Lumbar Disc Degeneration in Osteoporotic Men: Prevalence and Assessment of the Relation with Presence of Vertebral Fracture

Does vertebral osteoporosis delay or accelerate lumbar disc degeneration? A systematic review

The effect of vertebral osteoporosis on disc degeneration is still debated. The purpose of this study was to provide a systematic review of studies in this area to further reveal the relationship between the two. Relevant studies were searched in electronic databases, and studies were screened according to inclusion and exclusion criteria, and finally, basic information of the included studies was extracted and summarized. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A total of 34 publications spanning 24 years were included in our study. There were 19 clinical studies, including 12 prospective studies and 7 retrospective studies. Of these, 7 considered vertebral osteoporosis to be positively correlated with disc degeneration, 8 considered them to be negatively correlated, and 4 considered them to be uncorrelated. Two cadaveric studies were included, one considered the two to be negatively correlated and one considered them not to be correlated. Seven animal studies were included, of which five considered a positive correlation between vertebral osteoporosis and disc degeneration and two considered a negative correlation between the two. There were also 6 studies that used anti-osteoporosis drugs for intervention, all of them were animal studies. Five of them concluded that vertebral osteoporosis was positively associated with disc degeneration, and the remaining one concluded that there was no correlation between the two. Our systematic review shows that the majority of studies currently consider an association between vertebral osteoporosis and disc degeneration, but there is still a huge disagreement whether this association is positive or negative. Differences in observation time and follow-up time may be one of the reasons for the disagreement. A large number of clinical and basic studies are still needed in the future to further explore the relationship between the two.

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.

Higher-Impact Physical Activity Is Associated With Maintenance of Bone Mineral Density But Not Reduced Incident Falls or Fractures in Older Men: The Concord Health and Aging in Men Project

High-impact physical activities with bone strains of high magnitude and frequency may benefit bone health. This study aimed to investigate the longitudinal associations between changes in loading intensities and application rates, estimated from self-reported physical activity, with bone mineral density (BMD) changes over 5 years and also with incident falls over 2 years and long-term incident fractures in community-dwelling older men. A total of 1599 men (mean age 76.8 ± 5.4 years) from the Concord Health and Aging in Men Project (CHAMP) were assessed at baseline (2005-2007) and at 2- and 5-year follow-up. At each time point, hip and lumbar spine BMD were measured by dual-energy X-ray absorptiometry, and physical activity energy expenditure over the past week was self-reported via the Physical Activity Scale for the Elderly (PASE) questionnaire. Sum effective load ratings (ELRs) and peak force were estimated from the PASE questionnaire, reflecting the total and highest loading intensity and application rate of physical activities, respectively. Participants were contacted every 4 months over 2 years to self-report falls and over 6.0 ± 2.2 years for fractures. Hip fractures were ascertained by data linkage for 8.9 ± 3.6 years. Compared with sum ELR and PASE scores, peak force demonstrated the greatest standardized effect size for BMD maintenance at the spine (β = 9.77 mg/cm² ), total hip (β = 14.14 mg/cm² ), and femoral neck (β = 13.72 mg/cm² ) after adjustment for covariates, including PASE components (all p < .01). Only PASE scores were significantly associated with reduced falls risk (standardized incident rate ratio = 0.90, 95% confidence interval 0.81-1.00, p = .04). All physical activity measures were significantly associated with reduced incident fractures in univariate analyses, but none remained significant after multivariable adjustments. Older men who engaged in physical activity of high and rapid impact maintained higher BMD, while higher energy expenditure was associated with reduced falls risk. Coupling traditional physical activity data with bone loading estimates may improve understanding of the relationships between physical activity and bone health. © 2020 American Society for Bone and Mineral Research (ASBMR).

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.

The Radiology of Osteoporotic Vertebral Fractures Revisited

Until recently there has been little evidence available to validate any method by which to make an accurate diagnosis of an osteoporotic vertebral fractures (OVFs) from plain radiographs. In part this reflects a lack of a completely satisfactory "gold standard," but primarily it relates to the absence of well-designed prospective studies in this context. Historically, OVFs were recognized by evidence of macroscopic structural failure in vertebrae using the criteria applied elsewhere in the skeleton. This comprised altered alignment, fragmentation, cortical disruptions, and breaks, among other changes. However, these morphological criteria were replaced by vertebral morphometry, referring to the use of quantitative or quasi-quantitative measurement tools for fracture diagnosis. Vertebral morphometry emerged as an understanding of and treatment for osteoporosis evolved, mainly in response to the need for expeditious assessments of large numbers of spine images for epidemiological and pharmaceutical purposes. Although most of the descriptions of such morphometric tools have stressed that they were not to be applied to clinical diagnosis with respect to individual patients, this constraint has been widely disregarded. Here we review the major attempts to develop a diagnostic strategy for OVF and describe their characteristics in adults and children. Recent evidence suggests that morphometric (quantitative; ie, based on measurement of dimensions and shape description) criteria are inferior to morphologic (qualitative; ie, based on structural integrity) vertebral damage assessment in identifying people with low bone density and at an increased risk of future fracture. Thus there is now an evidentiary basis for suggesting that morphological assessment is the preferred strategy for use in diagnosing OVF from radiographs. © 2019 American Society for Bone and Mineral Research.

Bone mineral density and bone remodeling markers in chronic low back pain patients with active discopathy: A case-control exploratory study

OBJECTIVE

We aimed to compare bone mineral density (BMD) and bone remodeling markers in chronic low back pain (cLBP) patients with and without active discopathy (Modic 1 changes).

DESIGN

We conducted a single center case-control exploratory study. For 18 months, all patients referred to a tertiary care physical medicine and rehabilitation department in France were consecutively screened. Patients fulfilling the inclusion criteria were prospectively enrolled. Cases were defined as cLBP patients with lumbar active discopathy detected on MRI and controls as cLBP patients without active discopathy. Bone mineral density (BMD) at the spine, femoral neck and total femur was assessed by dual-energy X-ray absorptiometry, and bone remodeling markers were assessed in fasting serum samples. Overall, 37 cLBP patients (13 cases and 24 controls) fulfilled inclusion criteria and were included.

RESULTS

The median age was 42.0 years (Q1-Q3: 36.0-51.0) and mean (SD) LBP duration 72.3 (57.4) months. We found that BMD and levels of bone remodeling markers in cLBP patients did not differ with and without active discopathy.

CONCLUSION

Our results do not support the association between active discopathy and systemic bone fragility.

Effects of human parathyroid hormone 1-34 on bone loss and lumbar intervertebral disc degeneration in ovariectomized rats

PURPOSE

Lumbar intervertebral disc degeneration is a common cause of lower back pain that affects the physical and mental health of patients and increases social burden. Parathyroid hormone has been reported to be effective at inhibiting disc degeneration; however, these effects have not been fully established in vivo in ovariectomized (OVX) rats. Thus, in this study, we aimed to address this issue and examine the effects of parathyroid hormone treatment in OVX rats.

METHODS

Thirty female Sprague-Dawley rats, three months-old, were subjected to sham or ovariectomy surgery. Twelve weeks postsurgery, OVX rats were treated with either human parathyroid hormone [hPTH(1-34), 30 μg/kg/day] or vehicle (normal saline (NS)) treatment. The L3-6 spinal segments were harvested after 12 weeks treatment. Bone mineral density (BMD), micro-architectural parameters, and biomechanical assessment were measured at the lumbar vertebral bodies. Histology and immunohistochemistry were performed to analyze the characteristics of the lumbar intervertebral discs.

RESULTS

OVX + PTH rats had significantly higher BMD, percentage bone volume density, trabecular thickness, and biomechanical strength compared with those in Sham and OVX + NS rats. Histology and immunostaining revealed that disc degeneration was not significantly different between the OVX + NS rats and the OVX + PTH rats, compared with the Sham group; the structure of nucleus pulposus was disordered, the expression of collagen I was increased, and collagen II and aggrecan were decreased.

CONCLUSIONS

These findings confirmed that hPTH(1-34) treatment has substantial anabolic effects on bone mass and trabecular micro-architecture, while the excessively enhanced bone mass and strength were coupled with a non-significant effect on the disc degeneration in ovariectomized rats.

Orally administered simvastatin partially preserves lumbar vertebral bone mass but not integrity of intervertebral discs in ovariectomized rats

The present study aimed to investigate the effect of orally administered simvastatin on lumbar vertebral bone mass and intervertebral disc (IVD) degeneration in ovariectomized (OVX) rats. A total of 30 female Sprague-Dawley (SD) rats were subjected to either bilateral ovariectomy (n=20) or sham surgery (n=10). After 12 weeks, the OVX rats were orally administered either saline vehicle (OVX + V group; n=10), or 5 mg/kg/day simvastatin (OVX + SIM group; n=10). Following 12 weeks of treatment, necropsy was conducted and bone mineral density (BMD) was determined in the L5-6 vertebrae. Furthermore, the microstructure and biomechanical properties of the L3 vertebrae were detected by micro-computed tomography and compression testing, respectively. The L5-6 vertebrae were analyzed by measurement of IVD height, observation of histological changes by van Gieson staining, and evaluation of collagen-II (col-II), aggrecan (AGG) and collagen I (col-I) expression by immunohistochemical analysis. Rats in the OVX+V group had lower BMD, bone volume/trabecular volume ratio, maximum load and elastic modulus than the sham group. Rats in the OVX + SIM group had higher BMD and biomechanical strength values than the rats in the OVX+V group. Histological analysis showed that the OVX + V and OVX + SIM groups exhibited significantly higher disc degeneration scores and significantly lower IVD height than the sham group. Immunohistochemical analysis revealed lower expression levels of col-II and AGG, but higher levels of col-I in the annulus fibrosis and endplate in OVX+V rats compared with the sham group. The OVX + SIM group exhibited levels of col-II, AGG and col-I expression comparable with those of OVX+V rats, with the exception of an upregulation of col-II expression in the annulus fibrosis. These data demonstrate that simvastatin treatment partially prevented bone loss and the deterioration of biomechanical properties of lumbar vertebrae, but not the progression of IVD degeneration in OVX rats.

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.

Deletion of Opg Leads to Increased Neovascularization and Expression of Inflammatory Cytokines in the Lumbar Intervertebral Disc of Mice

STUDY DESIGN

Neovascularization and expression of inflammatory cytokines were examined in Osteoprotegerin (Opg) knockout (KO) mice that show intervertebral disc (IVD) degeneration.

OBJECTIVE

The aim of this study was to clarify the pathological changes in lumbar IVD degeneration in Opg KO mice.

SUMMARY OF BACKGROUND DATA

Osteoporosis is a controversial risk factor for IVD degeneration. Deletion of Opg resulted in IVD degeneration in mice. Neovascularization and inflammatory cytokines are key factors in IVD degeneration.

METHODS

Opg KO mice and their wild-type (WT) littermates were euthanized. Lumbar IVDs were harvested. Safranin O/Fast Green staining was performed to examine the pathological changes. Microcomputed tomographic (micro-CT) analysis was performed to determine the structural changes at the junction of lumbar IVD cartilage and vertebrae. Tartrate-resistant acid phosphatase (TRAP) staining was performed to evaluate osteoclast formation. Protein expression of vascular endothelial growth factor A (VEGF-A), CD31, VE-cadherin, CD 34, interleukin-1β (IL-1β), and tumor necrosis factors α (TNF-α) were analyzed by immunohistochemistry (IHC) assays. Gene expressions of IL-1β, IL-6, and TNF-α were analyzed by real-time polymerase chain reaction (RT-PCR).

RESULTS

In 12-week-old Opg KO mice, new bone was formed in the endplate cartilage of lumbar IVDs and this became more obvious in 24-week-old Opg KO mice. Three-dimensional (3D) μCT reconstruction analyses showed that the edges of the L4 and L5 vertebrae were rugged with bone marrow cavities in it. Protein expression of VEGF-A, CD31, VE-cadherin, and CD34 was increased in the endplate and growth plate of lumbar IVDs of Opg KO mice. Gene expression of IL-1β, IL-6, and TNF-α as well as protein expression of IL-1β and TNF-α were highly expressed in the lumbar IVDs of Opg KO mice.

CONCLUSION

Deletion of Opg leads to increased neovascularization and expression of inflammatory cytokines in the lumbar disc in Opg KO mice, which may play important roles in IVD degeneration.

LEVEL OF EVIDENCE

N/A.

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.

The Radiology of Osteoporotic Vertebral Fractures Redux

When a low-energy fracture occurs, then osteoporosis has progressed to the point of bony structural failure. Because vertebral fractures are the commonest type of osteoporotic fracture, the correct identification of them becomes important for diagnosis, risk estimation, and management. However, there are no uniformly agreed criteria for their diagnosis. The purpose of this review was to examine the diagnostic radiological strategies available and suggest a coherent approach to diagnosis. Diagnosis had come to focus on comparative changes in vertebral dimensions. However, it has become apparent that mild reductions in vertebral height are of uncertain implication. The importance of structural damage in diagnosis has become recognized in parallel. Relative reductions in vertebral height may not be a necessary nor sufficient criterion by which to diagnose a fracture.

Calcitonin suppresses intervertebral disk degeneration and preserves lumbar vertebral bone mineral density and bone strength in ovariectomized rats

We investigated the effect of calcitonin (CT) on lumbar intervertebral disk degeneration (LIDD) in rats with ovariectomy-induced osteopenia. CT protected ovariectomized rats from LIDD by, at least in part, modifying extracellular matrix metabolism of the disks and preserving the microarchitecture and biomechanical properties of adjacent vertebrae.

INTRODUCTION

The present study aimed to investigate the effect of CT on lumbar vertebral bone mineral density and intervertebral disk degeneration in ovariectomized (OVX) rats.

METHODS

We first subjected 50 3-month-old female rats to either OVX (n = 30) or sham (n = 20). Twelve weeks later, ten OVX and ten sham rats were necropsied. The remaining OVX rats began to receive either saline vehicle (OVX + V, n = 10), or salmon CT (OVX + CT, 16 IU/kg/2 days, n = 10). After 12 weeks of treatment, necropsy was conducted and bone mineral density was determined in L3-4 and L5-6 vertebrae. The microstructure and biomechanical properties of L3 vertebrae were detected by micro-computed tomography and compression test, respectively. L5-6 was also used to measure intervertebral disk height and observe intervertebral disk histological changes by Van Gieson staining and histological scores, as well as immunohistochemistry (IHC) analysis of matrix metalloprotease (MMP)-1, MMP-13, and collagen II expression.

RESULTS

At 12 weeks post-OVX, OVX rats had lower BV/TV and Tb.N and higher intervertebral disk histological score than sham rats. After 24 weeks, OVX + CT rats had higher BMD, BV/TV, Tb.N, and bone biomechanical strength values than OVX + V rats. Histological analysis showed OVX + CT rats had significantly lower disk degeneration scores than OVX + V rats. IHC analysis revealed CT treatment decreased expression of MMP-1 and MMP-13 and increased expression of collagen II compared with OVX + V rats.

CONCLUSIONS

Our data demonstrate that CT-treated OVX rats display less intervertebral disk degeneration and favorable changes in intervertebral disk metabolism, associated with higher trabecular bone mass, better trabecular microarchitecture, and better biomechanical strength when compared to vehicle-treated OVX rats.

Mapping trabecular disconnection "hotspots" in aged human spine and hip

Trabecular bone disconnection is an independent factor in age-related skeletal failure where real termini (ReTm; rare in youth) may cause weakness disproportionate to tissue loss, yet their structural contribution at vulnerable locations remains uncertain. ReTm (previously recorded at the iliac crest) were mapped in "normal" aged vertebral bodies (T11-L5 autopsy; 20 females, 10 males) and corresponding proximal femora (autopsy; 10 females). Results were compared with biomechanically failed femora from orthopaedic subjects aged >58 yr (osteoporosis OP, 10 females; osteoarthritis OA, 10 females). A novel direct 2D/3D histological method was applied to large, thick (300 μm) slices superficially silver-stained to separate ReTm (unstained) from apparent termini (planar artefacts, brown). Light microscope field co-ordinates enabled ReTm mapping and statistical testing relative to i) sex, ii) tissue sector and iii) slicing plane. In men ReTm populations were small and random while in women they were large and sector-specific. In vertebrae they clustered anterior/superior being rare posterior/inferior; in the femoral head they concentrated distal/superior and also near the fovea, being fewer distal/inferior. A distribution polarity was evident with 100% more ReTm observed transversely (i.e., on tensile-related cross struts) than longitudinally (i.e., on compression-related vertical struts). Their numbers rose in OP (BV/TV<14%, microCT) and in OA (BV/TV>14%), remaining polarised and sector-specific in OP only. Comparative experimentation by marrow elution of an OP animal model demonstrated "floating segments" as a possible outcome. Conclusions were supported statistically that trabecular disconnection "hotspots" at vulnerable locations are sex- and sector-specific, mainly transaxial, and subject to disease modulation.

The relationship between BPAQ-derived physical activity and bone density of middle-aged and older men

The bone-specific physical activity questionnaire (BPAQ) accounts for activities that affect bone but has not been used in studies with older adults. Relationships exist between the BPAQ-derived physical activity and bone density in healthy middle-aged and older men but not men with prostate cancer. Disease-related treatments detrimental to bone should be considered when administering the BPAQ.

INTRODUCTION

The bone-specific physical activity questionnaire (BPAQ) was developed to account for bone-specific loading. In this retrospective study, we examined the relationship between BPAQ-derived physical activity and bone mineral density (BMD) in middle-aged and older men with and without prostate cancer.

METHODS

Two groups, 36 healthy men and 69 men with prostate cancer receiving androgen suppression therapy (AST), completed the BPAQ and had whole body, total hip, femoral (FN) and lumbar spine BMD assessed by dual-energy X-ray absorptiometry.

RESULTS

Past (pBPAQ), current (cBPAQ) and total BPAQ (tBPAQ) scores for the healthy men were related to FN BMD (pBPAQ r = 0.36, p = 0.030; cBPAQ r s = 0.35, p = 0.034; tBPAQ r = 0.41, p = 0.014), and pBPAQ and tBPAQ were related to total hip (r s = 0.35, p = 0.035 and r s = 0.36, p = 0.029, respectively) and whole body BMD (r s = 0.44, p = 0.007 and r s = 0.45, p = 0.006, respectively). In men with prostate cancer, the BPAQ was not significantly associated with BMD. In stepwise regression analyses, body mass and tBPAQ predicted 30 % of the variance in total hip BMD (p = 0.003), cBPAQ predicted 14 % of the variance in FN BMD (p = 0.002), and body mass, age and tBPAQ predicted 47% of the variance in whole body BMD (p < 0.001) in healthy men. In men with prostate cancer, the BPAQ was not an independent predictor of BMD.

CONCLUSIONS

Although BPAQ-derived estimates of physical activity are related to bone status in healthy middle-aged and older men, the adverse effect of AST on bone appears to obscure this relationship in men with prostate cancer.