Ossification of the posterior longitudinal ligament: a review of literature

Intraoperative neuromonitoring in cervical degenerative spine surgery: a meta-analysis of its impact on neurological outcomes

The role of intraoperative neuromonitoring (IONM) in cervical degenerative spine surgery remains controversial, despite its established use in tumor and deformity surgeries. Although IONM is believed to mitigate neurological complications, its effectiveness in degenerative cervical surgery remains inconclusive. Our meta-analysis aimed at systematically reviewing studies comparing neurological outcomes in degenerative cervical spine surgeries performed with and without IONM. A comprehensive search of several databases, including PubMed, Cochrane, Scopus, and Embase was conducted from January 1st, 2000 until July 16th, 2024. The included articles consisted of randomised controlled trials (RCTs), prospective and retrospective cohort studies, and case-control studies. Seven studies including 187.162 patients, with 21.686 undergoing surgery with IONM and 165.476 without it, met inclusion criteria. The pooled analysis showed no statistically significant protective effect provided by IONM (OR = 0.90 [0.51-1.59]; p-value = 0.7140; τ² = 0.3817; I^2 = 80.4%). The significance of the results has been further evaluated through two sensitivity analyses: the former excluding articles based on encoded databases (OR = 1.09 [0.04-32.72]; p-value = 0.9626; τ² = 4.9524; I^2 = 80.3%), the latter removing articles whose heterogeneity substantially influenced the overall variance (OR = 0.72 [0.50-1.05]; p-value = 0.0880; τ² = 0.0242; I^2 = 38.5%). However, both analyses resulted in no significant outcomes. Additionally, a subgroup analysis and univariate meta-regression revealed that sample size (R² = 48.11%) significantly explains heterogeneity across studies, while the use of EMG alongside SSEP and MEP also emerged as a potentially protective approach (OR = 0.39 [0.20-0.79]). The pooled analysis showed no statistically significant effect of intraoperative neuromonitoring in reducing the post-operative complication rate in the context of degenerative cervical spine surgery. However, IONM has become a standard practice, often prompting surgeons to adjust intraoperative procedures or modify pharmacological or anaesthesiologic management in response to alerts, potentially benefiting the patient. While the decision to utilize IONM finally belongs to the surgeon depending on each case, additional research, including large-scale prospective studies, is recommended to clarify the benefits of IONM and to refine standardized guidelines for its use.

Ossification of posterior longitudinal ligament of the cervical spine: A review article

This article reviews the literature on the status of cervical OPLL in recent years, and reviews the etiology, clinical manifestations, imaging features, treatment and prognosis. Evidence was collected through PubMed and Google Scholar databases. After screening, weight removal and irrelevant articles, 57 articles were finally included in the review. Imaging is the only way to confirm the diagnosis, and CT and MRI are used to assess the patient's ossified material and spinal cord compression. Because there are hundreds of surgical approaches to cervical OPLL, each with advantages and disadvantages, clinicians must develop a personalized surgical plan based on the patient's preoperative relevant factors to maximize prognosis. Clinicians should also actively follow up on discharged patients, carefully analyze cases with a poor prognosis, and summarize their experiences.

Visceral fat obesity predicts ossification of the posterior longitudinal ligament: annual health examination data-based evidence

BACKGROUND CONTEXT

Recent studies have demonstrated a close association between the development of ossification of the posterior longitudinal ligament (OPLL) and obesity. However, the association between OPLL and visceral fat obesity, which is prevalent in the Asian population, remains unexplored.

PURPOSE

To examine the impact of visceral fat obesity on the development of asymptomatic OPLL.

STUDY DESIGN

Single-institution cross-sectional study.

PATIENT SAMPLE

Between 2020 and 2021, data were collected from 249 Japanese individuals (147 men and 102 women) who underwent computed tomography (CT) to assess both the visceral fat content and OPLL.

OUTCOME MEASURES

We assessed patient background information, serum data, and CT images, including the abdominal circumference (cm), total fat area (cm2), visceral fat area (cm2), and subcutaneous fat area (cm2) at the umbilicus level. OPLL localization was assessed using whole-spine CT images.

METHODS

The individuals were categorized into 4 groups based on obesity and visceral fat: nonobesity without visceral fat (n=85), obesity without visceral fat (n=18), nonobesity with visceral fat (n=44), and obesity with visceral fat (n=102). OPLL was classified as localized or diffuse when present in the cervical spine alone or in the cervical and thoracic spine, respectively. The prevalence of each type of OPLL was compared between the groups. Multivariable analysis was conducted to calculate the effect size of body mass index (BMI) on the prevalence of OPLL, comparing the high and low visceral fat groups.

RESULTS

The obesity with visceral fat group exhibited a significantly higher proportion of diffuse OPLL than did the nonobesity without visceral fat group (27.5% vs. 7.1%, p<.001). The effect size of BMI for the occurrence of diffuse OPLL was 2.1 times greater in the high visceral fat group (odds ratio [OR], 3.12; 95% confidence interval [CI], 1.66-5.87) than in the low visceral fat group (OR, 1.44; 95% CI, 0.64-3.22).

CONCLUSIONS

Our data show that visceral fat, in conjunction with BMI, influences the occurrence of OPLL in the Japanese population. This supports the hypothesis that systemic metabolic disorders share a disease mechanism with OPLL and indicates that the high prevalence of OPLL in Japan may be attributed to physical characteristics that promote visceral fat accumulation.

Prevalence of ossification of the posterior longitudinal ligament (OPLL) in the Pacific populations in Auckland, New Zealand: A retrospective multicentre study

INTRODUCTION

Primary objective was to investigate the prevalence of ossification of the posterior longitudinal ligament (OPLL) in a mixed demographic region, especially in the Pacific Island population. Secondary objective was to investigate the prevalence of diabetes mellitus and cervical diffuse skeletal hyperostosis (DISH) in patients with and without OPLL.

METHODS

Using the local picture archiving and communication system (PACS), cervical spine computed tomography (CT) examinations over a 2-month period were retrospectively assessed for the presence of OPLL. Basic demographic data were recorded-gender, age, ethnicity, presence of cervical DISH and the presence or absence of diabetes mellitus.

RESULTS

A total of 1692 CT examinations were included in the study. The distribution of the ethnic groups was 57.3% European, 12.09% Pacific peoples, 11.9% Māori, 11.53% Asian, 0.95% Middle Eastern/Latin American/African and 6.3% not specified. Overall, 47 cases of OPPL were identified (2.78%). The prevalence of OPPL in the Pacific ethnic groups was significantly higher than the European ethnic group 8.4% versus 0.6%, P < 0.05. The prevalence of OPLL was also significantly higher in the Asian (6.9%) and Māori (3.6%) than in the European ethnic group, P < 0.05. A significantly higher proportion of the patients with OPLL had underlying diabetes 20/47 (42.6%) compared with the study population 196/1692 (11.6%), P < 0.05. Seven cases of OPPL (14.9%) had associated cervical DISH, which was significantly higher compared with the study group (23/1692), P < 0.05. Using the Japanese Ministry of Health and Welfare classification system4, segmental type was the most common (34/47, 72.3%), followed by mixed (14.9%) and continuous types (12.8%).

CONCLUSION

The prevalence of OPLL is significantly higher among the Pacific populations in Auckland. There is also increased prevalence in the Asian and Māori populations.

Ossification of the posterior longitudinal ligament is linked to heterotopic ossification of the ankle/foot tendons

INTRODUCTION

Systemic osteogenesis has been speculated to be involved in the pathogenesis of ossification of the posterior longitudinal ligament (OPLL). Our purpose was to compare the radiologic prevalence and severity of heterotopic ossification in foot tendons of Japanese patients with OPLL and to determine their association with systemic heterotopic ossification.

MATERIALS AND METHODS

Clinical and radiographic data of 114 patients with OPLL were collected from 2020 to 2022. Control data were extracted from a medical database of 362 patients with ankle radiographs. Achilles and plantar tendon ossification were classified as grades 0-4, and the presence of osteophytes at five sites in the foot/ankle joint was assessed by radiography. Factors associated with the presence and severity of each ossification were evaluated by multivariable logistic regression and linear regression analysis.

RESULTS

The prevalence of Achilles and plantar tendon ossification (grade ≥ 2) was 4.0-5.5 times higher in patients with OPLL (40-56%) than in the controls (10-11%). The presence of Achilles tendon ossification was associated with OPLL, age, and coexisting plantar tendon ossification, and was most strongly associated with OPLL (standardized regression coefficient, 0.79; 95% confidence interval, 1.34-2.38). The severity of Achilles and plantar tendon ossification was associated with the severity of ossification of the entire spinal ligament.

CONCLUSIONS

The strong association of foot tendon ossification with OPLL suggests that patients with OPLL have a systemic osteogenesis background. These findings will provide a basis for exploring new treatment strategies for OPLL, including control of metabolic abnormalities.

The clinical efficacy of laminectomy fusion fixation and posterior single open-door laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL): a retrospective study

BACKGROUND

To compared the clinical efficacy of two surgical methods, posterior laminectomy fusion fixation, and posterior single open-door laminoplasty, in treating multilevel cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

The study retrospectively included 102 patients treated between December 2016 and December 2020. The patients were included into an observation group (56 cases) treated with total laminectomy and lateral screw fixation, and a control group (46 cases) treated with single open-door laminoplasty.

RESULTS

After 24 months, both groups showed significant improvement in Japanese Orthopaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores, indicating better clinical symptoms and functional recovery. There was no significant difference in preoperative JOA and VAS scores between the two groups (P > 0.05). At 24 months after surgery, there was no significant difference in JOA and VAS scores between the two groups (P > 0.05). However, the observation group had a significantly higher cervical curvature index (CCI) and lower range of motion (ROM) of the cervical spine compared to the control group (P < 0.05). The CCI in control group was lower than before surgery, while the CCI in observation group was higher than before surgery, and CCI in the control group was considerably lower than that in the observation group (P < 0.05). The complication rate was lower in the control group, with fewer cases of axial symptoms, fifth cervical nerve root palsy, and overall complications. The overall complication rate was 25.0% (14/56) in the observation group and 10.8% (5/46) in the control group (P < 0.05).

CONCLUSIONS

Both posterior laminectomy fusion fixation and posterior single open-door laminoplasty yield positive outcomes in improving clinical neurological function, cervical curvature, range of motion of the cervical spine, and cervical sagittal balance. Although open-door laminoplasty is less effective than total laminectomy in maintaining CCI and sagittal balance, it excels in preserving cervical range of motion, less surgical trauma and complications. Thus, open-door laminoplasty may be a suitable first-choice treatment for multi-segmental cervical OPLL, especially for patients with lordotic cervical spine physiological curvature.

High whole-body bone mineral density in ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

Recent studies suggest that ossification of the posterior longitudinal ligament (OPLL) is exacerbated by systemic metabolic disturbances, including obesity. However, although an increase in bone mineral density (BMD) measured at the lumbar spine has been reported in patients with OPLL, no studies have investigated the systemic BMD of patients with OPLL in detail.

PURPOSE

We investigated whether patients with OPLL develop increased whole-body BMD.

STUDY DESIGN

Single institution cross-sectional study.

PATIENT SAMPLE

Data were collected from Japanese patients with symptomatic OPLL (OPLL [+]; n=99). Control data (OPLL [-]; n=226) without spinal ligament ossification were collected from patients who underwent spinal decompression, spinal fusion, or hip replacement surgery.

OUTCOME MEASURES

Demographic data, including age, body mass index (BMI), comorbidities, history of treatment for osteoporosis, and history of vertebral and nonvertebral fractures, was obtained from all participants. In addition, whole-body BMD, including the lumbar spine, thoracic spine, femoral neck, skull, ribs, entire upper extremity, entire lower extremity, and pelvis, were measured in all participants using whole-body dual-energy X-ray absorptiometry.

METHODS

Patient data were collected from 2018 to 2022. All participants were categorized based on sex, age (middle-aged [<70 years] and older adults [≥70 years]), and OPLL type (localized OPLL [OPLL only in the cervical spine], diffuse OPLL [OPLL in regions including the thoracic spine]), and OPLL [-]) and each parameter was compared. The factors associated with whole-body BMD were evaluated via multivariable linear regression analysis.

RESULTS

Compared with the OPLL (-) group, the OPLL (+) group of older women had significantly higher BMD in all body parts (p<.01), and the OPLL (+) group of older men had significantly higher BMD in all body parts except the ribs, forearm, and skull (p<.01). The factors associated with increased BMD of both the femoral neck (load-bearing bone) and skull (nonload-bearing bone) were age, BMI, and coexisting diffuse OPLL in women and BMI and coexisting localized OPLL in men.

CONCLUSIONS

Patients with OPLL have increased whole-body BMD regardless of sex, indicating that it is not simply due to load-bearing from obesity. These findings suggested that OPLL is associated with a systemic pathology.

Dyslipidemia as a novel risk for the development of symptomatic ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

Obesity and visceral fat have been implicated as potential factors in the pathogenesis of the ossification of the posterior longitudinal ligament (OPLL); the details of the factors involved in OPLL remain unclear.

PURPOSE

We aimed to determine the association between dyslipidemia and symptomatic OPLL.

STUDY DESIGN

Single institution cross-sectional study.

PATIENT SAMPLE

Data were collected from Japanese patients with OPLL (n=92) who underwent whole-spine computed tomography scanning. Control data (n=246) without any spinal ligament ossification were collected from 627 Japanese participants who underwent physical examination.

OUTCOME MEASURES

Baseline information and lipid parameters, including triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) from fasting blood samples were collected to assess the comorbidity of dyslipidemia.

METHODS

Patient data were collected from 2020 to 2022. Patients with dyslipidemia were defined as those who were taking medication for dyslipidemia and who met one of the following criteria: TG ≥150 mg/dL, LDL-C ≥140 mg/dL, and/or HDL-C <40 mg/dL. The factors associated with OPLL development were evaluated using multivariate logistic regression analysis.

RESULTS

The comorbidity of dyslipidemia in the OPLL group was more than twice that in the control group (71.7% and 35.4%, respectively). The mean body mass index (BMI) of the OPLL group was significantly higher than that of the control group (27.2 kg/m2 and 23.0 kg/m2). Multivariate logistic regression analysis revealed that dyslipidemia was associated with the development of OPLL (regression coefficient, 0.80; 95% confidence interval, 0.11-1.50). Additional risk factors included age, BMI, and diabetes mellitus.

CONCLUSIONS

We demonstrated a novel association between dyslipidemia and symptomatic OPLL development using serum data. This suggests that visceral fat obesity or abnormal lipid metabolism are associated with the mechanisms of onset and exacerbation of OPLL as well as focal mechanical irritation due to being overweight.

Secondary analysis of a James Lind Alliance priority setting partnership to facilitate knowledge translation in degenerative cervical myelopathy (DCM): insights from AO Spine RECODE-DCM

OBJECTIVES

To explore whether a James Lind Alliance Priority Setting Partnership could provide insights on knowledge translation within the field of degenerative cervical myelopathy (DCM).

DESIGN

Secondary analysis of a James Lind Alliance Priority Setting Partnership process for DCM.

PARTICIPANTS AND SETTING

DCM stake holders, including spinal surgeons, people with myelopathy and other healthcare professionals, were surveyed internationally. Research suggestions submitted by stakeholders but considered answered were identified. Sampling characteristics of respondents were compared with the overall cohort to identify subgroups underserved by current knowledge translation.

RESULTS

The survey was completed by 423 individuals from 68 different countries. A total of 22% of participants submitted research suggestions that were considered 'answered'. There was a significant difference between responses from different stakeholder groups (p<0.005). Spinal surgeons were the group which was most likely to submit an 'answered' research question. Respondents from South America were also most likely to submit 'answered' questions, when compared with other regions. However, there was no significant difference between responses from different stakeholder regions (p=0.4).

CONCLUSIONS

Knowledge translation challenges exist within DCM. This practical approach to measuring knowledge translation may offer a more responsive assessment to guide interventions, complementing existing metrics.

Effect of K‑line on posterior cervical surgery versus anterior cervical surgery in patients with multi-level ossification of posterior longitudinal ligament

PURPOSE

To evaluate the influence of K-line on the outcome of open-door laminoplasty versus anterior cervical corpectomy decompression and fusion (ACCF) for patients with more than two levels of ossification of the posterior longitudinal ligament (OPLL).

METHODS

60 patients undergoing open-door laminoplasty and 62 patients undergoing ACCF from January 2013 to January 2020 with more than 2 years of follow-up were included. Eighty-four cases with the ossification mass not beyond the K-line were grouped as K-line (+), while thirty-eight cases were grouped as K-line (-). The operation time, intraoperative blood loss, hospital stay, preoperative, postoperative, and last follow-up JOA scores, and postoperative complications were investigated.

RESULTS

The improvement rate of JOA scores after posterior approaches in cases of group K-line (+) and K-line (-) was 72.4% and 53.1%, respectively, which showed a significant difference (P < 0.01). In group K-line (+), the improvement of JOA scores for open-door laminoplasty was 73.4% and 71.8% for ACCF, which showed no significant difference (P > 0.05). In group K-line (-), the improvement of JOA scores for ACCF was 52.1% and 42.9% for open-door laminoplasty, which showed a significant difference (P < 0.05). The incidence of C5 palsy was significantly lower in cases with ACCF than in cases with open-door laminoplasty (P < 0.05).

CONCLUSION

For patients with more than two levels of OPLL, preoperative K-line (+) predicates a better outcome than K-line (-). For cases with K-line (-), ACCF provides better neurologic function recovery. For patients with K-line (+), open-door laminoplasty provides the same neurologic function recovery of ACCF.

Predictors for cervical kyphotic deformity following laminoplasty: a systematic review and meta-analysis

OBJECTIVE

Laminoplasty is a common treatment for cervical spondylotic myelopathy (CSM) and for ossification of the posterior longitudinal ligament (OPLL). However, approximately 21% of patients undergoing laminoplasty develop cervical kyphotic deformity (KD). Because of the high prevalence rate of KD, several studies have sought to identify predictors for this complication, but the findings remain highly inconsistent. Therefore, the authors performed a systematic review and meta-analysis to establish reliable preoperative predictors of KD.

METHODS

PubMed, Scopus, and Web of Science databases were used to systematically extract potential references. The first phase of screening required the studies to be written in the English language, involve patients treated for CSM and/or OPLL via laminoplasty, and report postoperative cervical KD. The second phase required the studies to provide more than 10 patients and include a control group. The mean difference (MD) and odds ratio (OR) were calculated for continuous and dichotomous parameters. Study quality was evaluated using the Newcastle-Ottawa Scale. CSM and OPLL patients were further assessed by performing subgroup analyses.

RESULTS

Thirteen studies comprising patients who developed cervical KD (n = 296) and no KD (n = 1254) after receiving cervical laminoplasty for CSM or OPLL were included in the meta-analysis. All studies were retrospective cohorts and were rated as high quality. In the combined univariate analysis of CSM and OPLL patients undergoing laminoplasty, statistically significant predictors for postoperative KD included age (MD 2.22, 95% CI 0.16-4.27, p = 0.03), preoperative BMI (MD 0.85, 95% CI 0.06-1.63, p = 0.04), preoperative C2-7 range of flexion (MD 10.42, 95% Cl 4.24-16.59, p = 0.0009), preoperative C2-7 range of extension (MD -4.59, 95% CI -6.34 to -2.83, p < 0.00001), and preoperative center of gravity of the head to the C7 sagittal vertical axis (MD 26.83, 95% CI 9.13-44.52, p = 0.003). Additionally, among CSM patients, males were identified as having a greater risk for postoperative KD (OR 1.73, 95% CI 1.02-2.93, p = 0.04).

CONCLUSIONS

The findings from this study currently provide the largest and most reliable review on preoperative predictors for cervical KD after laminoplasty. Given that several of the included studies identified optimal cutoff points for the variables that are significantly associated with KD, further investigation into the development of a preoperative risk scoring system that can accurately predict KD in the clinical setting is encouraged. PROSPERO registration no.: CRD42022299795 (https://www.crd.york.ac.uk/PROSPERO/).

Systematic study of single-cell isolation from musculoskeletal tissues for single-sell sequencing

Background

The single-cell platform provided revolutionary way to study cellular biology. Technologically, a sophistic protocol of isolating qualified single cells would be key to deliver to single-cell platform, which requires high cell viability, high cell yield and low content of cell aggregates or doublets. For musculoskeletal tissues, like bone, cartilage, nucleus pulposus and tendons, as well as their pathological state, which are tense and dense, it’s full of challenge to efficiently and rapidly prepare qualified single-cell suspension. Conventionally, enzymatic dissociation methods were wildly used but lack of quality control. In the present study, we designed the rapid cycling enzymatic processing method using tissue-specific enzyme cocktail to treat different human pathological musculoskeletal tissues, including degenerated nucleus pulposus (NP), ossifying posterior longitudinal ligament (OPLL) and knee articular cartilage (AC) with osteoarthritis aiming to rapidly and efficiently harvest qualified single-cell suspensions for single-cell RNA-sequencing (scRNA-seq).

Results

We harvested highly qualified single-cell suspensions from NP and OPLL with sufficient cell numbers and high cell viability using the rapid cycling enzymatic processing method, which significantly increased the cell viability compared with the conventional long-time continuous digestion group (P < 0.05). Bioanalyzer trace showed expected cDNA size distribution of the scRNA-seq library and a clear separation of cellular barcodes from background partitions were verified by the barcode-rank plot after sequencing. T-SNE visualization revealed highly heterogeneous cell subsets in NP and OPLL. Unfortunately, we failed to obtain eligible samples from articular cartilage due to low cell viability and excessive cell aggregates and doublets.

Conclusions

In conclusion, using the rapid cycling enzymatic processing method, we provided thorough protocols for preparing single-cell suspensions from human musculoskeletal tissues, which was timesaving, efficient and protective to cell viability. The strategy would greatly guarantee the cell heterogeneity, which is critical for scRNA-seq data analysis. The protocol to treat human OA articular cartilage should be further improved.

Exosomal miR-140-5p inhibits osteogenesis by targeting IGF1R and regulating the mTOR pathway in ossification of the posterior longitudinal ligament

Background

Ossification of the posterior longitudinal ligament (OPLL) is a disabling disease whose pathogenesis is still unclear, and there are no effective cures or prevention methods. Exosomal miRNA plays an important role in the osteogenesis of ectopic bone. Therefore, we focused on the downregulation of miR-140-5p in OPLL cell-derived exosomes to explore the mechanism by which exosomal miR-140-5p inhibits osteogenesis in OPLL.

Results

Exosomes were isolated by differential centrifugation and identified by transmission electron microscopy, nanoparticle tracking analysis, and exosomal markers. Exosomal RNA was extracted to perform miRNA sequencing and disclose the differentially expressed miRNAs, among which miR-140-5p was significantly downregulated. Confocal microscopy was used to trace the exosomal miR-140-5p delivered from OPLL cells to human mesenchymal stem cells (hMSCs). In vitro, we verified that exosomal miR-140-5p inhibited the osteoblast differentiation of hMSCs by targeting IGF1R and suppressing the phosphorylation of the IRS1/PI3K/Akt/mTOR pathway. In vivo, we verified that exosomal miR-140-5p inhibited ectopic bone formation in mice as assessed by micro-CT and immunohistochemistry.

Conclusions

We found that exosomal miR-140-5p could inhibit the osteogenic differentiation of hMSCs by targeting IGF1R and regulating the mTOR pathway, prompting a further potential means of drug treatment and a possible target for molecular therapy of OPLL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01655-8.

Evidence for a genetic contribution to the ossification of spinal ligaments in Ossification of Posterior Longitudinal Ligament and Diffuse idiopathic skeletal hyperostosis: A narrative review

Diffuse Idiopathic Skeletal Hyperostosis (DISH) and Ossification of the Posterior Longitudinal Ligament (OPLL) are common disorders characterized by the ossification of spinal ligaments. The cause for this ossification is currently unknown but a genetic contribution has been hypothesized. Over the last decade, many studies on the genetics of ectopic calcification disorders have been performed, mainly on OPLL. Most of these studies were based on linkage analysis and case control association studies. Animal models have provided some clues but so far, the involvement of the identified genes has not been confirmed in human cases. In the last few years, many common variants in several genes have been associated with OPLL. However, these associations have not been at definitive levels of significance and evidence of functional significance is generally modest. The current evidence suggests a multifactorial aetiopathogenesis for DISH and OPLL with a subset of cases showing a stronger genetic component.

Association Between Vitamin A Intake and Disease Severity in Early-Onset Heterotopic Ossification of the Posterior Longitudinal Ligament of the Spine

STUDY DESIGN

A sex- and age-matched case-control study and a cross-sectional study.

OBJECTIVE

In our previous study, patients with early-onset (<50 years of age) ossification of the posterior longitudinal ligament (OPLL) had distinct features such as morbid obesity, a high prevalence of lifestyle-related diseases, and diffuse ossified lesions mainly affecting the thoracic spine. Our goals were to determine whether early-onset OPLL patients have unbalanced dietary habits and to identify nutritional factors associated with OPLL exacerbation.

METHODS

In Study 1, the simple brief-type self-administered diet history questionnaire (BDHQ) was used to compare nutrient intake levels of early-onset OPLL patients (n = 13) with those of sex- and age-matched non-OPLL controls (n = 39) or with those of common OPLL (onset age ≥ 50 years, n = 62). In Study 2, serological validation was conducted for thoracic OPLL patients (n = 77) and non-OPLL controls (n = 101) in a nationwide multicenter study in Japan.

RESULTS

The BDHQ showed that the early-onset OPLL patients had significantly lower intakes of vitamins A and B6 than non-OPLL controls. These results were validated by lower serum vitamins A and B6 levels in the early-onset thoracic OPLL patients. The severity of OPLL negatively correlated with serum vitamin A levels in male early-onset OPLL patients. The multiple regression analysis revealed that the severity of thoracic OPLL had an association with onset age and serum vitamin A level.

CONCLUSIONS

Vitamin A deficiency resulting from unbalanced dietary habits is associated with exacerbation of male early-onset OPLL.

Posterior Decompression and Fusion with Vertical Pressure Procedure in the Treatment of Multilevel Cervical OPLL with Kyphotic Deformity

Objective

To report the outcomes and feasibility of a new technique to change K‐line (−) to K‐line (+) via only a posterior approach to treat multilevel non‐continuous cervical ossification of the posterior longitudinal ligament (C‐OPLL) with kyphotic deformity.

Methods

In this study, 17 consecutive cases of patients who underwent vertical pressure procedure (VP) combined with posterior cervical single‐open‐door laminoplasty and instrumented fusion from January 1, 2017 to December 31, 2019 were enrolled. The following radiographic parameters: C2‐C7 Cobb angle, local Cobb angle, extent of OPLL, and the distance from OPLL to the K‐line(DK) were measured and analyzed. Clinically, the JOA score, VAS‐N and VAS‐A, NDI, and complications were collected from medical records to evaluate the clinical outcomes.

Results

All 17 cases shifted from K‐line (−) to K‐line (+).Comparing the preoperative images to the final follow‐up images, the mean C2‐7 Cobb angle changed from −6.94° ± 8.30° to 8.18° ± 4.43°, and the local Cobb angle altered from −9.12° ± 8.68° to 6.65° ± 6.11°. The mean DK increased from −2.64 ± 1.52 mm to 3.09 ± 2.19 mm. One patient showed C5 palsy and recovered within 3 months. The mean JOA score increased from 8.88 ± 2.11 to 14.71 ± 1.36. The average NDI decreased from 20.65 ± 7.80 to 8.94 ± 4.93. The mean VAS‐N and VAS‐A decreased from 3.44 ± 1.80 and 4.69 ± 1.97 to 1.25 ± 0.86 and 1.38 ± 1.16. All patients were followed up for at least 1 year.

Conclusion

A new technique added to posterior decompression and fusion (PDF), the vertical pressure procedure effectively corrects K‐line (−) to K‐line (+) and avoids the shortcomings of conventional anterior decompression and fusion (ADF) as well as PDF to provide a relatively safe and adequate decompression, cervical realignment. It pronounced satisfactory clinical outcome for extensive non‐continuous OPLL with kyphotic deformity even though OPLL remains ventral to the spinal cord.

The Prevalence of Degenerative Cervical Myelopathy-Related Pathologies on Magnetic Resonance Imaging in Healthy/Asymptomatic Individuals: A Meta-Analysis of Published Studies and Comparison to a Symptomatic Cohort

Degenerative cervical myelopathy (DCM) is a progressive cervical spinal cord injury brought about by mechanical stress from degenerative changes in the cervical spine. It is typically diagnosed on clinical symptoms and examination findings together with MRI findings. In this study, we explore the significance of these degenerative pathology to onset of DCM by performing the first meta-analysis on the prevalence of degenerative features reported on MRI amongst healthy and asymptomatic populations and compare this to the prevalence of degenerative features reported on MRI amongst a symptomatic population calculated in a previous review. We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines, cognizant of their adaptation for epidemiological studies. A search strategy was used to identify original research carrying out MRI screening of cervical spines of asymptomatic patients in MEDLINE and Embase from 1985 to present day. The search yielded a total of 1098 studies of which 17 were included in this meta-analysis covering a total of 5059 patients. Ossification of posterior longitudinal ligament (pooled asymptomatic prevalence of 0.4%, 95% Confidence Interval [0.1%, 0.8%]), enlargement of ligamentum flavum (pooled asymptomatic prevalence of 11.8%, 95% Confidence Interval [5.3%, 18.4%]) and degenerative multilevel disc pathology (pooled asymptomatic prevalence of 64.5%, 95% Confidence Interval [48.3%, 80.8%], I² 100%) were found to be significantly lower in asymptomatic populations. Symptomatic populations have a prevalence of 10.5% (95% Confidence Interval [7.7%, 13.3%]) for ossification of posterior longitudinal ligament, 56.8% (95% Confidence Interval [52.3%, 61.3%]) for enlargement of ligamentum flavum and 89.7% (95% Confidence Interval [86.9%, 92.5%]) for degenerative multilevel disc pathology [18]. Understanding the natural history of DCM is a recognised research priority, and whilst these perspectives require further evaluation, they may be of significant relevance to the evolving biomechanical understanding of the disease.

Progression of Ossification of Posterior Longitudinal Ligament After Anterior Cervical Discectomy and Fusion in Military Patients Exposed to Minor Trauma

Objective

Ossification of the posterior longitudinal ligament (OPLL) can progress even after cervical spine surgery and may cause neurological injury as a result of minor trauma. The purpose of this study was to investigate the preventive factors associated with OPLL progression after anterior cervical discectomy and fusion (ACDF), a procedure commonly performed in clinical practice.

Methods

We retrospectively investigated 295 male soldiers who underwent ACDF surgery between 2012 and 2017. Patients who were followed up for >12 months using dynamic radiography and computed tomography (CT) were included in the study. Radiological parameters investigated included OPLL progression, C2-C7 angles on dynamic radiography, segmental angles, C2-C7 cervical sagittal vertical axis (C2-C7 SVA), and the T1 slope. These parameters were measured preoperatively and 1 year postoperatively.

Results

A total of 49 patients were enrolled, and 10 patients were confirmed to have OPLL progression. Comparison between the OPLL progression and non-progression groups showed no statistically significant differences in pre- and postoperative cervical range of motion. However, statistically significant differences were observed in the postoperative neutral C2-C7 angle (progression -3.9°±6.4° vs. non-progression -13.4°±7.9°, p=0.001) and the SVA change (progression 5.8±7.9 mm vs. non-progression -3.7±6.3 mm, p=0.00). The cutoff values were -8.01° for the postoperative neutral C2-C7 angle and 1.4 mm for SVA changes.

Conclusion

Increased SVA (>1.4 mm) and a small postoperative neutral C2-C7 angle (>-8.01°) 1 year after ACDF were associated with OPLL progression. It is important to be mindful of these factors during follow-up after ACDF, because additional surgical treatment may be necessary for OPLL progression due to neurological injury caused by minor trauma.

Close association between non-alcoholic fatty liver disease and ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament (OPLL) of the spine is a disease of unknown etiology occurring frequently in individuals with metabolic disturbances. Obesity has been suggested as a potential risk factor for the severity of OPLL. We aimed to investigate whether non-alcoholic fatty liver disease (NAFLD) is associated with OPLL severity. We assessed the severity of NAFLD by a liver-to-spleen (L/S) ratio on computed tomography (CT) scans of 85 symptomatic OPLL patients at a single institution in Japan. We also assessed the severity of OPLL by CT reconstruction sagittal and axial images. The prevalence of NAFLD in middle-aged patients (age < 70 years, n = 50) was 80.3%, which was 2.5-8 times higher than that in the general Japanese population (9-30%). The ossification index of the spinal ligaments increased in proportion to the severity of fatty liver. The L/S ratio was revealed as a significant risk factor associated with the total ossification index (standardized β: -0.40, 95% confidence interval - 54.34 to - 4.22). This study suggests the potential contribution of NAFLD to the progression of OPLL. The close association between NAFLD and OPLL demonstrated in this study warrants further study to elucidate the causal nature of this relationship.

Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire as an outcome measure for ossification of posterior longitudinal ligament patients in East Asia: an investigation of reliability, validity, and responsiveness

Background

The surgical outcomes of individual patient with ossification of the posterior longitudinal ligament (OPLL) can vary depending on various patient-related factors. Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) is a well-developed tool for outcome measurement and considers both disease-specific and general health aspects. This study aimed to investigate the reliability, validity, and responsiveness of the JOACMEQ in patients with OPLL in mainland China and to compare post-operative outcomes of OPLL patients between mainland China and Japan.

Methods

This multicenter trial was performed between July 2009 and June 2019. The procedure for the JOACMEQ translation followed Beaton’s guidelines. All patients enrolled were diagnosed with OPLL and had completed the JOACMEQ, the modified Japanese Orthopaedic Association (mJOA) scale, and the 36-Item Short Form Health Survey (SF-36) before and after surgery. The reliability (Cronbach’s α and Pearson’s correlation), construct validity (factor analysis), concurrent validity (Spearman’s correlation with SF-36) and responsiveness (effect sizes) of JOACMEQ were evaluated. A mixed-model analytic approach was used to analyze differences in postoperative outcomes between the 2 countries.

Results

Ninety-one patients from mainland China and ninety-one patients from Japan were recruited. JOACMEQ showed satisfactory internal consistency (Cronbach’s α=0.75). In test-retest reliability evaluation, except for the bladder function domain, the JOACMEQ domains had good test-retest reliability (0.89–0.96). In factor analysis, most of the items (19/24) were well clustered. Regarding clinical validity, all 5 domains were found to have moderate correlations with the physical component summary (PCS) of SF-36 (r=0.25–0.50), and the bladder function and quality of life domains also had moderate correlations (r=0.25–0.50) with the mental component summary (MCS) of SF-36. JOACMEQ showed a variable responsiveness in different domains (effect size =0.17–0.84; standardized response means =0.15–0.85). Regarding postoperative improvements in the JOACMEQ score, mixed-model analysis revealed a significant difference in the quality of life domain between Chinese and Japanese patients (16.0±18.7 vs. 7.8±17.7, P<0.05).

Conclusions

JOACMEQ generally shows good reliability, good validity and mild responsiveness, and can identify the post-operative improvements in patients with OPLL in mainland China. Chinese OPLL patients showed a significantly larger improvement in postoperative quality of life compared to their Japanese counterparts.

The Prevalence of Asymptomatic and Symptomatic Spinal Cord Compression on Magnetic Resonance Imaging: A Systematic Review and Meta-analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

Cervical spinal cord compression (SCC) due to degenerative changes of the spine is a frequent finding on magnetic resonance imaging (MRI). While most people remain asymptomatic, a proportion develop symptoms of degenerative cervical myelopathy (DCM). DCM is an often-progressive neurological disease that can cause quadriplegia. The epidemiology of SCC and DCM is poorly understood. We sought to estimate the prevalence of degenerative cervical SCC and DCM from cross-sectional cohorts undergoing MRI.

METHODS

We conducted a systematic review and meta-analysis of MRI reports on human subjects older than 16 years with degenerative SCC. A predetermined search strategy was used to identify relevant literature on MEDLINE. Title and abstract screenings were followed by full text screening. Data was extracted and analyzed by fixed or random-effects models.

RESULTS

The present search returned 1506 publications. Following our exclusion criteria, 19 studies were included. Subgroup analysis of 3786 individuals estimated the prevalence of asymptomatic SCC in a healthy population as 24.2% with a significantly higher prevalence of SCC in older populations compared with younger populations and American/European populations compared with Asian populations. Subgroup analysis of 1202 individuals estimated the prevalence of DCM in a healthy population as 2.3%.

CONCLUSIONS

We present the first estimates of the prevalence of asymptomatic SCC and DCM. Studies investigating the epidemiology of SCC are heterogeneous in methodology and results. These data indicate the need for more studies into the epidemiology of SCC and DCM performed with consistent methodologies.

Sagittal Alignment in Patients with Thoracic Myelopathy Caused by the Ossification of the Ligamentum Flavum: A Retrospective Matched Case-Control Study

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

The aim of this study was to describe and compare the sagittal spinal alignment between patients with and without the ossification of the ligamentum flavum in the thoracic spine (TOLF).

SUMMARY OF BACKGROUND DATA

Although mechanical factors play an important role in the development of TOLF, limited evidence exists on the association of sagittal spinal alignment and TOLF in the literature.

METHODS

The present study assessed the preoperative sagittal alignment parameters in consecutive patients who underwent posterior decompression for TOLF in a single institution between January 2014 and December 2019. The sagittal parameters of the patients with TOLF were compared to those of the age- and sex-matched control group with lumbar spondylosis.

RESULTS

The TOLF group (n = 43 [23 men, 20 women]), with a mean age of 69.5 (range: 41-86) years, and the control group (n = 86) were compared. The TOLF group had a significantly smaller sacral slope (27.60 ± 7.49 vs. 30.61 ± 8.15, P = 0.045) and lumbar lordosis (36.84 ± 13.63 vs. 45.08 ± 9.90, P < 0.001) and a larger pelvic incidence minus lumbar lordosis (PI-LL, 8.06 ± 15.05 vs.1.00 ± 11.34, P = 0.004) than the control group. Moreover, the thoracic kyphosis was smaller in the TOLF group, although the difference was not statistically significant (25.73 ± 11.29 vs. 28.22 ± 9.34, P = 0.187). The TOLF group had a significantly smaller slope angle at the inflection point (11.97 ± 5.85 vs. 15.78 ± 5.62, P < 0.001) and a higher tendency to have a Roussouly type 2 morphology (46.5% vs. 36.0%, P = 0.252) than the control group.

CONCLUSION

This is the first study to describe the sagittal alignment in patients with TOLF. The TOLF group showed a hypolordotic spine with a larger PI-LL mismatch compared to the age- and sex-matched control group with lumbar spondylosis.Level of Evidence: 4.

Surgical Options in Treating Ossification of the Posterior Longitudinal Ligament: Single-Center Experience

BACKGROUND

Ossified posterior longitudinal ligament (OPLL) of the cervical spine can lead to spinal stenosis and become clinically symptomatic. The optimal approach in addressing OPLL is a debated topic and dependent on factors such as preoperative lordosis and levels affected.

METHODS

In this study, we retrospectively identified patients undergoing operative management for OPLL. Demographics, operative details, radiographic parameters, outcome measurements, and complications were compared between the different approaches for OPLL treatment.

RESULTS

We identified a total of 44 patients with 16 undergoing laminoplasty (Plasty), 18 anterior corpectomy and diskectomy (Ant), and 10 laminectomy and instrumentation (Linst). Ant had least OPLL levels with median (range) 3 (2-5), compared with Plasty 4 (2-7) and Linst 4 (3-6). Plasty was associated with the shortest operative time and hospital stay. Ant showed significant correction in kyphosis from 0.5° (-13 to 16°) to 9.5° (-7 to 20°). There was loss in lordosis in Plasty and Linst. Sagittal balance significantly increased irrespective of surgical approach with the least increase in the Ant group. Complications were least in the Plasty group with similar overall improvement in outcome measurements.

CONCLUSIONS

All 3 approaches in the management of OPLL were associated with clinical improvement without 1 approach surpassing the others. Laminoplasty had the advantage of addressing more levels of stenosis than the anterior approach and was associated with a shorter operating time. Laminoplasty patients had a shorter hospital stay than those undergoing laminectomy and instrumentation and appeared to have fewer complications than the other approaches. Laminoplasty is the preferred approach in patients with preserved motion and lordosis, with the anterior approach effective in the correction of kyphosis.

Genetic pathways disrupted by ENPP1 deficiency provide insight into mechanisms of osteoporosis, osteomalacia, and paradoxical mineralization

Ectonucleotide phosphatase/phosphodiesterase 1 (ENPP1) deficiency results in either lethal arterial calcifications ('Generalized Arterial Calcification of Infancy' - GACI), phosphate wasting rickets ('Autosomal Recessive Hypophosphatemic Rickets type 2' - ARHR2), early onset osteoporosis, or progressive spinal rigidity ('Ossification of the Posterior Longitudinal Ligament' - OPLL). As ENPP1 generates a strong endogenous mineralization inhibitor - extracellular pyrophosphate (PPi) - ENPP1 deficiency should not result in reduced bone volume, and therefore the mechanism ENPP1 associated osteoporosis is not apparent given current understanding of the enzyme's function. To investigate genetic pathways driving the skeletal phenotype of ENPP1 deficiency we compared gene expression in Enpp1^asj/asj mice and WT sibling pairs by RNAseq and qPCR in whole bones, and in the liver and kidney by qPCR, directly correlating gene expression with measures of bone microarchitectural and biomechanical phenotypes. Unbiased analysis of the differentially expressed genes compared to relevant human disease phenotypes revealed that Enpp1^asj/asj mice exhibit strong signatures of osteoporosis, ARHR2 and OPLL. We found that ENPP1 deficient mice exhibited reduced gene transcription of Wnt ligands in whole bone and increased transcription of soluble Wnt inhibitors in the liver and kidney, suggestive of multiorgan inhibition of Wnt activity. Consistent with Wnt suppression in bone, Collagen gene pathways in bone were significantly decreased and Fgf23 was significantly increased, all of which directly correlated with bone microarchitectural defects and fracture risk in Enpp1^asj/asj mice. Moreover, the bone findings in 10-week old mice correlated with Enpp1 transcript counts but not plasma [PPi], suggesting that the skeletal phenotype at 10 weeks is driven by catalytically independent ENPP1 function. In contrast, the bone findings in 23-week Enpp1^asj/asj mice strongly correlated with plasma PPi, suggesting that chronically low PPi drives the skeletal phenotype in older mice. Finally, correlation between Enpp1 and Fgf23 transcription suggested ENPP1 regulation of Fgf23, which we confirmed by dosing Enpp1^asj/asj mice with soluble ENPP1-Fc and observing suppression of intact plasma FGF23 and ALP. In summary, our findings suggest that osteoporosis associated with ENPP1 deficiency involves the suppression of Wnt via catalytically independent Enpp1 pathways, and validates Enpp1^asj/asj mice as tools to better understand OPLL and Paradoxical Mineralization Disorders.

Diffuse idiopathic skeletal hyperostosis (DISH) with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine without neurological deficit - A Case report

Introduction

Diffuse idiopathic skeletal hyperostosis (DISH), or Forestier disease, is a condition characterized by calcification and ossification of ligaments and enthuses (ligament and tendon insertion sites), which mainly affect the vertebral column. The clinical manifestation of DISH is variable. Some patients can be completely asymptomatic, whereas others can complain of painful stiffness, decreased range of movement, and myelopathy symptoms. OPLL usually produce myelopathy symptoms. Combined of OPLL and DISH are rare case.

Illustration

A 59 years old woman patient complained of neck and shoulder pain in the last 20 years ago, with decreased neck range of motion and dysphagia. There was no gross abnormality on patient's neck and back. Cervical x ray was showing a continuous ossification extending from the anterior surface of C2 to C7 in lateral radiograph. A similar ossification was also noticed on the posterior surface of the vertebral bodies from C2 to C6 abutting the spinal canal.

Discussion

Despite striking abnormal appearance of cervical DISH and OPLL seen on radiologic examinations, absence of myelopathy is an indication to non-operative treatment. Presence of dysphagia was not an indication of surgery in this patient, as dysphagia was not severe and myelopathy was absent. Patient was observed during her clinical course to document the progression of myelopathy. Prophylactic surgery was not indicated for this patient, and progression of myelopathy during observation is an indication for surgical intervention.

Conclusion

Diffuse and large abnormalities in cervical area with normal neurological function is not indication for surgery. Selective treatment based on individual case.

Fate of Ossification of Posterior Longitudinal Ligament Following Anterior Cervical Fusion: Progression of Cervical Ossification of Posterior Longitudinal Ligament After Vertebral Body Sliding Osteotomy or Laminoplasty

OBJECTIVE

In the treatment of ossification of posterior longitudinal ligament (OPLL)-induced cervical myelopathy, laminoplasty (LMP) is the most widely used surgical procedure. However, the progression of ossification masses is a well-known complication of LMP. This study aimed to investigate whether the novel anterior cervical decompression technique (vertebral body sliding osteotomy; VBSO) based on anterior column fusion suppresses the progression of OPLL compared with motion-preserving posterior decompression surgery (LMP).

METHODS

All 77 consecutive patients (VBSO group, n = 33; LMP group, n = 44) who underwent VBSO or LMP for cervical OPLL at our institute between January 2012 and November 2017 were included. A total of 62 and 86 cervical motion segments in the VBSO and LMP groups were investigated, respectively. The OPLL thickness was measured twice (immediate postoperative and final follow-up), and the change of OPLL thickness was compared between the 2 groups.

RESULTS

The increase in OPLL thickness in the VBSO group (-0.18 ± 0.24 mm) was significantly smaller than that in the LMP group (1.0 ± 0.9 mm, P < 0.001). Interestingly, in some patients, suppressed OPLL progression and decreased OPLL thickness were observed.

CONCLUSIONS

The solid fusion of the anterior column by VBSO is associated with the lower incidence of OPLL growth and potential for growth arrest.

Effect of Titanium Miniplate Fixation on Hinge Fracture and Hinge Fracture Displacement Following Cervical Open-Door Laminoplasty

BACKGROUND

Cervical spondylotic myelopathy is a neuromotor disorder responsible for functional limitations and decreased daily activities. Expansive open-door laminoplasty is the widely accepted procedure for the treatment of multilevel cervical spondylotic myelopathy. Among the various fixation procedures to secure the open lamina, miniplate fixation provides better clinical and radiological outcomes. However, the immediate effects on hinge fracture and hinge fracture displacement following miniplate fixation have not been proven until now. The purpose of our study was to elucidate the impact of cervical open-door angle on the status of spinal cord expansion and hinge fracture, hinge fracture displacement, and the role of implants used during surgery.

METHODS

For this retrospective study, 122 patients who had undergone surgery from September 2016 to November 2017 with preoperative and postoperative radiographs were enrolled. Clinical and radiological outcomes were assessed before and after surgery.

RESULTS

There were no significant differences in demographics, surgery time, blood loss, medical comorbidities, or perioperative and postoperative complications between 2 groups. The recovery rate and Nurick score before and at the follow-up show no statistical significance between the 2 groups, P value > .05 (P = .672) and P > .05 (P = .553), respectively. The statistical analysis shows that the mean hinge fracture in the miniplate group with a cervical open angle >30° was 2.42 ± 1.68 and with a <30° open angle, 0.05 ± 0.23; whereas, in the anchor group the mean hinge fracture in >30° cervical open angle was 2.227 ± 2.50 and in <30° was 0.409 ± 0.503. The results revealed statistical significance between 2 implant groups, P = .024 in the aspect of hinge fracture displacement and implant used.

CONCLUSION

Laminoplasty by titanium miniplate fixation holds the laminae securely, prevents hinge fracture displacement, and promotes spinal cord expansion better than suture anchor fixation.

SRμCT Reveals 3D Microstructural Alterations of the Vascular and Neuronal Network in a Rat Model of Chronic Compressive Thoracic Spinal Cord Injury

The complex pathology of chronic thoracic spinal cord compression involves vascular and neuroarchitectural repair processes that are still largely unknown. In this study, we used synchrotron radiation microtomography (SRμCT) to quantitatively characterize the 3D temporal-spatial changes in the vascular and neuronal network after chronic thoracic spinal cord compression in order to obtain further insights into the pathogenesis of this disease and to elucidate its underlying mechanisms. Direct 3D characterization of the spinal cord microvasculature and neural microstructure of the thoracic spinal cord was successfully reconstructed. The significant reduction in vasculature and degeneration of neurons in the thoracic spinal cord visualized via SRμCT after chronic compression were consistent with the changes detected by immunofluorescence staining. The 3D morphological measurements revealed significant reductions of neurovascular parameters in the thoracic spinal cord after 1 month of compression and became even worse after 6 months without relief of compression. In addition, the distinct 3D morphological twist and the decrease in branches of the central sulcal artery after chronic compression vividly displayed that these could be the potential triggers leading to blood flow reduction and neural deficits of the thoracic spinal cord. Our findings propose a novel methodology for the 3D analysis of neurovascular repair in chronic spinal cord compression, both qualitatively and quantitatively. The results indicated that compression simultaneously caused vascular dysfunction and neuronal network impairment, which should be acknowledged as concurrent events after chronic thoracic spinal cord injury. Combining neuroprotection with vasoprotection may provide promising therapeutic targets for chronic thoracic spinal cord compression.

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

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Association between ossification of the posterior longitudinal ligament and ossification of the nuchal ligament in the cervical spine

OBJECTIVES

To investigate the association between ossification of the posterior longitudinal ligament (OPLL) and ossification of the nuchal ligament (ONL) in terms of incidence and size.

METHODS

This retrospective study evaluated 297 patients who underwent CT of the cervical spine (C-spine). Two radiologists worked in consensus. The incidence of OPLL from patients with and without ONL was compared using Chi Square tests. The mean lengths of ONL from patients with and without OPLL were compared using Student t-test. The correlations between the length of ONL and the presence of OPLL and between the length of ONL and the length of OPLL were analyzed with Pearson correlations.

RESULTS

We found that OPLL occurred more frequently in patients with ONL than in patients without ONL (odd ratio = 2.524, p = 0.037); however, the mean length of ONL did not differ significantly patients with and without OPLL (p = 0.874). We found no significant correlation between the length of ONL and the length of OPLL (p = 0.233).

CONCLUSION

The presence of ONL was associated with the presence of OPLL. The length of OPLL and ONL showed no correlation.

Diffuse idiopathic skeletal hyperostosis in a 33-year-old woman with PCOS and metabolic syndrome: a rare scenario

Diffuse idiopathic skeletal hyperostosis (DISH) is a common degenerative enthesopathy seen in the elderly with male preponderance. It is uncommon in patients before 50 years of age and is extremely rare in patients younger than 40 years. We report a case of 33-year-old unmarried woman who presented with inflammatory spinal pain and stiffness, limited chest expansion, decreased range of spinal motion and postural abnormalities, all of which suggested the diagnosis of ankylosing spondylitis, considering the patient's age. But, further evaluation led us to the final diagnosis of DISH with associated metabolic syndrome and polycystic ovarian syndrome (PCOS). To the best of our knowledge, our patient is the first reported case of DISH in a woman less than 40 years of age, and also the first case of DISH associated with PCOS and metabolic syndrome.

Ossification of Posterior Longitudinal Ligament of Cervical Spine Among Omani Patients Referred for CT Scan at a Tertiary Care Hospital in Oman

Objectives

We sought to evaluate the proportion of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine and associated factors among Omani patients.

Methods

We reviewed the cervical spine computed tomography (CT) scans of all patients referred to the Radiology Department, Sultan Qaboos University Hospital, from 2011 to 2017. Descriptive statistics were employed to determine the proportion of OPLL. We used the chi-square test to determine the association of age, gender, and diabetes mellitus with OPLL.

Results

A total of 843 patients aged ≥ 20 years were included in the study. The proportion of OPLL was 2.7% and was more frequent in men (3.2%) than women (1.9%). The male to female ratio of OPLL was 1.7:1.0. OPLL occurrence was significantly more in non-diabetic patients (p < 0.001). No significant association was found between OPLL with gender (p = 0.281) and age (p = 0.878).

Conclusions

The observed proportion of OPLL in this single-center study is relatively low, but the finding is important as the condition can eventually lead to debilitating neurologic outcomes affecting the patient's quality of life. OPLL occurrence was significantly more in non-diabetic patients, which necessitate further research on OPLL in a larger sample across Oman.

Radiological Characteristics and Surgical Outcome of Patients with Long Ossification of the Posterior Longitudinal Ligament Resulting in Ossified Lesions in the Upper Cervical Spine

OBJECTIVE

Designing surgical strategies for ossified lesions in the upper cervical spine is challenging owing to the complex anatomic structures. The present study aimed to clarify the prevalence of ossified lesions in the upper cervical spine in patients with ossification in the posterior longitudinal ligament and illustrate the clinical features, radiological findings, and surgical outcomes of this abnormality.

METHODS

Demographic and clinical data were collected for all patients preoperatively and included age, gender, body mass index, alcohol and tobacco use, history of diabetes, visual analog score, and Japanese Orthopaedic Association score. The cervical angle, morphology of ossification in the posterior longitudinal ligament, K-line, occupation ratio, space available for the spinal cord, high-intensity zone, and compression ratio of the spinal cord were calculated. The operative approach, technique used, and complications were recorded.

RESULTS

A total of 38 patients were enrolled. The upper cervical segment in 23 patients was not surgically addressed. In the group with the upper cervical segment addressed surgically, 10 patients were treated with C3-C6 open-door laminoplasty and C2 partial laminectomy, 1 with C1-C7 laminoplasty, 1 with C2-C7 laminoplasty, 2 with C3-C6 total and C2 partial laminectomy, and 1 with C1-C5 laminectomy and occipitocervical fusion.

CONCLUSIONS

The development of ossified lesions in the upper cervical spine has a high incidence. Decompressive surgery for upper cervical spine segments should be recommended for patients with severe narrowing of the spinal canal and a high signal intensity that extends to the upper cervical segment of the spinal cord. We hope that the findings from the present study will aid in clinical decision-making and provide useful information that can be incorporated into future guidelines.

Neuroanesthesiology Update

This review provides a summary of the literature pertaining to the perioperative care of neurosurgical patients and patients with neurological diseases. General topics addressed in this review include general neurosurgical considerations, stroke, traumatic brain injury, neuromonitoring, neurotoxicity, and perioperative disorders of cognitive function.

Imaging Comparison Between Chinese and Japanese Patients With Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

A retrospective study.

OBJECTIVE

To identify the radiographic differences between Chinese and Japanese patients with cervical ossification of the posterior longitudinal ligament (OPLL) using computed tomography (CT) and magnetic resonance imaging (MRI), and to compare the characteristics of OPLL between the two nationalities.

SUMMARY OF BACKGROUND DATA

OPLL has a high prevalence in East Asia. However, the differences between Chinese and Japanese OPLL patients are poorly known.

METHODS

This was a retrospective study of Chinese (n = 300) and Japanese (n = 102) consecutive patients who received a diagnosis of cervical OPLL between January 2010 and December 2014. All patients underwent CT and MRI. The type and distribution of OPLL were determined. Spinal compression was assessed by MRI. OPLL type, distribution, comorbidity, and compression of the spinal cord were examined. The ossification index (OP-index) was used to evaluate the OPLL. Factors contributing to the OP-index were examined by multivariate analysis.

RESULTS

The Chinese patients were younger than the Japanese patients (P < 0.0001), and there were more women among the Chinese patients (P = 0.0002). The OP-index was higher among the Japanese patients (median, 5 vs. 4, P = 0.003). Among men, OPLL lesions were more frequent in the under 55-year-old Japanese at C7 (P = 0.04), in the 55 to 64-year-old Japanese at C4, C5, and C6 (all P < 0.05), and in the over 64-year-old Japanese at C3/4 (P = 0.01), compared with their Chinese counterparts. Among women, OPLL lesions were more frequent in the 55 to 64-year-old Japanese at C6 (P = 0.04). The multivariate analysis showed that only age was independently associated with the OP-index (odds ratio [OR] = 1.023, 95% confidence interval [CI]: 1.002-1.045, P = 0.034).

CONCLUSION

Japanese patients had a higher frequency of OPLL lesions at C5, C6, and C7. Age was independently associated with OPLL.

LEVEL OF EVIDENCE

3.

A rare case of extensive cervico-thoracic ossification of the posterior longitudinal ligament causing myelopathy

Ossification of the posterior longitudinal ligament (OPLL) most commonly occurs in the cervical spine, usually involving two to three segments; however, the disease has the potential to occur anywhere in the spine. We encountered a fifty-one year old male with progressive unsteadiness and bilateral lower limb weakness for a period of six months which eventually became worse resulting in inability to walk without assistance. Neurological examination revealed normal upper limb function; however, the lower limbs demonstrated motor dysfunction. Signs of myelopathy were elicited and the patient was subjected to detailed radiological evaluation. CT and MRI scans revealed an extensive cervico-thoracic continuous OPLL from C3 to T3 causing significant cord compression. In view of the deteriorating neurological status, extensive C3-T3 laminectomy with instrumented posterolateral fusion was done and the patient recovered without any immediate or delayed C5 palsy. This case highlights a rare occurrence or extensive OPLL involving eight segments at the cervico-thoracic region. This report also discusses surgical strategies for managing such extensive presentations and our technique to prevent C5 palsy.

Short-Term Clinical Evaluation of Enhanced Unilateral Open-Door Laminoplasty Using Titanium Mesh

Study Design

Observational, cross-sectional study.

Purpose

The purpose of this study was to evaluate the clinical efficacy and safety profile of open-door laminoplasty (ODL) using titanium mesh.

Overview of Literature

The most appropriate surgical management of degenerative spine disorders, particularly ossification of the posterior longitudinal ligament, remains controversial and continues unabated in the neurosurgical community. However, recently, ODL has become popular among surgeons. Many modifications have been developed since Hirabayashi in 1983 to enhance the clinical efficacy and safety of this procedure.

Methods

We reviewed the obtained data of patients with ossification of the posterior longitudinal ligament (OPLL) who underwent ODL using titanium mesh at Neurosurgery Subdivision, the Dr. Sardjito Hospital, Yogyakarta, Indonesia, during January 2013–December 2015. Motor improvement (Nurick score), axial neck pain (neck disability index [NDI]), and incidence of complications were pre- and postoperatively examined, and the clinical efficacy and safety of the procedure was evaluated. Data were analyzed using Wilcoxon signed-rank test and paired t-test.

Results

This study included five patients were included (i.e., four males and one female) with mean age of 47.00±9.68 years, where reassessments were done after mean follow up of 20.2±4.74 months. Mean duration of surgery was 165±12.55 minutes. Pre- and postoperative motor assessments were 3.4±1.52 and 2.0±1.22 (p =0.059), respectively. Axial neck pains using NDI were 23.60±7.44 and 12.40±6.50 (p =0.004) before and after operations, respectively. No infected postoperative scar was found, and only one patient had a left C5 motor palsy.

Conclusions

The results of the present study suggest that enhanced ODL using titanium mesh has favorable outcome and safety profile, which can pave the way for a suitable treatment in patients with OPLL.

Reshaping of Gait Coordination by Robotic Intervention in Myelopathy Patients After Surgery

The Ossification of the Posterior Longitudinal Ligament (OPLL) is an idiopathic degenerative spinal disease which may cause motor deficit. For patients presenting myelopathy or severe stenosis, surgical decompression is the treatment of choice; however, despite adequate decompression residual motor impairment is found in some cases. After surgery, there is no therapeutic approach available for this population. The Hybrid Assistive Limb® (HAL) robot suit is a unique powered exoskeleton designed to predict, support, and enhance the lower extremities performance of patients using their own bioelectric signals. This approach has been used for spinal cord injury and stroke patients where the walking performance improved. However, there is no available data about gait kinematics evaluation after HAL therapy. Here we analyze the effect of HAL therapy in OPLL patients in acute and chronic stages after decompression surgery. We found that HAL therapy improved the walking performance for both groups. Interestingly, kinematics evaluation by the analysis of the elevation angles of the thigh, shank, and foot by using a principal component analysis showed that planar covariation, plane orientation, and movement range evaluation improved for acute patients suggesting an improvement in gait coordination. Being the first study performing kinematics analysis after HAL therapy, our results suggest that HAL improved the gait coordination of acute patients by supporting the relearning process and therefore reshaping their gait pattern.

A Novel Technique for Cervical Facet Joint Hyperplasia-Spondylotic Radiculopathy by Laminar and Lateral Mass Screw Cofixations

OBJECTIVE

We sought to describe the novel technique and report the outcomes of cervical spondylotic radiculopathy caused by facet joint hyperplasia treated with minimally invasive surgery by laminar and lateral mass screw cofixations.

METHOD

In this retrospective study, patients with spondylotic radiculopathy caused by facet joint hyperplasia underwent this technique in our unit between January 2010 and June 2015. Hospital charts, magnetic resonance imaging studies, and follow-up records for all the patients were reviewed. Outcomes were assessed on the basis of neurologic status, magnetic resonance imaging, and visual analog scale for neck and radicular pain and by the short form-36 health survey questionnaire.

RESULTS

Thirteen men and 5 women, aged 47-73 years (mean, 61.8 years), were included in this study. The follow-up time ranged from 19-50 months (mean, 32.4 months). The mean visual analog scale scores for radicular pain and neck pain, as well as the scores for all 8 domains of the short form-36 health survey questionnaire, showed significant improvements (P < 0.05). Cervical lordosis showed bending, whereas the height of the targeted disk segment showed no change (P > 0.05). Complications included 2 cases of neck pain that lasted for 3 months.

CONCLUSION

Minimally invasive surgery by lamina and lateral mass screw cofixation is safe and effective for the treatment of cervical spondylotic radiculopathy caused by facet joint hyperplasia. In addition to sufficient decompression, this technique provides relative stability to the cervical spine.

Role of Runx2 polymorphisms in risk and prognosis of ossification of posterior longitudinal ligament

BACKGROUND

Our study was aimed at finding out if Runx2 SNPs (single-nucleotide polymorphisms) are related to susceptibility to and prognosis of ossification of posterior longitudinal ligament (OPLL).

METHODS

We selected 80 OPLL patients and another 80 independent patients without OPLL from September 2013 to November 2014. Serum was collected to detect the genotypes of rs1321075, rs12333172, and rs1406846 on Runx2 with direct sequencing analysis.

RESULTS

Differences in clinical characteristics, including age, weight, height, sex ratio, as well as smoking and drinking history, between OPLL and control groups appeared to be insignificant (all P-value >.05). The allele of rs1406846 (A) emerged as a key element in raising OPLL risk with the biggest statistical significance (P<.001). Conversely, alleles of rs967588 (T) and rs16873379 (C) were associated with reduced predisposition to OPLL less remarkably (both P=.033). Regarding rs16873379, the case group exhibited a smaller frequency of homozygote CC in comparison with TT genotype than the control group (P=.016). Furthermore, the improvement rate based on calculation of JOA score suggested that genotype AA of rs6908650 was beneficial for OPLL patients' recovery from posterior laminoplasty surgery (P<.05), while genotypes of rs16873379 (CC), rs1406846 (AA), and rs2677108 (CC) significantly restrained this process (P<.05). Besides, rs16873379, rs1406846, and rs2677108 were significantly associated with number of ossification segments (P<.05).

CONCLUSIONS

Runx2 SNPs (e.g., rs16873379, rs1406846, and rs2677108) were strongly correlated with onset and treatment efficacy of OPLL, and they might regulate severity of OPLL.

Establishment of a three-dimensional finite element model of severe kyphotic deformity secondary to ankylosing spondylitis

Objective To establish a three-dimensional (3D) finite element (FE) model of ankylosing spondylitis (AS) kyphosis that is a digital platform for further studies. Methods A 30-year-old man with AS kyphosis underwent computed tomography transverse scanning from T1 to the sacrococcyx. The images were imported into Mimics® 17.0 software to establish a 3D model of the posterior spine, which was then imported into Studio Geomagic 2013 software. Posterior spine convex geometry was established on the 3D geometric model for subsequent optimization of image processing. Unigraphics NX 8.5 produced the spinal kyphosis surface model. Modeled calcification of ligaments and partial resection of useless sacral bone were added. The model was imported into ANSYS 15.0 FE analysis software. Ligaments were added. Parameters were set to generate a 3D FE model of AS. Results and Conclusion A 3D FE model of AS was successfully established, providing a reliable digital platform for subsequent biomechanical analysis.

Ayurvedic management in cervical spondylotic myelopathy

The age related spondylotic changes may result in direct compressive and ischemic dysfunction of the spinal cord known as cervical spondylotic myelopathy (CSM). Symptoms often develop insidiously and are characterized by neck stiffness, unilateral or bilateral deep aching neck, arm and shoulder pain, and possibly stiffness or clumsiness while walking. The management available in current mainstream medicine is not satisfactory. Various Ayurvedic treatments have been in use for these manifestations. We present a case of CSM, which was treated with a combination of Panchakarma procedures and Ayurvedic oral drugs. The patient was considered suffering from Greevastambha (neck stiffness) and was treated with Shalishastika pinda svedana (sudation with medicated cooked bolus of rice) for one month and Mustadi yapana basti (enema with medicated milk) for 16 days along with oral Ayurvedic drugs such as Brihatavata chintamani rasa 50 mg, Ekangaveer ras-250 mg, Ardhangavatari rasa-125 mg Amrita satva (dry extract of Tinospora cordifolia Willd)-500 mg, Muktasukti pisti-500 mg, Ashwagandha churna (powder of Withania somnifera Dunal)-500 mg Dashmool kvatha ghana (solid extract of Dashmool kvatha)-500 mg, Trayodashanga guggulu-575 mg, twice a day with honey and Eranda paka-10 g twice a day with milk. Patient's condition which was assessed for symptoms of CSM and Chile's modified Japanese Orthopaedic Association (mJOA) score for cervical spondylotic myelopathy showed substantial improvement. This study shows that the cases of CSM may be successfully managed with Ayurvedic treatment.

A novel technique to correct kyphosis in cervical myelopathy due to continuous-type ossification of the posterior longitudinal ligament

OBJECTIVE

Although posterior decompressive surgery is widely used to treat patients with cervical myelopathy and multilevel ossification of the posterior longitudinal ligament (OPLL), a poor outcome is anticipated if the sagittal alignment is kyphotic (or K-line negative). Accordingly, it is mandatory to perform anterior decompression and fusion in patients with cervical kyphosis. However, it can be difficult to perform anterior surgery because of the high risk of complications. This present report proposes a novel “greenstick fracture technique” to change the K-line from negative to positive in patients with cervical myelopathy, OPLL, and kyphotic deformity.

METHODS

Four patients with cervical myelopathy, continuous-type OPLL, and kyphotic sagittal alignment (who were K-line negative) were indicated for surgery. Posterior laminectomy and lateral mass screw insertions using a posterior approach were performed, followed by anterior surgery. Multilevel discectomy and thinning of the OPLL mass by bur drilling was performed, then an intentional greenstick fracture at each disc level was made to convert the cervical K-line from negative to positive. Finally, posterior instrumentation using a rod was carried out to maintain cervical lordosis.

RESULTS

MRI showed complete decompression of the cord by posterior migration in all cases, which had been caused by cervical lordosis. Restoration of neurological defects was confirmed at the 1-year follow-up assessment. No specific complications were identified that were associated with this technique.

CONCLUSIONS

A greenstick fracture technique may be effective and safe when applied to patients with cervical myelopathy, continuous-type OPLL, and kyphotic deformity (K-line negative). However, further studies with more cases will be required to reveal its generalizability and safety.

540° Cervical Realignment Procedure for Extensive Cervical OPLL With Kyphotic Deformity

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to present a novel, two-stage [posterior and anterior-posterior (P-AP) 540°] procedure for extensive cervical ossification of the longitudinal ligament (OPLL) with kyphotic deformity.

SUMMARY OF BACKGROUND DATA

The optimal surgical strategy for extensive cervical OPLL remains a controversial issue. Neurological injury and dural defect are complications of anterior surgery, while a posterior surgery can lead to poor clinical outcomes related to incomplete decompression.

METHODS

We analyzed consecutive cases of patients who underwent procedure described herein, which consists of two stages: the first (P: laminectomy and facet release with segmental screw fixations without rod assembly) and the second 1 week later (AP: multilevel anterior cervical discectomy with fusions (ACDFs) at the apex of the deformity without decompression, placement of lordotic grafts, and posterior fusion). To assess the radiographic parameters, extent of OPLL, maximal canal occupying ratio (%), the distances from the maximal compression to the K-line, and C2-7 angle were analyzed. Clinically, we analyzed visual analog scale of neck and arm pain, neck disability index (NDI), Japanese Orthopedic Association (JOA) score, and complications.

RESULTS

A total of 18 patients were enrolled (M:F = 15:3, mean age 64.5 yrs, mean follow-up was 30 months). The mean extent of the OPLL was 3.8 vertebral body levels. Posterior fusion was performed on a mean 4.5 segments and anterior fusion was on a mean 2.4 segments. The mean C2-7 Cobb angle was improved from 10.5° to -12.2° at follow-up. The K-line distance to the maximal compression and canal occupying ratio were improved from -3.3 mm, 73.5% to 3.8 mm, 38.4%, respectively. Preoperative NDI and JOA scores were significantly improved (18.5 to 9.4 and 8.2 to 14.8) at the last follow-up.

CONCLUSION

The 540° P-AP procedure could provide safe decompression, cervical realignment, and favorable outcomes without the disadvantages of the conventional anterior and/or posterior surgery for extensive cervical OPLL with kyphotic deformity.

LEVEL OF EVIDENCE

4.