Biomechanical Evaluation of Rigid Interspinous Process Fixation Combined With Lumbar Interbody Fusion Using Hybrid Testing Protocol.

Rigid interspinous process fixation (RIPF) has been recently discussed as an alternative to pedicle screw fixation (PSF) for reducing trauma in lumbar interbody fusion (LIF) surgery. This study aimed to investigate biomechanics of the lumbar spine with RIPF, and also to compare biomechanical differences between two postoperative stages (before and after bony fusion). Based on an intact finite-element model of lumbosacral spine, the models of single-level LIF with RIPF or conventional PSF were developed and were computed for biomechanical responses to the moments of four physiological motions using hybrid testing protocol. It was found that compared with PSF, range of motion (ROM), intradiscal pressure (IDP), and facet joint forces (FJF) at adjacent segments of the surgical level for RIPF were decreased by up to 8.4%, 2.3%, and 16.8%, respectively, but ROM and endplate stress at the surgical segment were increased by up to 285.3% and 174.3%, respectively. The results of comparison between lumbar spine with RIPF before and after bony fusion showed that ROM and endplate stress at the surgical segment were decreased by up to 62.6% and 40.4%, respectively, when achieved to bony fusion. These findings suggest that lumbar spine with RIPF as compared to PSF has potential to decrease the risk of adjacent segment degeneration but might have lower stability of surgical segment and an increased risk of cage subsidence; When achieved bony fusion, it might be helpful for the lumbar spine with RIPF in increasing stability of surgical segment and reducing failure of bone contact with cage.

Strip SAR image simulation of a composite vehicle-ground model.

In this paper, the strip synthetic aperture radar (SAR) image of a composite vehicle-ground model is simulated by combining the electromagnetic scattering algorithm and radar imaging algorithm. A linear frequency modulated wave is incident on the composite model, which is partitioned into a mass of triangular patches. In the "stop-and-go" radar mode, for each patch, the amplitude of scattered echo in the frequency domain is solved by a hybrid method of physical optics (PO)-shooting and bouncing ray (SBR)-physical theory of diffraction (PTD). For the composite model, the total scattered echo in terms of range frequency and azimuth time is obtained by the vector superposition of echo on patches. Then the SAR image of the composite model is generated by the range-Doppler algorithm. In numerical simulations, both the electromagnetic scattering of a target by the SBR-PTD method and composite scattering by the PO-SBR-PTD method are validated and evaluated by comparing with the multilevel fast multipole method (MLFMM) in FEKO software. Moreover, the SAR image of the composite vehicle-ground model is also compared with the real image in Moving and Stationary Target Acquisition and Recognition database, which verifies the feasibility of the proposed method. SAR images of the composite model for different incident angles are also presented and analyzed.

Efficacy of Exenatide Administered Twice Daily in Body Mass Index Reduction in Patients with Type 2 Diabetes Mellitus.

Background: Exenatide is a glucagon-like peptide-1 receptor agonist that can reduce body weight. This study aimed to determine the efficacy of exenatide on body mass index (BMI) reduction in patients with type 2 diabetes mellitus (T2DM) with differing baseline body weight, blood glucose, and atherosclerotic status and to determine if there is a correlation between BMI reduction and cardiometabolic indices in these patients. Methods: This retrospective cohort study used data from our randomized controlled trial. A total of 27 T2DM patients treated with combination therapy of exenatide twice daily and metformin for 52 weeks were included. The primary endpoint was a change in the BMI from the baseline to week 52. The secondary endpoint was a correlation between BMI reduction and cardiometabolic indices. Findings. The BMIs of overweight and obesity patients and those with glycated hemoglobin (HbA1c) ≥ 9% significantly decreased -1.42 ± 1.48 kg/m2(P=0.015) and -0.87 ± 0.93 kg/m2(P=0.003), respectively, at the baseline after 52 weeks of treatment. There was no reduction in BMI in patients with normal weight, HbA1c <9%, the nonatherosclerosis group, and the atherosclerosis group. The decrease in BMI was positively correlated with changes in blood glucose, high-sensitivity C-reactive protein (hsCRP), and systolic blood pressure (SBP). Conclusion: BMI scores improved after exenatide treatment for 52 weeks in T2DM patients. Weight loss was affected by baseline body weight and blood glucose level. In addition, BMI reduction from the baseline to 52 weeks was positively correlated with baseline HbA1c, hsCRP, and SBP. Trial Registration. Chinese Clinical Trial Registry (ChiCTR-1800015658).

Biomechanical role of cement augmentation in the vibration characteristics of the osteoporotic lumbar spine after lumbar interbody fusion.

Under whole body vibration, how the cement augmentation affects the vibration characteristic of the osteoporotic fusion lumbar spine, complications, and fusion outcomes is unclear. A L1-L5 lumbar spine finite element model was developed to simulate a transforaminal lumbar interbody fusion (TLIF) model with bilateral pedicle screws at L4-L5 level, a polymethylmethacrylate (PMMA) cement-augmented TLIF model (TLIF-PMMA) and an osteoporotic TLIF model. A 40 N sinusoidal vertical load at 5 Hz and a 400 N preload were utilized to simulate a vertical vibration of the human body and the physiological compression caused by muscle contraction and the weight of human body. The results showed that PMMA cement augmentation may produce a stiffer pedicle screw/rod construct and decrease the risk of adjacent segment disease, subsidence, and rod failure under whole-body vibration(WBV). Cement augmentation might restore the disc height and segmental lordosis and decrease the risk of poor outcomes, but it might also increase the risk of cage failure and prolong the period of lumbar fusion under WBV. The findings may provide new insights for performing lumbar interbody fusion in patients affected by osteoporosis of the lumbar spine. Graphical abstract.

Hybrid PO-SBR-PTD method for composite scattering of a vehicle target on the ground.

In this paper, a hybrid method of physical optics (PO) shooting and bouncing ray (SBR) physical theory of diffraction (PTD), is adopted to investigate the composite scattering of a vehicle target on the ground. Where the scattering of ground is calculated by the PO method, the scattering of the vehicle target is computed by the SBR-PTD method, and the mutual couplings between them are solved by the ray tracing technique. In addition, an octree data structure is used to accelerate the ray tracing progress. A forward-backward ray tracing technique is employed to ensure the accuracy of the illuminated facet identification. In numerical simulation, the monostatic and bistatic scattering of a reduced-scale vehicle target are calculated by the SBR-PTD method and compared with the simulation results with the multilevel fast multipole method (MLFMM) in commercial software FEKO. And the composite scattering from a reduced-scale vehicle target on the planar ground by our PO-SBR-PTD method is also compared with the MLFMM. The results show that our methods can greatly reduce the computational time and memory requirement while keeping a satisfactory accuracy. Finally, the composite scattering from the vehicle target on the rough ground is demonstrated and analyzed for different incident parameters.

Frequency controlled beam scanning characteristic realized using a compact slow wave transmission line.

To simplify the design of a beam scanning device, we present a simple and compact structure to realize the frequency scanning characteristic based on a hybrid waveguide consisting of a spoof surface plasmon polariton (SSPP) transmission line and half-mode substrate integrated waveguide (HMSIW). Additionally, the radiation characteristic is implemented using periodically modulated slots. The scanning angle range covers backward to forward directions without an open stop band at the broadside. The results from both simulations and measurements show that the total scanning angle reaches 117° for a frequency range of 9-11.4 GHz. Owing to the inherent features of the HMSIW and the unique design of the SSPP transmission line, the entire structure is only 139.2mm×15mm in size. Moreover, the average gain is approximately 6.5 dBi. Overall, the compact size and good performance ensure that the proposed design is favorable for planar integrated communication systems.

Efficient conversion from spoof surface plasmon polaritons to radiation mode.

A direct conversion from spoof surface plasmon polaritons (SSPPs) to radiation mode is proposed. A modified parallel two-wire SSPP transmission line is the key to the conversion, which is composed of traditional unit cells with slots among them. Taking advantages of the slots, the phase velocity of electromagnetic waves is larger than that of light, leading to the radiation. Both simulated and measured results show that the radiation occurs from 7.6 to 11 GHz, and the radiation angle keeps nearly stable in the whole operating frequency band, which can be predicted by theoretical calculation. The average gain and efficiency is 6.41 dBi and around 90%, respectively. The simple structure with flexibly tunable operating frequency makes the proposed design promising in planar integrated communication systems.

Biomechanical analysis of lumbar interbody fusion supplemented with various posterior stabilization systems.

PURPOSE: Biomechanical comparison between rigid and non-rigid posterior stabilization systems following lumbar interbody fusion has been conducted in several studies. However, most of these previous studies mainly focused on investigating biomechanics of adjacent spinal segments or spine stability. The objective of the present study was to compare biomechanical responses of the fusion devices when using different posterior instrumentations. METHODS: Finite-element model of the intact human lumbar spine (L1-sacrum) was modified to simulate implantation of the fusion cage at L4-L5 level supplemented with different posterior stabilization systems including (i) pedicle screw-based fixation using rigid connecting rods (titanium rods), (ii) pedicle screw-based fixation using flexible connecting rods (PEEK rods) and (iii) dynamic interspinous spacer (DIAM). Stress responses were compared among these various models under bending moments. RESULTS: The highest and lowest stresses in endplate, fusion cage and bone graft were found at the fused L4-L5 level with DIAM and titanium rod stabilization systems, respectively. When using PEEK rod for the pedicle screw fixation, peak stress in the pedicle screw was lower but the ratio of peak stress in the rods to yield stress of the rod material was higher than using titanium rod. CONCLUSIONS: Compared with conventional rigid posterior stabilization system, the use of non-rigid stabilization system (i.e., the PEEK rod system and DIAM system) following lumbar interbody fusion might increase the risks of cage subsidence and cage damage, but promote bony fusion due to higher stress in the bone graft. For the pedicle screw-based rod stabilization system, using PEEK rod might reduce the risk of screw breakage but increased breakage risk of the rod itself.

Sitagliptin attenuates endothelial dysfunction independent of its blood glucose controlling effect.

Although the contributions of sitagliptin to endothelial dysfunction in diabetes mellitus were previously reported, the mechanisms still undefined. Autophagy plays an important role in the development of diabetes mellitus, but its role in diabetic macrovascular complications is unclear. This study aims to observe the effect of sitagliptin on macrovascular endothelium in diabetes and explore the role of autophagy in this process. Diabetic rats were induced through administration of high-fat diet and intraperitoneal injection of streptozotocin. Then diabetic rats were treated with or without sitagliptin for 12 weeks. Endothelial damage and autophagy were measured. Human umbilical vein endothelial cells were cultured either in normal glucose or in high glucose medium and intervened with different concentrations of sitagliptin. Rapamycin was used to induce autophagy. Cell viability, apoptosis and autophagy were detected. The expressions of proteins in c-Jun N-terminal kinase (JNK)-Bcl-2-Beclin-1 pathway were measured. Sitagliptin attenuated injuries of endothelium in vivo and in vitro. The expression of microtubuleassociated protein 1 light chain 3 II (LC3II) and beclin-1 were increased in aortas of diabetic rats and cells cultured with high-glucose, while sitagliptin inhibited the over-expression of LC3II and beclin-1. In vitro pre-treatment with sitagliptin decreased rapamycin-induced autophagy. However, after pretreatment with rapamycin, the protective effect of sitagliptin on endothelial cells was abolished. Further studies revealed sitagliptin increased the expression of Bcl-2, while inhibited the expression of JNK in vivo. Sitagliptin attenuates injuries of vascular endothelial cells caused by high glucose through inhibiting over-activated autophagy. JNK-Bcl-2-Beclin-1 pathway may be involved in this process.

Comparison of the effects of twice-daily exenatide and insulin on carotid intima-media thickness in type 2 diabetes mellitus patients: a 52-week randomized, open-label, controlled trial.

BACKGROUND: Exenatide, a glucagon like peptide 1 analog, has been suggested to reduce the cardiovascular disease risk factors, such as body weight, blood pressure and subclinical atherosclerosis in patients with type 2 diabetes mellitus (T2DM). This was the first randomized, open-label, controlled trial to compare the effects of exenatide versus insulin on subclinical atherosclerosis, as assessed by carotid-intima media thickness (CIMT), in patients with T2DM. METHODS: A total of 66 patients with T2DM admitted from March 10, 2015 to June 20, 2017 in the Department of Endocrinology, Beijing Hospital were randomized to receive twice-daily exenatide or aspartate 70/30 insulin for 52 weeks. The primary endpoint was change from baseline in CIMT, and secondary endpoints included changes at week 52 from baseline in body weight, glycemic markers, lipid metabolism markers, blood pressure, C-reactive protein, fibrinogen, 8-hydroxydeoxyguanosine, irisin, and brain natriuretic peptide. RESULTS: Exenatide more significantly reduced the CIMT from baseline compared with insulin after 52 weeks, with a mean difference of - 0.14 mm (95% interval confidence: - 0.25, - 0.02; P = 0.016). Weight and body mass index were both significantly reduced in the exenatide group over 52 weeks. Exenatide reduced total lipoprotein and low-density lipoprotein cholesterol levels more significantly than insulin at weeks 16 and 40. Correlation analyses showed that CIMT was positively correlated with low-density lipoprotein cholesterol. CONCLUSIONS: Twice-daily exenatide could prevent atherosclerosis progression in patients with T2DM over a 52-week treatment period compared with insulin therapy. Trial registration Chinese Clinical Trial Registry ChiCTR-1800015658.

Stress analysis of the implants in transforaminal lumbar interbody fusion under static and vibration loadings: a comparison between pedicle screw fixation system with rigid and flexible rods.

The use of a pedicle screw fixation system with rods made of more compliant materials has become increasingly popular for spine fusion surgery in recent years. The aim of this study was to compare stress responses of the implants in transforaminal lumbar interbody fusion (TLIF) when using flexible and conventional rigid posterior fixation systems. A previously validated intact L1-S1 finite element model was modified to simulate single-level (L4-L5) TLIF with bilateral pedicle screw fixation using two types of connecting rod (rigid and flexible rods). The von Mises stresses in the implants (including TLIF cage, pedicle screws and rods) for the rigid and flexible fixations were analyzed under static and vibration loadings. The results showed that compared with the rigid fixation, the use of flexible fixation decreased the maximum stress in the pedicle screws, but increased the maximum stress in the cage and the ratio of maximum stress in the rods to the yield stress. It was also found that with decreasing diameter of the flexible rod (i.e. increasing flexibility of the rod), the maximum stress was decreased in the pedicle screws but increased in the cage and the rods. The findings imply that compared with the rigid rod, application of the flexible rod in the pedicle screw fixation system for the TLIF might decrease the breakage risk of pedicle screws but increase the risk of cage subsidence and rod breakage. Moreover, flexibility of the rod in the flexible fixation system should be carefully determined.

Dispersion nonlinearity analysis of immersed gratings.

An immersed grating is a novel diffraction grating with higher spectral resolution than the classical reflective grating given. Its diffractive surface is immersed in an optical material with high refractive index (n>1). This article provides a comprehensive discussion of the nonlinear dispersion of an immersed grating based on the analysis of its diffraction angle and angular dispersion.

Efficient hybrid method for electromagnetic scattering from a coated object above a two-layered rough surface.

A powerful and efficient hybrid method combining the finite-element boundary-integral method with fast multipole method (FE-BI-FMM) is proposed in this paper to study the electromagnetic scattering characteristics from a coated object above a two-layered dielectric rough surface. The finite-element method (FEM) is applied to model the scattering from the coated object, and multiple interactions between the object and layered rough surface are handled by the FMM-enhanced boundary integral method (BIM). A hybrid solver is adopted to efficiently solve the FEM-BIM matrix equation. Several numerical results are presented, and the influence of several parameters of the composite model on the scattering characteristics is analyzed in detail. Both vertical and horizontal polarizations for the incident waves are considered.

Sensitivity of power and RMS delay spread predictions of a 3D indoor ray tracing model.

This study investigates the sensitivity of a three-dimensional (3D) indoor ray tracing (RT) model for the use of the uniform theory of diffraction and geometrical optics in radio channel characterizations of indoor environments. Under complex indoor environments, RT-based predictions require detailed and accurate databases of indoor object layouts and the electrical characteristics of such environments. The aim of this study is to assist in selecting the appropriate level of accuracy required in indoor databases to achieve good trade-offs between database costs and prediction accuracy. This study focuses on the effects of errors in indoor environments on prediction results. In studying the effects of inaccuracies in geometry information (indoor object layout) on power coverage prediction, two types of artificial erroneous indoor maps are used. Moreover, a systematic analysis is performed by comparing the predictions with erroneous indoor maps and those with the original indoor map. Subsequently, the influence of random errors on RMS delay spread results is investigated. Given the effect of electrical parameters on the accuracy of the predicted results of the 3D RT model, the relative permittivity and conductivity of different fractions of an indoor environment are set with different values. Five types of computer simulations are considered, and for each type, the received power and RMS delay spread under the same circumstances are simulated with the RT model.

Accuracy and precision assessment of a new blood glucose monitoring system.

BACKGROUND: Blood glucose self-monitoring by individuals with diabetes is essential in controlling blood glucose levels. The International Organization for Standardization (ISO) introduced new standards for blood glucose monitoring systems (BGMS) in 2013 (ISO 15197: 2013). The CONTOUR PLUS® (CONTOUR PLUS) BGMS has been demonstrated to meet the 2013 ISO standards; however, no Chinese data on CONTOUR PLUS accuracy and precision have been published. METHODS: This study evaluated the accuracy and precision of CONTOUR PLUS BGMS in quantitative glucose testing of capillary and venous whole blood samples obtained from 363 patients at three different hospitals. RESULTS: Results of fingertip and venous blood glucose measurements by the CONTOUR PLUS system were compared with laboratory reference values to determine accuracy. Accuracy was 98.1% (96.06%-99.22%) for fingertip blood tests and 98.1% (96.02%-99.21%) for venous blood tests. Precision was evaluated across a wide range of blood glucose values (5.1-17.2 mmol/L), testing three blood samples repeatedly 15 times with the CONTOUR PLUS blood glucose meter using test strips from three lots. All within-lot results met ISO criteria (i.e., SD<0.42 mmol/L for blood glucose concentration <5.55 mmol/L; CV<7.5% for blood glucose concentration ≥5.55 mmol/L). Between-lot variations were 1.5% for low blood glucose concentration, 2.4% for normal and 3.4% for high. CONCLUSIONS: Accuracy of both fingertip and venous blood glucose measurements by the CONTOUR PLUS system was >95%, confirming that the system meets ISO 15197: 2013 requirements.

The PI3K/AKT cell signaling pathway is involved in regulation of osteoporosis.

BACKGROUND: Osteoporosis is a systemic skeletal disease with the high incidence, serious complications, financial burden, and heavily decrease in living quality. METHODS: Proliferation of osteoblast was tested by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) method, alkaline phosphatase (ALP) activity of osteoblasts was tested by ALP REAGENT, Calcium level was determined by a colorimetric assay, mRNA expression of phosphoinositide-3 kinase (PI3K), 3-phosphoinositide-dependent protein kinase 1 (PDK1), Akt, Caspase-3, Caspase-7, Caspase-9, osteocalcin (OCN), Osterix and Runx2 of osteoblasts was tested by RNA preparation and quantitative reverse transcription polymerase chain reaction (RT-PCR), and protein expression of phospho-PI3K, phospho-PDK1 and phospho-Akt was measured by Western Blot analysis. RESULTS: In osteoporosis model rats, it found that mRNA expression of PI3K, PDK1 and Akt showed no changes while protein expression of phospho-PI3K, phospho-PDK1 and phospho-Akt in bone tissue was decreased dramatically. To further characterize the molecular mechanisms that regulate osteoporosis, we examined the contribution of the PI3K/Akt cell signaling pathway in cultured osteoblasts. It suggested that, the blockade of PI3K activation by LY294002, a specific inhibitor of the PI3K/Akt signaling pathway in osteoblasts, heavily inhibited cell proliferation, ALP activity, calcium accumulation, and mRNA expression of OCN, Osterix and Runx2. However, mRNA expression of Caspase-3 and Caspase-9 was promoted accordingly. CONCLUSION: The in vivo and in vitro studies indicated that the PI3K/Akt cell signaling pathway is involved in the inhibition of osteoporosis through promoting osteoblast proliferation, differentiation and bone formation.

An efficient hybrid method for scattering from arbitrary dielectric objects buried under a rough surface: TM case.

A hybrid method combining the finite element method (FEM) with the boundary integral equation (BIE) is presented in this paper to investigate two-dimensional (2D) electromagnetic scattering properties of multiple dielectric objects buried beneath a dielectric rough ground for TM case. In traditional FEM simulation, the artificial boundaries, such as perfectly matched layer (PML) and the absorbing boundary conditions (ABC), are usually adopted as truncated boundaries to enclose the whole model. However, the enclosed computational domain increases quickly in size for a rough surface with a large scale, especially for the scattering model of objects away from the rough surface. In the hybrid FEM-BIE method, one boundary integral equation is adopt to depict the scattering above the rough surface based on Green's function. Based on the domain decomposition technique, the computational region below the rough ground is divided into multiple isolated interior regions containing each object and the exterior region. Finite element formulations are only applied inside interior regions to derive a set of linear systems, and another boundary integral formula is developed below the rough surface which also acts as the boundary constraint of the FEM region. Compared with traditional FEM, the hybrid technique presented here is highly efficient in terms of computational memory, time, and versatility. Numerical simulations are carried out based on hybrid FEM-BIE to study the scattering from multiple dielectric objects buried beneath a rough ground.

A Biomechanical Comparison of 2 Different Topping-off Devices and Their Influence on the Sacroiliac Joint Following Lumbosacral Fusion Surgery.

OBJECTIVE: Interspinous spacer (ISS)-based and pedicle screw-rod dynamic fixator (PDF)-based topping-off devices have been applied in lumbar/lumbosacral fusion surgeries for preventing the development of proximal adjacent segment degeneration. However, little attention has been paid to sacroiliac joint (SIJ), which belongs to the adjacent joints. Accordingly, the objective of this study was to compare how these 2 topping-off devices affect the SIJ biomechanics. METHODS: A validated, normal finite-element lumbopelvic model (L3-pelvis) was initially adjusted to simulate interbody fusion with rigid fixation at the L5-S1 level, and then the DIAM or BioFlex system was instrumented at the L4-5 level to establish the ISS-based or PDF-based topping-off model, respectively. All the developed models were loaded with moments of 4 physiological motions using hybrid loading protocol. RESULTS: Compared with the rigid fusion model (without topping-off devices), range of motion and von-Mises stress at the SIJs were increased by 23.1%-64.1% and 23.6%-62.8%, respectively, for the ISS-based model and by 51.2%-126.7% and 50.4%-108.7%, respectively, for the PDF-based model. CONCLUSION: The obtained results suggest that the PDF-based topping-off device leads to higher increments in SIJ motion and stress than ISS-based topping-off device following lumbosacral fusion, implying topping-off technique could be linked to an increased risk of SIJ degeneration, especially when using PDF-based device.

Topology optimization and dynamic characteristic evaluation of W-shaped interspinous process device.

For reducing the adjacent segment degeneration of the lumbar spine, the interspinous process device as a kind of flexible non-fusion device was designed to overcome the deficiencies associated with rigid fusion devices. However, it was not clear how the interspinous process device influenced the human spine system, especially the lumbar spine under a vibration environment. This study was designed to evaluate the effect of StenoFix under the vibration condition and also to optimize the structure of the device to obtain better biomechanical performance. A finite element model of the intact lumbar spine was developed and validated. The surgical finite element model was constructed by implanting the interspinous process device StenoFix. Using topology optimization, a new device StenoFix-new was redesigned. The results showed that the interspinous process device decreased vibration amplitudes of annulus stress and intradiscal pressure under vibration at the surgical level. The redesigned StenoFix-new with the smaller stiffness exhibited a better dynamic flexibility performance than StenoFix. In addition, the range of motions of StenoFix-new was closer to the intact model than StenoFix at the surgical level. These results might encourage the designers to give more consideration to the dynamic characteristics of the human spine on the premise of ensuring the safety and strength of implanted devices.

Prediction of the biomechanical behaviour of the lumbar spine under multi-axis whole-body vibration using a whole-body finite element model.

Low back pain has been reported to have a high prevalence among occupational drivers. Whole-body vibration during the driving environment has been found to be a possible factor leading to low back pain. Vibration loads might lead to degeneration and herniation of the intervertebral disc, which would increase incidence of low back problems among drivers. Some previous studies have reported the effects of whole-body vibration on the human body, but studies on the internal dynamic responses of the lumbar spine under multi-axis vibration are limited. In this study, the internal biomechanical response of the intervertebral disc was extracted to investigate the biomechanical behaviour of the lumbar spine under a multi-axial vibration in a whole-body environment. A whole-body finite element model, including skin, soft tissues, the bone skeleton, internal organs and a detailed ligamentous lumbar spine, was used to provide a whole-body condition for analyses. The results showed that both vibrations close to vertical and fore-and-aft resonance frequencies would increase the transmission of vibrations in the intervertebral disc, and vertical vibration might have a greater effect on the lumbar spine than fore-and-aft vibration. The larger deformation of the posterior region of the intervertebral disc in a multi-axis vibration environment might contribute to the higher susceptibility of the posterior region of the intervertebral disc to injury. The findings of this study revealed the dynamic behaviours of the lumbar spine in multi-axis vehicle vibration conditions, and suggested that both vertical and fore-and-aft vibration should be considered for protecting the lumbar health of occupational drivers.