Hormones and growth factors in the pathogenesis of spinal ligament ossification

Global prevalence estimates of diffuse idiopathic skeletal hyperostosis: a systematic review and meta-analysis

Background

Diffuse idiopathic skeletal hyperostosis (DISH) is a whole-body disease characterized by ossification or calcification of joints and ligaments, which is present on all continents and in all ethnic groups. However, there is a lack of comprehensive information on the global prevalence and incidence of DISH.

Objective

To conduct a systematic review and meta-analysis to investigate the global prevalence of DISH.

Methods

Three electronic medical databases (Cochrane Database of Systematic Reviews, MEDLINE, and Embase) were used to conduct a systematic review of population-based and clinical-based studies reporting the prevalence of DISH from the time of commencement to February 2023. "Prevalence or epidemiology" and "diffuse idiopathic skeletal hyperostosis or DISH" were the search terms used. There were no language restrictions. Extract data based on features such as continent, gender, age, and race. Quality was assessed using the Critical Appraisal Tool for Prevalence Data Reporting Studies from the Joanna Briggs Institute, which synthesizes the available evidence using a random effects model.

Results

Among the 33 studies, the overall estimated prevalence of DISH in the general population (n=36925) was 11.92% (95% CI, 8.68%-15.59%), and the overall prevalence of DISH in clinical patients (n=22969) was about 14.30% (95%CI, 10.10%-19.09%). In 17 population-based studies, the prevalence of DISH was 10.07% (95% CI, 6.76%-13.95%) in Asia, 11.16% (95% CI, 6.19%-17.36%) in Europe, 13.46% in North America (95%CI, 12.20%-14.77%) and 30.07% (95%CI, 25.90%-34.49%) in Oceania. The overall prevalence of DISH by sex was 6.49% (95%CI, 3.65%-10.07%) in women and 17.87% (95%CI, 13.27%-22.98%) in men. The prevalence rate of Asians was 10.07% (95%CI, 6.76%-13.95%), that of white people was 11.90% (95%CI, 7.62%-16.98%), and that of black people was 8.77% (95%CI, 6.39%-11.67%). In 16 clinic-based studies, the prevalence of DISH was 16.32% (95%CI, 10.10%-23.67%) in Asia, 13.20% (95%CI, 9.89%-16.92%) in Europe, and 13.13%(95%CI, 3.79%-26.93%) in North America and 3.93% in Africa. According to gender classification, the overall prevalence of DISH was 10.16% (95%CI, 6.59%-14.38%) in women and 18.73% (95%CI, 12.84%-25.44%) in men. The prevalence rate of Asians was 16.45% (95%CI, 7.45%-28.05%), that of white people was 14.95% (95%CI, 10.28%-20.31%), and that of black people was 5.71% (95%CI, 2.57%-9.98%).

Conclusions

This study identifies the global prevalence of DISH in terms of population distribution, space, and time. The overall prevalence of DISH was approximately 11.92% (95%CI, 8.68%-15.59%) in the general population and 14.30% (95% CI, 10.10%-19.09%) in clinical patients. The prevalence of DISH was higher in males, and those aged 50 and over.

Predictive factors of poor surgical outcome in thoracic ossified ligamentum flavum: A multivariate analysis

OBJECTIVE

Ossified ligamentum flavum (OLF) of the spine is a rare cause of compressive myelopathy. OLF is prevalent in Asian countries. Surgery is the only treatment option for symptomatic patients. The recovery after surgery depends upon multiple clinical and radiological factors and varies significantly. We report our series of surgically managed thoracic OLF and the factors predicting poor outcomes.

METHODS

A retrospective study was conducted including 52 patients who underwent surgery for thoracic OLF. The pre-operative clinical status, radiology findings, intraoperative observations and complications were analyzed with post-op clinical outcomes. The mean follow-up period was 24 months (range 12-72).

RESULTS

There were 35 males and 17 females with a mean age of 49.5 years (range: 30-75). The mean duration of symptoms was 13 months (range: 1 month to 5 years). The mean modified Japanese Orthopedic Association (mJOA) score was 5.8 preoperatively, 5.5 postoperatively and improved to 7.5 at the last follow-up. A good recovery rate (>50 %) was found in 18 patients, poor recovery (<50 %) in 24 patients, seven remained unchanged and three patients had worsened. In univariate analysis, the statistically significant factors for the recovery rate were the number of OLF levels, CT axial classification (tuberous type), associated OALL and cervical OPLL, T2W cord signal changes, ossification of dura mater, dural tear, and CSF leak. Dural tear and the number of OLF levels were the most predictive factors for the poor outcome on multivariate analysis.

CONCLUSION

Predictors of poor surgical outcomes are the extent of OLF involved and dural tear. The patient improves with rehabilitation despite the immediate postoperative deterioration.

Possible involvement of vitamin K insufficiency in the progression of cervical ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament of the vertebral column (OPLL) is a disease characterised by ectopic bone formation in the spinal ligament that causes progressive neurological impairment. However, there are no suitable treatments for OPLL. Here, we compared the general characteristics and haemostasis of patients with OPLL and those with cervical spondylotic myelopathy. Those with OPLL had significantly longer prothrombin times and lower plasma protein C concentrations, consistent with vitamin K deficiency. Therefore, we next characterised the effects of vitamin K supplementation on spinal hyperostosis in ttw mice, a model of cervical OPLL, by feeding them standard chow, vitamin K-deficient chow, or standard chow accompanied by biweekly vitamin K2 injections for 6 weeks. We found that vitamin K supplementation resulted in longer stride lengths and superior inter-limb coordination using footprint analysis. Furthermore, supplementation caused a significant reduction in ectopic calcification of the cervical ligaments of the mice, according to microcomputed tomography analysis. Finally, supplementation caused an increase in the number of osteochondrogenic cells expressing Gla-rich protein, an inhibitor of ectopic calcification, and increased the circulating concentration. Thus, vitamin K insufficiency may be involved in the pathogenesis of OPLL and supplementation may represent a novel treatment for this condition.

Single-cell transcriptome profiling identifies the activation of type I interferon signaling in ossified posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is a condition comprising ectopic bone formation from spinal ligaments. This disease is a leading cause of myelopathy in the Asian population. However, the molecular mechanism underlying OPLL and efficient preventive interventions remain unclear. Here, we performed single-cell RNA sequencing and revealed that type I interferon (IFN) signaling was activated in the ossified ligament of patients with OPLL. We also observed that IFN-β stimulation promoted the osteogenic differentiation of preosteoblasts in vitro and activated the ossification-related gene SPP1, thereby confirming the single-cell RNA sequencing findings. Further, blocking the IFN-α/β subunit 1 receptor (IFNAR1) using an anti-IFNAR1 neutralizing antibody markedly suppressed osteogenic differentiation. Together, these results demonstrated that the type I IFN signaling pathway facilitated ligament ossification, and the blockade of this signaling might provide a foundation for the prevention of OPLL.

Ossification of the anterior longitudinal ligament affects the severity and distribution of neurological deficits following spinal cord injury without radiological abnormality

BACKGROUND

The incidence of spinal cord injury without radiological abnormality (SCIWORA) is increasing among older adults in developed countries. SCIWORA is commonly associated with ossification of the spinal ligament, specifically the ossification of the posterior longitudinal ligament (OPLL) and ossification of the anterior longitudinal ligament (OALL). OALL induces segmental spinal fusion and alters the biomechanical properties of the cervical spine; however, whether OALL modulates the severity of SCIWORA remains unknown. This study aimed to investigate the influence of OALL on the severity and distribution of neurological deficits following SCIWORA.

METHODS

This retrospective study included 122 patients with SCIWORA who were admitted to our hospital from April 2008 to March 2022. The neurological function of all the included patients was assessed via the American Spinal Injury Association (ASIA) Impairment Scale (AIS) at admission. Magnetic resonance imaging (MRI) and computed tomography were performed within 48 h of trauma. Central cord syndrome (CCS) was defined as the upper-extremity ASIA motor score being at least 10 points lesser than the lower-extremity motor score.

RESULTS

The study included 122 patients with a mean age of 65.1 years. Comparing mild (AIS grades C or D) and severe (AIS grades A or B) neurological deficits revealed that the former was independently associated with ground-level falls, OALL, and absence of prevertebral T2 high-intensity area on MRI. Although 39% of patients with SCIWORA exhibited OPLL as an etiology of cervical stenosis, OPLL demonstrated no significant effect on the severity of neurological deficits. CCS occurrence was independently associated with OALL and a larger cross-sectional cord area on MRI. Patients with OALL had significantly higher lower-extremity ASIA motor scores than those without OALL.

CONCLUSIONS

OALL was significantly associated with mild neurological deficits in the lower extremities and with the occurrence of CCS after SCIWORA.

Prevalence and distribution of ossification of the ligamenta flava in a 16th-18th century skeletal population sample from Poland

OBJECTIVE

This study aimed to determine the prevalence of the ossification of the ligamenta flava (OLF) among skeletal remains from Poland.

MATERIALS AND METHODS

124 skeletons aged 25 years and older were analyzed. The presence and size of OLF were observed macroscopically. OLF was recorded at the cranial and caudal attachment sites of each vertebra. The following factors were analyzed: age at death, sex, and presence of other spondyloarthropathies.

RESULTS

The crude prevalence of OLF in the analyzed series was 68.55 %. OLF was located most frequently in the lower thoracic spine. A statistically significant relationship was observed between the presence of OLF and age at death. OLF coincided with degenerative spondyloarthropathies of the thoracolumbar spine.

CONCLUSIONS

The results of this study indicate that OLF was not a rare condition in past populations of European ancestry. Analysis of OLF prevalence in skeletal materials can contribute to reconstruction of the conditions and lifestyles of past people.

SIGNIFICANCE

This study shed new light on the prevalence of OLF and provides information on the variability of OLF in past European populations. The evaluation of the prevalence of OLF represents an important contribution to the field of paleopathology in understanding disease changes in prehistoric and historic human populations.

LIMITATIONS

The analyzed material came from unknown populations without demographic data. Sex and age at death were assessed using standard anthropological methods.

SUGGESTIONS FOR FURTHER RESEARCH

It is important to understand the influence of sociocultural factors and physical activity patterns on the development of OLF.

Correlation Between the Severity of Multifidus Fatty Degeneration and the Size of Ossification of Posterior Longitudinal Ligament at Each Spinal Level

OBJECTIVE

This study aimed to investigate the correlation between ossification of the posterior longitudinal ligament (OPLL) size and multifidus fatty degeneration (MFD), hypothesizing that larger OPLL sizes are associated with worse MFD.

METHODS

One hundred four patients with cervical OPLL who underwent surgery were screened. OPLL occupying diameter and area ratios, the severity of MFD using the Goutallier classification, and range of motion (ROM) of cervical flexion-extension (ΔCobb) were measured. Correlation analyses between OPLL size, MFD severity, and ΔCobb were conducted. MFD severity was compared for each OPLL type using one-way analysis of variance.

RESULTS

The final clinical data from 100 patients were analyzed. The average Goutallier grade of C2-7 significantly correlated with the average OPLL diameter and area occupying ratios, and OPLL involved vertebral level (r = 0.58, p < 0.01; r = 0.40, p < 0.01; r = 0.47, p < 0.01, respectively). The OPLL size at each cervical level significantly correlated with MFD of the same or 1-3 adjacent levels. ΔCobb angle was negatively correlated with the average Goutallier grade (r = -0.31, p < 0.01) and average OPLL occupying diameter and area ratios (r = -0.31, p < 0.01; r = -0.35, p < 0.01, respectively). Patients with continuous OPLL exhibited worse MFD than those with segmental OPLL (p < 0.01).

CONCLUSION

OPLL size is clinically correlated with MFD and cervical ROM. OPLL at one spinal level affects MFD at the same and 1-3 adjacent spinal levels. The worsening severity of MFD is associated with the longitudinal continuity of OPLL.

Diffuse idiopathic skeletal hyperostosis (DISH) and trabecular bone score (TBS) in postmenopausal women: The Camargo cohort

OBJECTIVES

The potential relationship between diffuse idiopathic skeletal hyperostosis (DISH) and bone microstructure has not been studied in women. We aimed to assess the association between the trabecular bone score (TBS) and DISH in postmenopausal women, as well as the role of other parameters related to bone metabolism, such as bone mineral density (BMD), calciotropic hormones, and bone remodeling markers.

METHODS

Cross-sectional study, nested in a prospective population-based cohort (Camargo cohort). Clinical covariates, DISH, TBS, vitamin D, parathormone, BMD and serum bone turnover markers, were analyzed.

RESULTS

We have included 1545 postmenopausal women (mean age, 62±9 years). Those with DISH (n = 152; 8.2%) were older and had a significantly higher prevalence of obesity, metabolic syndrome, hypertension, and type 2 diabetes mellitus (p<0.05). Moreover, they had lower TBS values (p = 0.0001) despite having a higher lumbar spine BMD (p<0.0001) and a higher prevalence of vertebral fractures than women without DISH (28.6% vs. 15.1%; p = 0.002). When analyzing DISH through Schlapbach grades, women without DISH had a median TBS value consistent with a normal trabecular structure while the values for women with DISH from grades 1 to 3 were consistent with a partially degraded trabecular structure. Women with vertebral fractures and DISH had a mean TBS corresponding to a degraded trabecular structure (1.219±0.1). After adjusting for confounders, the estimated TBS means were 1.272 (1.253-1.290) in the DISH group, and 1.334 (1.328-1.339) in the NDISH group (p<0.0001).

CONCLUSION

An association between DISH and TBS has been shown in postmenopausal women, in which hyperostosis has been significantly and consistently related to trabecular degradation and, therefore, to deterioration in bone quality after adjusting for confounding variables.

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

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

Thoracic Myelopathy in Ossified Ligamentum Flavum: Surgical Management and Long-Term Outcome Following 2 Different Techniques of Surgical Decompression

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Thoracic ossified ligamentum flavum (TOLF) has been reported to present with varying degrees of neuro-deficit and multiple factors have been purported to affect its outcome. Purpose of study was to analyze factors affecting outcome and impact of ultrasonic osteotome (UO).

METHODS

We retrospectively reviewed patients treated for thoracic myelopathy secondary to OLF between 2010 and 2017. 77 patients with complete clinico-radiological records and 2 years follow-up were included. Initial 45 patients, conventional high-speed burr (HSB-group A) was used for decompression. In others, UO was used in combination with HSB (group B). Myelopathy was graded using modified Japanese orthopaedic association grading pre-operatively and each postoperative visit. At final follow-up, recovery rate was calculated. Radiological details including location, morphology, dural ossification, signal change and spinal ossifications were recorded.

RESULTS

Mean mJOA at presentation and final follow-up were 4.3±1.8 and 7.6±1.9 respectively (p = 0.001). HRR was 49.9±23 at final follow-up. A significant reduction in dural tear (12.5%; 29%) and surgical time (125.8±49.5; 189.4±52.5) were observed in group B (p = 0.00). However, there was no statistically significant difference (p = 0.18) in recovery rates between groups A (44.8±26.1) and B (52.8±24.3). Symptom duration (p = 0.00), severity of myelopathy (p = 0.04) and cord signal changes on MRI (p = 0.02) were important predictors of outcome.

CONCLUSION

Use of UO significantly reduced operative time and dural tears, although resulted in similar recovery rate as compared with HSB. Pre-operative severity of myelopathy, symptom duration and presence of cord signal change were the most significant predictors of outcome.

Early stages of diffuse idiopathic skeletal hyperostosis (DISH) and chronic inflammation: the Camargo Cohort Study

INTRODUCTION/OBJECTIVES

DISH has traditionally been considered a non-inflammatory rheumatic disorder. Currently, an inflammatory component has been theorized in the early phases of this condition (EDISH). The study is aimed at investigating a possible relationship between EDISH and chronic inflammation.

METHOD

Analytical-observational study: participants from the Camargo Cohort Study were enrolled. We collected clinical, radiological, and laboratory data. C-reactive protein (CRP), albumin-to-globulin ratio (AGR), and triglyceride-glucose (TyG) index were assessed. EDISH was defined by Schlapbach's scale grades I or II. A fuzzy matching with tolerance factor = 0.2 was performed. Subjects without ossification (NDISH), sex- and age-matched with cases (1:4), acted as controls. Definite DISH was an exclusion criterion. Multivariable analyses were performed.

RESULTS

We evaluated 987 persons (mean age 64 ± 8 years; 191 cases with 63.9% women). EDISH subjects presented more frequently obesity, T2DM, MetS, and the lipid pattern [↑TG ↓TC]. TyG index and alkaline phosphatase (ALP) were higher. Trabecular bone score (TBS) was significantly lower (1.310 [0.2] vs. 1.342 [0.1]; p = 0.025). CRP and ALP showed the highest correlation (r = 0.510; p = 0.0001) at lowest TBS level. AGR was lower, and its correlations with ALP (r =  - 0.219; p = 0.0001) and CTX (r =  - 0.153; p = 0.022), were weaker or non-significant in NDISH. After adjustment for potential confounders, estimated CRP means for EDISH and NDISH were 0.52 (95% CI: 0.43-0.62) and 0.41 (95% CI: 0.36-0.46), respectively (p = 0.038).

CONCLUSIONS

EDISH was associated with chronic inflammation. Findings revealed an interplay between inflammation, trabecular impairment, and the onset of ossification. Lipid alterations were similar to those observed in chronic-inflammatory diseases. Key Points • An inflammatory component has been theorized in early stages of DISH (EDISH) • In EDISH group compared to non-DISH, we observed significantly higher correlations between biomarkers and some relevant variables. In particular, with alkaline phosphatase (ALP) and with trabecular bone score (TBS) • EDISH has shown to be associated with chronic inflammation • The lipid alterations observed in the EDISH group were similar to those observed in chronic-inflammatory diseases.

Review of Basic Research about Ossification of the Spinal Ligaments Focusing on Animal Models

Ossification of the posterior longitudinal ligament (OPLL) is a heterotopic ossification that may cause spinal cord compression. With the recent development of computed tomography (CT) imaging, it is known that patients with OPLL often have complications related to ossification of other spinal ligaments, and OPLL is now considered part of ossification of the spinal ligaments (OSL). OSL is known to be a multifactorial disease with associated genetic and environmental factors, but its pathophysiology has not been clearly elucidated. To elucidate the pathophysiology of OSL and develop novel therapeutic strategies, clinically relevant and validated animal models are needed. In this review, we focus on animal models that have been reported to date and discuss their pathophysiology and clinical relevance. The purpose of this review is to summarize the usefulness and problems of existing animal models and to help further the development of basic research on OSL.

Comparison of the Short-Term Efficacy of Percutaneous Endoscopic Thoracic Decompression and Laminectomy in the Treatment of Thoracic Ossification of the Ligamentum Flavum

OBJECTIVE

This study aimed to investigate the short-term efficacy of percutaneous endoscopic thoracic decompression (PETD) under local anesthesia and traditional posterior thoracic laminectomy (PTL) in treating single-segment thoracic ossification of the ligamentum flavum (T-OLF).

METHODS

This was a retrospective review of the clinical information of 52 patients with T-OLF between September 2017 and September 2021. Based on the inclusion criteria, a total of 52 patients were included in the present research, 26 in the PETD group and 26 in the PTL group. The general preoperative data, intraoperative surgical conditions, preoperative and postoperative clinical information, and complications were collected. The modified Japanese Orthopedic Association score and recovery rate were evaluated preoperatively and at 3, 6, and 12 months postoperatively.

RESULTS

There was no statistically significant difference in the baseline parameters in either group (P > 0.05). There were statistically significant differences in operation time (94.62 vs. 144.62 minute) and blood loss (22.12 vs. 287.69 mL) between the PETD group and the PTL group. The modified Japanese Orthopedic Association score in the 2 groups improved from (5.46 ± 1.10) and (5.69 ± 1.01) preoperatively to (9.08 ± 0.90) and (8.88 ± 1.07) at 12 months postoperatively. The recovery rate was 84.6% in the PETD group and 76.9% in the PTL group. In addition, the complications in the PETD group were fewer than those in the PTL group.

CONCLUSIONS

The PETD under local anesthesia for T-OLF has many advantages, such as high patient acceptance, good short-term clinical outcomes, and few complications; therefore, this procedure should be promoted as a viable treatment option for T-OLF.

[Repeated cervical laminoplasty for progressive ossification of posterior longitudinal ligament: a case report]

Posterior longitudinal ligament ossification is a progressive disease resulting in severe multilevel spinal stenosis with myelopathy. Decompression via anterior or posterior approach is the main treatment option. Decompressive laminoplasty is currently considered the most effective and safest method. This procedure provides favorable outcomes with low trauma and short surgery time. Redo surgeries are rare and most often performed within 2 years after primary laminoplasty. The most common causes are progressive spinal stenosis following posterior longitudinal ligament ossification, insufficient primary decompression and progressive cervical spine kyphosis. Considering few data on redo laminoplasty, we present a patient with progressive ossification of posterior longitudinal ligament who underwent redo surgery at the same level in 10 years after primary laminoplasty.

Lumbar Spinal Canal Stenosis in Acromegaly: A Case Report and Literature Review

A 60-year-old Japanese man diagnosed with acromegaly at 28 years old had difficulty walking due to worsening back pain. He had been treated with somatostatin analog since 57 years old, but his pain and numbness continued to worsen. Lumbar magnetic resonance imaging showed disc bulging at L3/4 and 4/5, and he was diagnosed with lumbar spinal canal stenosis due to hypertrophy of the yellow ligament. Patients with acromegaly may complain of osteoarthropathy, so we must pay attention to the symptoms of spinal canal stenosis in collaboration with orthopedic specialists.

Analysis of the surgical strategy and postoperative clinical effect of thoracic ossification of ligament flavum with dural ossification

Purpose

Our research was designed to analyse the postoperative clinical results of patients suffering from single-segment thoracic ossification of the ligamentum flavum (TOLF) combined with dural ossification (DO) who underwent posterior laminar decompression and internal fixation.

Methods

This retrospective research included thirty-two patients who underwent surgery for ossifying the ligamentum flavum in the thoracic spine between January 2016 and January 2020. Patients were fallen into one group included patients with evidence of DO during surgery, and the other group included patients without evidence of DO. We assessed and compared general clinical characteristics and health-related outcomes before surgery and during follow-up.

Results

The DO group had a longer operation duration, more blood loss, and longer hospital stay (operation time: 94.75 ± 6.78 min vs. 80.00 ± 10.13 min, p < 0.001; blood loss: 331.67 ± 50.06 ml vs. 253.00 ± 48.24 ml, p < 0.001; length of hospital stay: 13.83 ± 2.76 days vs. 10.05 ± 2.33 days, p < 0.001).

Complications

There were 12 cases of cerebrospinal fluid leakage and 1 case of superficial wound infection in the DO group. However, the neurological recovery and health-associated quality of life (HRQOL) scores showed no statistically significant changes between the DO and non-DO groups (p > 0.05).

Conclusions

Posterior laminectomy and internal fixation combined with intraoperative resection of the ossified ligamentum flavum and dura is an efficient and relatively safe method for treating TOLF with DO, which can provide satisfactory results. Moreover, DO had no significant effect on postoperative neurological recovery and health-related quality of life scores.

Diffuse Spinal Hyperostosis Causing Severe Spinal Stenosis and Thoracic Myelopathy

Introduction

Spinal stenosis has a wide range of causes including disc herniation, facet hypertrophy, degenerative spondylosis, facet cyst, ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL). We present three cases of diffuse spinal hyperostosis causing severe spinal stenosis and myelopathy, which demonstrate a unique association between obesity and a novel syndrome of hyperostosis.

Case Presentation

This report describes 3 morbidly obese patients with diffuse spinal hyperostosis causing critical thoracic stenosis. Their presenting complaints focus on lower extremity weakness and the CT/MRI imaging is striking for diffuse hyper-ossification at thoracic levels. Two patients were subsequently managed with spinal decompression, and one patient was managed non-operatively.

Discussion

Metabolic changes associated with obesity may result in diffuse hyperostosis with ligament ossification and spinal stenosis. Pre-operative imaging is essential to identify the degree of ossification and potential dural involvement as this may complicate management.

Anatomical, morphometric and radiographic study of the humerus in lesser anteater (Tamandua mexicana Saussure, 1860): terminological and functional analyses

Tamandua is a neotropical mammal genus that belongs to the superorder Xenarthra. The thoracic limbs of Tamandua have anatomical adaptations that widely differ from other mammals, and there are frequently specimens in wildlife care centers with traumas in their limbs. However, there are few studies describing the radiographic and morphometric anatomy of the humerus in Tamandua, or describing partially the bone reliefs. Thus, the main objective of this study was to describe the characteristics of the humerus of Tamandua mexicana based on gross dissections, radiographies and measurements comparing with other studies in the three Vermilingua genera, and establishing more suitable terminology. Twelve thoracic limbs of six death specimens of Tamandua mexicana were analyzed. The bone reliefs, ligaments, muscles and neurovascular structures related to the humerus were identified, and the suitable terminology to the humerus of Tamandua was established. Morphometric measurements of each bone relief were taken, and the data were statistically analyzed with the Wilcoxon non-parametric test for functional proposes. The humerus of Tamandua has anatomical characteristics mainly to offer greater areas to the muscles that act on the shoulder flexion and hand movements. Even the articular reliefs are lesser than the adjacent non-articular reliefs, the muscles and ligaments are the anatomical structures that give more stabilization to the shoulder and elbow joints. The deltosupracondylar ligament can be partially ossified in older adult specimens, and neurovascular structures pass through the supracondylar foramen. These anatomical characteristics must be accounted for in the radiological diagnosis and surgical approaches.

Cervical Ossification of Ligamentum Flavum: Elaborating an Underappreciated but Occasional Contributor to Myeloradiculopathy in Aging Population Based on Synthesis of Individual Participant Data

PURPOSE

Cervical ossification of ligamentum flavum (COLF) is a rare clinical entity which can occasionally contribute to severe myeloradiculopathy. Many orthopedists are unfamiliar with or underestimate this pathology. Therefore, a comprehensive research is obligatory to reappraise the epidemiological, radiological, clinical and histopathological characteristics of COLF-myeloradiculopathy based on synthesis of individual patient data.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed, EMBASE, Scopus and Web of Science databases were searched for studies discussing COLF-myeloradiculopathy from the inception to December 2020.

RESULTS

A total of 94 cases from 54 studies were identified. The annual publications demonstrated a steady increase, and most reports were from Japan and China. The mean age was 58.76±13.39 years and nearly 60% of cases occurred in the 55-64 and 65-74 years age group. The male-female ratio was 1.4:1. Most cases belonged to East Asian population (60.64%). COLF predominately appeared in the lower cervical and cervicothoracic spine (76.60%) and mainly affected C4-5 (23.29%) and C5-6 (21.23%). Single-segment type ossification accounted for 62.76 and 45.45% of ossification lesions distributed bilaterally. The majority of COLF (81.1%) were spontaneous, and motor disturbance (76.4%), spinal ataxia (62.5%) and sensory disturbance (58.9%) were the most common manifestations. Histopathologically, it's a metaplastic process of endochondral ossification with the formation of mature lamellar bone which was distinguished from calcification of ligamentum flavum. About 21.28% of concurrent COLF and COPLL cases were identified as a separated group, with unique characteristics.

CONCLUSION

COLF is an underappreciated but potentially growing pathogeny of myeloradiculopathy in aging population, though its distinct epidemiological, radiological, clinical and histopathological features are not fully supported by current evidence. However, our findings will provide several referential data for future researches to shed light on COLF.

Acromegaly presenting with myelopathy due to ossification of posterior longitudinal ligament: a case report

Background

Acromegaly is a rare disease caused by high serum levels of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), often originating from a pituitary adenoma. Spinal and peripheral joint abnormalities are caused by these hormonal hypersecretions. In particular, the response to GH is involved in the onset of ossification of the spinal ligament in vitro, especially ossification of the posterior longitudinal ligament (OPLL). However, because acromegaly and OPLL are rare diseases, we seldom encounter them in combination. To the best of our knowledge in the English-language literature, this is the first reported case of acromegaly presenting with thoracic myelopathy due to OPLL.

Case presentation

A 47-year-old woman presented with lower extremity weakness and paresthesia, gait disorder, and bladder disorder without any trauma. The patient’s most remarkable symptom was paraplegia, and we diagnosed myelopathy due to cervical and thoracic OPLL. Furthermore, we suspected acromegaly because of the characteristic facial features, and we found a pituitary adenoma by contrast-enhanced MRI. Cervical and thoracic decompression, posterior fixation, and pituitary adenoma resection were performed.

Conclusion

We report a case of acromegaly that was detected after the diagnosis of OPLL. The main challenge in acromegaly is delayed in diagnosis. Even in this case, the facial features characteristic of acromegaly had appeared at least 9 years ago. Early diagnosis and treatment of acromegaly improve prognosis and reduce exposure to GH and IGF-1 through early intervention and seem to suppress the progression of ligament ossification. Orthopedic surgeons and neurosurgeons need to keep in mind that acromegaly is associated with bone/joint lesions and ossification of the spinal ligament and should aim to diagnose acromegaly early.

The Natural History of Ossification of Yellow Ligament of the Thoracic Spine on MRI: A Population-Based Cohort Study

PURPOSE

To assess the natural history of ossification of yellow ligament (OYL) in the thoracic spine and determine risk factors for progression based on a longitudinal population-based cohort.

METHODS

A prospective, longitudinal cohort study was performed on a population-based cohort of Southern Chinese volunteers. T2-weighted magnetic resonance imaging (MRI) was used at baseline to identify any OYL and was verified with computed tomography. Follow-up MRI was performed 5 years later. Parameters under study included the size of OYL, levels of involvement, morphology (round, triangular, beak), whether it crossed the midline and any disc degeneration.

RESULTS

A total of 114 (6.1%) individuals were identified to have OYL at baseline out of the 1864 individuals. Size progression occurred predominantly at the lower thoracic region. Majority of the new OYL were also in the lower thoracic spine and was associated with higher body mass index (BMI). Smokers were associated with OYL size progression while patients with higher BMI tended to develop new OYL at follow-up. Progression commonly occurred at the lower thoracic levels and regression occurred mostly at the upper thoracic levels.

CONCLUSIONS

This is the first population-based series addressing the natural history of OYL. Better understanding of the natural history of OYL may provide incentive to introduce preventive measures such as weight reduction and close monitoring for myelopathy development in those at-risk groups for progression. This is especially important for patients with lower thoracic OYL and who are smokers with higher BMI.

LEVEL OF EVIDENCE

1 (prognostic study).

Potential Link between Ossification of Nuchal Ligament and the Risk of Cervical Ossification of Posterior Longitudinal Ligament: Evidence and Clinical Implication from a Meta-Analysis of 8429 Participants

OBJECTIVE

The aim of the present paper was to evaluate the strength and the magnitude of the association between ossification of the nuchal ligament (ONL) and the risk of cervical ossification of the posterior longitudinal ligament (COPLL) and to determine whether there is a direct association or whether COPLL is a consequence of shared risk factors.

METHODS

Medline, Web of Science, Cochrane Library, and Embase databases were searched for studies evaluating the association of COPLL-ONL published before July 2020. Eligible studies were selected based on certain inclusion and exclusion criteria. Two investigators independently conducted the quality assessment and extracted the data, including study designs, countries, patients' age, gender, body mass index (BMI), and the risk of COPLL between individuals with and without ONL. A meta-analysis of homogenous data, a sensitivity analysis, a publication bias assessment, and a subgroup analysis were performed using Stata 12.0 software.

RESULTS

A total of 10 cohort studies involving 8429 participants were incorporated into this analysis. Pooled results demonstrated a statistically significant association between the presence of ONL and the increased COPLL risk (odds ratio [OR] 3.84; 95% confidence interval [CI] 2.68-5.52, P < 0.001). Furthermore, subgroup analyses indicated that this association was independent of study design (6.36-fold in case-control studies vs 3.22-fold in cross-sectional studies), sex (6.33-fold in male-female ratio >2.5 vs 2.91-fold in male-female ratio <2.5), age (4.28-fold in age ≥55 years vs 3.45-fold in age <55 years), and BMI (3.88-fold in BMI ≥ 25 kg/m² vs 2.43-fold in BMI < 25 kg/m² ), which also indicated that obese, older male patients with ONL had a higher risk of OPLL. Moreover, combined two articles revealed that patients with larger-type ONL had a significantly higher risk of long-segment COPLL compared with controls (OR 1.86; 95% CI 1.41-2.47, P < 0.001).

CONCLUSION

This is the first meta-analysis to demonstrate a strong and steady association between ONL and higher risk of COPLL. This association was independent of sex, age, and BMI. Considering that ONL is generally asymptomatic and easily detectable on X-ray, our findings implied that ONL might serve as an early warning sign of the onset of COPLL and provide clinicians an opportunity for early detection and early intervention.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

Cyclic stretch promotes the ossification of ligamentum flavum by modulating the Indian hedgehog signaling pathway

The Indian hedgehog (IHH) signaling pathway is an important pathway for bone growth and development. The aim of the present study was to examine the role of the IHH signaling pathway in the development of the ossification of ligamentum flavum (OLF) at the cellular and tissue levels. The expression levels and localization of the osteogenic genes Runt-related transcription factor 2 (RUNX2), Osterix, alkaline phosphatase (ALP), osteocalcin (OCN) and IHH were evaluated in OLF tissues by reverse transcription-quantitative PCR (RT-qPCR) and immunohistochemistry. Non-ossified ligamentum flavum (LF) sections were used as control samples. The tissue explant method was used to obtain cultured LF cells. In addition, OLF cells were subjected to cyclic stretch application for 0, 6, 12 or 24 h. The expression levels of osteogenic genes, and the IHH signaling pathway genes IHH, Smoothened (SMO), GLI family zinc finger 1 (GLI1), GLI2 and GLI3 were evaluated with RT-qPCR and western blotting. Osteogenic differentiation was further evaluated by assessing ALP activity and staining. Moreover, the effect of cyclopamine (Cpn), an IHH signaling inhibitor, on osteogenic differentiation was examined. The RT-qPCR and immunohistochemical results indicated that the mRNA and protein expression levels of RUNX2, Osterix, ALP, OCN and IHH were significantly higher in the OLF group compared with the LF group. Furthermore, application of cyclic stretch to OLF cells resulted in greater ALP activity, and significant increases in mRNA and protein expression levels of RUNX2, Osterix, ALP and OCN in a time-d00ependent manner. Cyclic stretch application also led to significant increases in IHH signaling pathway genes, including IHH, SMO, GLI1 and GLI2, while no significant effect was found on GLI3 expression level. In addition, it was found that Cpn significantly reversed the effect of cyclic stretch on the ALP activity, and the expression levels of RUNX2, Osterix, ALP, OCN, GLI1 and GLI2. Collectively, the present results suggested that the IHH signaling pathway may mediate the effect of cyclic stretch on the OLF cells.

The Role of Gene Expression Changes in ceRNA Network Underlying Ossification of Ligamentum Flavum Development

We aimed at exploring the role of gene expression changes regulated by non-coding RNAs in ossification of ligamentum flavum (OLF). Three microarray datasets, including long non-coding RNA (lncRNA)/mRNA expression profile (GSE106253), circular RNA (circRNA) expression profile (GSE106255), and microRNA (miRNA) expression profile (GSE106256), were downloaded from the public Gene Expression Omnibus repository. The differentially expressed (DE) mRNAs, lncRNAs, miRNAs, and circRNAs in OLF tissues were analyzed, compared with normal tissues. Two competing endogenous RNA (ceRNA) networks with lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA interactions were constructed, separately. Random walk with the restart model was applied to calculate the correlations of mRNAs with the published OLF-related genes. The top 50 mRNAs were subjected to function enrichment analysis and active small-molecule prediction. Total 2323 DE mRNAs, 1168 lncRNAs, 336 circRNAs, and 29 miRNAs were identified based on the microarray datasets. The LncRNA-related ceRNA network was constructed with 614 lncRNA-miRNA, 494 miRNA-mRNA, and 2099 lncRNA-mRNA interaction pairs; the circRNA-related ceRNA network was constructed with 153 circRNA-miRNA, 190 miRNA-mRNA, and 210 circRNA-mRNA interaction pairs. There were 17 OLF-related genes retrieved from previous literature, such as NPPS, COL6A1, and COL11A2, among which COL6A1 was the overlapped gene with mRNAs in the ceRNA network. Subsequently, top 50 mRNAs that closely correlated with COL6A1 in the ceRNA network were captured and these genes were closely related with the collagen catabolic process, regulation of cell growth, and neuronal action potential. DRD1 and COL6A1 were predicted to be the targets by small active molecule drugs. The collagen catabolic process may be implicated in OLF development. COL6A1 and DRD1 may be the candidate targets for OLF. However, further validations were needed.

BMP2 Modified by the m6A Demethylation Enzyme ALKBH5 in the Ossification of the Ligamentum Flavum Through the AKT Signaling Pathway

Ossification of the ligamentum flavum (OLF) is characterized by a process of ectopic bone formation in the ligamentum flavum. The definitive pathophysiology of OLF still remains unclear, but the epigenetic m6A modification plays an important role in OLF. In addition, no studies have reported the function of ALKBH5 in OLF development. In this study, we investigated the function of the m6A demethylation enzyme ALKBH5 in OLF. To evaluate the function of ALKBH5, OLF tissues and normal ligamentum flavum tissues were collected. In vitro methods, including HE, IHC and western blotting assays, were used to evaluate the association of ALKBH5 with OLF. In addition, we verified the effects of ALKBH5 on osteogenesis using alizarin red and ALP staining. MeRIP q-PCR was performed to investigate the methylation level of BMP2. Moreover, the mechanism of ALKBH5-mediated regulation of the ossification of the ligamentum flavum cells through the AKT signaling pathway was also verified. The present study showed that the expression of ALKBH5 increased in OLF tissues. The overexpression of ALKBH5 increased the expression of osteogenic genes and promoted the ossification of ligamentum flavum cells. Furthermore, BMP2 was significantly enriched in the ligamentum flavum cells of the anti-m6A group compared with those of the IgG group. The overexpression of ALKBH5 led to the activation of p-AKT, and BMP2 was regulated by ALKBH5 through the AKT signaling pathway. ALKBH5 promoted the osteogenesis of the ligamentum flavum cells through BMP2 demethylation and AKT activation. ALKBH5 was shown to be an important demethylation enzyme in OLF development.

Trabecular bone score and bone turnover markers in men with DISH: Data from the Camargo Cohort study

OBJECTIVE

Diffuse idiopathic skeletal hyperostosis (DISH) has been associated with an increased risk of vertebral fracture. To date, no studies have investigated the relationship between DISH and bone microstructure assessed by the trabecular bone score (TBS).

METHODS

Cross-sectional study, nested in a prospective population-based cohort. All men (968) aged≥50 years were included. Clinical covariates, DISH, TBS, serum bone turnover markers and bone mineral density (BMD) were analyzed.

RESULTS

Mean age of participants was 65 ± 9 years. 207 (21.6%) had DISH. DISH subjects were older, had higher body mass index (BMI) and abdominal perimeter, lower glomerular filtration rate (GFR), and higher prevalence of metabolic syndrome (MetS) than non-DISH (NDISH) subjects. Bone mineral density at the lumbar spine (LS-BMD) was significantly higher in the DISH group. TBS values were 1.317 [1.303-1.331] for DISH and 1.334 [1.327-1.341] for NDISH subjects, after adjusting by age, BMI, abdominal perimeter, arterial hypertension, diabetes mellitus, MetS, GFR, serum alkaline phosphatase (ALP), LS and femoral neck BMD (p = 0.03). Serum ALP levels were higher in DISH subjects, showing an inverse correlation with TBS that remained significant after adjusting by age and BMI.

CONCLUSIONS

TBS values were significantly lower in men with DISH irrespective of age, BMI and BMD, suggesting that the presence of DISH might be related to a worse trabecular microstructure.

Ossification of the Transverse Ligament of the Atlas on CT: Frequency and Associated Findings

목적

경추 전산화단층촬영(cervical spine CT; 이하 C-spine CT)과 일반촬영을 이용하여 환추횡인대골화증(ossification of the transverse ligament of the atlas; 이하 OTLA)과 연관된 영상 소견에 대하여 알아보았다.

대상과 방법

11년간 3975명의 환자에게서 촬영한 5201개의 C-spine CT를 분석하여 OTLA의 유무를 확인하였고, 이를 대조군과 비교하여 그 빈도와 연관된 영상 소견의 통계학적 유의성을 확인하였다.

결과

3975명 중 45명에서 OTLA가 확인되었다(1.1%). 그 빈도는 나이에 따라 증가하는 소견을 보였으며(p < 0.005), 80세 이상인 환자의 12%에서 관찰되었다. 척수 공간(space available for spinal cord; 이하 SAC)은 OTLA 환자군에서 유의하게 작은 것으로 확인되었으며(p < 0.005), 전방환추후두막(anterior atlantooccipital membrane)-Barkow 인대 복합체의 광물질침착(mineralization), 황색인대골화증(ossification of ligamentum flavum), 경추후만증 또한 유의미한 양의 상관관계를 보였다(p < 0.005).

결론

OTLA는 환자의 나이, SAC 협소, 경추후만증, 다른 경추인대의 골화증과 연관되어 퇴행성 척추병증, 전신적인 골 과잉 상태, 혹은 기계적 스트레스나 불안정성에 관련이 있을 것으로 생각된다.

Subjects with diffuse idiopathic skeletal hyperostosis have an increased burden of coronary artery disease: An evaluation in the COPDGene cohort

BACKGROUND AND AIMS

Diffuse idiopathic skeletal hyperostosis (DISH) is a common incidental finding on medical imaging and often thought to be benign. Our objective was to investigate whether DISH is associated with coronary artery disease as measured with the coronary artery calcification (CAC) score in a large cohort of current and former smokers.

METHODS

In a subset of subjects from the COPDGene study, DISH was scored by a minimum of two independent readers if there were four adjacent levels of flowing osteophytes and a third reader adjudicated discrepancies. CAC was calculated using a modified Agatston method. Associations of DISH with the presence and extent of CAC were analyzed with and without adjustment for COPD and known atherosclerotic risk factors, including age, sex, race, diabetes, hypertension, high cholesterol, body mass index and smoking.

RESULTS

DISH was present in 361 subjects (13.2%) from a total group of 2728. Median (interquartile range) Agatston was 81 (0-329) in DISH subjects compared to 0 (0-94 in subjects without DISH (p < 0.001). DISH prevalence was 8.8% in CAC = 0, 12.8% in CAC1-100, 20.0% in CAC100-400 and 24.7% in CAC.400. Subjects with DISH had a significantly higher risk of having coronary artery calcifications; OR [CI95%] 1.37[1.05-1.78] (p=0.019) after correction for age, gender, race, COPD and atherosclerotic risk factors.

CONCLUSIONS

Subjects with DISH, a common musculoskeletal disorder involving bone formation anterior to the spine, have an increased burden of coronary artery disease, and therefore DISH may be a more relevant incidental finding than commonly thought.

Epidemiology of ossification of the spinal ligaments and associated factors in the Chinese population: a cross-sectional study of 2000 consecutive individuals

Background

The epidemiology and cause of ossification of the spinal ligaments (OSL) remains obscure. To date, there is no study that comprehensively evaluates the prevalence, distribution, and concomitance of each type of OSL by CT among general Chinese population. We therefore aimed to comprehensively investigate epidemiological characteristics of OSL using whole spine CT in the Chinese population and examine the factors that correlate with the presence of OSL.

Methods

Ossification of the posterior longitudinal ligament (OPLL), ligamentum flavum (OLF), anterior longitudinal ligament (OALL), nuchal ligament (ONL), and diffuse idiopathic skeletal hyperostosis (DISH) were evaluated from the subjects who underwent PET/CT for the purpose of cancer screening in our hospital. Prevalence, distribution, and concomitance of OSL were reviewed. Logistic regression analysis was performed to identify the risk factors of OSL.

Results

A total of 2000 subjects (1335 men and 665 women) were included. The prevalence rate of cervical OPLL (C-OPLL) was 4.1%, thoracic OPLL (T-OPLL) 2.25%, lumbar OPLL (L-OPLL) 0.8%, thoracic OLF (T-OLF) 37.65%, lumbar OLF (L-OLF) 1.45%, ONL 31.5%, DISH 3.85%. The most commonly involved level was C5 for C-OPLL, T1 for T-OPLL, T10 for T-OLF, and T8/9 for OALL. 21% of subjects with C-OPLL had T-OPLL, 44% of C-OPLL had T-OLF, 38% of T-OPLL had C-OPLL, 53% of T-OPLL had T-OLF, 44% of L-OPLL had T-OPLL, and 56% of L-OPLL had T-OLF. The average age of OSL-positive subjects was significantly higher than that of OSL-negative subjects. The results of the multiple regression analysis revealed that males had a strong association with DISH (odds ratio, 3.15; 95% confidence interval, 1.27–7.78; P = 0.013).

Conclusion

The prevalence of OSL in the Chinese was revealed. Tandem ossification is not uncommon in people with OSL. There is a high incidence of multiple-regional OPLL in the whole spine. Approximately half of the subjects with OPLL coexist with T-OLF. For patients with clinical symptoms induced by OPLL, thorough evaluation of whole spine using CT is recommended.

Ossification of the posterior longitudinal ligament in the cervical spine: a review

Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

Rich table but short life: Diffuse idiopathic skeletal hyperostosis in Danish astronomer Tycho Brahe (1546-1601) and its possible consequences

The exhumation of Danish astronomer Tycho Brahe (1546–1601) was performed in 2010 to verify speculative views on the cause of his death. Previous analyses of skeletal and hair remains recovered from his grave refuted the presumption that he died from poisoning. These studies also outlined the possibility that he actually died from an acute illness, echoing the rather vague and inaccurate testimony of some historical records. We performed a detailed paleopathological analysis of Tycho Brahe’s skeletal remains, along with a reconstruction of his diet based on carbon and nitrogen stable isotopes analysis and an estimate of his physical status (relative body fat) based on medullar and cortical dimensions of the femoral shaft. The astronomer’s remains exhibit bone changes indicative of diffuse idiopathic skeletal hyperostosis (DISH). The study further allows us to classify him as obese (100% reliability according to our decision tree designed from Danish males), and points out his rich diet (high input of animal protein and/or marine resources) and high social status. Comorbidities of DISH and obesity are reviewed, and their influence on health status is discussed. We further consider some conditions associated with metabolic syndrome as possible causes of Tycho Brahe’s final symptoms (urinary retention, renal failure and coma), including diabetes, alcoholic ketoacidosis and benign prostatic hypertrophy. Although a definite and specific diagnosis cannot be established, our study points to today’s civilization diseases often associated with DISH and metabolic syndrome as the possible cause of death of Tycho Brahe.

Isolated ligamentum flavum ossification in primary hypoparathyroidism

Background:

The ligamenta flava can undergo ossification and calcification resulting in myelopathy. Only seven cases of ligamentum flavum ossification in association with hypoparathyroidism have been reported, most of which had concurrent osseous changes in other spinal ligaments. Here, we report a patient with hypoparathyroidism who presented with ligamentum flavum ossification causing both cervical and thoracic myelopathy.

Case Description:

A 43-year-old male presented with backache, urinary retention, and lower limb weakness for the last few days. Magnetic resonance imaging scan showed ossification of the ligamentum flavum in the cervical and thoracic regions, with severe spinal stenosis. Following spinal decompressive surgery, the patient made a complete recovery. Primary hypoparathyroidism was found to be the underlying cause for ligamentum flavum ossification.

Conclusion:

Ossification of ligamentum flavum secondary to hypoparathyroidism should be considered as a possible cause of myelopathy in all patients presenting with symptoms of spinal cord compression.

Multiplex analysis of serum hormone and cytokine in patients with cervical cOPLL: towards understanding the potential pathogenic mechanisms

Cervical ossification of the posterior longitudinal ligament (cOPLL) is one of the major causes of myelopathy. However, the mechanism underlying remains elusive. In the present study, using MILLIPLEX magnetic bead panel, we investigated four serum hormones and six serum cytokines in cOPLL patients and healthy subjects. The results showed that tumor necrosis factore-α (TNF-α) were significantly increased, and DDK-1 was significantly decreased in the serum from male and female cOPLL patients compared with those from healthy controls, respectively. Osteopontin (OPN) and fibroblast growth factor-23 (FGF-23) were significantly increased in male cOPLL patients compared with that in healthy male controls. Further analysis showed that FGF-23 and OPN significantly increased, dickkopf-1 (DKK-1) decreased in the extensive cOPLL group. In addition, a significant positive correlation between the OPN and FGF-23 was observed in male cOPLL patients. The results are useful for understanding the mechanism underlying cOPLL.

Dural ossification associated with ossification of ligamentum flavum in the thoracic spine: a retrospective analysis

OBJECTIVES

To investigate the incidence, distribution and radiological characteristics of dural ossification (DO) associated with ossification of ligamentum flavum (OLF) in the thoracic spine.

DESIGN

A retrospective radiographical analysis.

SETTING

This study was conducted at a single institution in China.

PARTICIPANTS

53 patients with OLF who underwent posterior decompression surgery between January 2011 and July 2015 in a single institution were enrolled in this study. The decompression segments were grouped according to imaging evaluation and intraoperative evidences.

OUTCOME MEASURES

The demographic distribution, radiological data and detailed surgical records were collected. First, preoperative CT images of decompressed segments were evaluated to identify imaging signs of DO. The 'tram tack sign' (TTS), 'comma sign' and 'bridge sign' were considered as characteristic imaging findings of DO in OLF. 4 kinds of confusing signs (false TTS) were identified and excluded. Then detailed surgical records were reviewed to finally identify segments with DO.

RESULTS

The incidence of DO in patients with OLF was 43.4%. The incidence of DO in OLF segments was 21.5%. OLF was more common in the lower thoracic spine, and more than half (53.8%) of the DO was located in T9-T12. TTS was the most common sign, but it might be misdiagnosed. After excluding 4 kinds of false TTS, the sensitivity and specificity of imaging diagnosis were 94.23% and 94.21%, respectively.

CONCLUSIONS

DO was relatively common in thoracic OLF, especially in T9-T12. TTS might be misdiagnosed. After excluding 4 kinds of false TTS, the accuracy of imaging diagnosis was relatively high.

Diffuse idiopathic skeletal hyperostosis: Diagnostic, clinical, and paleopathological considerations

Diffuse idiopathic skeletal hyperostosis (DISH) is a disease primarily affecting the spine. However, it is also associated with the ossification/calcification of tendon, ligament, and capsule insertions (entheses) occurring at multiple peripheral sites. The etiology of the condition is unknown, as the name suggests (diffuse idiopathic skeletal hyperostosis), although some correlations with diabetes mellitus, obesity, and age have been noted. Clinical diagnostic criteria have been adapted for paleopathological assessment of archeological skeletal remains, revealing some interesting patterns between monastic and lay populations; showing a higher incidence of DISH among individuals buried in monastic cemeteries. Although fascinating, the mechanisms behind this difference in prevalence are still not fully understood and have been attributed to the relatively richer diets of the monks and priests. The development of diagnostic criteria, where early stage cases of DISH can be identified as well as a better understanding of its causes, is paramount to the prevention of this potentially debilitating condition and perhaps this is where paleopathologists can assist. The use of dry bone rather than living patients for detailed assessment means that paleopathologists are less restricted by the techniques they can use in their investigations and the condition's occurrence in various archeological assemblages can provide interesting insights into its etiology. Clin. Anat. 29:870-877, 2016. © 2016 Wiley Periodicals, Inc.

Incidental Anterior Cruciate Ligament Calcification: Case Report

The calcification of knee ligaments is a finding noted only in a handful of case reports. The finding of an anterior cruciate ligament calcification has been reported once in the literature. Comparable studies involving the posterior cruciate ligament, medial collateral ligament and an ossicle within the anterior cruciate ligament are likewise discussed in reports of symptomatic patients. We report a case of incidentally discovered anterior cruciate ligament calcification. We discuss the likely etiology and clinical implications of this finding.

Extensive ossification of the ligamentum flavum treated with triple stage decompression: a case report

BACKGROUND CONTEXT

Concurrent ossification of the ligamentum flavum (OLF) in the cervical, thoracic, and lumbar spine is a rare occurrence often associated with rheumatologic abnormalities. Although the pathology may be asymptomatic and discovered incidentally on routine imaging, compression of the cord and surrounding nerve roots can produce myelopathic or radiculopathic symptoms that are best treated with surgical decompression. There is limited evidence to support the use of single versus multistage decompression for tandem ossification at multiple levels, although several factors including duration of symptoms have been associated with a worse prognosis.

PURPOSE

To describe the presence of extensive symptomatic tandem OLF with concurrent ossification of the posterior longitudinal ligament (PLL) and its treatment using multistage decompression.

STUDY DESIGN

Case report and literature review.

METHODS

The authors describe a case of a 35-year-old woman with OLF extending from the cervical to lumbar spine and tandem ossification of the cervical PLL. Her initial presentation was significant for symptoms consistent with thoracic myelopathy in the absence of radiculopathic findings, and initial imaging also demonstrated disc herniation at L4-L5 and L5-S1.

RESULTS

The patient was first treated with a thoracic laminectomy and fusion from T7 to T11, given her back pain and thoracic myelopathy. Persistence of myelopathic symptoms necessitated further surgical intervention with a posterior cervical decompression and fusion from C3 to T1. Finally, after the appearance of radiculopathic findings, she underwent a microscopic L4-L5 laminectomy with improvements in her symptoms and ambulation.

CONCLUSIONS

Symptomatic OLF in non-East Asian population is a rare occurrence. Its etiology is likely multifactorial, involving both biomechanical and genetic factors. Although early detection and management are necessary, multistage decompression can be an effective intervention for extensive multilevel ossification.

Femoral nerve entrapment in a dog with diffuse idiopathic skeletal hyperostosis

OBJECTIVE

To report femoral neuropathy caused by nerve entrapment associated with diffuse idiopathic skeletal hyperostosis (DISH).

STUDY DESIGN

Case report.

ANIMAL

Seven-year-old female spayed Boxer dog.

RESULTS

Entrapment of the right femoral nerve due to DISH caused a femoral nerve deficit and atrophy of muscle groups associated with the affected nerve. A combination of computed tomography and magnetic resonance imaging was performed to provide a diagnosis. Amputation of the right transverse process of the sixth lumbar vertebra at the level of nerve entrapment relieved the neurological abnormality.

CONCLUSIONS

Nerve entrapment leading to neurapraxia may occur concurrently with DISH and surgery in this case was successful in restoring function.

CLINICAL RELEVANCE

Peripheral neuropathy from nerve entrapment should be considered in patients with DISH. Surgical amputation of impinging osseous structures may be indicated for relief of femoral neuropathy.

Metabolic factors in diffuse idiopathic skeletal hyperostosis - a review of clinical data

OBJECTIVES

We aimed to review the literature linking metabolic factors to Diffuse Idiopathic Skeletal Hyperostosis (DISH), in order to assess associations between growth factors and DISH.

METHOD

We identified studies in our personal database and PubMed using the following keywords in various combinations: "diffuse idiopathic skeletal hyperostosis", "ankylosing hyperostosis", "Forestier's disease", "diabetes", "insulin", "obesity", "metabolic", "growth factors", "adipokines", "glucose tolerance" and "chondrocytes".

RESULTS

We were not able to do a systematic review due to variability in methodology of studies. We found positive associations between obesity (especially abdominal obesity), Type 2 diabetes mellitus, glucose intolerance, hyperinsulinemia and DISH.

CONCLUSION

Current research indicates that certain metabolic factors associate with DISH. More precise studies deriving from these findings on these and other newly identified bone-growth factors are needed.

Ossification of the ligamentum flavum

Ossification of the ligamentum flavum is a rare cause of thoracic myelopathy. It develops in East Asians more frequently than in people from other areas. The exact pathophysiology has not been elucidated yet; however, it largely depends on biomechanical alterations, especially changes in the tensile force. Because the spinal cord is compressed from the posterior side, the first and most common clinical manifestation is usually loss of functional gait and spastic paralysis, which develop as the spinal cord compression progresses. The choice of diagnostic imaging is T2 sagittal magnetic resonance imaging scanning. Whole spine scanning is mandatory to identify multiple areas of compression and any associated distal lumbar diseases. Fine computed tomography imaging is necessary to make a differential diagnosis and set up a precise surgical plan. Conservative treatment does not work in this disorder. Decompression surgery is the only option and prognosis after surgical treatment is better with this disorder than with other causes of thoracic myelopathy. The severity of preoperative symptoms and the time interval before surgical treatment are the most important prognostic factors.

Ossification of the posterior longitudinal ligament in not only the cervical spine, but also other spinal regions: analysis using multidetector computed tomography of the whole spine

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To evaluate ossification of the posterior longitudinal ligament (OPLL) of the whole spine in patients with cervical OPLL and to analyze which types of cervical OPLL were associated with the other lesions in the thoracic and/or lumbar spine.

SUMMARY OF BACKGROUND DATA

OPLL is most frequently seen in the cervical spine. The coexisting ossified lesions are sometimes observed in other spinal regions. However, coexisting OPLL in other spinal regions have not yet been precisely evaluated in patients with cervical OPLL.

METHODS

One hundred seventy-eight patients with a diagnosis of cervical OPLL whose plain radiographs were obtained were included. Computed tomographic images of the whole spine were obtained. The ossification index (OS index) was newly determined according to the sum of the levels of vertebral bodies and intervertebral discs with OPLL. The patients were divided into 2 groups, the group that had OPLL only in the cervical spine (C group) and the group that had OPLL in multilevel spinal regions other than the cervical spine (M group).

RESULTS

Ninety-five (53.4%) had OPLL not only in the cervical spine, but also in other spinal regions. The M group had more females than the C group. The incidence of bridge formation in the cervical spine was higher in M group than in C group. More females had a high OS index. A positive correlation was found between the OS index of the cervical spine and the OS index of the thoracic and lumbar spine; however, the r value was small.

CONCLUSION

This study demonstrated that more than half of the patients with cervical OPLL had coexisting OPLL in the thoracic and/or lumbar spine. We strongly recommend computed tomographic analysis of the whole spine for patients with radiographical evidence of OPLL in the cervical spine for the early detection of additional sites of ossification.

Immunohistochemical localization of mesenchymal stem cells in ossified human spinal ligaments

Mesenchymal stem cells (MSCs) have been isolated from various tissues and used for elucidating the pathogenesis of numerous diseases. In our previous in vitro study, we showed the existence of MSCs in human spinal ligaments and hypothesized that these MSCs contributed to the pathogenesis of ossification of spinal ligaments. The purpose of this study was to use immunohistochemical techniques to analyze the localization of MSCs in ossified human spinal ligaments in situ. Ossified (OLF) or non-ossified ligamentum flavum (non-OLF) samples from the thoracic vertebra were obtained from patients who had undergone posterior spinal surgery. Serial sections were prepared from paraffin-embedded samples, and double immunofluorescence staining was performed using antibodies against markers for MSCs (CD73, CD90 and CD105), endothelial cells (CD31), pericytes (α-smooth muscle actin), and chondrocytes (S100). Immunolocalization of MSCs was observed in the perivascular area and collagenous matrix in spinal ligaments. Markers for MSCs and pericytes were co-expressed in the perivascular area. Compared with non-OLF, OLF had a large amount of neovascularization in the fragmented ligament matrix, and a high accumulation of MSCs around blood vessels. The prevalence of MSCs in OLF within collagenous matrix was significantly higher than that in non-OLF. Chondrocytes near the ossification front in OLF also presented expression of MSC markers. MSCs may contribute to the ectopic ossification process of OLF through endochondral ossification.