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

Reduced Vertebral Hounsfield Unit Values in the Bridging Group of Ossification-Related Segments in Patients with Ossification of the Posterior Longitudinal Ligament of the Cervical Spine

BACKGROUND

Increased systemic bone mineral density has been reported in patients with ossification of the posterior longitudinal ligament (OPLL). This study investigated the differences in vertebral Hounsfield unit (HU) values between the bridged and nonbridged groups of patients with OPLL of the cervical spine at the ossification-related segments.

METHODS

A total of 436 ossification-related segments from 157 patients were involved in the study. X-ray and computed tomography scans were used to assess the segmental cervical range of motion (ROM), C2-7 Cobb angle, K-line, ossification thickness, maximum canal occupancy, HU values, and presence and type of OPLL.

RESULTS

In terms of imaging parameters, HU values were significantly higher in the OPLL group (P < 0.001), whereas the ROM was greater in the control group (P < 0.05). In the OPLL group, the K-line positive group had a better C2-7 Cobb angle and greater T1 slope. The ossification-related segments were divided into bridging and nonbridging groups, with smaller vertebral HU values, thicker ossification lesions, greater canal occupation, and reduced interbody mobility in the bridging group. However, we found no significant correlation among segmental ROM, ossified material thickness, maximum canal occupancy of the ossified material, and segmental HU values.

CONCLUSIONS

We found that the mean HU value of the cervical spine in patients with OPLL was higher than that of the control group, and the ROM was smaller than that of the control group, with the smallest ROM in the continuous type. In the ossification-related segments, the bridging group exhibited lower vertebral HU values, reduced segmental mobility, and thicker ossification thickness.

Relationship between diffuse idiopathic skeletal hyperostosis and lumbar paravertebral muscle fat infiltration: a CT-based retrospective study

PURPOSE

Plentiful evidence points to a significant correlation between paravertebral muscles and spinal diseases. Yet, no reports are available detailing the association between paravertebral muscle status and diffuse idiopathic skeletal hyperostosis (DISH). The purpose of this retrospective study was to assess the link between paravertebral muscle area as well as fat infiltration and DISH based on computer tomography.

METHODS

Data were obtained from patients with acute vertebral fractures who presented to a single spine center. All participants had whole spine lateral x-ray radiography for DISH diagnosis. Those with a history of spinal disease, fusion surgery, or tumors were excluded. Patients with or without DISH were propensity-matched by age, sex, and body mass index (BMI). Appropriate Mann-Whitney U-tests or independent t-tests were performed to evaluate the correlation between muscle area or fat infiltration of the L3 level paravertebral muscles and DISH.

RESULTS

A total of 114 DISH and 114 non-DISH patients were assessed. The fat infiltration in the paravertebral muscles was remarkably higher in the DISH group than in the non-DISH (p < 0.05), whereas there was no statistical difference in the muscle area of the two (p > 0.05).

CONCLUSION

In conclusion, the fat infiltration of the paravertebral muscles was significantly associated with DISH.

Adipokine dysregulation as an underlying pathology for diffuse ectopic ossification of spinal posterior longitudinal ligament in patients with obesity

BACKGROUND CONTEXT

Growing evidence suggests that obesity is implicated in the progression of heterotopic ossification of the posterior longitudinal ligament of the spine (OPLL), a major cause of myelopathy in Asians. However, it remains unclear whether dysregulation of adipokine production due to fat accumulation contributes to OPLL progression.

PURPOSE

To determine whether adipose-derived biochemical signals are associated with OPLL development or severity.

STUDY DESIGN/SETTING

A nationwide, multicenter, case-control study.

PATIENT SAMPLE

Patients with symptomatic thoracic OPLL (T-OPLL) who received treatment between June 2017 and March 2021 and 111 controls without OPLL.

OUTCOME MEASURES

OPLL severity index based on whole-spine computed tomography.

METHODS

Serum concentrations of adipokines, including leptin (Lep), tumor necrosis factor α (TNFα), and adiponectin (Adpn), as well as the Adpn/Lep ratio-an indicator of adipokine production dysregulation-were compared between the multiple-region OPLL and the single-region OPLL groups. Regression analysis was performed to examine the correlation between adipokine concentrations and OPLL severity index, which was calculated using whole-spine computed tomography images of 77 patients with T-OPLL within 3 years of onset. Using propensity score matching, the adipokine profiles of 59 patients with T-OPLL were compared with those of 59 non-OPLL controls.

RESULTS

Patients with multiple-region OPLL exhibited a higher body mass index (BMI), lower serum Adpn/Lep ratio, and higher serum concentration of osteocalcin (OCN) than those with single-region OPLL. The OPLL severity index exhibited a weak positive correlation with BMI and serum Lep levels and a weak negative correlation with the Adpn/Lep ratio. Serum TNFα and OCN concentrations were significantly higher in patients with T-OPLL than in controls with similar age, sex, and BMI.

CONCLUSIONS

Patients with diffuse OPLL over the entire spine are often metabolically obese with low Adpn/Lep ratios. In patients with OPLL, TNFα and OCN serum concentrations were essentially elevated regardless of obesity, suggesting a potential association with OPLL development. Considering the absence of therapeutic drugs for OPLL, the findings presented herein offer valuable insights that can aid in identifying therapeutic targets and formulating strategies to impede its progression.

Bone Density of Vertebral Bodies and Ossified Masses in Cervical Ossification of the Posterior Longitudinal Ligament: An Imaging Study Based on MRI, CT, and DEXA

Complications from anterior decompression fusion for cervical ossification of the posterior longitudinal ligament (OPLL) are often related to the bone mineral density (BMD) of vertebral bodies and ossified masses. The aim of this study was to clarify whether dual-energy X-ray absorptiometry (DEXA) T-scores reliably predict BMD in these structures, and whether vertebral bone quality (VBQ) and Hounsfield units (HU) can be effectively used to screen for osteopenia and osteoporosis. A total of 122 patients with cervical OPLL and 105 non-OPLL patients were included. Vertebral BMD was assessed by VBQ and HU, and ossified mass BMD was assessed by ossified mass bone quality (OMBQ) and ossification mass HU (OMHU). Overall, VBQ scores and HU values demonstrated weaker correlations with T-scores in the OPLL group compared with the non-OPLL group. Receiver operating characteristic curve analyses showed that VBQ and HU effectively discriminated osteopenia/osteoporosis in the OPLL cohort, with area under the curve values ranging from 0.763 to 0.827, similar to the non-OPLL. No significant differences in BMD were observed between the OPLL and non-OPLL groups based on the common assessment of VBQ, HU and DEXA-derived BMD (p > 0.05). Both OMBQ and OMHU showed good reliability and were significantly correlated with T-scores (p < 0.05). In patients with cervical OPLL, VBQ and HU remain effective screening tools for osteopenia/osteoporosis, potentially guiding or obviating the need for further DEXA scans. Additionally, our findings suggest that patients with lower T-scores may exhibit reduced BMD in both vertebral bodies and ossified masses.

Association between diabetes mellitus and ossification of the spinal ligament: a systematic review and meta-analysis

PURPOSE

Ossification of the spinal ligament (OSL) is a spinal disorder characterized by abnormal bone formation in the spinal ligaments. Although clinical studies suggested that diabetes mellitus (DM) was associated with OSL, no consistent conclusion was drawn about the relationship between DM and the onset of OSL.

METHODS

Studies with data on DM and OSL were retrieved by searching PubMed, Embase, Web of Science, and Cochrane Library from inception to August 23, 2023. Pooled estimates of odds ratios (ORs) with 95% confidence interval (95% CI) were calculated using random-effects models. Statistical analyses were performed by R 4.2.2 software.

RESULTS

A total of 17 studies with 70,945 participants were included. The quantitative findings demonstrated that a higher risk of DM was related to the onset of OSL (OR = 2.19, 95% CI: 1.27-3.79, p = 0.008). Subgroup analysis showed a higher rate of DM in OSL patients from Japan (OR = 3.29, 95% CI: 1.51-7.17, [Formula: see text] = 0.009) than from other regions. Moreover, patients with OSL had a higher rate of DM in age < = 60 group (OR = 3.46, 95% CI: 1.14-10.50, p = 0.035) than age > 60 group (OR = 2.26, 95% CI: 1.07-4.79, p = 0.036).

CONCLUSION

DM is significantly associated with an increased risk of developing OSL, especially in Japanese and people under 60 years old. Further studies with more participants were warranted to confirm the findings and provide new insights into the prevention and treatment of OSL.

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.

Hyperlipidemia, Obesity, and Diabetes, and Risk of Ossification of the Posterior Longitudinal Ligament

BACKGROUND

Several risk factors of ossification of the posterior longitudinal ligament (OPLL) have been established, including diabetes and obesity. However, the relationship between hyperlipidemia (HLD) and OPLL is incompletely understood.

METHODS

PearlDiver was queried to identify adults with (+) and without (-) HLD, diabetes, and obesity. Comparative analyses were performed on demographics, comorbidities, and OPLL rates before and after matching for age, sex, and comorbidities. Stepwise logistic regression modeling assessing the relationship between HLD and OPLL with the addition of predictor variables was also performed.

RESULTS

In total, 31,677 cervical OPLL patients, as well as 170,467 HLD+ and 118,665 HLD-, 168,985 Diabetes+ and 137,966 Diabetes-, and 150,363 Obesity+ and 142,553 Obesity- patients, were examined. Mean age ranged 43.44-59.46 years, 54.94-63.12% were females, and mean Charlson Comorbidity Index ranged from 0.06 from 1.53, all higher in those with the comorbidity. Before matching, OPLL rates were higher in those with HLD (HLD+=0.05% vs. HLD-=0.03%, P = 0.005), diabetes (Diabetes+=0.06% vs. Diabetes-=0.02%, P < 0.001), and obesity (Obesity+=0.05% vs. Obesity-=0.02%, P = 0.001). However, after matching by age, sex, and Charlson Comorbidity Index, the associations between the studied comorbidities and OPLL were attenuated (all P > 0.05). Stepwise regression modeling revealed an association between HLD and cervical OPLL that was most impacted by the addition of age (OR=1.95, R2 = 0.029 to OR=1.38, R2 = 0.075) and obesity (OR=1.21, R2 = 0.086 to OR=1.07, R2 = 0.111) into the model.

CONCLUSIONS

Cervical OPLL rates were higher in patients with HLD even after accounting for demographics and comorbidities. HLD may be an independent risk factor for OPLL development.

MRI-based vertebral bone quality score in cervical ossification of the posterior longitudinal ligament: a comparison with cervical spondylotic myelopathy using propensity score matching

BACKGROUND

Bone mineral density plays a key role in the assessment of operative instrumentation complications and clinical outcomes. The MRI-based vertebral bone quality (VBQ) score has been introduced as a novel marker of bone quality. However, few studies have investigated the relationship between VBQ score and patients associated with cervical ossification of the posterior longitudinal ligament (OPLL).

PURPOSE

The aims of the study were (1) to reveal bone mineral density between cervical OPLL and cervical spondylotic myelopathy (CSM) group by VBQ score, (2) to compare the VBQ score of cervical OPLL between male and female group, (3) to explore the relationship between segmental VBQ scores associated with OPLL.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Consecutive series of 425 patients at a single academic institution.

OUTCOME MEASURES

MRI based measurements of C2-C7 VBQ scores.

METHODS

Preoperative noncontrast T1-weighted MRIs of the cervical spine was used to measure the VBQ score. The VBQ score was defined as the mean value of the signal intensity of the vertebrae divided by that of the cerebrospinal fluid (CSF) space at the cisterna magna. Patients with cervical OPLL and CSM were matched based on age, sex, body mass index (BMI), comorbidity, medication history, diet habit, smoking, alcohol consumption via propensity score matching (PSM). Normality of each VBQ score was tested by the Shapiro-Wilk test. Wilcoxon's rank-sum test was used to compare matched cohorts. Kruskal-Wallis test was performed to compare the VBQ scores between segments. Multivariate logistic regression analysis was used to evaluate factors associated with the development of cervical OPLL.

RESULTS

A total of 425 patients were assessed. For final analysis, 135 paired patients were compared between the cervical OPLL and CSM groups, and 22 paired patients were compared between male and female group associated with cervical OPLL. There were no statistically significant differences in age, sex, BMI, comorbidity, medication history, diet habit, smoking, alcohol between the matched cohorts. OPLL group was associated with lower VBQ score compared with CSM group at C3, while there were no differences in VBQ score for the other levels between the two groups. There were no differences between male and female group associated with OPLL in C2-C7 VBQ scores. VBQ scores of cervical OPLL are variable between segments, with significantly lower scores at C6, C7 compared with C1-C5. Multivariate logistic regression analysis showed that BMI was correlated with the development of OPLL (regression coefficient, 0.162; 95% confidence interval, 0.010-0.037). Additional risk factors included hypertension, calcium supple history and smoking.

CONCLUSIONS

This study demonstrates that cervical OPLL is associated with lower VBQ score at C3, with no differences for the other levels when compared with CSM derived from measurements on MRI. No differences were found between male and female group associated with OPLL in C2-C7 VBQ scores. Cervical OPLL were found to have smaller VBQ score at C6, C7 compared with C1-C5. Our findings provide new insight for bone density assessment in cervical OPLL patient.

Total body bone mineral density and various spinal disorders: a Mendelian randomization study

Introduction

Observational studies have yielded inconsistent findings regarding the correlation between bone mineral density (BMD) and various spinal disorders. To explore the relationship between total-body BMD and various spinal disorders further, we conducted a Mendelian randomization analysis to assess this association.

Methods

Two-sample bidirectional Mendelian randomization (MR) analysis was employed to investigate the association between total-body BMD and various spinal disorders. The inverse-variance weighted (IVW) method was used as the primary effect estimate, and additional methods, including weighted median, MR-Egger, simple mode, and weighted mode, were used to assess the reliability of the results. To examine the robustness of the data further, we conducted a sensitivity analysis using alternative bone-density databases, validating the outcome data.

Results

MR revealed a significant positive association between total-body BMD and the prevalence of spondylosis and spinal stenosis. When total-body BMD was considered as the exposure factor, the analysis demonstrated an increased risk of spinal stenosis (IVW odds ratio [OR] 1.23; 95% confidence interval [CI], 1.14-1.32; P < 0.001) and spondylosis (IVW: OR 1.24; 95%CI, 1.16-1.33; P < 0.001). Similarly, when focusing solely on heel BMD as the exposure factor, we found a positive correlation with the development of both spinal stenosis (IVW OR 1.13, 95%CI, 1.05-1.21; P < 0.001) and spondylosis (IVW OR 1.10, 95%CI, 1.03-1.18; P = 0.0048). However, no significant associations were found between total-body BMD and other spinal disorders, including spinal instability, spondylolisthesis/spondylolysis, and scoliosis (P > 0.05).

Conclusion

This study verified an association of total-body BMD with spinal stenosis and with spondylosis. Our results imply that when an increasing trend in BMD is detected during patient examinations and if the patient complains of numbness and pain, the potential occurrence of conditions such as spondylosis or spinal stenosis should be investigated and treated appropriately.