Finite Element Study Research Articles

A novel nanohydroxyapatite/polyamide 66 strut for reducing subsidence after one-level anterior cervical corpectomy and fusion: a finite-element study

BackgroundThe aim of this study is to introduce a novel nanohydroxyapatite/polyamide 66(n-HA/PA66)n strut to improve biomechanical performance and reduce subsidence.MethodsOne validated intact and 2 ACCF-simulated C3–C7 cervical spine models were developed (old strut: Group A, new strut: Group B). In the ACCF models, C5 underwent corpectomy and was fixed by an anterior cervical plate. Screw angles were categorized as 1 (0 ) and 2 (45 ) and divided into 4 groups, A1, A2, B1 and B2, for each model. An axial force of 74 N and a moment couple of 1.0 Nm were imposed on the C3 vertebra. The range of motion (ROM) of each segment and the stress distribution on the screw–vertebra interface, strut, and strut–endplate interface were recorded and analysed.ResultsThere was no significant difference in ROM between Group A and Group B during bending, extension and rotation under 74 N axial pressure. The stress concentration on the strut body in Group A was higher than that in Group B. The peak stress values at the screw–vertebral interface in Groups A1 and A2 were higher than those in Groups B1 and B2, except for during extension and lateral bending. Under axial pressure, the peak stress values at the strut body–endplate interface during bending, extension and rotation were lower in the A1 and A2 groups than in the B1 and B2 groups. The Group B model showed much higher graft stress than the Group A model.ConclusionsBased on finite-element analysis, compared with the old strut, the novel strut showed better biomechanical performance at the screw–vertebra interface.

Automated manufacture and experimentation of composite overwrapped pressure vessel with embedded optical sensor

In recent years, the mobility (air/land) industry has been developing fuel-cell vehicles for mass adoption as hydrogen technology matures. Compared to conventional metallic design, the composite overwrapped pressure vessel without a metal or polymer liner results in a lightweight solution for gaseous hydrogen storage which further improves fuel efficiencies. Since the capabilities of automated fiber placement for making multi-stiffened structures are distinct from other automated manufacturing techniques, this study aimed to evaluate the feasibility of implementing AFP into the manufacture of a small scale COPV with a partially composite liner. The manufacturing related challenges are identified and discussed. During the manufacturing process, Distributed fiber optic sensor was embedded between the plies, as a structural health monitoring solution, to monitor the mechanical performance of the pressurized tank. In addition, finite element study was done to predict the internal strains for different pressure levels and the measured experimental strains at the sensor's location are found to be in close agreement with the finite element results. It is shown that such sensors can be integrated into automated fiber placement manufactured tanks for internal strain monitoring.

Torque moments and stress analysis in two passive self-ligating brackets across different incisor inclinations: A 3-dimensional finite element study

ObjectiveTo compare torque expression characteristics between rectangular slot (0.022″ x 0.028″) Damon Q passive self-ligating brackets (Ormco, Glendora, Calif) and square slot (0.021″ x 0.021″) Pitts 21 brackets (OC Orthodontics) using 0.019″ x 0.025″ Stainless Steel and 0.020″ x 0.020” Titanium Molybdenum alloy wires at various incisal inclinations using finite element analysis. The null hypothesis was that there were no differences in torque expression in both tested groups. MethodsReporting guidelines for in-silico studies using finite element analysis in medicine (RIFEM) were used. Damon Q and Pitts 21 brackets were scanned and 3D models generated. Brackets were placed on a 3-D model of a maxillary central incisor with its long axis inclined at 0⁰,5⁰,10⁰,15⁰ and 20⁰ to the occlusal plane. Final 0.019″ x 0.025″ SS and 0.020″ x 0.020” TMA archwires were inserted into slots of both tested brackets. Geometric models were converted into finite element models. Material properties were assigned for involved structures with automatic meshing performed by software. Torque movements were simulated with the FE program Ansys Space claim R 22. ResultsTorque moment values, torque expression and Von - Mises stress was higher in Pitts 21 than Damon Q at all inclination angles. There was a gradual increase in the magnitude of values with decrease in incisal inclination. ConclusionSquare slot passive self-ligating brackets show superior torque expression characteristics as compared to rectangular wire-rectangular slot combinations. The FEM results should be validated with in-vivo studies in order to confirm the findings.

Effect of Aligning Forces by Two Preadjusted Edgewise Techniques on a Buccally Positioned Maxillary Canine at Varying Vertical Displacements: A Finite Element Study.

To evaluate the effect of continuous arch and piggyback mechanics in a straight wire appliance (SWA) for the alignment of buccal and variably vertically positioned maxillary canines. A three-dimensional finite element model with near-normal occlusion and buccal and vertically displaced maxillary canines was used. Two groups were created to simulate two commonly used SWAs techniques, continuous archwire (Group 1) and piggyback models (Group 2). Each group had three subgroups with varying vertical displacement of the canine from 2 to 6 mm from the occlusal plane. The displacement and stress distribution were noted in each group. As the vertical displacement increased in Group 1, the concentration of von Mises stress increased progressively at the incisal third (0.36, 0.41 and 0.44 MPa) at 2, 4, and 6 mm, respectively, with decreased maximum occlusal movement in the vertical plane with respect to the canine. Group 2 exhibited a similar pattern but greater occlusal movement of the canine compared with Group 1. A vertical displacement of 4 mm is the optimal level at which continuous arch mechanics should be considered. For displacements beyond 4 mm, the piggyback wire technique is a suitable alternative.

Influence of muscle soft tissue and lower limbs on the vibration behavior of the entire spine inside the seated human body: A finite element study.

The objective of the study is to investigate the vibration behavior of the entire spine inside the human body and the influence of muscle soft tissue and lower limbs on spinal response under vertical whole-body vibration. This study conducted modal and random response analyses to simulate the modal displacements and stress of all intervertebral discs in the vertical principal mode in the skeleton, upper, and whole body. Additionally, the acceleration response of intervertebral discs under vertical random excitation was investigated. The results revealed that removing muscle soft tissue and lower limbs significantly changed the resonant frequency, modal displacement, and stress. Particularly, there was a rapid increase in vertical displacement of the lumbar spine in the skeleton model. The reason for that was due to the lack of soft tissue to provide stability, leading to significant lumbar spine bending. Under random excitation, the fore-aft acceleration of intervertebral discs in the skeleton model was considerably larger than that in the whole body, especially in the lumbar spine where it can reach up to four times higher. Conversely, the vertical response of the intervertebral discs inside the human body model was 1.4-2.4 times larger than that of the skeleton model. Muscle soft tissue contributes to the strength of the spine, reducing fore-aft response. The muscle soft tissue in the gluteal region, connected below the spine, can lower the vertical natural frequency and attenuate spinal impact. Although the lower limbs enhance spinal stability, stimulation from the feet can superimpose vibrational responses in the spine.

Physical activities aid in tumor prevention: A finite element study of bio-heat transfer in healthy and malignant breast tissues

The objective of the present research is to explore the temperature diffusion in healthy and cancerous tissues, with a specific focus on how physical activity impacts on the weakening of breast tumors. Previous research lacked numerical analysis regarding the effectiveness of physical activity in tumor prevention or attenuation, prompting an investigation into the mechanism behind physical activity and tumor prevention from a bio-heat transfer perspective. The study employs a realistic model of human breasts and tumors in COMSOL Multiphysics® to analyze temperature distribution by utilizing Penne's bio-heat equation. The research examines their influence on tissue temperature by varying tumor diameter (10–20 mm) and exercise intensities (such as walking speeds and other activities like carpentry, swimming, and marathon running). Results demonstrate that cancerous tissues generate notably more heat than normal tissues at rest and during physical activity. Smaller tumors exhibit higher temperatures during exercise, emphasizing the significance of tumor size in treatment effectiveness. Tumor temperatures range between 40 and 43.2 °C, while healthy tissue temperatures remain below 41 °C during physical activity. High-intensity exercises, particularly swimming, walking at 1.8 m/s, and marathon running, display a therapeutic effect on tumors, increasing effectiveness with intensity. The temperatures of healthy and malignant tissues rise noticeably due to constant metabolic heat and decreased blood flow. The study also identifies the optimal duration of high-intensity exercise, recommending at least 20 min for optimal therapeutic outcomes. The outcomes of this research would help individuals, doctors, and cancer researchers understand and weaken malignant tissues.

Stress concentration factors for RHS-to-RHS T-type moment-loaded end connections

The research presented in this paper is the continuation of a series of efforts to develop design formulae for rectangular hollow section (RHS)-to-RHS end connections and circular hollow section (CHS)-to-CHS end connections under fatigue loading. Normalized hot spot strains for the RHS-to-RHS T-type moment-loaded end connections (unreinforced and reinforced with a chord-end cap plate) are experimentally determined and compared to those in their regular connection counterparts (with sufficient chord continuity). Upon validation using the experimental data, a parametric finite-element study consisting of 448 models (including 336 stepped connections and 112 matched connections) is performed. The parametric study investigates the effects of chord end distance-to-width, branch-to-chord width, branch-to-chord thickness, and chord slenderness ratios, as well as the chord boundary condition (unreinforced or with a chord-end cap plate). Existing formulae in CIDECT Design Guide 8 for the calculation of the corresponding stress concentration factors (SCFs) are evaluated, and SCF correction factors are derived.

Biomechanical Effects of Stem Extension of Tibial Components for Medial Tibial Bone Defects in Total Knee Arthroplasty: A Finite Element Study.

The aim of this study was to investigate the biomechanical effects of stem extension with a medial tibial bone defect in primary total knee arthroplasty (TKA) on load distribution and stress in the proximal tibia using finite element (FE) analysis.FE simulations were performed on the tibia bone to evaluate the stress and strain on the tibia bone and bone cement. This was done to investigate the stress shielding effect, stability of the tibia plate, and the biomechanical effects in TKA models with various medial defects and different stem length models.The results demonstrated that in the bone defect model, the longer the stem, the lower the average von Mises stress on the cortical and trabecular bones. In particular, as the bone defect increased, the average von Mises stress on cortical and trabecular bones increased. The average increase in stress according to the size of the bone defect was smaller in the long stem than in the short stem. The maximal principal strain on the trabecular bone occurred mainly at the contact point on the distal end of the stem of the tibial implant. When a short stem was applied, the maximal principal strain on the trabecular bone was approximately 8% and 20% smaller than when a long stem was applied or when no stem was applied, respectively.The findings suggest that a short stem extension of the tibial component could help achieve excellent biomechanical results when performing TKA with a medial tibial bone defect.

Effect of Mixed Morphology (Simple Cubic, Face-Centered Cubic, and Body-Centered Cubic)-Based Electrodes on the Electric Double Layer Capacitance of Supercapacitors.

Supercapacitors store energy due to the formation of an electric double layer (EDL) at the interface of the electrodes and electrolyte. The present article deals with the finite element study of equilibrium electric double layer capacitance (EDLC) in the mixed morphology electrodes comprising all three fundamental crystal structures, simple cubic (SC), body-centered cubic (BCC), and face-centered cubic morphologies (FCC). Mesoporous-activated carbon forms the electrode in the supercapacitor with (C2H5)4NBF4/propylene carbonate organic electrolyte. Electrochemical interference is clearly demonstrated in the supercapacitors with the formation of the potential bands, as in the case of interference theory due to the increasing packing factor. The effects of electrode thickness varying from a wide range of 50 nm to 0.04 mm on specific EDLC have been discussed in detail. The interfacial geometry of the unit cell in contact with the electrolyte is the most important parameter determining the properties of the EDL. The critical thickness of the electrodes is 1.71 μm in all the morphologies. Polarization increases the interfacial potential and leads to EDL formation. The Stern layer specific capacitance is 167.6 μF cm-2 in all the morphologies. The maximum capacitance is in the decreasing order of interfacial geometry, as FCC > BCC > SC, dependent on the packing factor. The minimum transmittance in all the morphologies is 98.35%, with the constant figure of merit at higher electrode thickness having applications in the chip interconnects. The transient analysis shows that the interfacial current decreases with increasing polarization in the EDL. The capacitance also decreases with the increase of the scan rate.

Crystal plasticity finite element study on the microstructure and orientations evolution of {100} columnar grains in electrical steels

Most of the electrical steel slabs are composed of {100} columnar grains. After hot rolling, there is a texture gradient across the thickness. The surface shear textures (Goss texture{110}<100>, Brass texture{110}<112>, Copper texture{112}<111>) and certain <001>//ND fiber textures after hot rolling can be inherited into the finished sheet. The volume fraction and distribution of these textures after cold rolling significantly influence the magnetic properties. Therefore, a full-field crystal plasticity finite element method (CPFEM) was employed to simulate the evolution of microstructure and orientations of {100} columnar grains under plane strain compression and an additional displacement gradient component L13. Through qualitative and quantitative analysis of the simulated microstructure, it was found that under plane strain compression, {100}<110> grains were the most stable, followed by {100}<001> grains. Nearly {100}<021> orientation rotated towards {114}<481> orientation at the extremities of the simulation block. The additional displacement gradient component L13 enhanced the rotational effect. At the 45° shear direction and ends of the simulation block, the {110}<110> orientation originated from {100}<001> grains, the nearly {110}<112> orientation formed from {100}<021> grains, and the {112}<111> Copper orientation derived from {100}<110> grains. However, the simulation did not demonstrate the development of Goss shear orientation.

Effects of different tooth movement patterns and aligner thicknesses on maxillary arch expansion with clear aligners: a three-dimensional finite element study.

The objective of this study was to investigate the biomechanical effects of different tooth movement patterns and aligner thicknesses on teeth and periodontal tissues during maxillary arch expansion with clear aligners, to facilitate more precise and efficient clinical orthodontic treatments. Three-dimensional models including teeth, maxilla, periodontal ligament, and aligner were constructed and subjected to finite element analysis. Tooth displacement trends and periodontal ligament stresses were measured for seven tooth displacement patterns (divided into three categories including overall movement of premolars and molars with gradually increasing molar expansion in each step; distributed movement of premolars and molars; and alternating movement between premolars and molars at intervals) and two aligner thicknesses (0.5mm and 0.75mm) during maxillary arch expansion with clear aligners. When expanding the maxillary arch with clear aligners, the effective expansion of the target teeth mainly showed a tilting movement trend. Increasing the amount of molar expansion increased the buccal displacement of the first molar but decreased the buccal displacement of the premolars. The mean buccal displacement of the target teeth was greater in the posterior teeth interval alternating movement group (0.026mm) than in the premolar/molar distributed movement group (0.016mm) and the overall movement group (0.015mm). Increasing aligner thickness resulted in greater buccal displacement of the crowns and increased stress on the periodontal ligaments. Increasing the amount of molar expansion reduces the efficiency of premolar expansion. Alternating movement of premolars and molars at intervals achieves a higher arch expansion efficiency, but attention should be paid to the anchorage of adjacent teeth. Increasing the thickness of the aligner increases the expansion efficiency but may also increase the burden on the periodontal tissues.

Tooth movement analysis of maxillary dentition distalization using clear aligners with buccal and palatal mini-screw anchorages: A finite element study.

To assess the tooth movement trends during the three stages of maxillary dentition distalization with clear aligners (CA) and to compare the efficacy of different mini-screw anchorage systems. Three-dimensional (3D) finite element models of three anchorage systems (A, control group; B, buccal mini-screw anchorage group; C, palatal mini-screw anchorage group) were established. Three stages of simulating maxillary dentition distalization with CA included maxillary molar distalization (stage 1), maxillary premolar distalization (stage 2) and maxillary anterior teeth retraction (stage 3). Therefore, a total of nine models were constructed to analyse the 3D displacement of maxillary teeth during the distalization process. The displacement pattern of maxillary dentition during distalization was similar across the three groups, but with varying magnitudes. During stage 1, groups B and C exhibited greater amounts of molar distalization compared to group A. Group C also demonstrated the least amount of labial movement of the maxillary central incisor compared to the other two groups. During stage 2, the mesial displacement of the maxillary first molar was less significant in groups B and C than in group A. In the final stage, group C exhibited a greater amount of maxillary anterior retraction compared to groups A and B. The palatal mini-screw anchorage system was effective in reducing anchorage loss and improving the efficacy of maxillary dentition distalization with CA.

Finite element studies on Triply Periodic Minimal Surfaces (TPMS)–based hip replacement implants

Finite element studies on Triply Periodic Minimal Surfaces (TPMS)–based hip replacement implants

On low velocity impact response of Sandwich composite with jute/epoxy facesheet and cenosphere reinforced functionally graded Core: Experimental and finite element approach

AbstractThe assessment of energy absorption behavior has a vital role in determining suitability of lightweight composites for impact protection applications. This study focuses on evaluating the energy absorption characteristics of cenosphere reinforced epoxy syntactic foam core and jute epoxy facesheet sandwich composite subjected to low velocity impact. The syntactic foam is composed of lightweight cenospheres embedded within an epoxy matrix, resulting in a high‐strength and lightweight composite material. Low velocity impact tests were conducted using a drop tower apparatus to simulate realistic impact conditions. The impact force, energy absorption and damage mitigation of the syntactic foam specimens with varied weight percentage of Cenosphere (0%, 10%, 20% and 30%) were measured and analyzed to assess the energy absorption behavior. The gradation revealed that the weight of top layer when compared to bottom layer is 50.49%, 70.23% and 95.74% less in syntactic foam core with 10, 20 and 30 wt% Cenosphere respectively, indicating gradation. The study demonstrates that the addition of Cenosphere up to 20 wt% enhances the energy absorption capacity of the sandwich composites by 59.37%–93.44% compared to sandwich without Cenosphere reinforced core. However, beyond this threshold, a decline in energy absorption is observed when subjected to low‐velocity impact (LVI). Fractography analysis demonstrates that the incorporation of Cenosphere induces a rough fracture surface with deep river‐like topography, indicative of greater energy absorption during impact loading. This substantiates the conclusion that Cenosphere‐reinforced syntactic foams exhibit enhanced impact resistance, making them promising materials for structures subjected to low‐velocity impact events.Highlights Development of functionally graded core sandwich composite for low velocity impact applications. Assessing the performance of developed composites under low velocity impact loading. Determining the optimal weight percentage of cenospshere in functionally graded core. Studying the fractography of developed sandwich composites. Corelation between experimental and finite element studies.

Biomechanical Analysis of Orthodontic Miniscrew-Assisted Rapid Palatal Expansion on Dental and Bone Tissues: A Finite-Element Study

Abstract This study aims to delineate the biomechanical responses in both soft and hard tissues, alongside the interactions within the surrounding bone of a human skull subjected to clinical loadings generated by a miniscrew-assisted rapid palatal expansion (MARPE) device. Cone-beam computed tomography (CBCT) scans of a 20-year-old female skull were segmented. The skull bones were meticulously modeled to reconstruct a comprehensive three-dimensional (3D) model for finite-element analysis (FEA). A displacement of 0.125 mm was applied on each side (0.25 mm total) of the MARPE device to simulate one complete turn of the jackscrew. The outcomes revealed that the miniscrews experienced a maximum equivalent von Mises stress of 264.91 MPa. Notably, the separation of the midpalatal suture exhibited a quasi-parallel deformation with an average displacement of 0.247 mm and a standard deviation of 0.006,67 mm. The ratio of the rotational angle to the lateral displacement of the zygomaticomaxillary complex was 0.6436 degree/mm. No fracture of miniscrews was observed during the activation of one turn per day.

Nonlinear finite element analysis of shear defective reinforced concrete beam to column connections strengthened with three practical techniques

Extensive research efforts over the last decades have focused on the rehabilitation of vulnerable reinforced concrete (RC) beam to column moment resisting connections. Shear failure in the panel zone of the beam to column connections (BCCs) under the lateral seismic loads stands out as one of the main reasons of the vulnerability of moment resisting frames (MRFs), potentially resulting in severe consequences for the entire structure. The main aim of this study is to fairly investigate the effectiveness of three practical retrofitting methods to eliminate the joint shear failure in the RC beam to column connections which suffer from this undesirable brittle failure mode. To achieve this, a comprehensive review categorizing available retrofit techniques for shear-defective joints is first provided, outlining their advantages and limitations. The study then presents findings from a nonlinear three-dimensional (3D) finite element (FE) study on the performance of (RC) connections, characterized by predominant joint shear mode of failure and retrofitted using the three practical techniques. In this context, the FE model is validated through the monotonic simulation of quasi static cyclic tests conducted on connections strengthened by the three practical retrofitting methods from the literature. The selected methods were diagonal steel haunch method, RC planar joint expansion, and pre-tensioning of the joint core. The models, encompassing their precise geometric details, are applied to a full-scale exterior connection experiencing shear deficiencies to evaluate their effectiveness in real-world scenarios Additionally, a parametric study is conducted to assess the effects of various influential design variables on the effectiveness of these selected strengthening methods. These findings provide insights into the efficiency of retrofit techniques, thereby informing more robust design practices aimed at enhancing the performance and resilience of vulnerable shear defective RC BCCs retrofitted using the aforementioned strengthening techniques. The study has identified key design parameters crucial for the effectiveness of retrofit techniques in practical applications. These included haunch dimensions (thickness and length) for the haunch retrofit technique, additionally, the size of the added RC blocks for planar joint expansion technique and finally the enlargement size and the amount of applied prestressing bolt loads for pre-tensioning of the joint core retrofit technique.

Non-contact targeted removal of remnant powder particles from additive manufacturing builds with nano-second laser pulsing

Post-production precision cleaning is one critical challenge in Additive Manufacturing (AM) production of high-value, critical parts/builds. A part shedding particle during its operational use could cause severe complications in critical applications such as medical devices and aerospace components. This study presents a non-contact precision particle removal procedure based on a novel Dry Laser Cleaning (DLC) framework. DLC utilizes the thermo-elastic wave generation/propagation and high-frequency surface acceleration fields to dislodge and remove remnant particles due to inertial forces from a well-defined (user-specified) cleaning zone in a non-contact manner, as opposed to cleaning the entire build surface, which could lead to undesirable re-deposition and re-location of particles as well as high cost. The removal of spherical Stainless Steel 316 L (SS316L) micro-particles commonly used in AM from polished, atomically flat Silicon (Si) wafer substrates with uniform high free surface energy using a nano-second laser pulse is experimentally and computationally investigated. In general, a rough surface has a lower average free surface energy; thus, its cleaning, compared to Si wafer, is less challenging. The data with the SS316-Si material pair offers a consistent baseline. In parallel to experiments, a fully-coupled thermo-mechanical finite element study is also conducted for transient surface acceleration simulations to predict the effectiveness of SS316L micro-particle removal from a Si wafer substrate with laser pulsation. It is observed that SS316L micro-particles with a diameter larger than 5.61 μm, 8.43 μm, and 12.24 μm can be removed entirely at 3 mm, 6 mm, and 9 mm distances from its epicenter, respectively. Accordingly, a work-of-adhesion of 990.8 mJ/m2 is selected between the SS316-Si material pair, consistent with the literature. The reported experiments and simulations demonstrate the potential of the proposed rapid precision particle removal procedure for cleaning critical powder-based AM builds, where the targeted removal of particles is essential for the safe and reliable operation of high-value builds and parts.

Effect of cement volume on biomechanical response of a spine segment treated with a PEEK polymer implant: a finite element comparative study with vertebroplasty.

In the current study, a 3D finite element study was performed to investigate the biomechanical response of an osteoporotic spine segment treated with a novel transpedicular implant (V-STRUT©, Hyprevention, France) made of PEEK (polyetheretherketone) material combined with either injections of 2, 3, 4, 5 and 6 cc of cement. The objective was to assess numerically the biomechanical performance of the implant in combination with different doses of the injected bone cement and to compare its performance with the gold standard vertebroplasty (VP) technique. A female (69yo) was selected and a 3D finite element model of an osteoporotic spine segment was built based on a Computed Tomography (CT) scan performed from T12 to L2 with corresponding intervertebral discs and ligaments. A heterogeneous distribution of bone material properties was assigned to the bone using grey scale levels. Bilateral ellipsoid geometries of the inserted cement were retained for the V-STRUT and VP models based on experimental observation performed on different patients treated with the V-STRUT device. The current study demonstrated an optimal dose of 4 cc of bilaterally injected cement for the V-STRUT and VP techniques to restore the treated segment and confirmed that the V-STRUT device in combination with bone cement is superior to VP alone in establishing the normal stiffness and in reducing the applied stress to the immediately adjacent vertebral levels.

Does the novel artificial cervical joint complex resolve the conflict between stability and mobility after anterior cervical surgery? a finite element study.

Our group has developed a novel artificial cervical joint complex (ACJC) as a motion preservation instrument for cervical corpectomy procedures. Through finite element analysis (FEA), this study aims to assess this prosthesis's mobility and stability in the context of physiological reconstruction of the cervical spine. A finite element (FE)model of the subaxial cervical spine (C3-C7) was established and validated. ACJC arthroplasty, anterior cervical corpectomy and fusion (ACCF), and two-level cervical disc arthroplasty (CDA) were performed at C4-C6. Range of motion (ROM), intervertebral disc pressure (IDP), facet joint stress (FJS), and maximum von Mises stress on the prosthesis and vertebrae during loading were compared. Compared to the intact model, the ROM in all three surgical groups demonstrated a decline, with the ACCF group exhibiting the most significant mobility loss, and the highest compensatory motion in adjacent segments. ACJC and artificial cervical disc prosthesis (ACDP) well-preserved cervical mobility. In the ACCF model, IDP and FJS in adjacent segments increased notably, whereas the index segments experienced the most significant FJS elevation in the CDA model. The ROM, IDP, and FJS in both index and adjacent segments of the ACJC model were intermediate between the other two. Stress distribution of ACCF instruments and ACJC prosthesis during the loading process was more dispersed, resulting in less impact on the adjacent vertebrae than in the CDA model. The biomechanical properties of the novel ACJC were comparable to the ACCF in constructing postoperative stability and equally preserved physiological mobility of the cervical spine as CDA without much impact on adjacent segments and facet joints. Thus, the novel ACJC effectively balanced postoperative stability with cervical motion preservation.

Biomechanical analysis of single and multi-level artificial disc replacement (ADR) in cervical spine using multi-scale loadings: A finite element study.

Artificial disc replacement (ADR) is a clinical procedure used to diagnose cervical degenerative disc disease, preserving range of motion (ROM) at the fixation level and preventing adjacent segment degeneration (ASD). This study analyzed the biomechanics of ADR by examining range of motion (ROM), stress levels in bone and implants, and strain in the bone-implant interface using multi-scale loadings. The study focused on single- and double-level patients across various loading scales during physiological motions within the cervical spine. Results showed increased ROM in single-level and double-level fixations during physiological loadings, while ROM decreased at the adjacent level of fixation with the intact cervical spine model. The Prodisc-Implant metal endplate experienced a maximum von Mises stress of 432 MPa during axial rotation, confirming the long durability and biomechanical performance of the bone-implant interface.