A Novel Anatomical Self-locking Plate Fixation for Both-column Acetabular Fractures: - Finite Element Analysis

Abstract Background: Both-column acetabular fractures often require multiple plates for fixation, and the risk of internal implant failure is high. The author designed a posterior anatomic self-locking plate (PASP) to avoid the shortcomings. The stability of PASP was compared with two popular reconstruction plate fixation methods, and the influence of sitting, turning right and left on implants were explored. Methods: PASP, double reconstruction plate (DRP), and cross reconstruction plate (CRP) were assembled on the finite element model of both-column fractures of the left acetabulum. A load of 600N and a torque of 8N·m were loaded on the S1 vertebral body to detect stress and displacement changes when sitting, turning right and left. Results: The peak stress and displacement of three types of fixation methods on the left both-column fractures under three types of movements were CRP > DRP > PASP. PASP has the minimal value when turning left. The maximum peak of stress and displacement of PASP are 313.5 MPa and 1.15 mm respectively when turning right. Conclusion: PASP can provide higher stability than two reconstruction plates for both-column acetabular fractures. The rational movement after posterior DRP and PASP fixation for acetabular fracture is to turn to the ipsilateral side, which can avoid implant failure.

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Finite element and biomechanical analysis of risk factors for implant failure during tension band plating

Journal of International Medical Research ◽

10.1177/0300060520972075 ◽

2020 ◽

Vol 48 (11) ◽

pp. 030006052097207

Author(s):

Jing Ding ◽

Fei Wang ◽

Fangchun Jin ◽

Zhen-kai Wu ◽

Pin-quan Shen

Keyword(s):

Residual Stress ◽

Finite Element ◽

Finite Element Model ◽

Three Dimensional ◽

Biomechanical Model ◽

Element Model ◽

Tension Band ◽

Biomechanical Analysis ◽

Implant Failure ◽

Element Analysis

Objective Tension band plating has recently gained widespread acceptance as a method of correcting angular limb deformities in skeletally immature patients. We examined the role of biomechanics in procedural failure and devised a new method of reducing the rate of implant failure. Methods In the biomechanical model, afterload (static or cyclic) was applied to each specimen. The residual stress of the screw combined with different screw sizes and configurations were measured and compared by X-ray diffraction. With regard to static load and similar conditions, the stress distribution was analyzed according to a three-dimensional finite element model. Results The residual stress was close to zero in the static tension group, whereas it was very high in the cyclic load group. The residual stress of screws was significantly lower in the convergent group and parallel group than in the divergent group. The finite element model showed similar results. Conclusions In both the finite element analysis and biomechanical tests, the maximum stress of the screw was concentrated at the position where the screws enter the cortex. Cyclic loading is the primary cause of implant failure.

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Establishment of a Finite Element Model and Biomechanical Analysis of Different Fixation Methods for Total Talar Prosthesis Replacement

10.21203/rs.3.rs-515148/v1 ◽

2021 ◽

Author(s):

Qian dong Yang ◽

Le Chang ◽

Xuting Bian ◽

Lin Ma ◽

Tao Xu ◽

...

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Screw Fixation ◽

Articular Surface ◽

Three Dimensional ◽

Element Model ◽

Element Analysis ◽

Ankle Motion ◽

Fixation Methods ◽

Without Screws

Abstract Back ground：A three-dimensional finite element model of the whole foot with high geometric similarity was established and used to simulate the conditions after whole talar prosthesis implantation with several fixation methods, including Screw fixation of subtalar+talus-navicular joint, fixation with screws at only the subtalar joint, and fixation without screws. The biomechanical characteristics of the talus prosthesis were assessed in different gait phases to guide the selection of surgical methods in clinical practice.Methods：With the three-dimensional CT data of a volunteer's foot, Mimics13.0 and Geomagic10.0 software were used to carry out geometric reconstruction of the ankle-related tissues, and Hypermesh10.0 software was used for grid division and material attribute selection. Finally, the data were imported into Abaqus 6.9, and the simulated screw data were applied to different models. Finite element models with different fixation methods were simulated, and the stresses exerted by the human body in three gait phases (heel-strike, midstance and push-off) were simulated. The pressure changes in the articular surface around the talus or the prosthesis, the micromotion of the talus and the prosthesis and ankle motion were measured. Results：Finite element analysis on the biomechanical mechanism showed that screw fixation of the prosthesis in different gait phases mainly increases the pressure on the tibialis articular surface as well as decreases the pressure on the fused articular surface and joint micromotion, which hinders ankle motion. The indicator values were nearly the same in the models of fixation without screws and the normal state.Conclusion：The 3D finite element model created in this study has been verified to be an accurate and reliable model. The biomechanical mechanism varies by fixation method according to finite element analysis. Fixation of the prosthesis without screws yields values most similar to normal values.

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An Investigation into Scalpel Blade Sharpness Using Cutting Experiments and Finite Element Analysis

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.293-294.769 ◽

2005 ◽

Vol 293-294 ◽

pp. 769-776 ◽

Cited By ~ 3

Author(s):

C.T. McCarthy ◽

M. Hussey ◽

Michael D. Gilchrist

Keyword(s):

Finite Element ◽

Substrate Surface ◽

Peak Stress ◽

Element Model ◽

Von Mises Stress ◽

Element Analysis ◽

Sharpness Measurement ◽

Blade Tip ◽

Scalpel Blade ◽

Von Mises

This paper presents an investigation into the sharpness of a surgical scalpel blade. An experiment was carried out in which a surgical scalpel blade was pushed through an elastomeric substrate at a constant velocity. The force-displacement characteristics were examined by plotting the stiffness as a function of blade displacement and it was found that this curve could clearly identify the point where the material separates to form a cut. A blade sharpness measurement was defined as the energy required to initiate an opening or cut in the substrate. A finite element model was developed to examine the stress state in the substrate at the point where the opening initiates. The development of this model is described. The model was validated against the experiment and close agreement was obtained. The von-Mises stress distribution under the blade tip was plotted and it was shown that the peak stress actually occurs away from the blade tip, suggesting that material separation would initiate away from the substrate surface.

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Structural Stress Determination at a Hot-Spot

Journal of Pressure Vessel Technology ◽

10.1115/1.4046216 ◽

2020 ◽

Vol 142 (4) ◽

Author(s):

Goeun Han ◽

Sukru Guzey

Keyword(s):

Finite Element ◽

Hot Spots ◽

Hot Spot ◽

Single Point ◽

Equivalent Stress ◽

Peak Stress ◽

Element Model ◽

Cauchy Stress ◽

Structural Stress ◽

Element Analysis

Abstract Stress analysis by a finite element analysis program sometimes causes singularities in hot-spots. In a failure assessment, the structural stress, and membrane and bending stress should be determined in a highly stressed spot (hot-spot). When the structural stress at a hot-spot is disturbed by singularities, the stress result not only diverges, by reducing the element size, but also shows a decreased value compared to nominal stress because the stress is substituted into the von Mises equivalent stress equation. In the three-dimensional (3D) finite element model, it is hard to avoid the singularity problem at hot-spots particularly when it is subjected to loads in three axial directions. For the alternative, this study converts the 3D model into two-dimensional (2D) plane models to remove the singularity and to obtain reasonable structural stress values excluding the peak stress. The structural stress-estimating approaches applied in the 2D model were examined for whether they could avoid the structural stress reduction near the hot-spot with mesh insensitivity. The implemented approaches are stress linearization, single point away method, stress equilibrium, stress extrapolation, and the nodal force method. The results computed by each approach are compared and reconstructed to 3D stress by the Cauchy stress matrix. This study found that the difference in structural stress in 2D was eliminated after the 3D stress reconstruction.

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Biomechanical effect of medial cortical support and medial screw support on the locking plate fixation of the proximal humeral fractures with a medial gap: a finite element analysis

Acta Orthopaedica et Traumatologica Turcica ◽

10.3944/aott.2015.14.0204 ◽

2015 ◽

Cited By ~ 3

Author(s):

Pan Yang

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Locking Plate ◽

Plate Fixation ◽

Proximal Humeral Fractures ◽

Humeral Fractures ◽

Locking Plate Fixation ◽

Element Analysis ◽

Biomechanical Effect

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Finite element analysis comparison between superior clavicle locking plate with and without screw holes above fracture zone in midshaft clavicular fracture

BMC Musculoskeletal Disorders ◽

10.1186/s12891-019-2847-y ◽

2019 ◽

Vol 20 (1) ◽

Author(s):

Nachapan Pengrung ◽

Natthaphop Lakdee ◽

Chedtha Puncreobutr ◽

Boonrat Lohwongwatana ◽

Paphon Sa-ngasoongsong

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Axial Compression ◽

Fracture Zone ◽

Locking Plate ◽

Peak Stress ◽

Biomechanical Property ◽

Clavicular Fracture ◽

Element Analysis ◽

Cantilever Bending

Abstract Background Midshaft clavicular fractures are common fractures and generally treated conservatively. Among the surgical options, plate fixation is the most popular and has been biomechanically and clinically proven in numerous studies. However, implant failures caused by plate deformations or breakage still occur in up to 16.7% of cases, and recent studies showed that screw holes above fracture zone (SHFZ) might be the at-risk location. Using finite element analysis, this study aimed to test the biomechanical property of the superior clavicle locking plate (SCLP) with and without SHFZ in comminuted midshaft clavicular fracture. Methods Finite element models of comminuted midshaft clavicular fracture fixed with standard 8-hole titanium SCLP with screw holes (SHFZ plate) and without screw holes above fracture zone (No-SHFZ plate) were built. Both groups were tested under three different loading models (100-N cantilever bending, 100-N axial compression, and 1-Nm torsion). The average peak stress on medial clavicle, fracture zone, and lateral clavicle, and the peak stress on each screw hole (or the same position in the No-SHFZ plate) were measured and compared. Results The highest average peak stress on the fracture zone was higher than those on medial and lateral clavicles under all loading conditions in both plates. However, the No-SHFZ plate significantly reduced the average peak stress value on the fracture zone, compared to the SHFZ plate (45.0% reduction in cantilever bending, 52.2% reduction in axial compression, and 54.9% reduction in axial torsion). The peak stress value on the maximal stress point in the SHFZ and No-SHFZ plates with cantilever bending, axial compression, and torsion loads were 1257.10 MPa vs. 647.21 MPa, 186.42 MPa vs. 131.63 MPa, and 111.86 MPa vs. 82.41 MPa, respectively. Conclusion The weakest link of the SCLP construct in comminuted midshaft clavicular fracture fixation is the SHFZ, especially in the cantilever bending load. Additionally, the biomechanical property of the SCLP without SHFZ model (No-SHFZ plate) is superior to the standard SCLP model (SHFZ plate), with a significantly lower peak stress on the SHFZ location in all loading conditions. We recommend a new SCLP design with SHFZ to prevent implant failure and improve surgical outcomes.

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Biomechanics of Calcaneus Impacted by Talus: A Dynamic Finite Element Analysis

10.21203/rs.3.rs-600528/v1 ◽

2021 ◽

Author(s):

Mengquan Huang ◽

Bin Yu ◽

Yubiao Li ◽

Chunlai Liao ◽

Jun Peng ◽

...

Keyword(s):

Finite Element ◽

Articular Surface ◽

Three Dimensional ◽

Peak Stress ◽

Lateral Wall ◽

Element Model ◽

Calcaneal Fracture ◽

Element Analysis ◽

Average Maximum ◽

The Impact

Abstract BackgroundThe biomechanics of calcaneus impacted by the talus are unclear. We aimed to evaluate the biomechanical effect of the talus impacting on the calcaneus at different falling speed, and analyze the factors affecting calcaneal fracture.Methods A finite element model including the talus, calcaneus and ligaments was built using a variety of three-dimensional reconstruction software. The method of explicit dynamics was used to analyze the process of the talus impacting the calcaneus. Stress values of the posterior, middle, and anterior subtalar articular surface(PSAS, ISAS, ASAS), the calcaneocubic articular surface(CAS), the bottom of the calcaneus(BC), the medial wall (MW)and lateral wall (LW) of the calcaneus were extracted. Stress quantity and distribution changes in various parts of the calcaneus changed with speed were analyzed.ResultsPosterior subtalar articular surface reached the peak stress first during the process of talus impacting the calcaneus. The stress was mainly concentrated on the PSAS, ASAS, MW and GA. Comparing with the speed of 5m/s, the average maximum stress increased in each region of the calcaneus were: PSAS 73.81%, ISAS 7.11%, ASAS 63.57%, GA 89.10%, LW 140.16%, CAS 140.58%, BC 137.67%, MW 135.99% at a speed of 10m/s. The regions where the stress were concentrated changed, and the magnitude and sequence of stress peaks of calcaneus changed with speed also during the impact.Conclusion The falling speed affected the value and distribution of stress of the calcaneus, which was the most important factor leading to a calcaneal fracture. The magnitude and sequence of stress peaks might be important factors in determining the beginning and direction of fracture lines.

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