Endplate Damage Research Articles

Finite element analysis of biomechanical investigation on diverse internal fixation techniques in oblique lumbar interbody fusion

BackgroundTo establish a three-dimensional finite element model of the lumbar spine and investigate the impact of different fixation techniques on the biomechanical characteristics of oblique lumbar interbody fusion (OLIF).MethodsThe study aimed to establish and validate a comprehensive three-dimensional model of the lower lumbar spine (L3-S1) using the finite element method. L4-L5 was selected as the surgical segment, and four distinct OLIF surgical models were constructed: Stand-alone (SA), unilateral cortical bone trajectory screw (UCBT), bilateral cortical bone trajectory screw (BCBT), and bilateral pedicle screw (BPS). The models were underwent a pure moment of 10N·m to simulate lumbar extension, flexion, left bending, right bending, left and right rotation movements. Subsequently, the range of motion (ROM), cage stress, and fixation stress were calculated.ResultsIn the L3-L5 segment, the BCBT group showed the most limited range of motion (ROM) under exercise load, indicating superior stability within this group. The ROM and cage stress values were found to be highest in the SA group. In contrast, the cage and internal fixation stress in the BPS group were observed to be lowest (9.91 ~ 53.83MPa, 44.93 ~ 84.85 MPa). With the exception of right bending and right rotation, the UCBT group demonstrated higher levels of internal fixation stress (102.20 ~ 164.62 MPa).ConclusionsThe study found that OLIF-assisted internal fixation improved segmental stability and reduced cage stress. The BPS group had advantages over the CBT group in preventing endplate damage and reducing the risk of cage subsidence. However, BCBT group has distinct merits in maintaining surgical segment stability, distributing stress load on the spinal motor unit, and reducing the likelihood of adjacent segment degeneration (ASD).

Correlation Between Quantitative Cage Pressure Measurements and Surgeons' Qualitative Tactile Assessments During Extraction in Lumbar Lateral Interbody Fusion: A Cadaveric Study.

A cadaveric study. Measuring the pressure exerted on lumbar lateral interbody fusion (LLIF) cages and examining its correlation with qualitative assessment of tactile feedback related to pullout strength during cage extraction to determine the optimal cage height. No data exists on the relationship between the surgeon's tactile feedback related to pullout strength during the LLIF cage extraction and the cage pressures measured during surgery. We used four cadavers to insert the original stress-measuring cages at the L2/3 to L4/5 levels (12 intervertebral spaces) using the oblique lumbar lateral approach. The intervertebral disc height (IDH) was measured before cage insertion. These stainless-steel stress-measuring cages were designed with the same shape as standard cages and included a built-in load cell to measure the stress applied. The cage heights were set at 8, 10, and 12 mm and they were inserted sequentially from 8mm, with stress measurements taken at each step. Four spine surgeons qualitatively evaluated the extraction strength using three rating categories ("loose," "appropriate," and "hard to extract"). After cage removal, endplate damage (ED) and anterior longitudinal ligament injury (ALLI) were checked. The anterior part of the vertebral body was dissected to expose the ALL and it is checked for obvious injuries. Additionally, a surgical probe is used to check for ED and ALLI. The measured cage pressures were 45, 120, and 191 N for the "loose," "appropriate," and "hard to extract" ratings, respectively (P < 0.001). ED was observed in five intervertebral spaces, whereas no ALLI was noted. The average maximum pressure when ED occurred was 127 N. The primary risk factor for ED was identified as the difference between the height of the inserted cage and IDH, with a cut-off value of 4.5mm. The appropriate extraction strength corresponded to a cage pressure of 120 N. A cage pressure ≥127 N posed a risk for ED. ED incidence was high when the difference between the IDH and the height of the inserted cage exceeded 4.5mm. Level Three.

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

BackgroundOsteoporosis and degenerative disc disease (DDD) are prevalent in the elderly population. Damage to the vertebral endplate, which impairs nutrient supply to the disc, serves as both a significant initiator and a hallmark of DDD. This study was aimed to explore the association between osteoporosis and endplate damage. MethodsThis retrospective study included 205 patients with DDD who were treated at tianjin hospital from January 2019 to May 2023. We collected data on age, sex, body mass index (BMI), phantom-less quantitative computed tomography (PL-QCT) values, and total endplate scores (TEPS). The average PL-QCT value of L1-L4 and TEPS were used to represent volumetric bone mineral density (v-BMD) and the degree of endplate damage, respectively. Based on the average PL-QCT value of L1 and L2, patients were divided into three groups: normal group (BMD > 120 mg/cm3), osteopenic group (80 mg/cm3 ≤ BMD ≤ 120 mg/cm3), and osteoporosis group (BMD < 80 mg/cm3). Multiple linear regression models were used to identify independent factors associated with endplate damage. ResultsThe overall TEPS (4.3±1.3 vs 5.0±1.0 vs 5.9±1.5, p<0.01) and segment (L1/2-L4/5) TEPS (p<0.05) in each group showed significant difference (R=-0.5), increasing in order from normal group to osteoporosis group. A significant negative correlation was found between TEPS and PL-QCT values in overall and each segments (p<0.001). The PL-QCT values and age (p<0.05) were independent factors influencing endplate damage. There were significant differences in the average number of TEPS ≥7 segments per patient among the three groups, with 1.16, 0.41, and 0.2 segments/person from osteoporosis group to normal group. ConclusionsOur study showed a significant positive correlation between osteoporosis and endplate damage. Attention is warranted for patients with osteopenia to prevent progression to osteoporosis, potentially leading to exacerbated DDD. The management of patients with both DDD and osteoporosis necessitates comprehensive treatment strategies that address both the BMD and endplate aspects of these conditions.

Elective Spinal Transpedicular Ablation of the Basivertebral Nerve of the Vertebral Segment in Adult Spinal Deformity Patients.

Ablation of the basivertebral nerve (BVNA) innervating the vertebral endplate has become a standard treatment of vertebrogenic chronic low back pain (CLBP) arising from vertebral endplate damage. BVNA treatment of CLBP in clinical trials was successful and durable for pain relief and return to daily activities. This case review adds new information about older patients with adult degenerative spinal deformity (ASD) and associated comorbidities not previously described in clinical trials. One hundred and eighteen ASD patients with vertebrogenic CLBP in a community practice setting underwent 503 levels of BVNA (average 4.3 levels). Forty-one patients with minimal comorbidities (Group A) were compared to 77 patients with significant comorbidities (Group B). Visual analog scale (VAS 10 cm) and Oswestry Disability Index (ODI 100-point scale) were obtained before BVNA and at a last follow-up (LFU). Group A VAS at LFU was an average of 2 cm, a 7 cm improvement. Group B VAS at LFU was 3 cm, a 6 cm improvement. At LFU, Group A ODI mean was 14 points or minimal disability, with a 39-point improvement, and Group B improved 28 points to 29 but remained moderately disabled. At LFU, the lumbar stenosis with laminectomy and BVNA subgroup of 26 had mean VAS 2 cm and ODI 28-point improvement but remained on average 21 points with a final low moderate disability. Eleven laminectomy and BVNA patients had continued posterior column pain related to radiculopathy, and or peripheral neuropathy, and sacroiliac joint pain in 30%. Mobile spondylolisthesis in 21 patients in Group B at LFU had a 6 cm improvement of VAS and 25-point improvement of ODI but remained moderately disabled on ODI. At LFU in group B, there was a 20% incidence of continued stenosis and radiculopathy symptoms. At LFU, Lumbar fusion was recommended in 9. Vertebral compression fracture (VCF) occurred in 9 after BVNA (10%) of Group B. These patients were older (mean 78 years), and all had significant osteoporosis. Eight fractures were within the area of the BVNA, and 1 was an S2 sacral fracture. These VCF patients were treated with vertebroplasty or kyphoplasty and continued preventive care with added teriparatide. At LFU, the VCF subgroup had a modest 6 cm improvement in VAS to 4 cm and continued to have significant severe to moderate disability (Oswestry Disability Index average of 38 points). Clinical trials of BVNA treatment of CLBP found success and durability for pain relief and daily activities. Patients with ASD without comorbidities showed durable pain relief of vertebrogenic CLBP and return of daily activities similar to clinical trials. In those with comorbidities, the result was an improvement in pain and disability that could be diminished by the complications related to the comorbidities. This is new information about BVNA for older patients with spinal deformity and other comorbidities. This study could impact research practice and policy to expand indications of BVNA to patients with adult spinal deformity. This case series represents the only literature regarding patients with adult spinal deformity treated with BVNA. The results were predictable and reproducible. Many patients were satisfied, would have the procedure again and would recommend BVNA to friends and family. This finding should encourage acceptance of patients with ASD for BVNA and, in fact, BVNA should probably be done before any fusion to limit and choose levels for inclusion in fusion.

NOVEL METHODOLOGY FOR DEVELOPING A MACHINE LEARNING-BASED IMAGING TOOL FOR HYBRID VISUALIZATION OF MACROSCOPIC AND MICROSCOPIC DEGENERATIVE CHANGES IN THE INTERVERTEBRAL DISC

BackgroundMagnetic resonance imaging (MRI) algorithm identifies end stage severely degenerated disc as ‘black’, and a moderately degenerate to non-degenerated disc as ‘white’. MRI is based on signal intensity changes that identifies loss of proteoglycans, water, and general radial bulging but lacks association with microscopic features such as fissure, endplate damage, persistent inflammatory catabolism that facilitates proteoglycan loss leading to ultimate collapse of annulus with neo-innervation and vascularization, as an indicator of pain. Thus, we propose a novel machine learning based imaging tool that combines quantifiable microscopic histopathological features with macroscopic signal intensities changes for hybrid assessment of disc degeneration.Methods100-disc tissue were collected from patients undergoing surgeries and cadaveric controls, age range of 35–75 years. MRI Pfirrmann grades were collected in each case, and each disc specimen were processed to identify the 1) region of interest 2) analytical imaging vector 3) data assimilation, grading and scoring pattern 4) identification of machine learning algorithm 5) predictive learning parameters to form an interface between hardware and software operating system.ResultsKernel algorithm defines non-linear data in xy histogram. X,Y values are scored histological spatial variables that signifies loss of proteoglycans, blood vessels ingrowth, and occurrence of tears or fissures in the inner and outer annulus regions mapped with the dampening and graded series of signal intensity changes.ConclusionTo our knowledge this study is the first to propose a machine learning method between microscopic spatial tissue changes and macroscopic signal intensity grades in the intervertebral disc.No conflict of interest declared. Sources of FundingICMR/5/4-5/3/42/Neuro/2022-NCD-1, Dr TMA PAI SMU/ 131/ REG/ TMA PURK/ 164/2020.A part of the above study was presented as an oral paper at the International Society for the Study of Lumbar Spine (ISSLS) meeting held on 1–5th May 2023, Melbourne, Australia.

EFFECT OF SPINAL FUSION ON BIOMECHANICS OF FACET JOINTS: SYNCHRONIZED SPATIO-TEMPORAL AND MECHANICAL ANALYSIS

ObjectivesUnderstanding lumbar facet joint involvement and biomechanical changes post spinal fusion is limited. This study aimed to establish an in vitro model assessing mechanical effects of fusion on human lumbar facet joints, employing synchronized motion, pressure, and stiffness analysis.Methods and ResultsSeven human lumbar spinal units (age 54 to 92, ethics 15/YH/0096) underwent fusion via a partial nucleotomy model mimicking a lateral cage approach with PMMA cement injection. Mechanical testing pre and post-fusion included measuring compressive displacement and load, local motion capture, and pressure mapping at the facet joints. pQCT imaging (82 microns isotropic) was carried out at each stage to assess the integrity of the vertebral endplates and quantify the amount of cement injected.Before fusion, relative facet joint displacement (6.5 ± 4.1 mm) at maximum load (1.1 kN) exceeded crosshead displacement (3.9 ± 1.5 mm), with loads transferred across both facet joints. After fusion, facet displacement (2.0 ± 1.2 mm) reduced compared to pre-fusion, as was the crosshead displacement (2.2 ± 0.6 mm). Post-fusion loads (71.4 ± 73.2 N) transferred were reduced compared to pre-fusion levels (194.5 ± 125.4 N). Analysis of CT images showed no endplate damage post-fusion, whilst the IVD tissue: cement volume ratio did not correlate with the post-fusion behaviour of the specimens.ConclusionAn in vitro model showed significant facet movement reduction with stand-alone interbody cage placement. This technique identifies changes in facet movement post-fusion, potentially contributing to subsequent spinal degeneration, highlighting its utility in biomechanical assessment.Conflicts of interestNoneSources of fundingThis work was funded by EPSRC, under grant EP/W015617/1.

Correlation of MRI-Evaluated Degenerative Disc Disease with Positivity on Single-Photon Emission Computed Tomography Imaging in Patients with Chronic Low Back Pain

Chronic low back pain, affecting up to 58% of the population, often stems from intervertebral disc degeneration. Although magnetic resonance imaging (MRI) is commonly used for diagnostics, challenges arise in pinpointing pain sources due to frequent asymptomatic findings. Single-photon emission tomography (SPECT) integrated with computed tomography (CT) offers a promising approach, enhancing sensitivity and specificity. In this retrospective study, spanning 2016 to 2022, SPECT/CT imaging was performed on 193 patients meeting specific criteria. We correlated SPECT/CT findings with lumbar MRI results, utilizing Pfirrmann and Rajasekaran classifications for disc degeneration and endplate damage assessment. Logistic regression analysis adjusted for age and sex evaluated associations. Of 965 spinal levels assessed, SPECT/CT positivity strongly correlated with higher Pfirrmann grades and Rajasekaran endplate classifications. Notably, Modic changes (MCs) on MRI displayed a nonsignificant relationship with SPECT/CT positivity. Significant associations were observed in older patients with positive MCs, Pfirrmann grades, and Rajasekaran classifications. This comprehensive study, the largest of its kind, establishes a significant link between SPECT/CT positivity and advanced lumbar degenerative changes. Higher Pfirrmann grades and increased Rajasekaran endplate damage demonstrated substantial correlations with SPECT/CT positivity. Notably, MCs did not exhibit such association. Our findings underscore the potential of SPECT/CT in identifying pain generators in degenerative spinal conditions, offering valuable insights for future interventions.

Intervertebral Disc Degeneration Induced by Vertebral Body Fracture Associated with Microcirculation Disruption of the Subendplate

Among the causes of the progression of intervertebral disc (IVD) degeneration (IDD) is the loss of nutrient intake to the IVD through the microcirculation disruption of the subendplate. Also, the vertebral body fracture intervenes in the degeneration the adjacent IVD. This research aimed to create an animal model of IDD using these 2 strategies. Thirty male Sprague-Dawley rats were split into 3 groups: a control group, a middle vertebral body injury (MI) associated with ethanol injection (MI+EtOH) group, and an MI associated with phosphate-buffered saline injection group. A vertebral body fracture with or without endplate injection of ethanol was generated by either drilling a hole in the center of a caudal rat vertebral body to form a fracture with an unabated endplate or drilling a hole in the center of a rat coccygeal vertebral body with endplate injection of ethanol to establish a vertebral body fracture with endplate damage. X-ray, macroscopic, histologic, and biochemical evaluations were utilized to assess IDD at weeks 3 and6. According to X-ray findings, the MI+EtOH group demonstrated a significant decrease in intervertebral space height over time in comparison to the 2 other groups. The water content also was significantly decreased. Macroscopic and histological analysis demonstrated progressive degenerative changes in the IVD of the MI+EtOH group. The caudal vertebra fracture with ethanol injection is more likely to induce degeneration of adjacent IVD. This model effectively reproduced IDD, which may serve as a theoretical basis for future clinical intervention for IDD.

Hysterectomy—a possible risk factor for operative intervention in female patients for degenerative lumbar spine conditions: a case control and cohort study

Researchers have recently linked hysterectomy, which alters sex hormone levels, to diseases like osteoporosis, lumbar spondylolisthesis, hypertension and diabetes etc. However, the association between hysterectomy and lumbar disc herniation (LDH)/lumbar spinal stenosis (LSS) remains unclarified. To determine whether there is a correlation between hysterectomy and surgical intervention for LDH/LSS in women, further substantiated through imaging and clinical research. A case control and cohort study. The study group comprised 1202 female patients aged 45 and older who had undergone operative treatment due to LDH/LSS (825 for LDH and 377 for LSS), and the comparison group comprised 1168 females without lumbar diseases who visited health examination clinic during the same period. One hundred and 2 hysterectomized patients were further selected (Hysterectomy cohort) and matched approximately with the control cohort at a 1:2 ratio from the study group with a minimum follow-up of 2 years. Odds Ratios (ORs) and 95% Confidence Intervals (CIs) were calculated to assess the association between hysterectomy and surgical intervention for LDH/LSS in women after adjusted by confounding factors. Patients from both the hysterectomy and control cohorts underwent a comprehensive assessment. This assessment included the evaluation of several parameters: the functional cross-sectional area, fat infiltration rate, relative functional cross-sectional area of the lumbar paravertebral muscles, facet joint degeneration grade, cartilage endplate damage, Modic changes for the L3/4-L5/S1 segments, Pfirrmann grade of lumbar disc degeneration, and disc height index for the L1/2-L5/S1 segments. Additionally, the Visual Analog Scale (VAS) and Japanese Orthopaedic Association (JOA) scores were recorded preoperatively and at the last follow-up. Associations between hysterectomy and patients treated surgically for LDH or LSS were analyzed using multivariate binomial logistic regression analysis. Lumbar X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) were used to evaluate the imaging variables. Imaging and clinical variables were compared. Hysterectomized women were associated with requiring surgery due to LDH/LSS, with ORs of 2.613 (p<.001) and 2.084 (p=.006), respectively. The imaging evaluation further revealed that the hysterectomy cohort had more severe degeneration of the paraspinal muscles, facet joints, endplates, and intervertebral discs, Modic changes at L3/4-L5/S1 segments, and intervertebral height reduction at L1/2-L5/S1 segments when compared to the control cohort (p<.01). Compared to the control cohort, the hysterectomy cohort exhibited higher preoperative and last follow-up VAS scores for low back pain, and last follow-up JOA scores (p<.01). Based on the findings of this study, it seems that women who have had a hysterectomy are correlated with requiring surgical intervention due to LDH/LSS. Imaging and clinical studies also indicate that hysterectomized patients exhibited more severe lumbar degeneration and back pain.

How I do it: dual operation channels percutaneous endoscopic far-lateral transforaminal lumbar interbody fusion

BackgroundThe current surgical procedure of interbody fusion in the lumbar spine has several limitations including low efficiency, potential endplate damage, overdose radiation exposure, and failure of fusion.MethodsThrough the endoscopic operating channel, we efficiently removed the superior and inferior articular processes and decompressed the ligamentum flavum. Another operating channel was established under endoscopic monitoring to excise the annulus fibrosus, remove the cartilaginous endplate using open instruments, perform interbody bone grafting, and place a non-expandable polyetheretherketone open surgical fusion cage.ConclusionLumbar interbody fusion was performed successfully using a far-lateral transforaminal approach combined with dual operation channels of percutaneous endoscopic-assisted technique.

A comparative analysis of using cage acrossing the vertebral ring apophysis in normal and osteoporotic models under endplate injury: a finite element analysis.

Background: Lateral lumbar fusion is an advanced, minimally invasive treatment for degenerative lumbar diseases. It involves different cage designs, primarily varying in size. This study aims to investigate the biomechanics of the long cage spanning the ring apophysis in both normal and osteoporotic models, considering endplate damage, using finite element analysis. Methods: Model 1 was an intact endplate with a long cage spanning the ring apophysis. Model 2 was an endplate decortication with a long cage spanning the ring apophysis. Model 3 was an intact endplate with a short cage. Model 4 was an endplate decortication with a short cage. On the basis of the four original models, further osteoporosis models were created, yielding a total of eight finite element models. The provided passage delineates a study that elucidates the utilization of finite element analysis as a methodology to simulate and analyze the biomechanical repercussions ensuing from the adoption of two distinct types of intervertebral fusion devices (cages) within the physiological framework of a human body. Results: The investigation found no appreciable changes between Models 1 and 2 in the range of motion at the fixed and neighboring segments, the L3-4 IDP, screw-rod stress, endplate stress, or stress on the trabecular bone of the L5. Increases in these stresses were seen in models 3 and 4 in the ranges of 0.4%-676.1%, 252.9%-526.9%, 27.3%-516.6%, and 11.4%-109.3%, respectively. The osteoporotic models for scenarios 3 and 4 exhibit a similar trend to their respective normal bone density models, but these osteoporotic models consistently have higher numerical values. In particular, except for L3-4 IDP, the maximum values of these parameters in osteoporotic Models 3 and 4 were much higher than those in normal bone quality Models 1 and 2, rising by 385.3%, 116%, 435.1%, 758.3%, and 786.1%, respectively. Conclusion: Regardless of endplate injury or osteoporosis, it is advised to utilize a long cage that is 5mm longer on each side than the bilateral pedicles because it has good biomechanical features and may lower the likelihood of problems after surgery. Additionally, using Long cages in individuals with osteoporosis may help avoid adjacent segment disease.

Design and Biomechanical Evaluation of a Bidirectional Expandable Cage for Oblique Lateral Interbody Fusion

Oblique lateral interbody fusion (OLIF) surgery is a minimally invasive spinal surgery technique that has become increasingly popular in recent years. The primary objective of the current study was to design a minimally invasive expandable fusion device that can reduce iatrogenic nerve damage and minimize endplate damage during OLIF surgery, while restoring intervertebral height and alignment. The second objective was to use finite element analysis to evaluate the biomechanical stability of the newly designed expandable fusion device after implantation into the intervertebral space. A new bidirectional expandable cage was designed in this study. A finite element model (FEM) of L3-L5 lumbar segment was modified to simulate decompression and fusion. The modified FEMs were constructed in the following cases: intact model, bidirectional expandable cage (alone, with unilateral pedicle screws [UPSs], and with bilateral pedicle screws [BPSs]) model, conventional OLIF cage (alone, with UPSs, and with BPSs) model. To simulate physiological loadings, the models were subjected to a follower compressive pre-load of 400 N, in addition to 8.0 Nm of flexion, extension, lateral bending, and axial rotation moments. All modified FEMs exhibited a significant reduction in motion at L3-L5 compared to the intact model. Among the fusion models, the bidirectional expandable cage (BEC) with BPS model displayed the highest stiffness and demonstrated a reduced range of motion (48.5%-75.7%). Additionally, the peak stress on the endplate in the conventional OLIF cage (Conv-OLIF) model was generally lower than that in the BEC models. The cage in the BEC ALONE model exhibited the highest stress (93.87-176.3 MPa) on the endplate in most motion modes, while the cage in the Conv-OLIF+BPS model had the lowest stress (16.67-30.58 MPa) on the endplate in most motion modes. The maximum stress on the fixation in the BEC fusion models was generally lower than that in the Conv-OLIF fusion group under the same loading conditions. The OLIF ALONE model had the lowest stress on the adjacent disc, while the stress level in the BEC ALONE model was very close to it. The BEC implanted models had higher stiffness, and more proper stress distribution on the posterior fixation was comparable to that of the Conv-OLIF models. However, the endplate stress peaks and cage stress peaks of the BEC models were slightly higher than those of the Conv-OLIF models, though still within a clinically acceptable range. Taking into account both biomechanical and clinical perspectives, BEC-assisted unilateral pedicle screw fixation meet clinical demand and may serve as a viable alternative to Conv-OLIF fusion.

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

BackgroundTo explore the independent association between lumbar endplate damage and bone mineral density (BMD) in patients with degenerative disc disease (DDD).MethodsThis retrospective investigation was based out of a prospectively collected database from the Affiliated Kunshan Hospital of Jiangsu University. Data from 192 DDD patients, collected between December 2018 and January 2022, were chosen for the final analysis. The average total endplate score (TEPS) of lumbar(L) 1-L4 was assessed by magnetic resonance imaging (MRI), and represents the extent of endplate damage. Osteoporosis severity was assessed via the L1-L4 BMD evidenced by dual-energy x-ray absorptiometry (DXA). Other analyzed information included gender, age, body mass index (BMI), and osteophyte score (OSTS). Uni- and multivariate linear regression analyses were employed to evaluate the association between average TEPS and BMD of L1-L4. Moreover, the generalized additive model (GAM) was employed for non-linear association analysis.ResultsUpon gender, age, BMI, and OSTS adjustments, a strong independent inverse relationship was observed between average TEPS and BMD (β, -0.021; 95% CI, -0.035 to -0.007, P-value = 0.00449). In addition, the gender stratification analysis revealed a linear relationship in males, and a non-linear relationship in females. Specifically, there was a significantly stronger negative relationship between average TEPS and BMD in females, when the average TEPS was < 3.75 (β, -0.063; 95% CI, -0.114 to -0.013; P-value = 0.0157). However, at an average TEPS > 3.75, the relationship did not reach significance (β, 0.007; 95% CI, -0.012 to 0.027; P-value = 0.4592).ConclusionsThis study demonstrated the independent negative association between average TEPS and BMD values of L1-L4. Upon gender stratification, a linear relationship was observed in males, and a non-linear association in females. The findings reveal that patients with osteoporosis or endplate damage require more detailed examinations and treatment regimen.

Understanding the Interplay Between Paraspinal Muscle Atrophy and Lumbar Endplate Degeneration: A 3-Year Longitudinal Study.

Retrospective analysis of longitudinal data. To assess the association between the paraspinal musculature (PM) and lumbar endplate degeneration. The PM is essential for spinal stability, while the vertebral endplate is pivotal for nutrient transport and force distribution. The clinical importance of both has been highlighted in recent literature, though little is known about their interaction. We identified patients with lumbar MRI scans due to low back pain, with a 3-year interval between MRI scans. Endplate damage was assessed by the total endplate score (TEPS) at each lumbar level. The PM was evaluated for its functional cross-sectional area (fCSA) and fatty infiltration (FI) at the L4 level. We used a generalized mixed model to analyze the association between PM parameters and TEPS at timepoint one, adjusting for age, sex, BMI, diabetes, hypertension, and smoking status. The association with the progression of endplate damage was analyzed through an ordinal regression model, additionally adjusted for TEPS at baseline. 329 patients were included, with a median follow-up time of 3.4 years. Participants had a median age of 59 and a BMI of 25.8kg/m2. In the univariate analysis, FI of the posterior PM was significantly associated with TEPS at baseline (β: 0.08, P<0.001) and progression of TEPS (OR: 1.03, P=0.020) after adjustment for confounders. The β and OR in this analysis are per percent of FI. In a binary analysis, patients with FI ≥ 40% had an OR of 1.92 (P=0.006) for the progression of TEPS. This is the first longitudinal study assessing the relationship between PM and endplate degeneration, demonstrating the association between PM atrophy and progression of endplate degeneration. This insight may aid in identifying patients at risk for degenerative lumbar conditions and guide research into preventive measures.

Intervertebral disc degeneration and vertebral end plate damage in acute lumbar disc herniation

Abstract Background: Although microtrauma, gene polymorphisms, or subclinical infection could initiate lumbar disc herniation (LDH), the final pathway culminating in herniation can involve two possible trajectories—degeneration of nucleus pulposus or vertebral end plate (EP) damage. We performed a retrospective case–control study to understand the relative role played by disc degeneration (DD) and EP changes in acute LDH. Materials and Methods: MRI of 300 consecutive patients with acute LDH (&lt;6 weeks) was evaluated for the type of LDH, severity of DD by Pfirrmann’s grading, and EP Modic changes (MC) for its type, distribution, and location in EPs. Among the1500 discs evaluated in 300 patients, 308 had disc herniation (cases) and 1192 acted as controls. Results: 98.8% of LDH had grade ≥3 DD (P &lt; 0.001). The mean DD was higher in herniated discs (P &lt; 0.05). From a mean 1.98 in normal discs, it increased to 3.31 in disc bulges, 3.73 in disc protrusions/extrusions, and 3.83 in sequestrations. Herniated discs had more MCs than normal discs (38.3%, 118/308) (P &lt; 0.001). Although in normal discs, only 7.7% had MC, herniated disc subtypes showed a progressive increase in the incidence of MC (26.2% in disc bulges, 37.5% in disc protrusion/extrusions, and 58.3% in sequestrations). MC on both EP was strongly associated with LDH (odds ratio = 9.76). Posterior corner MC had a significant association with LDH (72.72%, P &lt; 0.001). Conclusion: DD seems to be a common thread in all patients (98.8%) with LDH, whereas EP damage seems to be specific pathway in a subset (38.3%). The study showed a significant degeneration of nucleus pulposus in most (98.8%) herniated discs. Compared with nonherniated discs, vertebral MC had a higher incidence in herniated discs (38%), and interestingly these were of subacute fatty type 2.

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

ObjectiveTo 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 methodsIVD 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.ResultsWell 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).ConclusionEnsured 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.

Minimally Invasive Transforaminal Lumbar Interbody Fusion with Expandable Cages.

Minimally invasive surgical transforaminal lumbar interbody fusion (MIS-TLIF) is an increasingly common procedure for the treatment of lumbar degenerative pathologies. The MIS-TLIF technique often results in less soft-tissue injury compared with the open TLIF technique, reducing postoperative pain and recovery time1-3. However, the narrow surgical aperture of this minimally invasive technique has increased the difficulty of interbody cage placement. Expandable cages were designed to improve ease of insertion, improve visualization around the cage on insertion, reduce neurological retraction and injury by passing the nerve root with the implant in a collapsed state, and enable better disc-height and lordosis restoration on expansion4. This procedure is performed with the patient under general anesthesia and in a prone position. The appropriate spinal level is identified with use of fluoroscopy, and bilateral paramidline approaches are made utilizing the Wiltse intermuscular approach. Pedicle screws are placed bilaterally. A pedicle-based retractor or tubular retractor is passed along the Wiltse plane, and bilateral inferior facetectomies are performed. A foraminotomy is performed, including a superior facetectomy on the side with compression of the exiting nerve root. A thorough discectomy with end-plate preparation is performed. The disc space is sized with use of trial components. The cage is then implanted with a pre-expansion height less than the trialed height and is expanded under fluoroscopy. After expansion, the cage is backfilled with allograft and local autograft. Finally, the rods are contoured and reduced bilaterally, followed by closure in a multilayered approach. Nonoperative alternatives to the minimally invasive TLIF technique include physical therapy or epidural corticosteroid injections. When surgical intervention is indicated, there are several approaches that can be utilized during lumbar interbody fusion, including the posterior, direct lateral, anterior, or oblique approaches5. Expandable cages are designed to be inserted in a collapsed configuration and expanded once placed into the interbody space. This design offers numerous potential advantages over static alternatives. The low-profile, expandable cages require less impaction during placement, minimizing iatrogenic end-plate damage. Additionally, expandable cages require less thecal and nerve-root retraction and provide a larger surface footprint once expanded. The MIS-TLIF technique has been shown to significantly reduce back pain, leg pain, and disability, and to significantly increase function, with most improvements observed after 12 months postoperatively. Patients may experience a 51% and 39% reduction in visual analogue pain scores and Oswestry Disability Index scores, respectively6. The results for expandable cages compared with traditional static cages in TLIF surgery require further study. The technique utilized during insertion and placement of interbody cages plays an important role in cage subsidence. To reduce the risk of cage subsidence, cages should be placed level with the end plate and in contact with the apophyseal ring anteriorly. Additionally, caution should be taken when expanding the cage to ensure that the cage is not overexpanded, which may also increase the risk of mechanical failure and intraoperative subsidence.It is critical to understand the flexibility of the disc space and the osseous quality of the patient in order to know how much expansion may be applied through the cage without subsidence.If bullet-type cages are utilized, the tip of the cage should cross midline of the vertebral body to avoid generating iatrogenic scoliosis.Spine bone density should be investigated preoperatively in at-risk patients in order to identify osteoporotic patients, who are at greater risk for subsidence and instrumentation failure.Although advances in device technology are welcomed, surgeons should maintain a strong focus on technique to reduce complications and improve clinical outcomes when utilizing expandable cages. TLIF = transforaminal lumbar interbody fusionMIS = minimally invasive surgeryALIF = anterior lumbar interbody fusionMRI = magnetic resonance imagingCT = computed tomographyPEEK = polyetheretherketoneAP = anterioposteriorEMG = electromyographyDVT = deep vein thrombosisPE = pulmonary embolusODI = Oswestry Disability IndexEXP = expandable.

The role of endplate injury in intervertebral disc degeneration after vertebral augmentation in OVCF patients.

Whether vertebral augmentation can induce or aggravate the degeneration of adjacent intervertebral discs remains controversial. The purpose of this study is to explore the role of endplate injury in intervertebral disc degeneration after vertebral augmentation. The imaging data of patients with single-segment osteoporotic vertebral compression fractures (OVCFs) were retrospectively analyzed. The upper and lower discs of the fractured vertebrae were defined as cranial and caudal discs, and the discs adjacent to the cranial discs were defined as control discs. According to the integrity of the cranial and caudal endplates, they were divided into an injury group and a noninjury group. At follow-up, the increase in the modified Pfirrmann score on MRI compared with the baseline grade was defined as the occurrence of a degenerative disc change (DDC). The changes in the disc height and the number of DDC cases on MRI during the follow-up in each group were analyzed. A total of 56 patients with OVCFs were included in this study, with an average follow-up time of 18.8 ± 14.1 months (3-62 months). In the cranial and caudal discs, the number of DDC cases in the endplate injury group was significantly higher than that in the noninjury group (P = 0.007 and P = 0.018). However, the number of DDC cases in the whole endplate injury group (including the cranial and caudal endplates) was significantly higher than that of the whole noninjury group (P = 0.000) and the control group (P = 0.000). The number of DDC cases in the whole noninjury group was not different from that of the control group (P = 0.192). At follow-up, the disc height of the cranial and caudal endplate injury group was significantly lower than the baseline (P = 0.000 and P = 0.001), but the disc height of the noninjury group was not significantly lower than the baseline (P = 0.074 and P = 0.082). Endplate injury is associated with adjacent intervertebral disc degeneration in OVCF patients after vertebral augmentation. Evaluation of endplate damage before vertebral enhancement in OVCF patients has an important reference value for predicting the outcome of adjacent intervertebral discs after surgery.

Modic type 2 changes are fibroinflammatory changes with complement system involvement adjacent to degenerated vertebral endplates.

Vertebral endplate signal intensity changes visualized by magnetic resonance imaging termed Modic changes (MC) are highly prevalent in low back pain patients. Interconvertibility between the three MC subtypes (MC1, MC2, MC3) suggests different pathological stages. Histologically, granulation tissue, fibrosis, and bone marrow edema are signs of inflammation in MC1 and MC2. However, different inflammatory infiltrates and amount of fatty marrow suggest distinct inflammatory processes in MC2. The aims of this study were to investigate (i) the degree of bony (BEP) and cartilage endplate (CEP) degeneration in MC2, (ii) to identify inflammatory MC2 pathomechanisms, and (iii) to show that these marrow changes correlate with severity of endplate degeneration. Pairs of axial biopsies (n=58) spanning the entire vertebral body including both CEPs were collected from human cadaveric vertebrae with MC2. From one biopsy, the bone marrow directly adjacent to the CEP was analyzed with mass spectrometry. Differentially expressed proteins (DEPs) between MC2 and control were identified and bioinformatic enrichment analysis was performed. The other biopsy was processed for paraffin histology and BEP/CEP degenerations were scored. Endplate scores were correlated with DEPs. Endplates from MC2 were significantly more degenerated. Proteomic analysis revealed an activated complement system, increased expression of extracellular matrix proteins, angiogenic, and neurogenic factors in MC2 marrow. Endplate scores correlated with upregulated complement and neurogenic proteins. The inflammatory pathomechanisms in MC2 comprises activation of the complement system. Concurrent inflammation, fibrosis, angiogenesis, and neurogenesis indicate that MC2 is a chronic inflammation. Correlation of endplate damage with complement and neurogenic proteins suggest that complement system activation and neoinnervation may be linked to endplate damage. The endplate-near marrow is the pathomechanistic site, because MC2 occur at locations with more endplate degeneration. MC2 are fibroinflammatory changes with complement system involvement which occur adjacent to damaged endplates.

P4. Independent expansion of the anterior and posterior height of a lateral expandable cage can improve the contact area and load distribution at the cage-endplate interface

<h3>BACKGROUND CONTEXT</h3> Compared to their traditional static counterparts, expandable cages offer clinical advantages by allowing for the use of smaller surgical access corridors to achieve similar lordosis correction without endplate damage from large impaction forces. However, as with static cages, the risk of implant subsidence due to stresses on the vertebral endplate remains an area of concern. Although early clinical outcomes have been reported for individual expandable cage designs, how the endplate contact area and load distribution are affected by specific cage expansion trajectories remains unclear. <h3>PURPOSE</h3> To assess and quantify differences in contact area and load distribution from different lateral expandable interbody cage designs. <h3>STUDY DESIGN/SETTING</h3> Comparative biomechanics analysis using established synthetic spine units. <h3>OUTCOME MEASURES</h3> Cage-endplate contact area, anterior-posterior load distribution, segmental lordosis angle. <h3>METHODS</h3> Discectomies and cage placement were performed on synthetic functional lumbar spine units (n = 3). Three different expandable cage designs were evaluated, each with their own unique expansion trajectory: cranio-caudal, arc-based, and independent anterior and posterior height expansion. For the third cage, a differential expander was used to increase the two heights, anterior and posterior, according to the path of least resistance. A Tekscan calibrated pressure mapping sensor was placed between the cage and the synthetic endplate. The functional spine units were mounted on a servo-hydraulic testing frame and a constant 250N compressive axial preload was applied with unconstrained rotations and translations. The cages were then fully expanded and segmental lordosis angle along with pressure measurements were collected. To allow for a consistent comparison among cages, the surface contact area was normalized by the footprint of each respective cage. To determine the uniformity in the contact load profile, the local load distribution was demarcated in half along the anterior-posterior (A-P) aspect of the cage. The symmetry of the loading profile was characterized by dividing the cumulative anterior force magnitude by the overall force (50% indicates perfectly balanced A-P loading) quantified using the pressure mapping sensor. Friedman's test was performed (α = 0.05) to compare the effect of expansion trajectory on the outcome measures (values reported as median [range]). <h3>RESULTS</h3> Expansion trajectory had a significant effect on cage-endplate contact area and the resultant A-P loading distribution (p = 0.050), but not segmental lordosis angle (p = 0.097). Independent expansion resulted in the highest cage-endplate contact area (93% [92 to 98%]) compared to cranio-caudal (84% [81 to 90%]) and arc-based (62% [56 to 63%]) expansion. Furthermore, independent expansion resulted in a near-even A-P loading distribution (48% [42 to 51%]), compared to cranio-caudal (34% [22 to 36%]), and arc-based (97% [94 to 99%]) expansion. <h3>CONCLUSIONS</h3> Of the cage designs evaluated, the expandable cage with independent anterior and posterior height expansion resulted in the highest cage-endplate contact area and most uniform load distribution, both important considerations fundamental for a successful fusion procedure and the mitigation of implant subsidence risk. With a larger sample size, our continuing studies will investigate the interaction of various cage placement options and expansion mechanisms. <h3>FDA DEVICE/DRUG STATUS</h3> MOD-EX XLIF Interbody System (Approved for this indication), RISE-L Spacer (Approved for this indication)