Disc degeneration contributes to the denser bone in the subendplate but not in the vertebral body in patients with lumbar spinal stenosis or disc herniation

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.

Using advanced imaging to measure bone density, compression fracture risk, and risk for construct failure after spine surgery

Low bone mineral density (BMD) can predispose to vertebral body compression fractures and postoperative instrumentation failure. DEXA is considered the gold standard for measurement of BMD, however it is not obtained for all spine surgery patients preoperatively. There is a growing body of evidence suggesting that more routinely acquired spine imaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI) can be opportunistically used to measure BMD. Here we review available studies that assess the validity of opportunistic screening with CT-derived Hounsfield Units (HU) and MRI-derived vertebral vone quality (VBQ) to measure BMD of the spine as well the utility of these measures in predicting postoperative outcomes. Additionally, we provide screening thresholds based on HU and VBQ for prediction of osteopenia/ osteoporosis and postoperative outcomes such as cage subsidence, screw loosening, proximal junctional kyphosis, and implant failure.

Bioenergetic dysfunction in the pathogenesis of intervertebral disc degeneration

Intervertebral disc (IVD) degeneration is a frequent cause of low back pain and is the most common cause of disability. Treatments for symptomatic IVD degeneration, including conservative treatments such as analgesics, physical therapy, anti-inflammatories and surgeries, are aimed at alleviating neurological symptoms. However, there are no effective treatments to prevent or delay IVD degeneration. Previous studies have identified risk factors for IVD degeneration such as aging, inflammation, genetic factors, mechanical overload, nutrient deprivation and smoking, but metabolic dysfunction has not been highlighted. IVDs are the largest avascular structures in the human body and determine the hypoxic and glycolytic features of nucleus pulposus (NP) cells. Accumulating evidence has demonstrated that intracellular metabolic dysfunction is associated with IVD degeneration, but a comprehensive review is lacking. Here, by reviewing the physiological features of IVDs, pathological processes and metabolic changes associated with IVD degeneration and the functions of metabolic genes in IVDs, we highlight that glycolytic pathway and intact mitochondrial function are essential for IVD homeostasis. In degenerated NPs, glycolysis and mitochondrial function are downregulated. Boosting glycolysis such as HIF1α overexpression protects against IVD degeneration. Moreover, the correlations between metabolic diseases such as diabetes, obesity and IVD degeneration and their underlying molecular mechanisms are discussed. Hyperglycemia in diabetic diseases leads to cell senescence, the senescence-associated phenotype (SASP), apoptosis and catabolism of extracellualr matrix in IVDs. Correcting the global metabolic disorders such as insulin or GLP-1 receptor agonist administration is beneficial for diabetes associated IVD degeneration. Overall, we summarized the recent progress of investigations on metabolic contributions to IVD degeneration and provide a new perspective that correcting metabolic dysfunction may be beneficial for treating IVD degeneration.

Efficacy of two opportunistic methods for screening osteoporosis in lumbar spine surgery patients

PURPOSE

Hounsfield unit (HU) measurements and vertebral bone quality (VBQ) scores are opportunistic screening methods for evaluating bone quality. Since studies comparing the efficacies of the two methods are rare, this retrospective study aimed to examine the efficacy of VBQ scores compared with that of HU measurements for diagnosing osteoporosis in lumbar spine surgery patients.

METHODS

We selected patients who had undergone spinal surgery between January 2020 and May 2022 from our database. The VBQ scores based on magnetic resonance imaging (MRI) and HU measurements based on computed tomography (CT) were calculated. Correlation analysis of the dual-energy X-ray absorptiometry (DEXA) T score and study parameters was performed. The Delong test and decision curve analysis (DCA) were used to compare the efficacies of the two methods.

RESULTS

We included 118 consecutive patients who underwent selective spinal surgery. The VBQ score and HU measurement were significantly correlated with the DEXA T score. Based on the Delong test, HU measurement predicted osteoporosis more effectively than the VBQ score did. The DCA revealed that the VBQ score performed better than the HU measurement did.

CONCLUSIONS

The calculation of VBQ scores is a novel opportunistic screening method for diagnosing osteoporosis; however, CT-based HU measurements outperform MRI-based VBQ scores. HU measurements can be used as a screening method when pre-operative CT scans are available.

Association between lumbar endplate damage and bone mineral density in patients with degenerative disc disease

BACKGROUND

To explore the independent association between lumbar endplate damage and bone mineral density (BMD) in patients with degenerative disc disease (DDD).

METHODS

This retrospective investigation was based out of a prospectively collected database from the Affiliated Kunshan Hospital of Jiangsu University. Data from 192 DDD patients, collected between December 2018 and January 2022, were chosen for the final analysis. The average total endplate score (TEPS) of lumbar(L) 1-L4 was assessed by magnetic resonance imaging (MRI), and represents the extent of endplate damage. Osteoporosis severity was assessed via the L1-L4 BMD evidenced by dual-energy x-ray absorptiometry (DXA). Other analyzed information included gender, age, body mass index (BMI), and osteophyte score (OSTS). Uni- and multivariate linear regression analyses were employed to evaluate the association between average TEPS and BMD of L1-L4. Moreover, the generalized additive model (GAM) was employed for non-linear association analysis.

RESULTS

Upon gender, age, BMI, and OSTS adjustments, a strong independent inverse relationship was observed between average TEPS and BMD (β, -0.021; 95% CI, -0.035 to -0.007, P-value = 0.00449). In addition, the gender stratification analysis revealed a linear relationship in males, and a non-linear relationship in females. Specifically, there was a significantly stronger negative relationship between average TEPS and BMD in females, when the average TEPS was < 3.75 (β, -0.063; 95% CI, -0.114 to -0.013; P-value = 0.0157). However, at an average TEPS > 3.75, the relationship did not reach significance (β, 0.007; 95% CI, -0.012 to 0.027; P-value = 0.4592).

CONCLUSIONS

This study demonstrated the independent negative association between average TEPS and BMD values of L1-L4. Upon gender stratification, a linear relationship was observed in males, and a non-linear association in females. The findings reveal that patients with osteoporosis or endplate damage require more detailed examinations and treatment regimen.

The Relationship Between Bone Mineral Density and Lumbar Disc Herniation in Postmenopausal Women

INTRODUCTION

In previous studies, the relationship between BMD (bone mineral density) and LDH (lumbar disc herniation) has been investigated in young people, except for postmenopausal women. The aim of this study was to evaluate this association in postmenopausal women.

METHODS

A cross-sectional analysis of 545 consecutive postmenopausal women was performed at a single center. The study included patients aged 45 to 85 with low back pain. Age, weight, height, L1-L4 BMD, L1-L4 T-score, L1-L4 Z-score, femoral neck BMD, femoral neck T-score, and femoral neck Z-score of patients were collected. MRI scans were assessed for the diagnosis of LDH. To explore the impact of the number of herniated segments, patients with LDH were further divided into single-level and multi-level LDH groups.

RESULTS

Five hundred and thirteen postmenopausal women were included in the final analysis. The mean age of the patients was 61.3±8.6 years in the LDH group and 58.4±7.8 years in the non-LDH group (p=0.001). The LDH group had higher lumbar (p<0.001) and femoral neck (p<0.05) BMD, T, and Z-scores than the non-LDH group. In binary logistic regression analysis, age, lumbar, and femoral neck BMD were significantly associated with LDH (p<0.001, p=0.03, and p=0.040, respectively). Patients with multi-level herniation had significantly higher rates of obesity (BMI ≥30) compared to patients with single-level herniation (58.0% vs. 47.0%; p=0.031). However, in terms of obesity rates, the LDH group and the non-LDH group were statistically similar (53.9% vs. 54.2%; p=0.961). There was no association between the single and multi-level herniation groups in terms of L1-4 and femoral neck BMD (p=0.760 and 0.435, respectively).

CONCLUSION

Higher lumbar bone mineral density and higher femoral neck bone mineral densities were found to be associated with lumber disc herniation in postmenopausal women with low back pain. These results suggest that bone mineral density assessment may be useful in clinical practice to determine which patients are at higher risk of lumbar disc herniation.

Multifunctional Drug-Loaded Phase-Change Nanoparticles Inhibit the Epithelial-Mesenchymal Transition of Hepatocellular Carcinoma by Affecting the Activity of Activated Hepatic Stellate Cells

Objectives. Preparation of a multifunctional drug-loaded phase-change nanoparticle (NP), pirfenidone perfluoropentane liposome NPs (PPL NPs), and combined with low-intensity focused ultrasound (LIFU) to influence epithelial mesenchymal transition (EMT) for hepatocellular carcinoma (HCC) by inhibiting the activity of activated Hepatic Stellate Cells (a-HSCs). Methods. PPL NPs were prepared by the thin film dispersion method. The appearance, particle size, zeta potential, encapsulation efficiency, drug loading rate, drug release in vitro, and stability of PPL NPs were tested. The role of a-HSCs in HCC metastasis was studied by CCK-8, colony formation assay, apoptosis, cellular uptake assay, wound healing assay, and Transwell assay. Western blot was used to detect the related protein expression levels. In vitro and vivo, the acoustic droplet vaporization (ADV) of PPL NPs was tested at different times and LIFU intensities. Biosafety of the PPL NPs was assessed by measuring nude mouse body weight and hematoxylin and eosin (H&E) staining. Results. The results showed that the PPL NPs had good biosafety, with an average particle size of 346.6 ± 62.21 nm and an average zeta potential of -15.23 mV. When the LIFU power is 2.4 W/cm2, it can improve the permeability of cells, further promote the uptake of drugs by cells, and improve the toxicity of drugs. In vitro experiments showed that PPL NPs could inhibit the proliferation of a-HSCs cells, thereby affecting the metastasis of HCC, and were related to the TGFβ-Smad2/3-Snail signaling pathway. Both in vivo and in vitro PPL NPs enhanced ultrasound imaging by LIFU-triggered ADV. Conclusion. The PPL NPs designed and prepared in this study combined with LIFU irradiation could significantly alter the EMT of HCC by inhibiting LX2. Clinically, PPL NPs will also be considered a promising contrast agent due to their ultrasound imaging capabilities.