Association of lumbar disc degeneration with osteoporotic fractures; the Rotterdam study and meta-analysis from systematic review

[Translated article] Anatomical and biomechanical factors of osteoporotic vertebral fracture and the occurrence of cascade fractures

Osteoporosis weakens the structural strength of bone to such an extent that normal daily activity may exceed the capacity of the vertebra to bear this load. Vertebral fracture and deformity is a hallmark of osteoporosis. The detriment of trabecular bone properties alone cannot explain the occurrence of osteoporotic vertebral fracture. The ability of the spine to bear and resist loads depends on the structural capacity of the vertebrae, but also on loading conditions arising from activities of daily living or low-energy trauma. This review describes the mechanical properties of the vertebral bone, the structural load-bearing capacity of the various elements forming the spine, the neuromuscular control of the trunk, as well as the biomechanics of the loads to which the spine is subjected in relation to the presence of osteoporosis and the risk of vertebral fracture. A better understanding of biomechanical factors may help to explain both the high incidence of osteoporotic vertebral fractures and their mechanism of production. Consideration of these issues may be important in the development of prevention and management strategies.

The Reciprocal Relationship Between Lumbar Intervertebral Disk Degeneration and the MRI-based Vertebral Bone Quality Score

STUDY DESIGN

Retrospective longitudinal study.

OBJECTIVE

To investigate the association between lumbar intervertebral disk degeneration (DD) and the vertebral bone quality (VBQ) score.

BACKGROUND

The VBQ score that is based on magnetic resonance imaging has been proposed as a measure of lumbar spine bone quality and is a significant predictor of healthy versus osteoporotic bone. However, the role of segmental contributing factors on VBQ is unknown.

METHODS

Nonsurgical patients who underwent repeated lumbar magnetic resonance imaging scans, at least three years apart primarily for low back pain were retrospectively included. VBQ was assessed as previously described. DD was assessed using the Pfirrmann grading (PFG) scale. PFG grades were summarized as PFG L1-4 for the upper three lumbar disk levels, as PFG L4-S1 for the lower two lumbar disc levels, and as PFG L1-S1 for all lumbar disc levels. Multivariable linear mixed models were used with adjustments for age, sex, race, body mass index, and the clustering of repeated measurements.

RESULTS

A total of 350 patients (54.6% female, 85.4% White) were included in the final analysis, with a median age at baseline of 60.1 years and a body mass index of 25.8 kg/m 2 . VBQ significantly increased from 2.28 at baseline to 2.36 at follow-up ( P = 0.001). In the unadjusted analysis, a significant positive correlation was found between PFG L1-4 , PFG L1-S1 , and VBQ at baseline ( P < 0.05) that increased over time ( P < 0.005). In the adjusted multivariable analysis, PFG L1-4 ( β = -0.0195; P = 0.021), PFG L4-S1 ( β = -0.0310; P = 0.007), and PFG L1-S1 ( β = -0.0160; P = 0.012) were independently and negatively associated with VBQ.

CONCLUSIONS

More advanced and long-lasting DD is associated with lower VBQ indicating less bone marrow fat content and potentially stronger bone. VBQ score as a marker of bone quality seems affected by DD.

Anatomical and biomechanical factors of osteoporotic vertebral fracture and the occurrence of cascade fractures

Osteoporosis weakens the structural strength of bone to such an extent that normal daily activity may exceed the capacity of the vertebra to bear this load. Vertebral fracture and deformity is a hallmark of osteoporosis. The detriment of trabecular bone properties alone cannot explain the occurrence of osteoporotic vertebral fracture. The ability of the spine to bear and resist loads depends on the structural capacity of the vertebrae, but also on loading conditions arising from activities of daily living or low-energy trauma. This review describes the mechanical properties of the vertebral bone, the structural load-bearing capacity of the various elements forming the spine, the neuromuscular control of the trunk, as well as the biomechanics of the loads to which the spine is subjected in relation to the presence of osteoporosis and the risk of vertebral fracture. A better understanding of biomechanical factors may help to explain both the high incidence of osteoporotic vertebral fractures and their mechanism of production. Consideration of these issues may be important in the development of prevention and management strategies.

The Advantages of Radiofrequency Echographic MultiSpectrometry in the Evaluation of Bone Mineral Density in a Population with Osteoarthritis at the Lumbar Spine

BACKGROUND

Osteoarthritis (OA) in the lumbar spine can potentially lead to an overestimation of bone mineral density (BMD), and this can be a challenge in accurately diagnosing conditions like osteoporosis, where precise measurement of BMD is crucial. Radiofrequency Echographic Multi Spectrometry (REMS) is being recognized as an innovative diagnostic tool for assessing bone status. The purpose of this study was to evaluate whether the use of REMS may enhance the identification of osteoporosis in patients with osteoarthritis.

METHODS

A cohort of 500 patients (mean age: 63.9 ± 11.2 years) diagnosed with osteoarthritis and having a medical prescription for dual-energy X-ray absorptiometry (DXA) were recruited for the study. All patients underwent BMD measurements at lumbar spine and femoral sites by both DXA and REMS techniques.

RESULTS

The T-score values for BMD at the lumbar spine (BMD-LS) by DXA were significantly higher with respect to BMD-LS by REMS across all OA severity scores, and the differences were more pronounced in patients with a higher degree of OA severity (p < 0.001). Furthermore, the percentage of subjects classified as "osteoporotic", on the basis of BMD by REMS was markedly higher than those classified by DXA, both when considering all skeletal sites (39.4% vs. 15.1%, respectively) and the lumbar spine alone (30.5% vs. 6.0%, respectively). A similar pattern was observed when OA patients were grouped according to the Kellgren-Lawrence grading score.

CONCLUSIONS

The findings from our study indicate that, in a population with varying severity levels of osteoarthritis, REMS demonstrated a higher capability to diagnose osteoporosis compared to DXA, and this could lead to earlier intervention and improved outcomes for patients with bone fragility, reducing the likelihood of fractures and associated complications.

Patient-related risk factors and lifestyle factors for lumbar degenerative disc disease: a systematic review

OBJECTIVE

Back pain is a very widespread disease pattern and is one of the most frequent causes for consultation of a physician in general. In most cases, discogenic changes are the pathomorphological correlate of back pain. Numerous risk factors have been identified for these degenerative changes, but the influence and significance of the risk factors remain unclear, which was the aim of this systematic review.

METHODS

A systematic literature search of the commonly used Pubmed database was performed using specific MESH terms. Further selection of the included studies was performed according to the PRISMA scheme, taking into account scientific merit as well as the relation to the research question.

RESULTS

A total of 111 studies out of 1035 found were finally included in the literature search. 134 risk factors for disc degeneration and disc herniation were identified. These were divided into (1) patient-specific risk factors (n░=░34), (2) radiological risk factors (n░=░31), (3) lifestyle risk factors (n░=░6), (4) workplace-related risk factors (n░=░12), (5) genetic risk factors (n░=░50), and (6) other risk factors (n░=░1). Non-adjustable risk factors were age >50 years (OR 1.7/year), female gender (OR 1.41), family disposition (OR 4.0), comorbidities like atherosclerosis (OR 2.24), arthritic changes in other joints (OR 3.1) and history of injuries of the back (OR 3.1). Adjustable factors were elevated BMI (OR 2.77), comorbidities like hypertension (OR 1.25), dyslipidemia (OR 1.26) and diabetes mellitus (OR 6.8), as well as lifestyle habits like smoking (OR 3.8).

DISCUSSION

In summary, intervertebral disc degenerations and herniations represent multifactorial events whose risk factors can be partly influenced and partly not influenced. This systematic review highlights the current state of knowledge as a basis for creating patient-specific algorithms to calculate risk for the development or progression of degenerative disc changes and disc herniations.

The association of lumbar disc degeneration with lumbar vertebral trabecular volumetric bone mineral density in an urban population of young and middle-aged community-dwelling Chinese adults: a cross-sectional study

INTRODUCTION

Lumbar intervertebral disc degeneration (LDD) and osteoporosis (OP) are age-related conditions that induce low back pain and have an impact on quality of life. The relationship between LDD and changes in bone mineral density (BMD) is, however, contentious and ever-changing. The purpose of this study is to investigate the relationship between lumbar vertebral volumetric BMD (vBMD) and LDD in an urban population of young and middle-aged community-dwelling Chinese adults.

MATERIALS AND METHODS

719 participants were recruited from among the subjects enrolled in a 10-year longitudinal study of degeneration of the spine and knee being conducted at the Beijing Jishuitan Hospital. The severity of LDD was graded using the five-grade Pfirrmann classification, and lumbar vertebral vBMD was measured using quantitative computed tomography (QCT). The relationship between the grade of intervertebral disc degeneration and lumbar vertebral vBMD was analyzed, and multiple linear regression was performed to adjust for covariates.

RESULTS

The mean lumbar vBMD decreased as the grade of LDD increased (171.5 g/cm3, 147.8 g/cm3, and 124.3 g/cm3, respectively; P < 0.001). After adjusting for age, a higher LDD stage was associated with a lower mean L2-L4 vBMD, although a statistically significant correlation was observed only in men (standardized coefficient β = - 0.656, P = 0.004). In men, there was a negative correlation between single-vertebra vBMD and degeneration of adjacent intervertebral discs, particularly those involving the L3 vertebra (L2-3 disc: β = - 0.333, P < 0.001, L3-4 disc: β = - 0.398, P < 0.001), as well as the mean grade of the L2-4 discs (β = - 0.448, P < 0.001). However, the L5-S1 disc had a smaller correlation with age than others, and no statistically significant associations with lumbar vBMD were observed in either men (β = - 0.024, P = 0.729) or women (β = - 0.057, P = 0.396).

CONCLUSION

Our study found that the degree of LDD was negatively associated with lumbar trabecular vBMD, although (excepting the L5-S1 disc), the relationship was statistically significant only in men.

Radiofrequency Echographic Multi Spectrometry (R.E.M.S.): New Frontiers for Ultrasound Use in the Assessment of Bone Status-A Current Picture

Osteoporosis is a frequently occurring skeletal disease, and osteoporosis-related fractures represent a significant burden for healthcare systems. Dual-Energy X-ray Absorptiometry (DXA) is the most commonly used method for assessing bone mineral density (BMD). Today, particular attention is being directed towards new technologies, especially those that do not use radiation, for the early diagnosis of altered bone status. Radiofrequency Echographic Multi Spectrometry (REMS) is a non-ionizing technology that evaluates the bone status at axial skeletal sites by analyzing raw ultrasound signals. In this review, we evaluated the data on the REMS technique present in the literature. The literature data confirmed diagnostic concordance between BMD values obtained using DXA and REMS. Furthermore, REMS has adequate precision and repeatability characteristics, is able to predict the risk of fragility fractures, and may be able to overcome some of the limitations of DXA. In conclusion, REMS could become the method of choice for the assessment of bone status in children, in women of childbearing age or who are pregnant, and in several secondary osteoporosis conditions due to its good precision and replicability, its transportability, and the absence of ionizing radiation. Finally, REMS may allow qualitative and not just quantitative assessments of bone status.

Genetics of Intervertebral Disc Degeneration

PURPOSE OF REVIEW

Intervertebral disc degeneration is a contributor to chronic back pain. While a part of the natural aging process, early or rapid intervertebral disc degeneration is highly heritable. In this review, we summarize recent progress towards unraveling the genetics associated with this degenerative process.

RECENT FINDINGS

Use of large cohorts of patient data to conduct genome-wide association studies (GWAS) for intervertebral disc disease, and to lesser extent for aspects of this process, such as disc height, has resulted in a large increase in our understanding of the genetic etiology. Genetic correlation suggests that intervertebral disc disease is pleiotropic with risk factors for other diseases such as osteoporosis. The use of Mendelian Randomization is slowly establishing what are the causal relationships between intervertebral disc disease and factors previously correlated with this disease. The results from these human genetic studies highlight the complex nature of this disease and have the potential to lead to improved clinical management of intervertebral disc disease. Much additional work should now be focused on characterizing the causative relationship various co-morbid conditions have with intervertebral disc degeneration and on finding interventions to slow or halt this disease.

Could radiofrequency echographic multispectrometry (REMS) overcome the overestimation in BMD by dual-energy X-ray absorptiometry (DXA) at the lumbar spine?

BACKGROUND

Osteoarthritis (OA) and vertebral fractures at the lumbar spine lead to an overestimation of bone mineral density (BMD). Recently, a new approach for osteoporosis diagnosis, defined as radiofrequency echographic multi-spectrometry (REMS), represents an innovative diagnostic tool that seems to be able to investigate bone quality and provide an estimation of fracture risk independent of BMD. The aim of this paper was to evaluate whether the use of REMS technology can favor the diagnosis of osteoporosis in subjects with an apparent increase in BMD.

METHODS

In a cohort of 159 postmenopausal (66.2 ± 11.6 yrs) women with overestimated BMD by DXA at the lumbar spine, we performed an echographic scan with the REMS technique.

RESULTS

The mean values of BMD at different skeletal sites obtained by the DXA and REMS techniques showed that the BMD T-scores by REMS were significantly lower than those obtained by the DXA technique both at the lumbar spine (p < 0.01) and at all femoral subregions (p < 0.05). In OA subjects, the percentage of women classified as "osteoporotic" on the basis of BMD by REMS was markedly higher with respect to those classified by DXA (35.1% vs 9.3%, respectively). Similarly, the REMS allows a greater number of fractured patients to be classified as osteoporotic than DXA (58.7% vs 23.3%, respectively).

CONCLUSIONS

REMS technology by the analysis of native raw unfiltered ultrasound signals appears to be able to overcome the most common artifacts, such as OA and vertebral fracture of the lumbar spine, which affect the value of BMD by DXA.

Advances in research on fat infiltration and lumbar intervertebral disc degeneration

Low back pain (LBP) is a disabling condition with no available cure, severely affecting patients' quality of life. Intervertebral disc degeneration (IVDD) is the leading cause of chronic low back pain (CLBP). IVDD is a common and recurrent condition in spine surgery. Disc degeneration is closely associated with intervertebral disc inflammation. The intervertebral disc is an avascular tissue in the human body. Transitioning from hematopoietic bone marrow to bone marrow fat may initiate an inflammatory response as we age, resulting in bone marrow lesions in vertebrae. In addition, the development of LBP is closely associated with spinal stability imbalance. An excellent functional state of paraspinal muscles (PSMs) plays a vital role in maintaining spinal stability. Studies have shown that the diminished function of PSMs is mainly associated with increased fat content, but whether the fat content of PSMs is related to the degree of disc degeneration is still under study. Given the vital role of PSMs lesions in CLBP, it is crucial to elucidate the interaction between PSMs changes and CLBP. Therefore, this article reviews the advances in the relationship and the underlying mechanisms between IVDD and PSMs fatty infiltration in patients with CLBP.

The Association of Lumbar Disc Herniation with Lumbar Volumetric Bone Mineral Density in a Cross-Sectional Chinese Study

Little is known about the effect of lumbar intervertebral disc herniation (LDH) on lumbar bone mineral density (BMD), and few previous studies have used quantitative computed tomography (QCT) to assess whether the staging of LDH correlates with lumbar vertebral trabecular volumetric bone mineral density (Trab.vBMD). To explore the relationship between lumbar Trab.vBMD and LDH, seven hundred and fifty-four healthy participants aged 20–60 years were enrolled in the study from an ongoing study on the degeneration of the spine and knee between June 2014 and 2017. QCT was used to measure L2–4 Trab.vBMD and lumbar spine magnetic resonance images (MRI) were performed to assess the incidence of disc herniation. After 9 exclusions, a total of 322 men and 423 women remained. The men and women were divided into younger (age 20–39 years) and older (age 40–60 years) groups and further into those without LDH, with a single LDH segment, and with ≥2 segments. Covariance analysis was used to adjust for the effects of age, BMI, waistline, and hipline on the relationship between Trab.vBMD and LDH. Forty-one younger men (25.0%) and 59 older men (37.3%) had at least one LDH segment. Amongst the women, the numbers were 46 (22.5%) and 80 (36.4%), respectively. Although there were differences in the characteristics data between men and women, the difference in Trab.vBMD between those without LDH and those with single and ≥2 segments was not statistically significant (p > 0.05). These results remained not statistically significant after further adjusting for covariates (p > 0.05). No associations between lumbar disc herniation and vertebral trabecular volumetric bone mineral density were observed in either men or women.

Trabecular Architecture and Mechanical Heterogeneity Effects on Vertebral Body Strength

PURPOSE OF REVIEW

We aimed to synthesize the recent work on the intra-vertebral heterogeneity in density, trabecular architecture and mechanical properties, its implications for fracture risk, its association with degeneration of the intervertebral discs, and its implications for implant design.

RECENT FINDINGS

As compared to the peripheral regions of the centrum, the central region of the vertebral body exhibits lower density and more sparse microstructure. As compared to the anterior region, the posterior region shows higher density. These variations are more pronounced in vertebrae from older persons and in those adjacent to degenerated discs. Mixed results have been reported in regard to variation along the superior-inferior axis and to relationships between the heterogeneity in density and vertebral strength and fracture risk. These discrepancies highlight that, first, despite the large amount of study of the intra-vertebral heterogeneity in microstructure, direct study of that in mechanical properties has lagged, and second, more measurements of vertebral loading are needed to understand how the heterogeneity affects distributions of stress and strain in the vertebra. These future areas of study are relevant not only to the question of spine fractures but also to the design and selection of implants for spine fusion and disc replacement. The intra-vertebral heterogeneity in microstructure and mechanical properties may be a product of mechanical adaptation as well as a key determinant of the ability of the vertebral body to withstand a given type of loading.

Intervertebral disc degeneration associated with vertebral marrow fat, assessed using quantitative magnetic resonance imaging

OBJECTIVE

To investigate the potential clinical application of quantitative MRI in assessing the correlation between lumbar vertebrae bone marrow fat deposition and intervertebral disc degeneration.

MATERIALS AND METHODS

A total of 104 chronic lower-back pain volunteers underwent 3.0-T MRI with T2-weighted imaging, T2 mapping, and iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL-IQ) between August 2018 and June 2019. Each disc was assessed with T2 value by T2 mapping, and the L1-S1 vertebral bone marrow fat fraction was assessed by IDEAL-IQ. The differences and relationship between T2 value and the adjacent vertebral bone marrow fat fraction values within the five Pfirrmann groups, five age groups, and five lumbar levels were statistically analyzed.

RESULTS

The vertebral bone marrow fat fraction had a significant negative correlation with T2 values of nucleus pulposus' T2 values (p < 0.001). However, the significant negative correlation was only found between T2 values of nucleus pulposus and adjacent vertebral bone marrow fat in Pfirrmann II-III, L1/2-L5/S1 level, and 40-49 years' age groups. Pfirrmann grades of the intervertebral disc were positively correlated with adjacent vertebrae bone marrow fat fraction (p < 0.05).

CONCLUSION

Lumbar bone marrow fat deposition significantly increases during the early stages of intervertebral disc degeneration. Quantitative measurements of bone marrow fat deposition and water content of intervertebral discs have a predictive value and are an important supplement to the qualitative traditional classification strategies for the early stages of intervertebral disc degeneration.

Full-endoscopic spine surgery for radiculopathy after osteoporotic vertebral compression fractures: a case report

Full-endoscopic spine surgery (FESS) is a suitable treatment for lumbar disc herniation (LDH) and foraminal stenosis. Here, we describe the usefulness of FESS for treating radiculopathy after osteoporotic vertebral compression fractures (OVCFs). Between October 2018 and April 2019, three female patients (mean age, 81.7 years) with radiculopathy after OVCFs underwent FESS. Decompression of the corresponding nerve root was achieved using several FESS techniques, including foraminoplasty, discectomy, and removal of osteophyte or cement leakage. The mean operative time was 60.7 min. Preoperative and postoperative statuses were evaluated using numerical rating scale (NRS) scores. The mean pre- and postoperative NRS scores were 9 and 2.3, respectively. We observed no postoperative complications. Our results demonstrate that FESS is a safe and effective minimally invasive treatment for radiculopathy after OVCFs, with the potential to be an alternative to vertebroplasty, balloon kyphoplasty (BKP), or lumbar interbody fusion.

A Meta-analysis Assessing the Association Between COL11A1 and GDF5 Genetic Variants and Intervertebral Disc Degeneration Susceptibility

STUDY DESIGN

Meta-analysis to collect relevant studies to assess the association between COL11A1 and GDF5 genetic variants and susceptibility to IDD.

OBJECTIVE

The aim of this study was to assess whether or not COL11A1 and GDF5 genetic variants were associated with susceptibility to IDD.

SUMMARY OF BACKGROUND DATA

IDD or LDH is a major public health problem. There have been several studies evaluating the relationship between COL11A1 and GDF5 genetic variants with risk of intervertebral disc degeneration (IDD). However, the studies were limited in discrete outcome and sample size, and some of the results were contradictory.

METHODS

We systematically searched the relevant publications in electronic databases. Eligible studies were included based on the defined criteria. The pooled odds ratios (ORs) with its 95% confidence intervals (CIs) were received using STATA 15. Subgroup analysis, sensitivity analysis, publication bias, and the "Trim and fill" method were performed in the meta-analysis.

RESULTS

A total of 3287 IDD cases and 5115 controls were incorporated into the meta-analysis. Our results demonstrated that COL11A1 rs1676486 was significantly associated with increased IDD susceptibility under all genetic models (allele model T vs. C: OR = 1.40, 95% CI 1.23-1.59, P = 0.000; homozygote model TT vs. CC: OR = 1.89, 95%CI 1.40-2.56, P = 0.000; dominant model TT+TC vs. CC: OR = 1.52, 95% CI 1.29-1.80, P = 0.000; recessive model TT vs. TC + CC: OR = 1.58, 95% CI 1.18-2.12, P = 0.002). However, GDF5 rs143383 was not (allele model T vs. C: OR = 1.15, 95% CI 0.91-1.44, P = 0.244; homozygote model TT vs. CC: OR = 1.22, 95% CI 0.75-2.00, P = 0.429; dominant model TT vs. CC+CT: OR = 1.22, 95% CI 0.95-1.57, P = 0.112; recessive model TC + TT vs. CC: OR = 1.12, 95% CI 0.73-1.73, P = 0.594). Subgroup analysis indicated ethnicity was not the source of heterogeneity. Sensitivity analysis, publication bias, and the "Trim and fill" method demonstrated the meta-analysis was of reliability.

CONCLUSION

Our results suggested that COL11A1 rs1676486 was significantly associated with IDD and the T allele was a risky factor. However, GDF5 rs143383 was not.

LEVEL OF EVIDENCE

1.

Disc degeneration promotes regional inhomogeneity in the trabecular morphology of loaded rat tail vertebrae

Background

There is a close relationship between the vertebral trabecular morphology and the condition of the associated disc.

Objective

The relationship between disc degeneration and vertebral trabecular inhomogeneity is unclear. This study aimed to analyse the regional changes of vertebral trabecular morphology after disc degeneration.

Methods

Thirty male Sprague–Dawley rats were randomly assigned to five groups. Group 1 served as an experimental group for the assessment of disc degeneration induced by needle puncture. Group 2 served as a sham group for trabecular morphology analysis. In Group 3, rats had their tail bent between the eighth and tenth coccygeal vertebrae. In Group 4, the tail of rats was bent with a compression load of 4.5 N. In Group 5, rats first underwent disc degeneration induced by a needle puncture before their tail was bent with a compressive load of 4.5 N. Magnetic resonance imaging was performed on all groups, and histological examination was performed on rodents from Group 1. The ninth coccygeal vertebrae of rats from Groups 2–5 were scanned by Micro-computed tomography. Trabecular morphologic changes were assessed in the concave and convex regions by bone volume fraction, trabecular number, trabecular thickness and trabecular separation.

Results

Vertebral trabecular morphology in the concave region improved significantly, whereas the convex region was of significantly lower trabecular morphologic parameters with disc degeneration. The difference in trabecular morphologic parameters between the convex and concave regions increased significantly after disc degeneration.

Conclusion

Disc degeneration promotes regional inhomogeneity in the vertebral trabecular morphology, with the convex region of the vertebrae having the worse trabecular bone morphology than the concave region.

The translational potential of this article

Our study indicates that disc degeneration promotes regional inhomogeneity in the vertebral trabecular morphology. Regional variations in trabecular microarchitecture are helpful to predict vertebral fragility. This may help to elucidate the mechanisms by which disc degeneration contributes to vertebral fracture.

Long term prognosis of Scheuermann's disease: The association with fragility fracture - The MINOS cohort

The aim was to assess the association of Scheuermann's disease (SCD) with fracture risk (vertebral, peripheral) and bone mineral density (BMD) in older men. SCD was assessed on the baseline lateral spine radiographs using the Berlin criteria in 766 men aged 50-85. We evaluated the association of SCD and its diagnostic criteria with incident fracture (vertebral over 7.5 years, peripheral over 10 years) and BMD (baseline). SCD prevalence was 25.2%. SCD and its criteria showed inconsistent associations with BMD at different skeletal sites. Eighty-four men had incident fractures. After adjustment for age, weight, spine BMD, prevalent vertebral fractures, prior falls and score of disc space narrowing due to osteoarthritis (DSN-OA), SCD was not associated with vertebral fracture risk. Vertebral endplate irregularities (EI), one of its diagnostic criteria, were associated with higher vertebral fracture risk (OR = 3.26, 95% CI: 1.34-7.94, p < 0.01). Vertebral fracture risk was higher in men with EI and low spine BMD vs. men without these characteristics (OR = 12.84, 95% CI: 3.12-52.83, p < 0.005). EI was associated with higher vertebral fracture risk in men without severe DSN-OA and without prevalent vertebral fractures. Peripheral fracture risk was lower in men with SCD (HR = 0.39, 95% CI: 0.18-0.83, p < 0.02) and EI. Peripheral fracture risk was higher in men without SCD who had low femoral neck BMD vs. men with SCD and normal BMD (HR = 4.68, 95% CI: 1.09-20.03, p < 0.05). In conclusion, EI were associated with high vertebral fracture risk. SCD and EI were associated with lower peripheral fracture risk. The associations of SCD and its criteria with BMD were inconsistent.

Meta-Analysis of the Association Between FAS Ligand and TRAIL Genetic Polymorphisms and Intervertebral Disc Degeneration Susceptibility in Chinese Han population

STUDY DESIGN

Meta-analysis to collect all the relevant studies to further investigate whether or not the FAS ligand (FASL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) genetic polymorphisms are associated with susceptibility to intervertebral disc degeneration (IDD) in Chinese Han population.

OBJECTIVE

To investigate whether or not the FASL and TRAIL genetic polymorphisms are associated with susceptibility to IDD in Chinese Han population.

SUMMARY OF BACKGROUND DATA

FASL and TRAIL are both apoptotic gene. Several studies have assessed the associations of FASL and TRAIL gene with risk of IDD in Chinese Han population, but the results are inconsistent.

METHODS

We systematically searched the PubMed, EMBASE, Medline, Scopus, Web of Science, CBM, and the Cochrane Library databases. Eligible studies assessing the polymorphisms in the FASL and TRAIL gene and risk of IDD were incorporated. The pooled odds ratio (OR) with its 95% confidence intervals (95% CI) was used.

RESULTS

Six studies with a total of 1766 IDD cases and 1533 controls were finally included in the meta-analysis. Meta-analysis of FASL-844C/T (rs763110) polymorphism was statistically associated with decreased IDD risk under all genetic models (allele model: OR = 0.68, 95% CI 0.59-0.80, P = 0.000; homozygote model: OR = 0.35, 95% CI 0.25-0.53, P = 0.000; dominant model: OR = 0.38, 95% CI 0.25-0.58, P = 0.000; recessive model: OR = 0.69, 95% CI 0.58-0.84, P = 0.000). There was a significant association between TRAIL-1595C/T (rs1131580) polymorphism with increased IDD risk under each genetic model (allele model: OR = 1.77, 95% CI 1.47-2.13, P = 0.000; homozygote model: OR = 2.44, 95% CI 1.70-3.51, P = 0.000; dominant model: OR = 1.67, 95% CI 1.22-2.29, P = 0.002; recessive model: OR = 3.13, 95% CI 2.40-4.08, P = 0.000). In addition, the association between TRAIL-1525G/A (rs1131568) polymorphism and the susceptibility of IDD was statistically significant under all genetic models.

CONCLUSION

The present meta-analysis demonstrated that FASL and TRAIL polymorphisms were significantly associated with susceptibility to IDD in Chinese Han population.

LEVEL OF EVIDENCE

1.

Degenerative inter-vertebral disc disease osteochondrosis intervertebralis in Europe: prevalence, geographic variation and radiological correlates in men and women aged 50 and over

Objectives

To assess the prevalences across Europe of radiological indices of degenerative inter-vertebral disc disease (DDD); and to quantify their associations with, age, sex, physical anthropometry, areal BMD (aBMD) and change in aBMD with time.

Methods

In the population-based European Prospective Osteoporosis Study, 27 age-stratified samples of men and women from across the continent aged 50+ years had standardized lateral radiographs of the lumbar and thoracic spine to evaluate the severity of DDD, using the Kellgren-Lawrence (KL) scale. Measurements of anterior, mid-body and posterior vertebral heights on all assessed vertebrae from T4 to L4 were used to generate indices of end-plate curvature.

Results

Images from 10 132 participants (56% female, mean age 63.9 years) passed quality checks. Overall, 47% of men and women had DDD grade 3 or more in the lumbar spine and 36% in both thoracic and lumbar spine. Risk ratios for DDD grades 3 and 4, adjusted for age and anthropometric determinants, varied across a three-fold range between centres, yet prevalences were highly correlated in men and women. DDD was associated with flattened, non-ovoid inter-vertebral disc spaces. KL grade 4 and loss of inter-vertebral disc space were associated with higher spine aBMD.

Conclusion

KL grades 3 and 4 are often used clinically to categorize radiological DDD. Highly variable European prevalences of radiologically defined DDD grades 3+ along with the large effects of age may have growing and geographically unequal health and economic impacts as the population ages. These data encourage further studies of potential genetic and environmental causes.

Effects of alendronate on lumbar intervertebral disc degeneration with bone loss in ovariectomized rats

BACKGROUND CONTEXT

Osteoporosis adversely affects disc degeneration cascades, and prophylactic alendronate (ALN) helps delay intervertebral disc degeneration (IDD) in ovariectomized (OVX) rats. However, there remains no information regarding whether ALN affects IDD with bone loss.

PURPOSE

This study aimed to observe the effects of ALN on degenerative discs with bone loss induced by OVX in rats.

STUDY DESIGN

This study used controlled in vivo experiments in rodents.

METHODS

Thirty female Sprague-Dawley rats were randomly assigned to undergo sham surgery (n=10) or OVX surgery (n=20); 3 months later, the OVX animals were injected with either ALN (OVX+ALN, 15 µg/kg/2w, n=10) or normal saline (OVX+vehicle treatment [V], n=10). At 3 months after the ALN intervention, van Gieson staining and immunohistochemistry were used to investigate histologic and metabolic changes in the discs. Bone mineral density (BMD), micro-computed tomography, and biomechanical tests were conducted to determine the biological properties of the vertebrae.

RESULTS

The OVX+ALN group exhibited significantly reduced morphologic degenerative alterations in both the nucleus pulposus and annulus fibrosus, with a markedly lower IDD score than that of the OVX+V group. The OVX+ALN samples showed increased disc height and decreased cartilage end plate thickness and bony area compared with the OVX+V group. Compared with saline, ALN administration markedly inhibited the type I collagen, matrix metalloprotease (MMP)-1, and MMP-13 expression levels while increasing the type II collagen and aggrecan expression levels in the disc matrix. Compared with the OVX+V group, OVX+ALN vertebrae revealed significantly enhanced BMD with increased biomechanical strength, as well as increased percent bone volume and trabecular thickness.

CONCLUSIONS

ALN has favorable effects on disc degeneration with bone loss and helps to alleviate IDD while enhancing the biological and mechanical properties of vertebrae and end plates.

Thoracolumbar kyphosis is associated with compressive vertebral fracture in postmenopausal women

The main aim of this retrospective cross-sectional study was to examine the relationship between vertebral compression fracture and thoracolumbar Cobb angles. Fracture prevalence was found to be significantly higher for patients with moderate [odds ratio (OR) = 4.78 (2.88-7.95)] or severe kyphosis [OR = 10.7 (5.11-22.40)] than for patients with mild kyphosis. The relationship between degree of thoracolumbar kyphosis and vertebral compression fracture was analyzed.

INTRODUCTION

The hypothesis that vertebral compression fracture in women is related to thoracolumbar kyphosis severity was tested, and a clinically important cutoff degree of sagittal thoracolumbar Cobb angle (TLCobb) was determined.

METHODS

Demographic data, clinical data, and quantitative computed tomography (QCT) findings were compiled for 212 postmenopausal women with thoracolumbar fracture (study group) and 150 postmenopausal women with degenerative lumbar disease (control group). Group proportions and characteristics were compared with chi-squared tests and unpaired t tests, respectively.

RESULTS

In this retrospective cross-sectional study cohort, 17 patients had T11 fractures, 79 had T12 fractures, 89 had L1 fractures, and 27 had L2 fractures. QCT findings and TLCobb differed between the study and control groups (both p < 0.001). No significant differences were found in body mass index (BMI), disk height, or coronal TLCobb. After adjustment for age, BMI, and QCT findings, fracture prevalence was found to be higher in the thoracolumbar kyphosis study group than in the control group [OR = 6.16, 95% confidence interval (CI) 3.88-9.78]. Sagittal TLCobbs of 7.5-15° and >15° were associated with an increased fracture prevalence, with ORs of 4.78 (2.88-7.95) and 10.7 (5.11-22.40), respectively.

CONCLUSION

Vertebral fracture prevalence in postmenopausal women was found to be associated with thoracolumbar kyphosis. A TLCobb sagittal angle >15° should be considered an indicator for vertebral fracture assessment.

Relationship between spinal osteoarthritis and vertebral fractures in men older than 50 years: data from the Camargo Cohort Study

Spinal osteoarthritis has been suggested as a risk factor for vertebral fractures. However, results are conflicting: most of the data are focused on the lumbar region, and referred to postmenopausal women, whereas data for men are scarce. The aim of this study is to assess the relationship between spinal osteoarthritis and vertebral fractures in men over 50 years of age. We conducted a cross-sectional study, nested in a prospective population-based cohort, including 507 community-dwelling men, 93 of them with at least one vertebral fracture. Vertebral fractures, osteophytosis, and disc space narrowing (DSN) were assessed by lateral thoracic and lumbar radiographs. Anthropometric, clinical, and densitometric variables were also analyzed. A multiple logistic regression model was performed. Eighty-five percent of vertebral fractures were located at the thoracic spine. Osteophytosis and DSN showed a bimodal distribution, with major frequency peaks at mid- and distal lumbar spine. The three distributions overlapped around the T9 vertebra. We did not find any relationship between lumbar osteoarthritis and vertebral fractures. Nevertheless, thoracic osteophytosis (OR, 1.84; 95 % CI, 1.05-3.17; p = 0.03) and DSN (OR, 2.52; 95 % CI, 1.43-4.46; p = 0.001) were found to be independently associated with prevalent vertebral fractures, after adjusting for confounders. Our results suggest a positive relationship between radiologic osteoarthritic changes at the thoracic spine and prevalent vertebral fractures in men more than 50 years of age. Osteoarthritis may act as a local risk factor, in addition to other mechanical factors, resulting in a greater propensity to fracture, especially at the mid-thoracic region.

Osteoporosis and osteoarthritis: shared mechanisms and epidemiology

PURPOSE OF REVIEW

Osteoporosis and osteoarthritis are different diseases, with differences in risk factors, bone mineral density (BMD), BMI, phenotype, morbidity and mortality. We review new data on the role of bone metabolism in osteoporosis and osteoarthritis.

RECENT FINDINGS

The insights in the common convergent and divergent risk factors between osteoarthritis and osteoporosis have resulted in new findings on the role of BMD, BMI, falls, genetics and epigenetics in the pathophysiology of both diseases and on the increased fracture risk in osteoporosis and osteoarthritis. The relation between BMD, BMI and fracture risk in osteoarthritis is dependent on the stage, definition and location of the osteoarthritis and method of BMD measurement. It has been suggested that osteoarthritis should be further specified in terms of bone involvement.

SUMMARY

These new findings open the way to better understand the bone subtypes of osteoarthritis (osteoporotic, bone forming and erosive) and the common and different ways bone is involved in osteoporosis and osteoarthritis. Much can be expected from further prospective studies, when taking into account the heterogeneous nature of both osteoporosis and osteoarthritis.

Quantitative imaging methods in osteoporosis

Osteoporosis is characterized by a decreased bone mass and quality resulting in an increased fracture risk. Quantitative imaging methods are critical in the diagnosis and follow-up of treatment effects in osteoporosis. Prior radiographic vertebral fractures and bone mineral density (BMD) as a quantitative parameter derived from dual-energy X-ray absorptiometry (DXA) are among the strongest known predictors of future osteoporotic fractures. Therefore, current clinical decision making relies heavily on accurate assessment of these imaging features. Further, novel quantitative techniques are being developed to appraise additional characteristics of osteoporosis including three-dimensional bone architecture with quantitative computed tomography (QCT). Dedicated high-resolution (HR) CT equipment is available to enhance image quality. At the other end of the spectrum, by utilizing post-processing techniques such as the trabecular bone score (TBS) information on three-dimensional architecture can be derived from DXA images. Further developments in magnetic resonance imaging (MRI) seem promising to not only capture bone micro-architecture but also characterize processes at the molecular level. This review provides an overview of various quantitative imaging techniques based on different radiological modalities utilized in clinical osteoporosis care and research.

Older men with severe disc degeneration have more incident vertebral fractures-the prospective MINOS cohort study

OBJECTIVE

Data on the relationship between disc degeneration (DD) and fragility fractures in men are limited. The aim of this study was to prospectively analyse the risk of vertebral and non-vertebral fractures in men with thoracolumbar DD according to the severity of its radiological signs: disc space narrowing (DSN), osteophytes and endplate sclerosis.

METHODS

Men >50 years of age (n = 765) had lateral spine radiographs and DXA and were monitored prospectively. We analysed the risk of incident vertebral (7.5 years) and non-vertebral fractures (10 years) in men according to the severity of DD.

RESULTS

After adjustment for age and weight, BMD increased with increasing total DSN score, endplate sclerosis and osteophytosis. Over 7.5 years, 28 incident vertebral fractures occurred in 27 men. After adjustment for age, BMI, spine BMD, prior fractures and abdominal aortic calcifications, the vertebral fracture risk was 3-fold higher in the upper DSN quartile vs men without DSN. After adjustment for the same confounders, vertebral fracture risk was also nearly 3-fold higher in the upper DSN quartile vs the three lower quartiles combined. Over 10 years, 61 men sustained non-vertebral fragility fractures. After adjustment for age, BMI, hip BMD, abdominal aortic calcifications and prior falls and fractures, the non-vertebral fracture risk decreased with increasing DSN score. The risk of non-vertebral fracture was half as high in men above the median total DSN score vs men below the median.

CONCLUSION

In older men, severe DD is associated with higher BMD. Multilevel severe DSN is associated with higher vertebral fracture risk and lower non-vertebral fracture risk.

Effective modulus of the human intervertebral disc and its effect on vertebral bone stress

The mechanism of vertebral wedge fractures remains unclear and may relate to typical variations in the mechanical behavior of the intervertebral disc. To gain insight, we tested 16 individual whole discs (between levels T8 and L5) from nine cadavers (mean±SD: 66±16 years), loaded in compression at different rates (0.05-20.0% strain/s), to measure a homogenized "effective" linear elastic modulus of the entire disc. The measured effective modulus, and average disc height, were then input and varied parametrically in micro-CT-based finite element models (60-μm element size, up to 80 million elements each) of six T9 human vertebrae that were virtually loaded to 3° of moderate forward-flexion via a homogenized disc. Across all specimens and loading rates, the measured effective modulus of the disc ranged from 5.8 to 42.7MPa and was significantly higher for higher rates of loading (p<0.002); average disc height ranged from 2.9 to 9.3mm. The parametric finite element analysis indicated that, as disc modulus increased and disc height decreased across these ranges, the vertebral bone stresses increased but their spatial distribution was largely unchanged: most of the highest stresses occurred in the central trabecular bone and endplates, and not anteriorly. Taken together with the literature, our findings suggest that the effective modulus of the human intervertebral disc should rarely exceed 100MPa and that typical variations in disc effective modulus (and less so, height) minimally influence the spatial distribution but can appreciably influence the magnitude of stress within the vertebral body.

Osteoporotic Vertebral Fractures as Part of Systemic Disease

Our understanding of the genetic control of skeletogenesis and bone remodeling is expanding, and normally, bone resorption and bone formation are well balanced through regulation by hormones, growth factors, and cytokines. Osteoporosis is considered a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue. Consequent increased bone fragility results in higher fracture risk. The most common osteoporotic fractures are located in the spine, and they form a significant health issue. A large variety of systemic diseases are associated with risk of osteoporotic vertebral fractures, illustrating its multifactorial etiology. Prevalences of these conditions vary from common to extremely rare, and incidence peaks differ according to etiology. This review appreciates different aspects of osteoporotic vertebral fractures as part of systemic disease, including genetic, immunologic, inflammatory, metabolic, and endocrine pathways. It seems impossible to be all-comprehensive on this topic; nevertheless, we hope to provide a reasonably thorough overview. Plenty remains to be elucidated in this field, identifying even more associated diseases and further exposing pathophysiological mechanisms underlying osteoporotic vertebral fractures.

Meta-analysis of the association between COL9A2 genetic polymorphisms and lumbar disc disease susceptibility

STUDY DESIGN

Meta-analysis to collect all the relevant studies to date to further investigate whether or not the COL9A2 gene rs12077871, rs12722877, and rs7533552 polymorphism are associated with susceptibility to lumbar disc disease (LDD).

OBJECTIVE

The aim of this study was to assess the association between the COL9A2 gene rs12077871, rs12722877, and rs7533552 and LDD.

SUMMARY OF BACKGROUND DATA

LDD is a common musculoskeletal disease with strong genetic determinants. COL9A2 encodes the α2 (IX) chain of type IX collagen, which is the major collagen component of the hyaline cartilage. Growing numbers of studies have revealed the association between COL9A2 polymorphisms and susceptibility to LDD. However, those studies have yielded contradictory results.

METHODS

Data were collected from the following electronic databases: PubMed, Web of Knowledge, and China National Knowledge Infrastructure, with the last report up to November 30, 2013. The odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of association under the allelic genetic model. We summarized the data on the association between COL9A2 rs12077871, rs12722877, and rs7533552 polymorphism and LDD in the overall studies.

RESULTS

Nine case-control studies, including 1522 LDD cases and 1646 controls, were identified. The results indicated that the rs12077871, rs12722877, and rs7533552 variants in COL9A2 were not associated with LDD (rs12077871: C vs. T, OR = 0.541, 95% CI = 0.256-1.147, P = 0.109; rs12722877: C vs. G, OR = 1.199, 95% CI = 0.992-1.448, P = 0.06; rs7533552: A vs. G, OR = 0.993, 95% CI = 0.815-1.069, P = 0.320). Furthermore, the Egger test and the Begg funnel plot did not show any evidence of publication bias.

CONCLUSION

Our results suggest that the COL9A2 rs12077871, rs12722877, and rs7533552 polymorphisms may not be associated with LDD. More studies based on larger sample sizes and homogeneous samples of patients with LDD are needed to confirm these findings.

LEVEL OF EVIDENCE

2.