tomography (CT) images of 233 cervical OPLL patients. The severity of ossification was evaluated using ossification index for each spinal ligament, calculated as the sum of the level of ossification. We compared the severity of ossification in each spinal ligament between patients with ONL and those without ONL. Furthermore, we investigated how the number of segments, where ONL exists, affects the severity of ossification in each spinal ligament. ResultsOne hundred thirty patients (55.8%) had co-existing ONL in the cervical OPLL patients included in this study. The ONL (+) group included more male and aged patients. The cervical ossification indexes of OPLL and OALL were higher in ONL (+) patients than in ONL (−) patients. The thoracolumbar ossification indexes of OALL and OSIL were also higher in ONL (+) patients. Logistic regression analysis revealed that age, gender and cervical OA-index were independent factors correlating to the existence of ONL. In the cervical spine, both the ossification indexes of OALL and OPLL increased as the levels of ONL increased. Similarly, in the thoracolumbar spine, both the ossification indexes of OALL and OSIL were increased as the levels of cervical ONL increased. In the multiple regression analysis, cervical OA-index and thoracolumbar OSI-index showed significant correlation with the number of ONL levels. ConclusionsCo-existence of ONL in cervical OPLL patients was associated with the severity of spinal hyperostosis especially in cervical OPLL, OALL, thoracolumbar OALL and OSIL.

Cervical posterior longitudinal ligament ossification : Microscopy-assisted anterior corpectomy and fusion.

To explore the clinical efficacy and safety of microscopy-assisted anterior corpectomy and fusion for cervical ossification of the posterior longitudinal ligament (OPLL). Aretrospective review of 32cervical OPLL patients who underwent microscopy-assisted anterior corpectomy and fusion from June 2012 to March 2017 was carried out. Patients were evaluated with outcome metrics: Japanese Orthopaedic Association (JOA) scores (17points method), visual analog scale (VAS), and radiographic parameters of the lordotic angle. The complications during treatment and follow-up were recorded. This study included 32patients (15males and 17females) with amean age of 58.3 ± 2.9years (range 42-68years). The average duration of follow-up was 19.0 ± 3.5 months (range 11-46months). The scores of postoperative VAS significantly decreased (P < 0.05). The average JOA score at 12months postoperation significantly improved (p < 0.05). The lordotic angle increased after surgery (P < 0.05). There was no titanium mesh subsidence, no pseudarthrosis or hardware failure at 1‑year follow-up. One cerebrospinal fluid leakage in the surgery was managed using a gelatine sponge and the patient recovered after 1week: One patient developed laryngeal nerve injury symptom of hoarseness and recovered spontaneously in 2 weeks without intervention and 1 patient suffered slight postoperative infection. There was no worsening of neurological function. Microscopy-assisted anterior cervical anterior surgery appears to be asafe and effective treatment option for selected cases of cervical posterior longitudinal ligament ossification.