Osteoporosis and Endplate Damage Correlation Using a Combined Approach of Hounsfield Unit Values and Total Endplate Scores: A Retrospective Cross-Sectional Study

A modular cage may prevent endplate damage and improve spinal deformity correction

BACKGROUND

Anterior lumbar interbody fusion is performed to fuse pathological spinal segments, generally, with a monobloc cage inserted by impact forces. Recently developed three-part modular cages attempt to reduce the impact forces, minimize the damage to the endplates and allow more lordosis angle correction.

METHODS

Human lumbar motion segments (L2-3, L4-5) were used to simulate the implantation procedure of monobloc vs. modular stand-alone cages (n = 12). After preparing and embedding, a discectomy was performed followed by the two different types of cage implantation. Macroscopic images, microcomputed tomography scans and Artificial-Intelligence-based lordosis angle measurements were conducted and analyzed in the intact and implanted state and endplate damage was evaluated.

FINDINGS

The modular and monobloc group had similar impact on three defined damage classes both groups fell into the mid-damage class (29 %); the modular group fell to 13 % in the low-damage class while the monobloc one to 17 % in the high-damage class. Fragmentation appeared more in the monobloc group (71 %), while defects appeared equally. The modular implantation achieved a median lordosis of 21.3° versus 19.5° for the monobloc (P = 0.132) leading to 34 % higher increase for the modular procedure.

INTERPRETATION

Endplate damage occurs in both procedures but severe damage like bone fragmentation can be avoided with modular implantation. Bone fragmentation seems to affect and minimize the desired lordosis angle after cage implantation. This in vitro study underlines the need of new implantation procedures to achieve increased lordosis with anterior lumbar interbody fusion to restore the patients sagittal balance successfully.

Impact of Cage Placement on Vertebral Endplate Cyst Formation and Bone Union in Transforaminal Lumbar Interbody Fusion

Study DesignRetrospective cohort study.ObjectivesTo determine the ideal cage placement position in transforaminal lumbar interbody fusion (TLIF) surgery to prevent vertebral endplate cyst (VEC) formation and improve bone union rates.MethodsThis study retrospectively analyzed 69 patients who underwent TLIF, and 88 intervertebral levels were observed. Patients were categorized into peripheral, central, and mixed types based on the cage placement. The incidence of VEC formation and endplate injuries (EIs) were assessed using computed tomography 1 year postoperatively. Factors associated with VEC formation and non-union, including patient demographics, clinical data, cage placement, Hounsfield unit values, and intraoperative EIs, were analyzed.ResultsVECs occurred in 55.7% of surgical levels and were significantly associated with non-union (P < .001). Center-type cage placement was a strong predictor of VEC formation (P = .028, OR = 16.3, 95% confidence interval [CI]: 1.36-195.0), along with EIs (P = .003, OR = 5.86, 95% CI: 1.80-19.0). In contrast, pre-existing VECs appeared to have a protective effect (P = .046, OR = 0.272, 95% CI: 0.076-0.979).ConclusionsCage placement in the central region significantly increases the risk of VEC formation and non-union. Periphery-type placement may be preferable to reduce endplate damage and improve fusion outcomes. Preventing EIs and optimizing cage positioning are critical to minimize VEC formation. Further prospective studies are needed to refine surgical strategies and improve long-term outcomes following TLIF.

Correlation Between Osteoporosis and Endplate Damage in Degenerative Disc Disease Patients: A Study Based on Phantom-Less Quantitative Computed Tomography and Total Endplate Scores

BACKGROUND

Osteoporosis and degenerative disc disease (DDD) are prevalent in the elderly population. Damage to the vertebral endplate, which impairs nutrient supply to the disc, serves as both a significant initiator and a hallmark of DDD. This study was aimed to explore the association between osteoporosis and endplate damage.

METHODS

This retrospective study included 205 patients with DDD who were treated at Tianjin Hospital from January 2019 to May 2023. We collected data on age, sex, body mass index, phantom-less quantitative computed tomography (PL-QCT) values, and total endplate scores (TEPS). The average PL-QCT value of L1-L4 and TEPS were used to represent volumetric bone mineral density (BMD) and the degree of endplate damage, respectively. Based on the average PL-QCT value of L1 and L2, patients were divided into 3 groups: normal group (BMD > 120 mg/cm3), osteopenic group (80 mg/cm3 ≤ BMD ≤ 120 mg/cm3), and osteoporosis group (BMD < 80 mg/cm3). Multiple linear regression models were used to identify independent factors associated with endplate damage.

RESULTS

The overall TEPS (4.3 ± 1.3 vs. 5.0 ± 1.0 vs. 5.9 ± 1.5, P < 0.01) and segment (L1/2-L4/5) TEPS (P < 0.05) in each group showed significant difference (R = -0.5), increasing in order from normal group to osteoporosis group. A significant negative correlation was found between TEPS and PL-QCT values in overall and each segment (P < 0.001). The PL-QCT values and age (P < 0.05) were independent factors influencing endplate damage. There were significant differences in the average number of TEPS ≥7 segments per patient among the 3 groups, with 1.16, 0.41, and 0.2 segments/person from osteoporosis group to normal group.

CONCLUSIONS

Our study showed a significant positive correlation between osteoporosis and endplate damage. Attention is warranted for patients with osteopenia to prevent progression to osteoporosis, potentially leading to exacerbated DDD. The management of patients with both DDD and osteoporosis necessitates comprehensive treatment strategies that address both the BMD and endplate aspects of these conditions.

Single-cell RNA sequencing reveals the differentiation and regulation of endplate cells in human intervertebral disc degeneration

Low back pain (LBP) is largely attributed to intervertebral disc degeneration (IVDD), of which the endplate changes are an important component. However, the alterations in cell fate and properties within the endplates during degeneration remain unknown. Here, we firstly performed the single-cell RNA-sequencing analysis (scRNA-seq) of the cells focusing on degenerative human endplates. By unsupervised clustering of the 8,534 single-cell based on the gene expression, we identified nine distinct cell types. We employed Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, and the single-cell regulatory network inference and clustering (SCENIC) to determine the enriched pathways and transcriptional activities across seven chondrocyte subpopulations. Furthermore, two cell fates of chondrocyte differentiation were found by trajectory analysis, one was enriched in inflammation-related genes, and the other was related to extracellular matrix (ECM). Additionally, the intercellular interactions of macrophages (MA) and chondrocytes, T cells/natural killer cells (T/NK) and chondrocytes were examined by ligand-receptor pairs analysis, showing the important regulative function of FN1 from MA and CD74 from T/NK during endplate degeneration. Overall, our findings provide novel perspectives on the endplate degeneration at the single-cell level and a whole-transcriptome size.

Intervertebral Disk Degeneration and Bone Mineral Density: A Bidirectional Mendelian Randomization Study

This study aimed to investigate the causal relationship between bone mineral density (BMD) and intervertebral disk degeneration (IVDD) using a two-sample bidirectional Mendelian randomization analysis. Summary-level data from the Genome-Wide Association Study (GWAS) were used. Instrumental variables (IVs) for IVDD were selected from the large-scale Genome-Wide Association Study (GWAS) (20,001 cases and 164,682 controls). Bone mineral density (BMD) at five different sites (heel (n = 426,824), total body (TB) (n = 56,284), forearm (FA) (n = 8143), femoral neck (FN) (n = 32,735), and lumbar spine (LS) (n = 28,498)) was used as a phenotype for OP. Bidirectional causality between IVDD and BMD was assessed using inverse variance weighting (IVW) and other methods. Related sensitivity analyses were performed. Myopia was also analyzed as a negative control result to ensure the validity of IVs. Heel bone mineral density (heel BMD), total body bone mineral density (TB-BMD), femoral neck bone mineral density (FN-BMD), and lumbar spine bone mineral density (LS-BMD) have a direct causal relationship on intervertebral disk degeneration (IVDD) [heel BMD-related analysis: beta = 0.06, p = 0.03; TB-BMD-related analysis: beta = 0.18, p = 8.72E-08; FN-BMD-related analysis: beta = 0.15, p = 4.89E-03; LS-BMD-related analysis: beta = 0.16, p = 1.43E-04]. There was no evidence of a significant causal effect of IVDD on BMD. In conclusion, our study found a significant positive causal effect of lower BMD on IVDD, and we identified significant causal effects of heel, TB-, FN-, and LS-BMD on IVDD, but there was no evidence of a significant causal effect of IVDD on BMD.

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.

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.

CT-based analysis of sagittal and coronal lumbar endplate morphology: multivariate analysis of factors associated with endplate depth

PURPOSE

Lumbar endplate morphology varies in individuals; thus, custom-made implants are sometimes more useful than standardized implants. This study aimed to analyze endplate morphology and factors associated with endplate depth using computed tomography (CT) in a non-symptomatic population.

METHODS

In total, 118 lumbar CT images of non-symptomatic individuals without severe degenerative change (aged 20-79 years) were retrospectively reviewed. The following radiographic parameters were measured in each lumbar vertebral segment (T12-S1) to determine endplate depth: superior/inferior endplate depth in the midsagittal and midcoronal planes, disk angle, and height. The relationship between baseline demographics (age, sex, body mass index [BMI], Hounsfield unit of the L1 vertebral body, and pelvic incidence [PI]) and endplate depth was analyzed.

RESULTS

Toward the caudal level, the superior endplate depth increased, sagittal inferior depth decreased, and coronal inferior depth increased. Multivariate analysis revealed that endplate depth was significantly associated with age (p < 0.001), while inferior endplate depth was associated with PI (p = 0.01). Superior endplate depth was associated with female sex (sagittal: p = 0.005, coronal: p = 0.002). Endplate depth, except for the inferior coronal region, was associated with low BMI (sagittal superior: p = 0.005; coronal superior and sagittal inferior: p = 0.02).

CONCLUSION

Endplate depths tend to be larger toward the caudal level, particularly in the superior endplate. Surgeons should thoroughly evaluate the preoperative CT image because various endplate morphologies require attention to cage shape when performing lumbar interbody fusion, especially in patients who are older, are female, have low BMI, and have large PI.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Correlation between intervertebral disc degeneration and bone mineral density difference: a retrospective study of postmenopausal women using an eight-level MRI-based disc degeneration grading system

Purpose

To explore the correlation between intervertebral disc degeneration (IDD) and bone mineral density (BMD) difference between adjacent vertebrae.

Methods

A retrospective analysis of 114 postmenopausal women who were treated in our hospital from January 2021 to December 2021. The degree of lumbar(L)1–5 IDD was scored according to an 8-grade scoring system. The lumbar vertebrae BMD was detected, and the BMD difference was calculated. The subjects were grouped according to age and whether the disc was severe IDD. Data were collected for statistical analysis.

Results

The prevalence of osteoporosis in the 51–60-year-old group was lower than that in the other groups, while the prevalence of modic changes in the 71–80-year-old group was higher than that in the 51–70-year-old group (P < 0.05). At the L1/2 level, the prevalence of severe IDD in the 81-90y group was higher than that in the 51-70y group (P < 0.05). At the L2/3 level, the prevalence of severe IDD in the 71-90y group was higher than that in the 51-60y group, and the prevalence of severe IDD in the 71-80y group was higher than that in the 61-70y group (P < 0.05). The L2/3 disc score was positively correlated with the L3-L2 BMD difference (P < 0.05). At the level of L1-2, the BMD difference in the non-severe IDD group was smaller than that in the severe IDD group (P < 0.05).

Conclusion

For postmenopausal women, an increase in BMD difference is correlated with IDD. Osteoporosis is more common in people over 60 years old, and the possibility of modic change in 71-80y is higher than in other age groups. The incidence of severe IDD also increases with aging, especially for the L1/2 and L2/3 discs.