Age-related degenerative changes and sex-specific differences in osseous anatomy and intervertebral disc height of the thoracolumbar spine

A Biomechanical Evaluation of a Novel Interspinous Process Device: In Vitro Flexibility Assessment and Finite Element Analysis

The interspinous process device (IPD) has emerged as a viable alternative for managing lumbar degenerative pathologies. Nevertheless, limited research exists regarding mechanical failure modes including device failure and spinous process fracture. This study developed a novel IPD (IPD-NEW) and systematically evaluated its biomechanical characteristics through finite element (FE) analysis and in vitro cadaveric biomechanical testing. Six human L1-L5 lumbar specimens were subjected to mechanical testing under four experimental conditions: (1) Intact spine (control); (2) L3-L4 implanted with IPD-NEW; (3) L3-L4 implanted with Wallis device; (4) L3-L4 implanted with Coflex device. Segmental range of motion (ROM) was quantified across all test conditions. A validated L1-L5 finite element model was subsequently employed to assess biomechanical responses under both static and vertical vibration loading regimes. Comparative analysis revealed that IPD-NEW demonstrated comparable segmental ROM to the Wallis device while exhibiting lower rigidity than the Coflex implant. The novel design effectively preserved physiological spinal mobility while enhancing load distribution capacity. IPD-NEW demonstrated notable reductions in facet joint forces, device stress concentrations, and spinous process loading compared to conventional implants, particularly under vibrational loading conditions. These findings suggest that IPD-NEW may mitigate risks associated with facetogenic pain, device failure, and spinous process fracture through optimized load redistribution.

Application of standing hyperextension lateral radiograph and full-length spine computed tomography scout view in the prone position in spinal flexibility assessment for patients with symptomatic old osteoporotic thoracolumbar fracture with kyphotic deformity: A comparative analysis

Background

Accurate assessment of thoracolumbar kyphosis (TLK) flexibility is paramount in preoperative planning for patients with symptomatic old osteoporotic thoracolumbar fractures (so-OTLF) exhibiting kyphotic deformity. While conventional standing hyperextension lateral radiographs (SHLR) are utilized, comparative analyses with prone computed tomography (CT) scout views in the sagittal plane remain limited. This study aims to evaluate and compare the efficacy of SHLR and full-length spine CT (FLS-CT) scout views in the prone position for assessing TLK flexibility in so-OTLF patients.

Methods

A retrospective analysis was conducted on patients with so-OTLF and kyphotic deformity who underwent posterior corrective fusion surgery. Sagittal parameters were measured independently by two spine surgeons using standing radiographs, SHLR, and prone FLS-CT scout views. TLK flexibility was quantified as the difference between standing and either SHLR or FLS-CT measurements. Paired t-tests were employed to compare sagittal Cobb angles and TLK flexibility between hyperextension and prone positions. Intra- and interobserver reliability were assessed using the intraclass correlation coefficient (ICC).

Results

Thirty-four patients (mean age 66.1 ± 7.2 years, 30 females) were included. The mean TLK on standing radiographs was 50.9° ± 13.8°. SHLR demonstrated a mean TLK reduction of 7.8° (95 % CI: 6.6°-9.1°) to 43.1° ± 12.6° (P < 0.05). FLS-CT revealed a mean TLK of 31.8° ± 12.4°, a reduction of 19.1° (95 % CI: 17.4°-20.9°) compared to standing radiographs (P < 0.05). TLK flexibility in the prone position was significantly higher than in the hyperextension position (mean difference: 11.3°, P < 0.001). Both SHLR and FLS-CT demonstrated high intra- and interobserver reliability (ICC >0.82), with FLS-CT exhibiting superior reliability (intraobserver ICC: 0.97, interobserver ICC: 0.94) compared to SHLR (intraobserver ICC: 0.90, interobserver ICC: 0.82).

Conclusions

Prone FLS-CT scout views provide a more accurate assessment of TLK flexibility in patients with so-OTLF and kyphotic deformity compared to conventional SHLR. This enhanced accuracy may facilitate improved preoperative evaluation and surgical planning.

Difference of Disk Degeneration and Segmental Range of Motion due to Lumbar Disk Level among Age and Gender: 639 Asymptomatic Volunteer Data

Introduction

There is limited evidence between lumbar disk degeneration and normal lumbar segmental range of motions (SRMs), because previous studies were skewed by age and lacked large cohort of asymptomatic data. We aimed to characterize the normal lumbar SRMs according to age and gender and determine its association with disk degeneration.

Methods

A total of 639 healthy Japanese volunteers (≥50 individuals of each decade of age from 20 to 79) without any symptom or morphological spinal abnormalities, who underwent lumbar radiograph and magnetic resonance image (MRI), were selected retrospectively. SRMs were evaluated by the flexion-extension radiographs taken in the recumbent position. Disk degenerations were assessed according to the Pfirrmann grade using MRI T2 imaging.

Results

The mean SRMs became larger in the lower lumbar level. The range of the mean SRMs was smallest at L1-2 and largest at L4-5: 6 to 9 degrees at L1/2, to peaking at 11-14 degrees at L4/5 in male, and 6-8 degrees at L1/2, to peaking at 11-17 degrees at L4/5 in female. Lumbar disk degeneration progressed faster with age in the lower lumbar spine than in the upper lumbar level. SRM did not change depending on the severity of disk degeneration in upper lumbar spine, but significantly decreased with progressive disk degeneration in the lower lumbar spine.

Conclusions

These findings could help to identify the normal lumbar SRMs that might be useful to evaluate the instability or inflexibility in the clinical situation. Furthermore, our results demonstrated the transition of the normative lumbar SRMs based on age, gender, and lumbar level.

Assessment of the Effectiveness of Fascial Manipulation in Patients with Degenerative Disc Disease of the Lumbosacral Spine

Background: The aim of this study was to evaluate the effectiveness of Fascial Manipulation in patients with disc herniations of the lumbar spine confirmed by magnetic resonance imaging. Material and Methods: This study included 69 patients with intervertebral disc damage of the lumbar spine, as confirmed by magnetic resonance imaging. Patients were divided into two groups: a study group and a control group. The control group (C) was treated conservatively with treatments such as interference currents, diadynamic currents, tens currents, galvanization, Sollux lamps, local cryotherapy, magnetic fields, therapeutic massages of the spine, and mobility exercises. The study group (S) was subjected to therapy using Fascial Manipulation, which included two treatments-the first on the day the patient reported for the study and the second a week later. Patients for this study were selected at random. Results: This study presents a statistically significant difference between the treatment effects, as assessed by the degree of pain (p < 0.001) and mobility limitation (p < 0.001), as well as the presence of stretch symptoms (p < 0.001): all three parameters improved significantly more in the study group compared to the control group. Conclusion: Fascial Manipulation is an effective method for treating pain in patients with disc herniations of the lumbar spine; in addition to reducing pain, it improves the range of motion and the results of SLR and PKB tests. In lumbar spine pain in disc herniations, treatment using Fascial Manipulation is definitely more effective than treatment according to the traditional physiotherapy regimen.

Imaging observation of intervertebral disc degeneration in patients with old thoracolumbar fracture-related kyphotic deformity

Old thoracolumbar fracture with kyphosis (OTLFK) often results in low back pain, with intervertebral disc degeneration being a significant contributor. We hypothesized that patients with OTLFK exhibit distinct patterns of disc degeneration compared to those with chronic low back pain without kyphotic deformity. This study aimed to investigate the characteristics of disc degeneration in OTLFK patients and explore its association with sagittal spinal parameters and endplate injury. A retrospective analysis was conducted on 52 patients with OTLFK (observation group, OG) and 104 age-, gender-, and BMI-matched patients with chronic low back pain (control group, CG) treated at our hospital between February 2017 and March 2023. Intervertebral disc degeneration from T11/12 to L5/S1 was assessed using MRI T2-weighted images and the Pfirrmann grading system. Sagittal spinal parameters-including lumbar lordosis (LL), thoracic kyphosis (TK), local kyphosis Cobb angle (LKCA), thoracolumbar kyphosis (TLK), pelvic tilt(PT), sacral slope(SS), and sagittal vertical axis (SVA)-and endplate injury grades were measured in the OG. Differences in disc degeneration between the two groups were compared, and correlations between disc degeneration, sagittal parameters, and endplate injury were analyzed. The OG exhibited significantly higher overall disc degeneration grades compared to the CG (p < 0.05), particularly at levels T11/12, T12/L1, L1/2, and L2/3. In the OG, grade IV and V degenerations were predominantly found from T11/12 to L2/3, whereas in the CG, they were mainly at L4/5 and L5/S1. Disc degeneration in the OG was significantly correlated with sagittal parameters and endplate injury grades (p < 0.05). Patients with OTLFK have higher grades of disc degeneration in the thoracolumbar region compared to those with chronic low back pain without kyphosis. Disc degeneration in OTLFK is associated with abnormal sagittal alignment and endplate injury, suggesting that kyphotic deformity and altered spinal biomechanics contribute to accelerated disc degeneration.

Characteristics and mechanical mechanisms of intervertebral disc degeneration in old thoracolumbar fractures with kyphosis: clinical observations and finite element analyses

BACKGROUND

Low back pain is a common complication in patients with old thoracolumbar fractures with kyphosis (OTLFK), and intervertebral disc degeneration (IDD) is a major contributor. Mechanical abnormalities are believed to play a key role in the development to IDD. This study aimed to investigate the characteristics of lumbar disc degeneration and underlying mechanical mechanisms in patients with OTLFK.

METHODS

A total of 52 patients with OTLFK were included from February 2017 to March 2023 as the observation group (OG). A control group (CG) of individuals with chronic low back pain were matched for age, body mass index, and gender. The disc degeneration grades and distribution in both groups were observed. Intact, 20°, 30°, and 40° kyphotic finite element (FE) models were established. Intervertebral disc pressures (IDPs) were calculated under standing, flexion, extension, lateral bending, and axial rotation conditions.

RESULTS

The overall IDD in the OG was higher than that in the CG. The grades from T11 to L3 were higher in the OG (p < 0.05), while there was no significant difference from L4 to S1. Degeneration levels IV and V were concentrated in the T11-L3 segment in the OG; whereas, in the CG, this was in L4/5 and L5/S1 (p < 0.05). The FE analysis results showed that, in the kyphotic model, the IDP was higher than the intact model in the standing position, flexion, lateral bending, and rotation, but lower in extension.

CONCLUSIONS

Patients with OTLFK exhibit higher-grade disc degeneration concentrated in the thoracolumbar segment. Abnormal mechanical stress may contribute to this degeneration, highlighting the importance of managing stress in kyphotic deformities.

Surgical management of spinal pathologies in the octogenarian: a narrative review

Optimal management paradigms of spinal pathologies in the octogenarian population are controversial given the higher incidence of comorbidities with concern for poor prognosis and fear of increased complications associated with surgical management. In this narrative review, we aim to detail the complex clinical considerations when approaching odontoid screw fixation/instrumented fusion, spinal decompression, and spinal fusion in the octogenarian. Literature review was conducted via Google Scholar and PubMed databases, with literature selected based on statistical power and clinical relevance to the following pathologies/surgical techniques: odontoid fracture, surgical decompression, and surgical fusion in the octogenarian. The aforementioned pathologies were selected based on prevalence in the advanced-age population in which surgical screening techniques and management remain nonuniform. Preoperative evaluation of the octogenarian patient increasingly includes frailty, sarcopenia, and osteopenia/osteoporosis assessments. In cases of odontoid fracture, conservative management appears to provide beneficial clinical outcomes with lower rates of complication compared to surgery; however, rates of radiographic odontoid fusion are far lower in conservatively managed patients. Regarding surgical decompression and fusion, the presence of comorbidities may be more predictive of outcome rather than age status, with the advent of minimally invasive techniques providing safety and efficacy in the surgical management of this age cohort. Age status may be less pertinent than previously thought in the decision to pursue spinal surgery for odontoid fracture, spinal decompression, or spinal fusion; however, each of these procedures has respective risks and benefits that must be considered within the context of each patient's comorbidity profile.

Finite element analysis of precise puncture vertebral augmentation in the treatment of different types of osteoporotic vertebral compression fractures

BACKGROUND

Osteoporosis vertebral compression fracture (OVCF) secondary to osteoporosis is a common health problem in the elderly population. Vertebral augmentation (VA) has been widely used as a minimally invasive surgical method. The transpedicle approach is commonly used for VA puncture, but sometimes, it is limited by the anatomy of the vertebral body and can not achieve good surgical results. Therefore, we propose the treatment of OVCF with precise puncture vertebral augmentation (PPVA). This study used finite element analysis to explore the biomechanical properties of PPVA in the treatment of osteoporotic vertebral compression fractures (OVCFs) with wedge, biconcave, and collapse deformities.

METHOD

Three-dimensional finite element models of the fractured vertebral body and adjacent superior and inferior vertebral bodies were established using Computed Tomography (CT) data from patients with OVCF, both before and after surgery. Evaluate the stress changes of the wedged deformed vertebral body, biconcave deformed vertebral body, collapsed deformed vertebral body, and adjacent vertebral bodies before and after PPVA.

RESULT

In vertebral bodies with wedge deformity and collapsed deformity, PPVA can effectively reduce the stress on the vertebral body but increases the stress on the vertebral body with biconcave deformity. PPVA significantly decreases the stress on the adjacent vertebral bodies of the wedge deformed vertebral body, and decreases the stress on the adjacent superior vertebral body of biconcave deformity and collapsed deformed vertebral bodies, but increases the stress on the adjacent inferior vertebral bodies. PPVA improves the stress distribution of the vertebral body and prevents high-stress areas from being concentrated on one side of the vertebral body.

CONCLUSION

PPVA has shown positive surgical outcomes in treating wedge deformed and collapsed deformed vertebral bodies. However, its effectiveness in treating biconcave vertebral body is limited. Furthermore, PPVA has demonstrated favorable results in addressing adjacent superior vertebral body in three types of fractures.

Normal Functional Local Alignment and Segmental Motion at the Thoracolumbar Junction: A Cross-Sectional Study of Healthy Subjects

OBJECTIVE

Several studies have investigated the mechanical behavior of the thoracolumbar spine. However, finding an accurate reference for the normal functional local alignment and segmental motion (SM) at the thoracolumbar junction (TLJ) is challenging. Therefore, this study aimed to assess age- and sex-related changes and differences in local alignment and SM at the TLJ.

METHODS

The study recruited healthy subjects aged 20 to 79 without complaints of back pain. Healthy subjects (60 males and 60 females) with appropriate imaging results were enrolled in the study. The subjects were divided into age groups (20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years); each group included 10 subjects of each sex.

RESULTS

The SM at the TLJ was small but noticeable, and the motion gradually increased toward the lower level of the TLJ, closer to the lumbar region. No significant differences were observed between male and female subjects in any SM measurements at the TLJ. The SM at the TLJ gradually decreased with age, while local kyphosis of TLJ progressed. The results also showed that the thoracolumbar slope value did not change with age and remained at a mean of -12.8 ± 7.2° (P = 0.893).

CONCLUSIONS

This study's results provide valuable guidance for appropriate surgical planning and rehabilitation of patients with spinal diseases or trauma. Furthermore, the results can be the basis for categorizing accurate criteria to evaluate the degree of disability after treatment.

Accurate Intervertebral Disc Segmentation Approach Based on Deep Learning

Automatically segmenting specific tissues or structures from medical images is a straightforward task for deep learning models. However, identifying a few specific objects from a group of similar targets can be a challenging task. This study focuses on the segmentation of certain specific intervertebral discs from lateral spine images acquired from an MRI scanner. In this research, an approach is proposed that utilizes MultiResUNet models and employs saliency maps for target intervertebral disc segmentation. First, a sub-image cropping method is used to separate the target discs. This method uses MultiResUNet to predict the saliency maps of target discs and crop sub-images for easier segmentation. Then, MultiResUNet is used to segment the target discs in these sub-images. The distance maps of the segmented discs are then calculated and combined with their original image for data augmentation to predict the remaining target discs. The training set and test set use 2674 and 308 MRI images, respectively. Experimental results demonstrate that the proposed method significantly enhances segmentation accuracy to about 98%. The performance of this approach highlights its effectiveness in segmenting specific intervertebral discs from closely similar discs.

Nonviral overexpression of Scleraxis or Mohawk drives reprogramming of degenerate human annulus fibrosus cells from a diseased to a healthy phenotype

Background

Intervertebral disc (IVD) degeneration is a major contributor to low back pain (LBP), yet there are no clinical therapies targeting the underlying pathology. The annulus fibrosus (AF) plays a critical role in maintaining IVD structure/function and undergoes degenerative changes such as matrix catabolism and inflammation. Thus, therapies targeting the AF are crucial to fully restore IVD function. Previously, we have shown nonviral delivery of transcription factors to push diseased nucleus pulposus cells to a healthy phenotype. As a next step in a proof-of-concept study, we report the use of Scleraxis (SCX) and Mohawk (MKX), which are critical for the development, maintenance, and regeneration of the AF and may have therapeutic potential to induce a healthy, pro-anabolic phenotype in diseased AF cells.

Methods

MKX and SCX plasmids were delivered via electroporation into diseased human AF cells from autopsy specimens and patients undergoing surgery for LBP. Transfected cells were cultured over 14 days and assessed for cell morphology, viability, density, gene expression of key phenotypic, inflammatory, matrix, pain markers, and collagen accumulation.

Results

AF cells demonstrated a fibroblastic phenotype posttreatment. Moreover, transfection of SCX and MKX resulted in significant upregulation of the respective genes, as well as SOX9. Transfected autopsy cells demonstrated upregulation of core extracellular matrix markers; however, this was observed to a lesser effect in surgical cells. Matrix-degrading enzymes and inflammatory cytokines were downregulated, suggesting a push toward a pro-anabolic, anti-inflammatory phenotype. Similarly, pain markers were downregulated over time in autopsy cells. At the protein level, collagen content was increased in both MKX and SCX transfected cells compared to controls.

Conclusions

This exploratory study demonstrates the potential of MKX or SCX to drive reprogramming in mild to moderately degenerate AF cells from autopsy and severely degenerate AF cells from surgical patients toward a healthy phenotype and may be a potential nonviral gene therapy for LBP.

Neurological Safety of Endoscopic Transforaminal Lumbar Interbody Fusion: A Magnetic Resonance Neurography Study

OBJECTIVE

A magnetic resonance neurography (MRN) study was conducted to assess the neurological safety of endoscopic transforaminal lumbar intervertebral fusion (endo-TLIF).

MATERIALS AND METHODS

A total of 56 healthy volunteers (29 men, 27 women; average age, 44 yr; age range, 21-60 yr) were included in the study. Coronal MRN images were collected from L2/L3 to L5/S1. The working triangle, modified working zone, and safest working zone areas, as well as the vertical and horizontal safe operation diameters, were measured. Linear regression analyses were conducted to explore the correlations between general characteristics (sex, age, height, body mass index) and the measured radiographic indicators.

RESULTS

MRN can effectively evaluate the operation zone of endo-TLIF. The safest working zone, modified working zone, and working triangle areas were largest at L4/L5 (92.4±23.4, 136±35.6, and 197±41.7 mm 2 , respectively) and smallest at L2/L3 (45.5±12.9, 68.1±19.5, and 92.6±24.4 mm 2 , respectively). The vertical safe operation diameter was large at L4/L5 and L2/L3 (5.34±0.8 and 5.42±0.9 mm, respectively) and smallest at L5/S1 (2.94±0.9 mm). The horizontal safe operation diameter was large at L4/L5 (7.28±1.2 mm) and smaller at L5/S1 and L2/L3 (4.28±1.0 and 4.77±0.8 mm, respectively).

CONCLUSIONS

L4/L5 has the lowest risk of nerve injury, and may be the safest level for beginners initiating endo-TLIF in their practice. We recommend that coronal MRN is routinely performed before endo-TLIF to minimize the risk of neurological injury.

Even mild intervertebral disc degeneration reduces the flexibility of the thoracic spine: an experimental study on 95 human specimens

BACKGROUND CONTEXT

Intervertebral disc degeneration represents one of multiple potential trigger factors for reduced passive spinal mobility and back pain. The effects of age-related degenerative intervertebral disc changes on spinal flexibility were however mainly investigated for the lumbar spine in the past, while intervertebral disc degeneration is also highly prevalent in the thoracic spine.

PURPOSE

To evaluate the effect of the degeneration grade on the range of motion and neutral zone of the thoracic spine.

STUDY DESIGN

Experimental study including combined radiological grading of intervertebral disc degeneration and biomechanical testing of 95 human thoracic functional spinal units (min. n=4 per level from T1-T2 to T11-T12) from 33 donors (15 female / 18 male, mean age 56 years, age range 37-80 years).

METHODS

Degeneration grades of the intervertebral discs were assessed using the validated x-ray grading scheme of Liebsch et al. (0=no, 1=mild, 2=moderate, 3=severe degeneration). Motion segments were loaded with pure moments in flexion/extension, lateral bending, and axial rotation to determine range of motion and neutral zone at 5 Nm.

RESULTS

All tested specimens exhibited degeneration grades between zero and two. Range of motion significantly decreased for grades one and two compared with grade zero in any motion direction (p<.05), showing the strongest decrease in extension comparing grade two with grade zero (-42%), while no significant differences were detected between grades one and two. Similar trends were found for the neutral zone with the strongest decrease in extension also comparing grade two with grade zero (-47%). Donor age did not significantly affect the range of motion, whereas the range of motion was significantly reduced in specimens from male donors due to the significantly higher degeneration grade in this study.

CONCLUSIONS

Even mild intervertebral disc degeneration reduces the range of motion and neutral zone of the thoracic spine in any motion plane, whereas progressing degeneration does not further affect its flexibility. This is in contrast to the lumbar spine, where a more gradual decrease of flexibility was found in prior studies, which might be explained by differences between thoracic and lumbar intervertebral disc morphologies.

CLINICAL SIGNIFICANCE

Thoracic intervertebral disc degeneration should be considered as one of multiple potential causal factors in patients showing reduced passive mobility and middle back pain.

Influence of Age and Gender on Intervertebral Disk Degeneration and Height in the Thoracolumbar Spine

Introduction

Intervertebral disk degeneration is a universal and natural process. However, no reports have summarized anatomical age-related intervertebral disk height and disk degenerative changes in the thoracolumbar spine or examined sex-specific differences. This study aimed to establish age-related changes and gender-specific differences of intervertebral disk height and disk degeneration of the thoracolumbar spine in a large cohort of relatively healthy subjects and also to evaluate the relationship between the degree of thoracolumbar disk height and disk degeneration.

Methods

Six hundred and twenty-seven relatively healthy subjects (307 males and 320 females; average age, 49.6±16.5 years) were enrolled. We included at least 50 males and 50 females in each decade of life between the 20s and the 70s. We measured intervertebral disk height from T10/T11 to L5/S1, vertebral body height from T10 to S1 on lateral neutral radiographs. Lumbar disk degeneration was defined according to the Pfirrmann classification in sagittal plane magnetic resonance imaging.

Results

Age-related decreases in intervertebral disk height were most prominent at L4/L5 in middle-aged and elderly individuals of both sexes. The grade of disk degeneration significantly increased with age in both genders at every level. Mild disk degeneration was observed even in the 20s. The disk degeneration occurred around the L4/L5 level. Although grade V disk degeneration was not identified for males in the 20s and the 30s, it appeared after the 40s and then increased further with age. The intervertebral disk height at the lower lumbar disks decreased with a progression in the disk degeneration grade in both genders.

Conclusions

This large-scale cross-sectional analysis of the thoracolumbar spine in relatively healthy subjects demonstrated that lumbar disk height narrowing progresses with age and is correlated with the progression of disk degeneration.

Automatic Segmentation of Specific Intervertebral Discs through a Two-Stage MultiResUNet Model

The automatic segmentation of intervertebral discs from medical images is an important task for an intelligent clinical system. In this study, a deep learning model based on the MultiResUNet model for the automatic segmentation of specific intervertebral discs is presented. MultiResUNet can easily segment all intervertebral discs in MRI images; however, when only certain specific intervertebral discs need to be segmented, problems with segmentation errors, misalignment, and noise occur. In order to solve these problems, a two-stage MultiResUNet model is proposed. Connected-component labeling, automatic cropping, and distance transform are used in the proposed method. The experimental results show that the segmentation errors and misalignments of specific intervertebral discs are greatly reduced, and the segmentation accuracy is increased to about 94%. The performance of the proposed method proves its usefulness for the automatic segmentation of specific intervertebral discs over other deep learning models, such as the U-Net, CNN-based, Attention U-Net, and MultiResUNet models.