Intervertebral disc decompression following endplate damage: implications for disc degeneration depend on spinal level and age

A nerve root decompression position identified by 3D CT scan: the modified reversed contralateral axial rotation position for patients with lumbar disc prolapse

BACKGROUND

Nerve root compression in the lumbar intervertebral foramen (LIVF) is a consistent feature of radicular syndrome. There is debate about movements and positions that may reduce compression for possible use in conservative treatment.

PURPOSE

To investigate real-time effects of specific 3 dimensional positioning of the trunk on the cross sectional area (CSA) of the LIVF in patients with lumbar disc prolapse and radiculopathy using 3D-CT scan imaging.

METHODS

Ninety males aged between 20 and 40 years with unilateral lumbar disc prolapse and radiculopathy were separated into three equal groups based on the level of disc prolapse. Group (A): L3/L4, group (B): L4/L5, and group (C): L5/S1. All underwent three separate imaging sessions; first in the supine position to establish baseline data (Baseline-Image 1), followed by a modified reversed contralateral axial rotation position (Image 2), and finally the same position as Image 2 but after 48 h of using the position as a therapeutic intervention (Image 3). The CSA of LIVF at L3/L4, L4/L5, and L5/S1 levels and the angles of straight leg raising (SLR) test were measured following each imaging session.

RESULTS

Two-way mixed MANOVA analysis revealed that the mean values of the CSA of LIVF and the angle of SLR test were significantly increased in Image 2 compared with Baseline-Image 1 across all tested groups (P = 0.001). Moreover, the measured outcome variables were significantly increased in Image 3 compared with Image 2 and Baseline-Image 1 across all tested groups (P = 0.001).

CONCLUSION

The modified reversed contralateral axial rotation position of the trunk had a real-time decompression effect on the impinged nerve roots in patients with unilateral lumbar disc prolapse and radiculopathy.

Vertebral Endplate Defects Induced Mechanical Alterations and Disc Calcification

Study DesignCross sectional comparative study.ObjectivesThe current study aims to explore the calcification potential (BMP2 expression) of intervertebral discs and its association with the presence of vertebral endplate defects visible on MRI.MethodsForty-seven herniated lumbar disc samples obtained from patients aged 20-76 (31 M/16F) undergoing surgery. Five-µm thin sections were stained with H&E in order to assign a histological degeneration score (HDS) from 0-15 on the basis of cell density (0-5), structural alterations (0-4), granular changes (0-3) and mucus degeneration (0-3). Sections were immuno-stained with anti BMP-2 antibodies to observe the calcification potential in these discs. In addition, pre-operativeT2-T1 W MRI images of the lumbar spine were analyzed for the presence and type (typical or atypical) of vertebral endplate defects, grade of disc degeneration (Pfirrmann grade I-V), presence of high intensity zones (HIZ), and Modic changes at the operated level.ResultsVertebral endplate defects, Modic changes & HIZ were observed in 81%, 29% and 21% of patients respectively. Mean HDS & BMP-2 expression was 9 ± 2 and mean 71 ± 36 spots/mm2 respectively. Discs with adjacent vertebral endplate defects showed increased cell density (P = .004), mucus degeneration (P = .002), HDS (P = .01) and BMP-2 expression (P = .01). Discs with HIZ also had increased HDS, but significance was seen with increased BMP2 expression (P = .006). HDS showed a positive correlation with BMP 2 expression (r = .30, P = .04).ConclusionThese findings suggest that the altered mechanical environment of discs is strongly associated with BMP-2 expression which is an important marker of intervertebral disc calcification.

Characterization of bone & cartilage endplate junction in the human lumbar spine: novel ultrastructural insights & association with elemental composition, vascularity and degeneration

OBJECTIVE

Intervertebral disc (IVD)-related pathology is associated with integrity of cartilaginous endplate (CEP), bony endplate (BEP) and their junction. However, ultrastructural details of the CEP, BEP and IVD and their interplay with disc degenerative features such as fissures and calcification are understudied. The current study aimed to ultra structurally explore CEP-BEP junction to IVD features.

METHODS

Fifty-nine lumbar motion segments from 13 male human cadavers (range, 21-80 years of age) were analyzed macroscopically, histologically and through scanning electron microscope. The fissures present in CEP & IVD and gaps at the junction of CEP-BEP & CEP-IVD were measured and correlated with calcification, vascular channels and disc degeneration. Energy-dispersive X-ray analysis (EDX) provided the elemental composition of the CEP, BEP and IVD.

RESULTS

Ultrastructural analysis revealed gaps at the CEP-BEP junction which were occasionally bridged by fine fibrillar adhesions. These junctional gap-width were in significant positive correlation with age (p = 0.001), spinal-level (p = 0.01), severity of disc degeneration (p < 0.001) and IVD calcification (p < 0.001). The vascular channels of BEP around the CEP were in significant positive correlation with age (p = 0.003), junctional gap-width (p < 0.001) & severity of disc degeneration (p < 0.001). EDX distribution of calcium in CEP was also associated significantly with junctional gap-width & vascularity (p = 0.03, p = 0.04, respectively).

CONCLUSION

This is the first study to ultrastructurally assess and map lumbar CEP, BEP and IVD in humans, noting discovery of specific phenotypic patterns of intradiscal calcification, fissures, vascularity and degeneration severity as associated with novel anatomical structures of "adhesion bridges and gaps" which are implicated in marked inflammation and pain.

Network Pharmacology and Experimental Validation to Elucidate the Pharmacological Mechanisms of Luteolin Against Chondrocyte Senescence

BACKGROUND

Luteolin, a flavonoid found in various medicinal plants, has shown promising antioxidant, anti-inflammatory, and anti-aging properties. The cartilaginous endplate (CEP) represents a crucial constituent of the intervertebral disc (IVD), assuming a pivotal responsibility in upholding both the structural and functional stability of the IVD.

OBJECTIVE

Exploring the precise mechanism underlying the protective effects of luteolin against senescence and degeneration of endplate chondrocytes (EPCs).

METHODS

Relevant targets associated with luteolin and aging were obtained from publicly available databases. To ascertain cellular functions and signaling pathways, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were employed. Core genes were identified through the construction of a protein-protein interaction (PPI) network. Molecular docking (MD) was utilized to assess the binding affinity of luteolin to these core genes. Finally, the impact of luteolin on the senescence and degeneration of EPCs was evaluated in an in vitro cellular senescence model induced by tert-butyl hydroperoxide (TBHP).

RESULTS

There are 145 overlapping targets between luteolin and senescence. Analysis using GO revealed that these targets primarily participate in cellular response to oxidative stress and reactive oxygen species. KEGG analysis demonstrated that these markers mainly associate with signaling pathways such as p53 and PI3K-Akt. MD simulations exhibited luteolin's binding affinity to P53, Cyclin-dependent kinase (CDK)2, and CDK4. Cell cycle, cell proliferation, and β- galactosidase assays confirmed that luteolin mitigated senescence in SW1353 cells. Western blot assays exhibited that luteolin significantly suppressed the expression of Matrix Metallopeptidase (MMP) 13, P53, and P21, while concurrently promoting CDK2, CDK4, and Collagen Type II Alpha 1 (COL2A1) expression.

CONCLUSION

In summary, luteolin demonstrated beneficial properties against aging and degeneration in EPCs, offering novel insights to mitigate the progression of intervertebral disc degeneration (IVDD).

Reference intervals of adjacent disc height in fresh osteoporotic vertebral compression fractures and the association with postoperative adjacent segment complications: a quantitative study in Chinese postmenopausal women

BACKGROUND

Preoperative adjacent disc height (DH) was found as an independent risk factor for adjacent segment degeneration (ASD) after percutaneous kyphoplasty (PKP), indicating the preoperative status of the adjacent intervertebral discs may be closely related to adjacent segment complications. To establish the reference intervals (RIs) for adjacent DH of fresh osteoporotic vertebral compression fracture (OVCF) in Chinese postmenopausal women, and investigate the association with adjacent segment complications after PKP.

METHODS

Consecutive inpatients diagnosed with fresh OVCF between November 2015 and August 2023 were reviewed. The enrolled patients were divided into subgroups based on injured vertebral level; then, the cranial and caudal DH were measured. The characteristics of DH among subgroups were identified, and specific RIs were established using the indirect Hoffmann method. The associations between DH and adjacent segment complications were assessed using multivariate analysis.

RESULTS

The DH of the cranial disc was significantly lower than the corresponding caudal disc in all vertebral levels, which showed an increasing trend from T11 to L4. The RIs of DH were as follows: T11 (cranial), 2.14-5.14 mm; T11 (caudal), 2.64-5.89 mm; T12 (cranial), 2.69-5.77 mm; T12 (caudal), 3.18-6.57 mm; L1 (cranial), 3.05-6.59 mm; L1 (caudal), 3.40-8.29 mm; L2 (cranial), 3.68-8.36 mm; L2 (caudal), 4.57-9.78 mm; L3 (cranial), 4.53-8.92 mm; L3 (caudal), 5.26-10.07 mm; L4 (cranial), 4.70-11.42 mm; and L4 (caudal), 5.52-12.12 mm. Increased risks of adjacent segment complications after PKP were observed in patients with decreased adjacent DH.

CONCLUSION

The estimated vertebral level and disc level-specific RIs for adjacent DH of fresh OVCF were established in the Chinese postmenopausal women population. A decrease in adjacent DH posed high risks of adjacent segment complications after PKP for treating OVCF.

Comprehensive analysis of damage evolution in human annulus fibrosus: Numerical exploration of mechanical sensitivity to biological age-dependent alteration

BACKGROUND AND OBJECTIVE

The annulus fibrosus is an essential part of the intervertebral disc, critical for its structural integrity. Mechanical deterioration in this component can lead to complete disc failure, particularly through tears development, with radial tears being the most common. These tears are often the result of both mechanical and biological factors. This study aims to numerically investigate the mechanisms of radial failure in the annulus tissue, taking into account the mechanical and age-dependent biological damage origins. A newly developed microstructure-based model was upgraded to predict damage evolution in the different annulus regions.

METHODS

The study employs a computational model to predict mechanical failures in various annulus regions, using experimental data for comparison. The model incorporates age-dependent microstructural changes to evaluate the effects of biological aging on the mechanical behavior. It specifically includes a detailed analysis of the temporal changes in circumferential rigidity and failure strain of the annulus.

RESULTS

The model demonstrated a strong ability to replicate the experimental responses of the different annulus regions to failure. It revealed that age-related microstructural changes significantly impact the rigidity and failure response of the annulus, particularly in the posterior regions and as well the anterior inner side. These changes increase susceptibility to rupture with aging. A correlation was also observed between the composition of collagen fibers, water content, and the annulus transversal response in both radial and axial directions.

CONCLUSION

The findings challenge previous assumptions, showing that age-dependent microstructural changes have a notable effect on the annulus mechanical properties. The computational model closely aligns with experimental observations, underscoring the determinant role of oriented collagen fibers in radial failure. This study enhances the understanding of annulus failure and provides a foundation for further research on the impact of aging on disc mechanical integrity and failure.

Osteopontin deficiency promotes cartilaginous endplate degeneration by enhancing the NF-κB signaling to recruit macrophages and activate the NLRP3 inflammasome

Intervertebral disc degeneration (IDD) is a major cause of discogenic pain, and is attributed to the dysfunction of nucleus pulposus, annulus fibrosus, and cartilaginous endplate (CEP). Osteopontin (OPN), a glycoprotein, is highly expressed in the CEP. However, little is known on how OPN regulates CEP homeostasis and degeneration, contributing to the pathogenesis of IDD. Here, we investigate the roles of OPN in CEP degeneration in a mouse IDD model induced by lumbar spine instability and its impact on the degeneration of endplate chondrocytes (EPCs) under pathological conditions. OPN is mainly expressed in the CEP and decreases with degeneration in mice and human patients with severe IDD. Conditional Spp1 knockout in EPCs of adult mice enhances age-related CEP degeneration and accelerates CEP remodeling during IDD. Mechanistically, OPN deficiency increases CCL2 and CCL5 production in EPCs to recruit macrophages and enhances the activation of NLRP3 inflammasome and NF-κB signaling by facilitating assembly of IRAK1-TRAF6 complex, deteriorating CEP degeneration in a spatiotemporal pattern. More importantly, pharmacological inhibition of the NF-κB/NLRP3 axis attenuates CEP degeneration in OPN-deficient IDD mice. Overall, this study highlights the importance of OPN in maintaining CEP and disc homeostasis, and proposes a promising therapeutic strategy for IDD by targeting the NF-κB/NLRP3 axis.

Detection and Characterization of Endplate Structural Defects on CT: A Diagnostic Accuracy Study

STUDY DESIGN

Diagnostic test study.

OBJECTIVE

To determine the reliability and validity or diagnostic accuracy of two previously described endplate structural defect (EPSD) assessment methods.

SUMMARY OF BACKGROUND DATA

Studies of EPSD may further the understanding of pathoanatomic mechanisms underlying back pain. However, clinical imaging methods used to document EPSD have not been validated, leaving uncertainty about what the observations represent.

MATERIALS AND METHODS

Using an evaluation manual, 418 endplates on CT sagittal slices obtained from 19 embalmed cadavers (9 men and 10 women, aged 62-91 yr) were independently assessed by two experienced radiologists and a novice for EPSD using the two methods. The corresponding micro-CT (µCT) from the harvested T7-S1 spines were assessed by another independent rater with excellent intra-rater reliability (k=0.96).

RESULTS

Inter-rater reliability was good for the presence (k=0.60-0.69) and fair for specific phenotypes (k=0.43-0.58) of EPSD. Erosion, for which the Brayda-Bruno classification lacked a category, was mainly (82.8%) classified as wavy/irregular, while many notched defects (n=15, 46.9%) and Schmorl's nodes (n=45, 79%) were recorded as focal defects using Feng's classification. When compared to µCT, endplate fractures (n=53) and corner defects (n=28) were routinely missed on CT. Endplates classified as wavy/irregular on CT corresponded to erosion (n=29, 21.2%), jagged defects (n=21, 15.3%), calcification (n=19, 13.9%), and other phenotypes on µCT. Some focal defects on CT represented endplate fractures (n=21, 27.6%) on µCT. Overall, with respect to the presence of an EPSD, there was a sensitivity of 70.9% and a specificity of 79.1% using Feng's method, and 79.5% and 57.5% using Brayda-Bruno's method. Poor to fair inter-rater reliability (k=0.26-0.47) was observed for defect dimensions.

CONCLUSION

There was good inter-rater reliability and evidence of criterion validity supporting assessments of EPSD presence using both methods. However, neither method contained all needed EPSD phenotypes for optimal sensitivity, and specific phenotypes were often misclassified.

CT-based surrogate parameters for MRI-based disc height and endplate degeneration in the lumbar spine

PURPOSE

This study investigated potential use of computed tomography (CT)-based parameters in the lumbar spine as a surrogate for magnetic resonance imaging (MRI)-based findings.

METHODS

In this retrospective study, all individuals, who had a lumbar spine CT scan and MRI between 2006 and 2012 were reviewed (n = 198). Disc height (DH) and endplate degeneration (ED) were evaluated between Th12/L1-L5/S1. Statistics consisted of Spearman correlation and univariate/multivariable regression (adjusting for age and gender).

RESULTS

The mean CT-DH increased kranio-caudally (8.04 millimeters (mm) at T12/L1, 9.17 mm at L1/2, 10.59 mm at L2/3, 11.34 mm at L3/4, 11.42 mm at L4/5 and 10.47 mm at L5/S1). MRI-ED was observed in 58 (29%) individuals. CT-DH and MRI-DH had strong to very strong correlations (rho 0.781-0.904, p < .001). MRI-DH showed higher absolute values than CT-DH (mean of 1.76 mm). There was a significant association between CT-DH and MRI-ED at L2/3 (p = .006), L3/4 (p = .002), L4/5 (p < .001) and L5/S1 (p < .001). A calculated cut-off point was set at 11 mm.

CONCLUSIONS

In the lumbar spine, there is a correlation between disc height on CT and MRI. This can be useful in trauma and emergency cases, where CT is readily available in the lack of an MRI. In addition, in the middle and lower part of the lumbar spine, loss of disc height on CT scans is associated with more pronounced endplate degeneration on MRIs. If the disc height on CT scans is lower than 11 mm, endplate degeneration on MRIs is likely more pronounced.

LEVEL AND DESIGN

Level III, a retrospective study.

The effect of structural changes on the low strain rate behaviour of the intervertebral disc

The annuus fibrosus (AF) and nucleus pulposus (NP) of the intervertebral disc (IVD) work in conjunction to dissipate spinal loads. In this study we have isolated the contribution of the NP to the overall response of the disc and investigated the effect of extreme structural changes to the disc on the mechanical behaviour. Linear stiffness, overall load range, hysteresis area and total energy were used to evaluate the impact of these changes on the spine and surrounding structures. Six porcine lumbar isolated disc specimens were tested in 6 DOFs with a 400 N compressive axial preload at low strain rates in three conditions: intact (IN), after total nucleotomy (NN) and after the injection of bone cement into the nuclear void (SN). The latter two conditions, NN and SN, were chosen to emulate the effect of extreme changes to the NP on disc behaviour. When comparing with intact specimens, significant changes were noted primarily in axial compression-extension, mediolateral bending and flexion-extension. NN and SN cases demonstrated significant increases in linear stiffness, overall load range and total energy for mediolateral bending and flexion-extension compared to the intact (IN) state. SN also demonstrated a significant increase in total energy for axial compression-extension, and significant decreases in the elastic contribution to total energy in all axes except flexion-extension. These changes to total energy indicate that surrounding spinal structures would incur additional loading to produce the same motion in vivo after structural changes to the disc.

Comparison of predictive value for cage subsidence between MRI-based endplate bone quality and vertebral bone quality scores following transforaminal lumbar interbody fusion: a retrospective propensity-matched study

BACKGROUND CONTEXT

Cage subsidence after lumbar fusion can lead to many adverse outcomes. Low bone mineral density (BMD) is a widely recognized risk factor for cage subsidence. Conventional methods can predict and evaluate BMD, but there are many shortcomings. Recently, MRI-based assessment of bone quality in specific parts of the vertebral body has been proposed, including scores for vertebral bone quality (VBQ) and endplate bone quality (EBQ). However, the predictive accuracy of the two scoring systems for cage subsidence after transforaminal lumbar interbody fusion (TLIF) remains unknown. Therefore, we investigated MRI-based VBQ and EBQ scores for assessing bone quality and compared their predictive value for cage subsidence after TLIF.

PURPOSE

To compare the predictive value between MRI-based VBQ and EBQ scores for cage subsidence after TLIF.

STUDY DESIGN/SETTING

A retrospective case-control study.

PATIENTS SAMPLE

Patients with degenerative lumbar diseases underwent single-level TLIF at our medical center between 2014 and 2020, all of whom had preoperative MRIs available.

OUTCOMES MEASURES

Cage subsidence, disc height, VBQ score, EBQ score, upper and lower vertebral body bone quality (UL-VBQ) score.

METHODS

Data were retrospectively examined for a consecutive sample of 346 patients who underwent TLIF at our medical center between 2014 and 2020. Patients who subsequently experienced cage subsidence or not were matched to each other based on propensity scoring, and the two matched groups (52 patients each) were compared using conditional logistic regression to investigate the association between the potential radiographic factors and cage subsidence. Scores for VBQ and EBQ were assessed for their ability to predict cage subsidence in the matched patients based on the area under the receiver operative characteristic curve (AUC).

RESULTS

Among matched patients, those who suffered cage subsidence had significantly higher VBQ score (3.7 vs 3.1, p<.001) and EBQ score (5.0 vs 4.3, p<.001), and regression linked greater risk of subsidence to higher VBQ score (OR 4.557, 95% CI 1.076-19.291, p=.039) and higher EBQ score (OR 5.396, 95% CI 1.158-25.146, p=.032). A cut-off VBQ score of 3.4 predicted the cage subsidence among matched patients with an AUC of 0.799, sensitivity of 84.6%, and specificity of 69.2%. A cut-off EBQ score of 4.7 predicted subsidence with an AUC of 0.829, sensitivity of 76.9%, and specificity of 82.7%.

CONCLUSION

Higher VBQ and EBQ scores are associated with a greater risk of cage subsidence following TLIF, and EBQ may perform better because of greater specificity.

MRI phenotypes of herniated discs associated with adjacent disc degeneration

Adjacent segment degeneration is commonly observed in patients after fusion surgery. Among the associated risk factors is the preoperative presence of adjacent disc degeneration (ADD). The risk factors and other spine phenotypes associated with preoperative ADD is critical to understand the pathological process and better prognosis postsurgery. Current study aims to assess and compare the magnetic resonance imaging (MRI) spinal phenotype of herniated level with and without ADD. Preoperative T2W sagittal lumbar MRI images of 155 lumbar disc herniated patients were analyzed for the presence of ADD (Pfirrmann grade III and above). The herniated disc level was assessed for the presence and absence of vertebral endplate (VEP) defects, Modic changes, and high intensity zone (HIZ). Mean age of patients was 38 ± 2 years, almost 62% were males. ADD was found in 57%, VEP defects were seen in 62% of the herniated level, 24.5% showed Modic changes, 3.8% showed spondylolishthesis, and 15.5% revealed HIZ. Age and other demographic factors did not have any significant effect on the presence of ADD, the patients with extruded and sequestered discs had more ADD (p = 0.02). VEP defects were significantly higher in levels with ADD (p = 0.02). Patients with ADD had significantly VEP defect scores (p = 0.01), Modic score (p = 0.002), HIZ score (0.02), and posterior bulge score (p < 0.001). Findings suggest that affected levels with VEP defects and severe grade of disc herniation have the greater likelihood of having ADD. Once developed this ADD may also affect the other spinal levels, and also can affect postoperative prognosis.

Disc degeneration is easily occurred at the same and adjacent cephalad level in cervical spine when Modic changes are present

OBJECTIVE

This research aimed to evaluate the influence of Modic changes (MCs) on disc degeneration at the same and adjacent cephalad levels in the cervical spine.

METHODS

This research retrospectively reviewed 1036 patients with neck pain, upper limb pain, or numbness who were treated at our out-patient clinic and underwent cervical MRI and cervical anteroposterior/lateral radiography from Jan, 2016 to Jan, 2021. MCs and disc degeneration parameters at same and nearby cephalad levels of MCs were evaluated. Discs were divided into the MCs, adjacent, and control groups, and the association between MCs and disc degeneration at the same and adjacent cephalad levels was investigated.

RESULTS

Of the 1036 patients whose MRI scans were reviewed, 986 met the inclusion criteria (503 women and 483 men; average age, 62.8 years; scope of 35-79 years). The prevalence of MCs in the cervical spine was 13.0% (128/986). Type I, II, III changes were observed in 38 (29.69%), 82 (64.06%), and 8 (6.25%) patients, respectively. MCs were most frequently identified at the C5-6 (59/986; 5.98%) and C6-7 (38/986; 3.85%) levels. Disc with MCs showed worse outcomes with regard to disc degeneration grade, anterior osteophyte formation than the adjacent and control groups (p < 0.05), whereas they were more severe in the adjacent group compared to normal group.

CONCLUSION

Our findings indicate that MCs increased disc degeneration at the same and nearby cephalad levels in cervical spine, and the severity of degeneration at the same segment was more serious than that at the cephalad level.

The association between vertebral endplate defects, subchondral bone marrow changes, and lumbar intervertebral disc degeneration: a retrospective, 3-year longitudinal study

PURPOSE

To investigate the influence of vertebral endplate defects and subchondral bone marrow changes on the development of lumbar intervertebral disc degeneration (DD).

METHODS

Patients > 18 y/o without any history of lumbar fusion who had repeat lumbar magnetic resonance imaging scans primarily for low back pain (LBP) performed at a minimum of 3 years apart at a single institution, and no spinal surgery in between scans were included. Total endplate score (TEPS), Modic changes (MC), and Pfirrmann grading (PFG) per lumbar disc level were assessed. DD was defined as PFG ≥ 4.

RESULTS

Three hundred and fifty-three patients (54.4% female) were included in the final analysis, comprising 1765 lumbar intervertebral discs. The patient population was 85.6% Caucasian with a median age of 60.1 years and a body mass index (BMI) of 25.8 kg/m2. A cutoff score of 5 was identified for the TEPS above which both the prevalence of DD and the odds of developing DD increased. The probability of developing DD did not differ significantly between lumbar disc levels (P = 0.419). In the multivariable analysis with adjustments for age, sex, race, body mass index (BMI), MC, TEPS cutoff > 5, and spinal level, only age (OR = 1.020; P = 0.002) was found to be an independent risk factor for developing intervertebral DD.

CONCLUSION

Our results suggest that TEPS does not unequivocally predict intervertebral DD in patients with LBP, since higher degrees of endplate defects might also develop secondarily to DD, and MC tend to occur late in the cascade of degeneration.

Spinal injury rates and specific causation in motor vehicle collisions

Motor vehicle collisions (MVCs) are a leading cause of acute spinal injuries. Chronic spinal pathologies are common in the population. Thus, determining the incidence of different types of spinal injuries due to MVCs and understanding biomechanical mechanism of these injuries is important for distinguishing acute injuries from chronic degenerative disease. This paper describes methods for determining causation of spinal pathologies from MVCs based on rates of injury and analysis of the biomechanics require to produce these injuries. Rates of spinal injuries in MVCs were determined using two distinct methodologies and interpreted using a focused review of salient biomechanical literature. One methodology used incidence data from the Nationwide Emergency Department Sample and exposure data from the Crash Report Sample System supplemented with a telephone survey to estimate total national exposure to MVC. The other used incidence and exposure data from the Crash Investigation Sampling System. Linking the clinical and biomechanical findings yielded several conclusions. First, spinal injuries caused by an MVC are relatively rare (511 injured occupants per 10,000 exposed to an MVC), which is consistent with the biomechanical forces required to generate injury. Second, spinal injury rates increase as impact severity increases, and fractures are more common in higher-severity exposures. Third, the rate of sprain/strain in the cervical spine is greater than in the lumbar spine. Fourth, spinal disc injuries are extremely rare in MVCs (0.01 occupants per 10,000 exposed) and typically occur with concomitant trauma, which is consistent with the biomechanical findings 1) that disc herniations are fatigue injuries caused by cyclic loading, 2) the disc is almost never the first structure to be injured in impact loading unless it is highly flexed and compressed, and 3) that most crashes involve predominantly tensile loading in the spine, which does not cause isolated disc herniations. These biomechanical findings illustrate that determining causation when an MVC occupant presents with disc pathology must be based on the specifics of that presentation and the crash circumstances and, more broadly, that any causation determination must be informed by competent biomechanical analysis.

Ultra-short echo time MR imaging in assessing cartilage endplate damage and relationship between its lesion and disc degeneration for chronic low back pain patients

OBJECTIVE

To investigate the feasibility of ultra-short echo time (UTE) magnetic resonance imaging (MRI) in the assessment of cartilage endplate (CEP) damage and further evaluate the relationship between total endplate score (TEPS) and lumbar intervertebral disc (IVD) degeneration for chronic low back pain patients.

MATERIALS AND METHODS

IVD were measured in 35 patients using UTE imaging at 3T MR. Subtracted UTE images between short and long TEs were obtained to depict anatomy of CEP. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated to assess the image quality quantitatively. A new grading criterion for endplate damage evaluation was developed based on Rajasekaran.S grading system in this study. Two radiologists were employed to evaluate CEP and bony vertebral endplates (VEP) using this new grading criterion and assess TEPS, independently. Cohen's kappa analysis was applied to evaluate the inter-observer agreement of endplate damage assessment between two radiologists, and the Kendall's TAU-B analysis was employed to determine the relationship between TEPS and IVD degeneration evaluated with Pfirrmann grading.

RESULTS

Well structural CEP was depicted on subtracted UTE images and confirmed by high SNR (33.06±2.92) and CNR values (9.4±2.08). Qualified subtracted UTE images were used by two radiologists to evaluate the degree of CEP and VEP damage. Excellent inter-observer agreement was confirmed by high value in Cohen's kappa test (0.839, P < 0.001). Ensured by this, 138 endplates from 69 IVDs of 35 patients were classified into six grades based on the new grading criterion and TEPS of each endplate was calculated. In addition, the degeneration degree of IVDs were classified into five grades. Finally, using Kendall's TAU-B analysis, significant relationship was obtained between endplate damage related TEPS and IVD degeneration (r = 0.864, P < 0.001).

CONCLUSION

Ensured by high image quality, UTE imaging might be considered an effective tool to assess CEP damage. Additionally, further calculated TEPS has shown strong positive association with IVD degeneration, suggesting that the severity of endplate damage is highly linked with the degree of IVD degeneration.

Comparison of the biomechanical effects of lumbar disc degeneration on normal patients and osteoporotic patients: A finite element analysis

BACKGROUND

Some older patients who suffered from both conditions (disc degeneration and osteoporosis) have higher surgical risks and longer postoperative recovery times. Understanding the relation between disc degeneration and osteoporosis is fundamental to know the mechanisms of orthopedic disorders and improve clinical treatment. However, there is a lack of finite element (FE) studies to predict the combined effects of disc degeneration and osteoporosis. So the aim of the present study is to explore the differences of biomechanical effects of lumbar disc degeneration on normal patients and osteoporotic patients.

METHODS

A normal lumbar spine finite element model (FEM) was developed based on the geometric information of a healthy male subject (age 35 years; height 178 cm; weight 65 kg). This normal lumbar spine FEM was modified to build three lumbar spine degeneration models simulating mild, moderate and severe grades of disc degeneration at the L4-L5 segment. Then the degenerative lumbar spine models for osteoporotic patients were constructed on the basis of the above-mentioned degeneration models. Firstly, the normal model (flexion: 8 Nm; extension: 6 Nm; lateral bending: 6 Nm; torsion: 4 Nm) and degenerative models (10 Nm) were calibrated under pure moment load, respectively. Secondly, under a 400 N follower load, the 7.5 Nm moments of different directions were applied on all models to simulate different motion postures. Finally, under the above loading conditions, we calculated and analyzed the range of motion (ROM), Mises stress in cortical (MSC1), Mises stress in endplate (MSE), Mises stress in cancellous (MSC2), and Mises stress in post (MSP).

RESULTS

Compared with disc degeneration patients without osteoporosis, the ROM, MSC1, and MSE of osteoporosis patients with various disc degeneration decreased in all postures, while the MSC2 and MSP increased. With increase in the degree of disc degeneration, the reduction proportions of ROM and MSE in osteoporotic patients gradually increased, while the reduction percentages in MSC1 of osteoporotic patients gradually decreased. The increase percentages of MSC2 in osteoporotic patients gradually increased. Given the progressive changes of disc degeneration, the changes in MSP in osteoporosis patients were uneven.

CONCLUSION

In summary, the effect of disc degeneration on flexibility in the two kinds of patients (osteoporosis and non-osteoporosis patients) was nearly same. By comparing the remaining biomechanical parameters (MSC1, MSE, MSC2, and MSP), we found that degenerated intervertebral discs caused changes in loading patterns of osteoporosis patients. Disc degeneration reduced the Mises stress in the cortical and endplate, which increased the Mises stress in the cancellous and post. That is to say, in order to cope with the changes in bone stresses caused by disc degeneration and osteoporosis, clinicians should be more careful in choosing the surgical option for osteoporotic patients with disc degeneration.

Targeting Ferroptosis Holds Potential for Intervertebral Disc Degeneration Therapy

Intervertebral disc degeneration (IVDD) is a common pathological condition responsible for lower back pain, which can significantly increase economic and social burdens. Although considerable efforts have been made to identify potential mechanisms of disc degeneration, the treatment of IVDD is not satisfactory. Ferroptosis, a recently reported form of regulated cell death (RCD), is characterized by iron-dependent lipid peroxidation and has been demonstrated to be responsible for a variety of degenerative diseases. Accumulating evidence suggests that ferroptosis is implicated in IVDD by decreasing viability and increasing extracellular matrix degradation of nucleus pulposus cells, annulus fibrosus cells, or endplate chondrocytes. In this review, we summarize the literature regarding ferroptosis of intervertebral disc cells and discuss its molecular pathways and biomarkers for treating IVDD. Importantly, ferroptosis is verified as a promising therapeutic target for IVDD.

[Biomechanical evaluation of effects of percutaneous cement discoplasty and percutaneous cement interbody fusion on spinal stability]

OBJECTIVE

To investigate the effects of percutaneous cement discoplasty (PCD) and percutaneous cement interbody fusion (PCIF) on spinal stability by in vitro biomechanical tests.

METHODS

Biomechanical test was divided into intact (INT) group, percutaneous lumbar discectomy (PLD) group, PCD group, and PCIF group. Six specimens of L _{4, 5} (including vertebral bodies and intervertebral discs) from fresh male cadavers were taken to prepare PLD, PCD, and PCIF specimens, respectively. Before treatment and after the above treatments, the MTS multi-degree-of-freedom simulation test system was used to conduct the biomechanical test. The intervertebral height of the specimen was measured before and after the axial loading of 300 N, and the difference was calculated. The range of motion (ROM) and stiffness of the spine in flexion, extension, left/right bending, and left/right rotation under a torque of 7.5 Nm were calculated.

RESULTS

After axial loading, the change of intervertebral height in PLD group was more significant than that in other three groups ( P<0.05). Compared with INT group, the ROM in all directions significantly increased and the stiffness significantly decreased in PLD group ( P<0.05). Compared with INT group, the ROM of flexion, extension, and left/right rotation in PCD group significantly increased and the stiffness significantly decreased ( P<0.05); compared with PLD group, the ROM of flexion, extension, and left/right bending in PCD group significantly decreased and the stiffness significantly increased ( P<0.05). Compared with INT group, ROM of left/right bending in PCIF group significantly decreased and stiffness significantly increased ( P<0.05); compared with PLD group, the ROM in all directions significantly decreased and the stiffness significantly increased ( P<0.05); compared with PCD group, the ROM of flexion, left/right bending, and left/right rotation significantly decreased and stiffness significantly increased ( P<0.05).

CONCLUSION

Both PCD and PCIF can provide good biomechanical stability. The former mainly affects the stiffness in flexion, extension, and bending, while the latter is more restrictive on lumbar ROM in all directions, especially in bending and rotation.

Similarity and difference between aging and puncture-induced intervertebral disc degeneration

The purpose of our study was to investigate the changes in micromorphology and mechanical properties of intervertebral discs degeneration induced by aging and puncture. Normal group (NG), 2 weeks post-puncture degeneration group (PDG) and aging degeneration group (ADG) each included 10 rats. Plain film, magnetic resonance imaging, and histological testing were utilized to assess intervertebral disc degeneration. Atomic force microscope was utilized to analyze the microstructure and elastic modulus of the intervertebral disc, while immunohistochemistry was employed to assess alterations in the cell matrix using collagen I, collagen II, matrix metalloproteinase-3 (MMP-3), and tumour necrosis factor-α (TNF-α). The results showed that the disc height ratio between PDG and ADG decreased. In the PDG and ADG group, histological scores both increased, the gray value of the T2 signal decreased, the proportion of MMP-3 and TNF-positive cells in intervertebral disc tissues was higher (p < 0.05) and the IOD values of COL-2 lower in intervertebral disc tissues (p < 0.05). The elastic modulus of PDG and ADG annulus fibers (AF) increased compared to the NG (p < 0.05); when compared to PDG, the elastic modulus of ADG AF decreased (p < 0.05). The elastic modulus of PDG and ADG collagen increased in the nucleus pulposus (NP, p < 0.05); ADG had a greater AF diameter than NG and PDG (p < 0.05). The results indicated that ADG fiber diameter thickens, and chronic inflammation indicators rise; PDG suffers from severe extracellular matrix loss. The degeneration of the ADG and PDG intervertebral discs is different. The results provide foundation for clinical research.

Traumatic vertebra and endplate fractures promote adjacent disc degeneration: evidence from a clinical MR follow-up study

OBJECTIVES

The integrity of endplate is important for maintaining the health of adjacent disc and trabeculae. Yet, pathological impacts of traumatic vertebra and endplate fractures were less studied using clinical approaches. This study aims to investigate their effects on the development of adjacent disc degeneration, segmental kyphosis, Modic changes (MCs), and high-intensity zones (HIZs).

MATERIALS AND METHODS

Magnetic resonance (MR) images of patients with acute traumatic vertebral compression fractures (T11-L5) were studied. On MR images, endplate fractures were evaluated as present or absent. Disc signal, height, bulging area, sagittal Cobb angle, MCs, and HIZs were measured on baseline and follow-up MR images to study the changes of the disc in relation to vertebra fractures and endplate fractures.

RESULTS

Ninety-seven patients were followed up for 15.4 ± 14.0 months. There were 123 fractured vertebrae, including 79 (64.2%) with endplate fractures and 44 (35.8%) without. Both the adjacent and control discs decreased in signal and height over time (p < 0.001), and the disc adjacent to vertebral fractures had greater signal and height loss than the control disc (p < 0.05). In the presence of endplate fractures, the adjacent discs had greater signal decrease in follow-up (p < 0.05), as compared to those without endplate fractures. Sagittal Cobb angle significantly increased in segments with endplate fractures (p < 0.05). Vertebra fractures were associated with new occurrence of MCs in the fractured vertebra (p < 0.001) but not HIZs in the adjacent disc.

CONCLUSIONS

Traumatic vertebral fractures were associated with accelerated adjacent disc degeneration, which appears to be further promoted by concomitant endplate fractures. Endplate fractures were associated with progression of segmental kyphosis.

Measuring the thickness of vertebral endplate and shell using digital tomosynthesis

The vertebral endplate and cortical shell play an important structural role and contribute to the overall strength of the vertebral body, are at highest risk of initial failure, and are involved in degenerative disease of the spine. The ability to accurately measure the thickness of these structures is therefore important, even if difficult due to relatively low resolution clinical imaging. We posit that digital tomosynthesis (DTS) may be a suitable imaging modality for measurement of endplate and cortical shell thickness owing to the ability to reconstruct multiplanar images with good spatial resolution at low radiation dose. In this study, for 25 cadaveric L1 vertebrae, average and standard deviation of endplate and cortical shell thickness were measured using images from DTS and microcomputed tomography (μCT). For endplate thickness measurements, significant correlations between DTS and μCT were found for all variables when comparing thicknesses measured in both the overall endplate volume (R² = 0.25-0.54) and when measurements were limited to a central range of coronal or sagittal slices (R² = 0.24-0.62). When compared to reference values from the overall shell volume, DTS thickness measurements were generally nonsignificant. However, when measurement of cortical shell thickness was limited to a range of central slices, DTS outcomes were significantly correlated with reference values for both sagittal and coronal central regions (R² = 0.21-0.49). DTS may therefore offer a means for measurement of endplate thickness and, within a limited sagittal or coronal measurement volume, for measurement of cortical shell thickness.

Correlation of Modic Changes with Sagittal Lumbopelvic Parameters

Purpose

The main aim of this retrospective study was to analyze lumbopelvic sagittal parameters among the three different types of Modic changes (MCs). Furthermore, correlations between the sizes of MCs and the number of involved lumbar levels with lumbopelvic parameters are investigated.

Methods

A total of 263 adult subjects with MCs at a single institution from September 2015 to October 2020 who underwent lumbar x-ray examinations and magnetic resonance imaging were included in this retrospective study. Types of MCs, sizes of MCs, lumbar levels involved by MCs as well as lumbopelvic sagittal parameters from each subject were evaluated by two authors.

Results

Lumbar lordosis (LL), sacral slope (SS), and pelvic incidence (PI) in subjects with MC grade 1 were significantly smaller than in those with MC grade 2 and grade 3 (p<0.05). Lumbopelvic sagittal parameters decreased significantly as the sizes aggravated (p<0.01). Triple lumbar levels with MCs showed a significant increase in PI-LL (p<0.05) and decrease in LL (p<0.01), SS (p<0.01), and PI (p<0.01) when compared to MCs at single and double lumbar levels.

Conclusion

MC grade 1, severe MCs, and lumbar multi-segmental MCs were significantly linked to lumbar sagittal imbalance.

PREVALENCE AND CHARACTERISTICS OF UPPER LUMBAR DISC HERNIATIONS IN OUR PRACTICE: A RETROSPECTIVE ANALYSIS

ABSTRACT Introduction: Upper lumbar disc herniations (ULDH) are considered infrequent injuries (1-11%). They present, most often in older adults, with special clinical features that make diagnosis and therapeutic decision-making difficult. The prevalence, location, and management of these herniations and the medical history of our patients were analyzed. Methods: Sex, age, injury level, previous surgery, and patient treatment data from July 2018 to May 2021 were collected retrospectively. During this period, 179 patients underwent surgery, 33 of whom patients presented ULDH. Results: Thirty-three patients were included in the study (18 male and 15 female). Ages ranged from 39 to 85 years, with a predominance of elderly patients. The levels operated were L1-L2 in seven patients, L2-L3 in ten patients, L3-L4 in fourteen patients, and surgery in two levels (L2-L3, L3-L4) in two patients. In our practice, microdiscectomy is the preferred approach and was performed in all cases, with the addition of fusion in four of the 33 patients. Finally, a history of low lumbar disc herniation (LLDH) surgery was found in 16 patients. Conclusions: In our population, ULDHs are a rare entity with lower prevalence at the higher lumbar levels. They occur more frequently in elderly patients and clinical presentation can vary, which is a challenge for surgeons. In older adults, the development of lumbar kyphosis due to vertebral wedging is considered a risk factor for the development of ULDH. Surgical management by microdiscectomy is considered a technique with good results for this pathology. Level of Evidence III; Retrospective, longitudinal, descriptive, observational study.

Hounsfield Unit for Assessing Bone Mineral Density Distribution Within Cervical Vertebrae and Its Correlation With the Intervertebral Disc Degeneration

STUDY DESIGN

Retrospective radiological analysis.

OBJECTIVE

To assess bone mineral mass distribution within cervical vertebrae based on Hounsfield unit (HU) measurement, and explore its correlation with intervertebral disc degeneration.

METHOD

Three hundred and twenty-four patients with degenerative cervical spine disease were retrospectively reviewed and divided into six groups according to age. HU measurement of the whole vertebrae from C3 through C7 was obtained, then HU measurement within upper and lower part of the vertebrae on sagittal plane were obtained from C3 through C7. Disc degeneration on MRI was graded from I to V using the Pfirrmann classification.

RESULTS

There was a significant difference in the HU value from C3 to C7 among Group II to Group VI, the HU value presented consistently decreasing trend from young patients to old patients. In C6 and C7 vertebrae, there were significant differences in HU values between upper and lower parts of the vertebrae. More importantly. In all groups, HU values were highest in the upper part of the C4 vertebrae and then gradually decreased towards C3 and C7. HU value of both upper and lower vertebrae presented decreasing trend along with the aggravation of the disc degeneration.

CONCLUSION

HU values are not typically consistent throughout all levels of the cervical spine and the distribution within the vertebrae is not homogeneous. Decreased vertebral BMD and vertebral osteoporosis may trigger or exacerbate the adjacent intervertebral disc degeneration.

Diagnostic Role of Magnetic Resonance Imaging in Low Back Pain Caused by Vertebral Endplate Degeneration

Low back pain (LBP) is a common health issue worldwide with a huge economic burden on healthcare systems. In the United States alone, the cost is estimated to be $100 billion each year. Intervertebral disc degeneration is considered one of the primary causes of LBP. Moreover, the critical role of the vertebral endplates in disc degeneration and LBP is becoming apparent. Endplate abnormalities are closely correlated with disc degeneration and pain in the lumbar spine. Imaging modalities such as plain film radiography, computed tomography, and fluoroscopy are helpful but not very effective in detecting the causes behind LBP. Magnetic resonance imaging (MRI) can be used to acquire high-quality three-dimensional images of the lumbar spine without using ionizing radiation. Therefore, it is increasingly being used to diagnose spinal disorders. However, according to the American College of Radiology, current referral and justification guidelines for MRI are not sufficiently clear to guide clinical practice. This review aimed to evaluate the role of MRI in diagnosing LBP by considering the correlative contributions of vertebral endplates. The findings of the review indicate that MRI allows for fine evaluations of endplate morphology, endplate defects, diffusion and perfusion properties of the endplate, and Modic changes. Changes in these characteristics of the endplate were found to be closely correlated with disc degeneration and LBP. The collective evidence from the literature suggests that MRI may be the imaging modality of choice for patients suffering from LBP. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 3.

Comorbidities associated with cervical spine degenerative disc disease

Determining important links between medical comorbidities and cervical spine degenerative disc disease (DDD) will help elucidate pathomechanisms of disc degeneration. Electronic medical records and magnetic resonance imaging were retrospectively reviewed to evaluate 799 patients assessed for cervical spine pathology. Bivariate analysis identified older age, diabetes, ASA class, cancer, COPD, depression, hypertension, hypothyroidism, Medicare status, peripheral vascular disease, history of previous cervical spine surgery, smoking, and lower median household income as having strong associations with increased cumulative grade of cervical spine DDD. This study provides evidence suggesting aging and accumulation of medical comorbidities influence severity of cervical spine DDD.

TELD with limited foraminoplasty has potential biomechanical advantages over TELD with large annuloplasty: an in-silico study

Background

Facetectomy, an important procedure in the in–out and out–in techniques of transforaminal endoscopic lumbar discectomy (TELD), is related to the deterioration of the postoperative biomechanical environment and poor prognosis. Facetectomy may be avoided in TELD with large annuloplasty, but iatrogenic injury of the annulus and a high grade of nucleotomy have been reported as risk factors influencing poor prognosis. These risk factors may be alleviated in TELD with limited foraminoplasty, and the grade of facetectomy in this surgery can be reduced by using an endoscopic dynamic drill.

Methods

An intact lumbo-sacral finite element (FE) model and the corresponding model with adjacent segment degeneration were constructed and validated to evaluate the risk of biomechanical deterioration and related postoperative complications of TELD with large annuloplasty and TELD with limited foraminoplasty. Changes in various biomechanical indicators were then computed to evaluate the risk of postoperative complications in the surgical segment.

Results

Compared with the intact FE models, the model of TELD with limited foraminoplasty demonstrated slight biomechanical deterioration, whereas the model of TELD with large annuloplasty revealed obvious biomechanical deterioration. Degenerative changes in adjacent segments magnified, rather than altered, the overall trends of biomechanical change.

Conclusions

TELD with limited foraminoplasty presents potential biomechanical advantages over TELD with large annuloplasty. Iatrogenic injury of the annulus and a high grade of nucleotomy are risk factors for postoperative biomechanical deterioration and complications of the surgical segment.

The Results of Using a Transforaminal Lumbar Interbody Fusion Cage at the Upper Lumbar Level

Aim

The aim of this study is to apply surgical treatments to upper lumbar disc hernias in order to provide lumbar stability and lumbar lordosis using a transforaminal lumbar interbody fusion (TLIF) cage and to preserve the success rate of surgical results by protecting neural structures without excessive subject tension.

Material and methods

Between 2012 and 2017, 32 patients who had undergone an operation for upper lumbar disc herniation and who had received a transforaminal lumbar interbody fusion cage using a posterior technique were evaluated retrospectively.

Results

The radiological and clinical findings, surgical methods, and results of the patients were evaluated. In our study, 25 (78.1%) of the patients with upper lumbar disc hernias who were evaluated retrospectively were female and seven (21.9%) were male. Their average age was 55.43 years. The average follow-up was 21.75 months. The most common complaints were lower back pain, leg pain, and claudication. In the findings from neurological examinations, a positive result on the femoral stretching test occurred in 30 (93.7%) patients. In the degenerative spinal structure of patients at the L1-2 and L2-3 levels, a transforaminal lumbar interbody fusion was performed via a wide laminectomy with posterior stabilization due to a wide-bottomed disc hernia and stenosis. Only one of the patients with a neurological deficit still had a motor deficit after surgery.

Conclusion

While planning a surgery for upper lumbar disc hernias, the anatomical features of this region and the patients' radiological and neurological findings should be carefully evaluated. If TLIF is performed during upper lumbar region surgery, it may be preferable to perform it using a posterior technique.

The Influence of Axial Compression on the Cellular and Mechanical Function of Spinal Tissues; Emphasis on the Nucleus Pulposus and Annulus Fibrosus: A Review

In light of the correlation between chronic back pain and intervertebral disc (IVD) degeneration, this literature review seeks to illustrate the importance of the hydraulic response across the nucleus pulposus (NP)-annulus fibrosus (AF) interface, by synthesizing current information regarding injurious biomechanics of the spine, stemming from axial compression. Damage to vertebrae, endplates (EPs), the NP, and the AF, can all arise from axial compression, depending on the segment's posture, the manner in which it is loaded, and the physiological state of tissue. Therefore, this movement pattern was selected to illustrate the importance of the bracing effect of a pressurized NP on the AF, and how injuries interrupting support to the AF may contribute to IVD degeneration.

Reduce the fractured central endplate in thoracolumbar fractures using percutaneous pedicle screws and instrumentational maneuvers: Technical strategy and radiological outcomes

INTRODUCTION

Traumatic thoracolumbar burst fracture is a common condition without a clear consensus on the best treatment approach. Percutaneous pedicle screw fixation (PPSF) techniques are widely used in practice, while its ability to correct fracture deformity is relatively weak, especially for the central area of the endplate. In this study, we reported a novel technique to reduce the fractured central endplate in thoracolumbar burst fractures.

METHODS

The new reduction technique uses six percutaneous pedicle screws for the fractured vertebra and its adjacent vertebrae. Pedicle screws implanted in the two adjacent vertebrae were parallel to the superior vertebral endplate, as routinely required. Two monoaxial pedicle screws implanted in the fractured vertebra were placed toward the anteroinferior portion of the fractured vertebral body. After routine instrumentation and ligamentotaxis reduction, the bolt heads of the four screws implanted in the adjacent vertebrae were first tightened, and then the bolt heads of the screws implanted in the fractured vertebra were gradually tighten to elevate the collapsed endplate. A fundamental principle of this technique is to implant the pedicle screw in the fractured vertebra towards the anteroinferior portion of the vertebra in such a way that the angle between the pedicle screw and the rod is oblique on lateral fluoroscopy. As such, when the bolt heads were tightened, the pedicle screws can be swung up to reduce the endplate fragments.

RESULTS

The novel technique was performed in 24 patients with neurologically intact thoracolumbar AO type A3 fractures. The middle vertebral height ratio was significantly improved from 69.7%±7.6% after routine reduction to 85.1%±4.5% postoperatively (p<0.01). No complication was noticed for this new reduction technique. At 6-month follow-up, no significant correction loss of the middle and posterior vertebral height ratios, Cobb angle, and vertebral wedge angle was observed, while 5.8% of correction loss was observed for the anterior vertebral height ratio.

CONCLUSION

The described reduction technique is simple, safe, and effective in reducing the collapsed central endplate in thoracolumbar burst fractures. Such a practical reduction strategy does not need additional medical costs.

Association Between Vertebral Dimensions and Lumbar Modic Changes

STUDY DESIGN

Population-based birth cohort study.

OBJECTIVE

The aim of this study was to evaluate the relationship between vertebral dimensions and lumbar MC.

SUMMARY OF BACKGROUND DATA

Low back pain (LBP) has become the leading cause of disability worldwide. Modic changes (MC) of the lumbar spine are one potential LBP-associated etiological factor. Mechanical stress is considered to play a key role in the development of MC through damage to endplates. There is speculation that vertebral dimensions play a role in some degenerative changes in the spine. Previous studies have also shown a positive association between moderate-to-vigorous physical activity (MVPA) and both vertebral dimensions and MC. In this study, we aimed to evaluate the relationship between vertebral dimensions and MC.

METHODS

The study population consisted of 1221 participants from the Northern Finland Birth Cohort 1966 who underwent lumbar magnetic resonance imaging (MRI) and physical activity measurements at the age of 46-48. The presence of Type 1 (MC1) and Type 2 (MC2) MC and the height, axial cross-sectional area (CSA), and volume of the L4 vertebra were determined from MRI scans. MVPA (≥3.5 metabolic equivalents) was measured by a wrist-worn accelerometer. We analyzed the association between lumbar MC and vertebral height, CSA, and volume using logistic regression models before and after adjustment for sex, height, weight, smoking, education level, and MVPA.

RESULTS

Vertebral height was positively associated with the presence of MC2 (odds ratio [OR] 3.51; 95% confidence interval [CI] 1.43-8.65), whereas vertebral CSA was not associated with the presence of lumbar MC. Vertebral volume was positively associated with the presence of any MC (OR 1.04; 95% CI 1.00-1.07), but the association did not persist when analyzing MC1 and MC2 separately.

CONCLUSION

Vertebral height was associated with the presence of MC2. Further studies are needed to clarify the role of vertebral dimensions as independent risk factors for MC.Level of Evidence: 3.

Chlorogenic Acid retards cartilaginous endplate degeneration and ameliorates intervertebral disc degeneration via suppressing NF-κB signaling

AIMS

Intervertebral Disc Degeneration (IDD) is a key factor involved in low back pain (LBP) which affects approximately 540 million individuals worldwide. Chlorogenic Acid (CGA), a natural compound, exerts anti-inflammatory property in several diseases. Here, we aim to investigate the biological effect of CGA on IDD and explore the underlying mechanism.

MATERIALS AND METHODS

Lumbar spine instability (LSI) model in mice was utilized to mimic process of IDD. The effects of CGA in response to LSI were evaluated by luminescent imaging, micro-CT, histomorphology, and immunohistochemistry in vivo. Besides, the cytotoxicity of CGA on chondrocytes was detected by cell counting kit-8 (CCK-8) and the biological effects were assessed by polymerase chain reaction (PCR) in vitro.

KEY FINDINGS

We found that CGA treatment dramatically suppressed the NF-κB activity in LSI mice. Moreover, administration of CGA mitigated cartilaginous endplate degeneration and postponed IDD development accompanying a decrease of inflammatory and catabolic mediators. Specifically, CGA ameliorated endplate degeneration might be related to its protective effects against endplate chondrocytes apoptosis and trans-differentiation. We further elucidated that CGA exerted these biological effects mainly by repressing NF-κB signaling in cartilage endplate.

SIGNIFICANCE

Our study has illustrated, for the first time, the curative effects as well as the latent mechanism of CGA in IDD and our results suggested that CGA administration might be used as an alternative therapy for IDD.

Influence of crack length and anatomical location on the fracture toughness of annulus fibrosus

Fracture toughness (J_c) of a soft biological tissue is an important mechanical property that characterizes its resistance to crack or tear extension. To date, no information is available on fracture toughness of annulus fibrosus (AF); therefore, its defect tolerance is not known. The present study modified a previously introduced method to determine J_c of ovine AF. Then, the effect of the notch length on the failure pattern and J_c was investigated. Also, the test samples of anterior and lateral regions were collected to determine the effect of the location on J_c. Results showed that for a notch length of less than 45% of total width, no crack extension occurred, but for a notch length above 45% of the width, crack propagation and ultimately the failure of the AF were observed. However, statistical analysis indicated no significant difference on J_c (p = 0.5) for the initial notch length of 50% and 70% of total width. The fracture toughness was significantly higher for the samples extracted from the lateral site than those from the anterior site (p < 0.05). Dissimilar failure patterns were observed for different initial notch lengths. Among the parameters studied, the defect tolerance of AF was dependent on the initial tear size.

Association between non-traumatic vertebral fractures and adjacent discs degeneration: a cross-sectional study and literature review

Background

Previous clinical studies reported that thoracolumbar vertebral fractures (VFs) associated with high energy spine trauma cause adjacent intervertebral disc (IVD) degeneration; however, the effect of non-traumatic VFs on the progression of adjacent disc degeneration remains to be determined. The purpose of this study was to examine the association between non-traumatic VFs and degenerative changes of adjacent IVDs.

Methods

Ninety-eight consecutive patients undergoing spinal surgery were included in this study. VFs were semi-quantitatively evaluated by lateral lumbar radiography. Five hundred eighty-eight vertebral bodies (from T12 to L5) and 486 discs (from T12/L1 to L4/L5) were analyzed. The degree of IVD degeneration was evaluated by magnetic resonance imaging (MRI) and classified into two groups according to Pfirrmann’s classification. Grades I, II and III were defined as the early stage of IVD degeneration and Grades IV and V as the advanced stage. Intradiscal vacuum phenomena (VPs) were evaluated by computed tomography. Adjacent IVDs were categorized according to the locations of VFs (superior, inferior, and bilateral). Associations between the presence of VFs and the extent of IVD degeneration or the presence of VPs were statistically analyzed.

Results

IVDs adjacent to VFs were identified in 115 IVDs (31.1% of total; superior: 11.4%, bilateral: 8.6%, inferior: 11.1%). The presence of VFs was significantly associated with MRI grades of adjacent IVD degeneration (P < 0.01) and the prevalence of VPs within adjacent IVDs (P < 0.01). From logistic regression analysis, age, disc level, and VFs were independent related factors for disc degeneration (P < 0.05).

Conclusion

This study showed that VFs were an independent related factor for adjacent disc degeneration and occurrence of intradiscal VPs. VFs may affect the micro-environment of adjacent IVDs, leading to disc degeneration and disc rupture.

Degeneration alters structure-function relationships at multiple length-scales and across interfaces in human intervertebral discs

Intervertebral disc (IVD) degeneration and associated back pain place a significant burden on the population. IVD degeneration is a progressive cascade of cellular, compositional, and structural changes, which results in a loss of disc height, disorganization of extracellular matrix architecture, tears in the annulus fibrosus which may involve herniation of the nucleus pulposus, and remodeling of the bony and cartilaginous endplates (CEP). These changes to the IVD often occur concomitantly, across the entire motion segment from the disc subcomponents to the CEP and vertebral bone, making it difficult to determine the causal initiating factor of degeneration. Furthermore, assessments of the subcomponents of the IVD have been largely qualitative, with most studies focusing on a single attribute, rather than multiple adjacent IVD substructures. The objective of this study was to perform a multiscale and multimodal analysis of human lumbar motion segments across various length scales and degrees of degeneration. We performed multiple assays on every sample and identified several correlations between structural and functional measurements of disc subcomponents. Our results demonstrate that with increasing Pfirrmann grade there is a reduction in disc height and nucleus pulposus T2 relaxation time, in addition to alterations in motion segment macromechanical function, disc matrix composition and cellular morphology. At the cartilage endplate-vertebral bone interface, substantial remodeling was observed coinciding with alterations in micromechanical properties. Finally, we report significant relationships between vertebral bone and nucleus pulposus metrics, as well as between micromechanical properties of the endplate and whole motion segment biomechanical parameters, indicating the importance of studying IVD degeneration as a whole organ.

Cervical spinal instability causes vertebral microarchitecture change and vertebral endplate lesion in rats

Background

The vertebral endplate (VEP) was damaged after spinal instability induced by cervical muscle section (CMS). Whether CMS induces bone formation and mechanical loading change in the vertebra is still obscure. This study was aimed to explore mechanical loading change and endplate damage after CMS.

Methods

Forty-eight rats were randomly divided into the CMS group and the sham group. The C6/7 segments were harvested at 4, 8, and 12 weeks after surgery. The microarchitectures of the C6 vertebra ​and the vertebral endplate lesions and intervertebral disc height of C6/7 were measured by micro-computed tomography. Micro-finite element analysis was used to evaluate biomechanical properties of the C6 vertebra. Bone remodelling of the C6 vertebra ​and the endplate ​sclerosis and intervertebral disc degeneration of C6/7 were evaluated by histological and immunohistochemical analyses.

Results

CMS significantly induced bone formation of the C6 ventral vertebra ​and increased the biomechanical properties of mainly the ventral side at 4 weeks, which was gradually rebalanced throughout the rest of the study. CMS also significantly increased protein expression of transforming growth factor-β1 (TGF-β1) and phosphorylated small mothers against decapentaplegic (pSmad)2/3 ​at 4 weeks. Moreover, tartrate-resistant acid phosphatase staining showed that osteoclast-positive cells were slightly in number decreased at 4 weeks, but were obviously increased at 8 weeks. The VEP of the ventral side was abraded earlier followed by calcification in situ later after CMS, consistent with the biomechanical enhancements observed. The degree of endplate degeneration was aggravated with time. Finally, CMS decreased intervertebral disc height and increased disc degeneration scores with time.

Conclusions

Spinal instability induced by CMS increases bone mass and biomechanical loading of the ventral side of vertebra in the early stage, which might initiate VEP damage and cause intervertebral disc degeneration.

The translational potential of this article

Our study indicates that vertebral trabecular changes may involve in intervertebral disc degeneration induced by spinal instability. This may help to elucidate the mechanisms by which disc degeneration occur.

METTL3 promotes IL-1β-induced degeneration of endplate chondrocytes by driving m6A-dependent maturation of miR-126-5p

METTL3 is an important regulatory molecule in the process of RNA biosynthesis. It mainly regulates mRNA translation, alternative splicing and microRNA maturation by mediating m6A‐dependent methylation. Interleukin 1β (IL‐1β) is an important inducer of cartilage degeneration that can induce an inflammatory cascade reaction in chondrocytes and inhibit the normal biological function of cells. However, it is unclear whether IL‐1β is related to METTL3 expression or plays a regulatory role in endplate cartilage degeneration. In this study, we found that the expression level of METTL3 and methylation level of m6A in human endplate cartilage with different degrees of degeneration were significantly different, indicating that the methylation modification of m6A mediated by METTL3 was closely related to the degeneration of human endplate cartilage. Next, through a series of functional experiments, we found that miR‐126‐5p can play a significant role in IL‐1β–induced degeneration of endplate chondrocytes. Moreover, we found that miR‐126‐5p can inhibit the PI3K/Akt signalling pathway by targeting PIK3R2 gene, leading to the disorder of cell vitality and functional metabolism. To further determine whether METTL3 could regulate miR‐126‐5p maturation, we first confirmed that METTL3 can bind the key protein underlying pri‐miRNA processing, DGCR8. Additionally, when METTL3 expression was inhibited, the miR‐126‐5p maturation process was blocked. Therefore, we hypothesized that METTL3 can promote cleavage of pri‐miR‐126‐5p and form mature miR‐126‐5p by combining with DGCR8.

Transforaminal endoscopic decompression and uninstrumented allograft lumbar interbody fusion: A feasibility study in patients with end-stage vacuum degenerative disc disease

OBJECTIVE

The authors investigated the feasibility of a transforaminal endoscopic decompression and un-instrumented lumbar interbody fusion procedures with cancellous bone allograft in patients painful with end-stage degenerative vacuum disc disease.

PATIENTS & METHODS

Twenty-nine patients who underwent endoscopic transforaminal foraminal and lateral recess decompression and direct intraoperative endoscopic visualization of a painful, hollow collapsed, rigid intervertebral disc space were grafted with cancellous allograft chips. In addition to the radiographic assessment of fusion, patients were followed for a minimum of 2 years postoperatively, and clinical outcomes were evaluated with VAS, ODI, and modified MacNab criteria.

RESULTS

At the final follow, mean VAS and ODI scores reduced from 7.34 ± 1.63 and 50.03 ± 10.64 preoperatively to 1.62 ± 1.741 and 6.69 ± 4.294 postoperatively (p < 0.0001). Excellent and Good clinical outcomes, according to Macnab criteria, were obtained in 34.5 % and 62.1 % of patients, respectively. Only one patient had minimal improvement from "Poor" preoperatively to "Fair" postoperatively. This female patient was treated for lumbar disc herniation L5/S1 and had an incomplete fusion at the final follow up. Computed tomography assessment of interbody fusion at the last follow-up showed successful fusion in 91.4 % of patients.

CONCLUSIONS

Un-instrumented interbody fusion by packing a hollow interspace with cancellous bone allograft chips can be considered as an adjunct to endoscopic foraminal and lateral recess decompression in select patients with validated painful, collapsed, and rigid motion segments. It can be safely done in an outpatient setting at a low burden to patients.

Curcumin prevents tension-induced endplate cartilage degeneration by enhancing autophagy

AIMS

Intermittent cyclic tension stimulation(ICMT) was shown to promote degeneration of endplate chondrocytes and induce autophagy. However, enhancing autophagy can alleviate degeneration partly. Studies have shown that curcumin can induce autophagy and protect chondrocytes, we speculated that regulation of autophagy by curcumin might be an effective method to improve the stress resistance of endplate cartilage. In this study, human cervical endplate cartilage specimens were collected, and expression of autophagy markers was detected and compared.

MAIN METHODS

Human cervical endplate chondrocytes were cultured to establish a tension-induced degeneration model, for which changes of functional metabolism and autophagy levels were detected under different tension loading conditions. Changes in functional metabolism of endplate chondrocytes were observed under high-intensity tension loading in the presence of inhibitors, inducers, and curcumin to regulate the autophagy level of cells. In addition, a rat model of lumbar instability was established to observe the degeneration of lumbar disc after curcumin administration.

KEY FINDINGS

Through a series of experiments, we found that low-intensity tension stimulation can maintain a stable phenotype of endplate chondrocytes, but high-intensity tension stimulation has a negative effect. Moreover, with increasing tension intensity, the degree of degeneration of endplate chondrocytes was gradually aggravated and the level of autophagy increased. Besides, curcumin upregulated autophagy, inhibited apoptosis, and reduced phenotype loss of endplate chondrocytes induced by high-intensity tension loading, thereby relieving intervertebral disc degeneration induced by mechanical imbalance.

SIGNIFICANCE

Curcumin mediated autophagy and enhanced the adaptability of endplate chondrocytes to high-intensity tension load, thereby relieving intervertebral disc degeneration.

Vertebral endplate defects: nomenclature, classification and measurement methods: a scoping review

PURPOSE

To summarize the scope of nomenclature and measurement methods used to document endplate defects in the health sciences literature.

METHODS

The scoping review followed the York framework and was reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews. The databases of PubMed, Scopus, Embase and CINAHL were searched using key terms. Screening and selection were conducted by two independent reviewers. A standardized, pilot-tested form was used for extracting data, which were analyzed descriptively.

RESULTS

The review included 211 studies, originating from 29 countries, with the USA (18.8%) and China (12.26%) as leading contributors. Thirty-four different terms for structural endplate defects were reported, but were never defined in most studies (65%). Of the 34 different terms used, some appeared to represent the same phenomenon, while the same terms were occasionally defined differently between studies. Schmorl's nodes were most commonly investigated (n = 99 studies) and defined similarly across studies, with the main difference relating to whether the indentation (node) was required to have a sclerotic margin. There were also similarities in definitions for endplate sclerosis. However, there was great variability in the definitions of other terms, such as lesions, irregularities, abnormalities, erosions and changes.

CONCLUSION

With the possible exception of Schmorl's nodes, we lack a common language for effectively communicating structural endplate findings. This review provides a foundation and impetus for standardizing terminology and core measures to improve communication and synthesis of the growing body of endplate research to advance related knowledge. These slides can be retrieved under Electronic Supplementary Material (paragraph). Then process the ppt slide as graphical image.

Stem Cell Senescence: the Obstacle of the Treatment of Degenerative Disk Disease

Intervertebral disc (IVD) has a pivotal role in the maintenance of flexible motion. IVD degeneration is one of the primary causes of low back pain and disability, which seriously influences patients' health, and increases the family and social economic burden. Recently, stem cell therapy has been proven to be more effective on IVD degeneration disease. However, stem cell senescence is the limiting factor in the IVD degeneration treatment. Senescent stem cells have a negative effect on the self-repair on IVD degeneration. In this review, we delineate that the factors such as telomerase shortening, DNA damage, oxidative stress, microenvironment and exosomes will induce stem cell aging. Recent studies tried to delay the aging of stem cells by regulating the expression of aging-related genes and proteins, changing the activity of telomerase, improving the survival microenvironment of stem cells and drug treatment. Understanding the mechanism of stem cell aging and exploring new approaches to delay or reverse stem cell aging asks for research on the repair of the degenerated disc.

Mechanics and Biology Interact in Intervertebral Disc Degeneration: A Novel Composite Mouse Model

The aim of this study was to distinguish the characteristics of intervertebral disc degeneration (IVDD) originating from mechanics imbalance, biology disruption, and their communion, and to develop a composite IVDD model by ovariectomy combined with lumbar facetectomy for mimicking elderly IVDD with osteoporosis and lumbar spinal instability. Mice were randomly divided into four groups and subjected to sham surgery (CON), ovariectomy (OVX), facetectomy (mechanical instability, INS) or their combination (COM), respectively. Radiographical (n = 4) and histological changes (n = 8) of L4/5 spinal segments were analyzed. Tartrate-resistant acid phosphatase (TRAP) staining was conducted to detect osteoclasts, and expression of osterix (OSX), type I collagen (Col I), type II collagen (Col II) and vascular endothelial growth factor (VEGF) were evaluated by immunochemistry. OVX affected the body's metabolism but INS did not, as the body weight increased and uterus weight decreased in OVX and COM mice compared to CON and INS mice. OVX, INS, and COM caused IVDD in various degrees at 12 weeks after surgery. However, the major pathogeneses of OVX- and INS-induced IVDD were different, which focused on endplate (EP) remodeling and annulus fibrosus (AF) collapse, respectively. OVX induced osteopenia of vertebra. In contrast, INS promoted the stress-adaptive increase of subchondral bone trabeculae. The COM produced a reproducible severe IVDD model with characteristics of sparse vertebral trabeculae, cartilaginous EP ossification, subchondral bone sclerosis, fibrous matrix disorder, angiogenesis, disc stiffness, as well as space fusion. Additionally, all groups had elevated bone and cartilage turnover compared with CON group, as the quantity of trap + osteoclasts and the osteogenic OSX expression increased in these groups. Likewise, the VEGF expression levels were similar, accompanied by the altered matrix expression of disc, including the changed distribution and contents of Col II and Col I. The findings suggested that the composite mouse model to some extent could effectively mimic the interactions of biology and mechanics engaged in the onset and natural course of IVDD, which would be more compatible with the IVDD of elderly with vertebral osteoporosis and spinal instability and benefit to further clarify the complicated mechanobiological environment of elderly IVDD progression.

Current perspectives on the role of biomechanical loading and genetics in development of disc degeneration and low back pain; a narrative review

Degenerative changes in the disc have long been of interest; they are thought to be strongly associated with low back pain and caused by inappropriate loading or through injury. However, independent of the magnitude of occupational spinal loading, twin studies find that the heritability of lumbar disc degeneration is 34-74%. This finding has led to intensive searches for susceptibility genes; some genes associated with disc degeneration have been identified, though all with small effects on the degenerative process. The complex nature of degenerative changes suggests that many different genes are involved, and that interactions with environmental factors are influential in progression of degeneration. Low back pain itself also appears heritable (30-46%). The most important clinical question though, is not how discs degenerate but is disc degeneration related to low back pain. Imaging studies find many people with degenerate discs or even with discs showing pathological features such as herniations, are asymptomatic. However results are obscured by the lack of consistent definitions of the phenotypes of disc degeneration and of low back pain. Epidemiological studies could help disentangle these complex relationships, but they will only be successful once consistent classifications and phenotypes of both disc degeneration and low back pain are developed.

Patients with Modic type 2 change have a severe radiographic representation in the process of lumbar degeneration: a retrospective imaging study

Background

There are few studies to investigate changes in imaging parameters of Modic changes (MCs). The imaging studies examining the distinctions in the lumbar sagittal parameters between MCs and lumbar disc degeneration (LDD) are still lacking. The purpose of this study was to identify the differences in the lumbar sagittal parameters among patients for LDD with/without Modic type 2 change (MII).

Methods

A total of 208 patients with lumbar degenerative disease from January 2017 to August 2018 volunteered for this study. Sixty-two patients with MII were used as the MC group. The other 146 patients served as the disc degeneration (DD) group. The DD scores and sagittal parameters were measured on magnetic resonance imaging (MRI) and X-ray by using Surgimap software.

Results

The prevalence of MII for patients with degenerative lumbar diseases in this study was 29.81%, primarily located at L5/S1. There were significant differences in lumbar lordosis (LL) and sacral slope (SS) between these two groups (P < 0.05). Similarly, the significant decrease in intervertebral height index (IHI) was found at L3-S1 in the MC group, compared with the DD group (P < 0.05). However, a significant difference in intervertebral angle (IVA) was observed only at L5/S1 (P < 0.05). The MC group had the smaller endplate concave angle (ECA) than the DD group from L3 caudal endplate to S1 cranial endplate (P < 0.05).

Conclusions

MII has a severe radiographic representation in the process of lumbar degeneration than patients without MII, and the overconcentration of load caused by the smaller LL, SS, and IVA may be a reasonable explanation to answer why MCs are more common at the L5/S1.

Associations Between Intervertebral Disc Degeneration Grading Schemes and Measures of Disc Function

Disc degeneration is a major cause of spinal dysfunction and pain, but grading schemes concentrate on tissue changes rather than altered function. The aim of this study was to compare disc degeneration grading systems with each other, and with biomechanical measures of disc function. Sixty-six motion segments (T8-9 to L5-S1) were dissected from cadavers aged 48-98 years. Disc function was assessed by measuring nucleus pressure (IDP) and maximum stresses in the annulus under 1 kN of compression. Detailed "scores" of disc degeneration were based on independent radiographic, macroscopic, and microscopic evaluations. For each evaluation, scores were used to assign a degeneration "grade" (I-IV), and functional measures were then correlated with degeneration scores and grades. Results showed that all measures were reliable (intraclass correlation coefficients: 0.82-0.99). Macroscopic and microscopic assessments were highly correlated with each other (r: 0.57-0.89, p < 0.001) but only weakly correlated with radiographic features. The overall macroscopic and microscopic scores of degeneration increased significantly with age and at lower spinal levels, although the influence of age was less marked in the case of the microscopic scores. IDP decreased with age and at lower spinal levels, but annulus stresses were more variable. Importantly, IDP and annulus stresses decreased consistently with all measures of disc degeneration, and these associations remained strong after controlling for age, gender, and spinal level. We conclude that radiographic and tissue-based assessments of disc degeneration are consistent with each other, and are more closely related to mechanical (dys)function than to age or spinal level. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1946-1955, 2019.

Wedge-shaped vertebrae is a risk factor for symptomatic upper lumbar disc herniation

Background

At present, much is unknown about the etiology and pathogenesis of ULDH. However, it is interesting to note that many ULDH patients have a radiographic feature of adjacent vertebral wedge deformation. The purpose of this study is to investigate the relationship between symptomatic upper lumbar disc herniation (ULDH) and wedge-shaped vertebrae (WSV).

Methods

This was a retrospective study of 65 patients with single-level ULDH, who had undergone surgery at our medical center between January 2012 and December 2016. Clinical data including clinical and radiological evaluation results were performed.

Results

The incidence of WSV in the ULDH group (44.6%, 29/65) was more than in the lower lumbar disc herniation group (21.5%, 14/65). And there were statistically significant differences in WSV (χ² = 7.819, P = 0.005), wedging angle of the vertebrae (WAV) (t = 9.013, P < 0.001), and thoracolumbar kyphotic angle (TL) (t = 8.618, P < 0.001) between two groups. Based on multivariate logistic regression analysis, WAV (OR = 0.783, 95% CI = 0.687–0.893, P < 0.001) and TL (OR = 0.831, 95% CI = 0.746–0.925, P = 0.001) were independently associated with ULDH. The cutoff values of WAV and TL were 5.35° and 8.35°, which were significantly associated with ULDH (OR = 3.667, 95% CI = 1.588–8.466, P = 0.002).

Conclusion

The WSV is an independent risk factor for ULDH. WAV > 5.35° and TL > 8.35° were the predictors for ULDH. It should be noted that the patients with vertebral wedge deformation combined with thoracolumbar kyphosis have a higher risk of ULDH.

Mechanical Function of the Nucleus Pulposus of the Intervertebral Disc Under High Rates of Loading

STUDY DESIGN

Bovine motion segments were used to investigate the high-rate compression response of intervertebral discs (IVD) before and after depressurising the nucleus pulposus (NP) by drilling a hole through the cranial endplate into it.

OBJECTIVE

To investigate the effect of depressurising the NP on the force-displacement response, and the energy absorption in IVDs when compressed at high strain rates.

SUMMARY OF BACKGROUND DATA

The mechanical function of the gelatinous NP located in the center of the IVDs of the spine is unclear. Removal of the NP has been shown to affect the direction of bulge of the inner anulus fibrosus (AF), but at low loading rates removal of the NP pressure does not affect the IVD's stiffness. During sports or injurious events, IVDs are commonly exposed to high loading rates, however, no studies have investigated the mechanical function of the NP at these rates.

METHODS

Eight bovine motion segments were used to quantify the change in pressure caused by a hole drilled through the cranial endplate into the NP, and eight segments were used to investigate the high-rate response before and after a hole was drilled into the NP.

RESULTS

The hole caused a 28.5% drop in the NP pressure. No statistically significant difference was seen in peak force, peak displacement, or energy-absorption of the intact, and depressurized NP groups under impact loading. The IVDs absorbed 72% of the input energy, and there was no rate dependency in the percentage energy absorbed.

CONCLUSION

These results demonstrate that the NP pressure does not affect the transfer of load through, or energy absorbed by, the IVD at high loading rates and the AF, rather than the NP, may play the most important role in transferring load, and absorbing energy at these rates. This should be considered when attempting surgically to restore IVD function.

LEVEL OF EVIDENCE

N/A.

Multidimensional vertebral endplate defects are associated with disc degeneration, modic changes, facet joint abnormalities, and pain

The aim of the current study was to investigate the multi-dimensional characteristics of lumbar endplate defects in humans in relation to disc degeneration and other MRI phenotypes as well as their role with pain and disability. A total of 108 subjects were recruited and underwent 3T MRI of the lumbar spine. Structural endplate defects were identified and their dimensions were measured in terms of maximum width and depth, and were then standardized to the actual width of the endplate and depth of the vertebral body, respectively. Both width and depth of all endplate defects in each subject were added separately and scores were assigned on the basis of size from 1 to 3. Combining both scores provided "cumulative endplate defect scores." Disc degeneration scores, Modic changes, disc displacement, HIZ, and facet joint changes were assessed. Subject demographics, pain profile, and Oswestry Disability Index (ODI) were also obtained. Endplate defects were observed in 67.5% of the subjects and in 13.5% of the endplates. All dimensions of endplate defects showed significance with disc degenerative scores, Modic changes, and posterior disc displacement (p < 0.05). Maximum width (p = 0.009) and its standardized value (p = 0.02), and cumulative endplate defect scores (p = 0.004) increased with narrow facet joints. Cumulative endplate defect scores showed a strong positive association with ODI (p < 0.05) compared to disc degenerative scores. Large size endplate defects were strongly associated with degenerative spine changes and more back-related disability. Findings from this study stress the need to assess endplate findings from a multi-dimensional perspective, whose role may have clinical utility. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.