scholarly journals Custom-made talar component of total ankle replacement implant, with or without lateral articular facet: A finite element analysis

2020 ◽  
Author(s):  
Min Zhu ◽  
Kang-lai Tang ◽  
Zhong-min Jin ◽  
Zhi Xu ◽  
Guo-cheng Feng ◽  
...  
Keyword(s):  
Finite Element ◽  
Contact Surface ◽  
Total Ankle Replacement ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Contact Type ◽  
Articular Facet ◽  
Ankle Replacement ◽  
Custom Made ◽  
Surface Contact

Abstract Background: The present patient dissatisfaction with and high failure rates of total ankle replacement (TAR) are likely due to current prosthesis designs, which are not patient-specific and anatomy-based, leading to unphysiological motion at the replaced joint. The design of customized prostheses is already possible by means of medical imaging and additive manufacturing technology.Methods: In this study, dome and geometric fixtures of custom-made talar components for TAR were designed, and we investigated two kinds of talar components: 2-surface contact type (Type-1, without lateral articular facet) and 3-surface contact type (Type-2, with lateral articular facet). The effects of the above two prostheses on the loading stress of the prosthesis contact surface were comparatively analysed with three-dimensional finite element models.Results: The maximum and average von Mises stress values of the 3-surface prosthesis were smaller than those of the 2-surface prosthesis. In terms of contact surface pressure, the maximum and average values of the 3-surface prosthesis are almost equal to those of the 2- surface type. In terms of the tangential slip distribution of the contact surface, the maximum and average values of the 3-surface prosthesis were smaller than those of the 2-surface prosthesis.Conclusions: The custom-made talar component of the total ankle replacement implant reproduced the anatomical morphology of the natural articular surfaces well. The 3-surface contact type prosthesis with lateral articular facet, compared to the 2-surface contact type without lateral articular facet, offers better static stability by affecting the internal and external forces.

scholarly journals Influences of Different Implant Material Combinations on the Stress Distribution of the Foot Following Total Ankle Replacement: a Finite Element Analysis

2021 ◽  
Author(s):  
Jian Yu ◽  
Dahang Zhao ◽  
Wen-Ming Chen ◽  
Pengfei Chu ◽  
Shuo Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Articular Surface ◽  
Reaction Force ◽  
Total Ankle Replacement ◽  
Von Mises Stress ◽  
Cobalt Chromium ◽  
Polyether Ether Ketone ◽  
Implant Material ◽  
Ankle Replacement ◽  
Ether Ketone

Abstract Background A proper combination of implant materials for Total Ankle Replacement (TAR) may reduce stress at the implant and the foot. This study aimed to investigate the biomechanical influences for different implant material combinations using the finite element (FE) method. Methods A validated foot model was modified to simulate TAR with the INBONE II ankle system at the second peak ground reaction force. Six types of materials were used (Ceramic, cobalt–chromium–molybdenum alloy (CoCrMo), Titanium alloy (Ti6Al4V), carbon-fiber-reinforced Polyether-ether-ketone (CFR-PEEK), Polyether-ether-ketone (PEEK), and used ultra-high molecular weight polyethylene (UHMWPE)). Results The von Mises stress at the bearing articular surface decreased with implant stiffness. The combination of CFR-PEEK on UHMWPE presented the lowest stress of 14.82 MPa. A low implant stiffness of the talar component, rather than the bearing, relieved the stress at the resected surface of the talus. Conclusions Soft implant material provided a stress reduction at the bearing and adjacent bones. CFR-PEEK seemed to be a good alternative to implant metal components.

scholarly journals Evaluation of Bone–Implant Interface Stress and Strain Using Heterogeneous Mandibular Bone Properties Based on Different Empirical Correlations

2021 ◽  
Author(s):  
Mostafa Omran Hussein ◽  
Mohammed Suliman Alruthea
Keyword(s):  
Finite Element ◽  
Group Iv ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Dental Arch ◽  
Stress And Strain ◽  
Bone Implant ◽  
Bone Properties ◽  
Group I ◽  
Von Mises

Abstract Objective The purpose of this study was to compare methods used for calculating heterogeneous patient-specific bone properties used in finite element analysis (FEA), in the field of implant dentistry, with the method based on homogenous bone properties. Materials and Methods In this study, three-dimensional (3D) computed tomography data of an edentulous patient were processed to create a finite element model, and five identical 3D implant models were created and distributed throughout the dental arch. Based on the calculation methods used for bone material assignment, four groups—groups I to IV—were defined. Groups I to III relied on heterogeneous bone property assignment based on different equations, whereas group IV relied on homogenous bone properties. Finally, 150 N vertical and 60-degree-inclined forces were applied at the top of the implant abutments to calculate the von Mises stress and strain. Results Groups I and II presented the highest stress and strain values, respectively. Based on the implant location, differences were observed between the stress values of group I, II, and III compared with group IV; however, no clear order was noted. Accordingly, variable von Mises stress and strain reactions at the bone–implant interface were observed among the heterogeneous bone property groups when compared with the homogenous property group results at the same implant positions. Conclusion Although the use of heterogeneous bone properties as material assignments in FEA studies seem promising for patient-specific analysis, the variations between their results raise doubts about their reliability. The results were influenced by implants’ locations leading to misleading clinical simulations.

scholarly journals Finite-element analysis of the influence of tibial implant fixation design of total ankle replacement on bone–implant interfacial biomechanical performance

2020 ◽  
Vol 28 (3) ◽  
pp. 230949902096612
Author(s):  
Jian Yu ◽  
Chao Zhang ◽  
Wen-Ming Chen ◽  
Dahang Zhao ◽  
Pengfei chu ◽  
...  
Keyword(s):  
Finite Element ◽  
Total Ankle Replacement ◽  
Implant Design ◽  
Fixation Method ◽  
Implant Loosening ◽  
Implant Fixation ◽  
Bone Resection ◽  
Bone Implant ◽  
Initial Stability ◽  
Ankle Replacement

Purpose: Implant loosening in tibia after primary total ankle replacement (TAR) is one of the common postoperative problems in TAR. Innovations in implant structure design may ideally reduce micromotion at the bone–implant interface and enhance the bone-implant fixation and initial stability, thus eventually prevents long-term implant loosening. This study aimed to investigate (1) biomechanical characteristics at the bone–implant interface and (2) the influence of design features, such as radius, height, and length. Methods: A total of 101 finite-element models were created based on four commercially available implants. The models predicted micromotion at the bone–implant interface, and we investigated the impact of structural parameters, such as radius, length, and height. Results: Our results suggested that stem-type implants generally required the highest volume of bone resection before implantation, while peg-type implants required the lowest. Compared with central fixation features (stem and keel), peripherally distributed geometries (bar and peg) were associated with lower initial micromotions. The initial stability of all types of implant design can be optimized by decreasing fixation size, such as reducing the radius of the bars and pegs and lowering the height. Conclusion: Peg-type tibial implant design may be a promising fixation method, which is required with a minimum bone resection volume and yielded minimum micromotion under an extreme axial loading scenario. Present models can serve as a useful platform to build upon to help physicians or engineers when making incremental improvements related to implant design.

scholarly journals The Role of Axial Rotation in Total Ankle Replacement

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0009
Author(s):  
Ali-Asgar Najefi ◽  
Andrew Goldberg
Keyword(s):  
Surgical Techniques ◽  
Axial Rotation ◽  
Total Ankle Replacement ◽  
Tibial Tuberosity ◽  
Ct Scans ◽  
Patient Specific ◽  
Ankle Arthritis ◽  
Ankle Replacement ◽  
Wright Medical Technology ◽  
The Mean

Category: Ankle Arthritis Introduction/Purpose: The importance of implant orientation in the axial rotational plane is ill understood. No Total ankle replacement (TAR) implant deals specifically with rotation as part of the surgical technique. Preoperative computed tomography (CT) scan–derived patient-specific plans and guides (PROPHECY, Wright Medical Technology, Memphis, TN) have been developed for TAR scanning the knee and ankle for the purposes of patient specific instrumentation. The objectives of this study were to establish the range and relationship between the transtibial axis at the knee, the tibial tuberosity, and the transmalleolar axis using these CT scans in an adult population with ankle arthritis. Methods: 150 CT Scans of patients with end stage ankle osteoarthritis undergoing Psi, we measured the relationship between the transtibial axis, the tibial tuberosity and the transmalleolar axis (Figure 1). All CT scans were analysed using the Solidworks software (Dassault Systèmes). Varus or valgus arthritis, tibiotalar angle and presence of deformity was also recorded. Results: The mean difference in the axial plane between the transmalleolar axis and the tibial tuberosity was 17.9 ± 9.3 degrees externally rotated. There was a large range which was between -5 and 53 degrees of external rotation. The mean foot angle was 15.4 ± 11.1 degrees relative to the implant position. All planned implant positions were mean 1.0 ± 1.8 degrees (range -3.8 – 1.7 degrees) internally rotated to the transmalleolar axis. Varus or valgus ankle arthritis did not correlate with rotation of the tibial axis (p=0.4). Conclusion: There is a wide variation in rotational alignment of the tibia, which cannot be accurately assessed clinically or using plain radiographs. Surgical techniques that reference the tibial tuberosity to plan component alignment can be misleading and lead to implant malalignment. We recommend routine preoperative CT scanning prior to ankle replacement surgery and recommend research to assess the effects of axial rotation of implant performance and survival.

Finite element analysis of a total ankle replacement during the stance phase of gait

2006 ◽  
Vol 39 (8) ◽  
pp. 1435-1443 ◽  
Author(s):  
B. Reggiani ◽  
A. Leardini ◽  
F. Corazza ◽  
M. Taylor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stance Phase ◽  
Total Ankle Replacement ◽  
Element Analysis ◽  
Ankle Replacement

scholarly journals Influence of sagittal root positions on the stress distribution around custom-made root-analogue implants: a three-dimensional finite element analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chunping Lin ◽  
Hongcheng Hu ◽  
Junxin Zhu ◽  
Yuwei Wu ◽  
Qiguo Rong ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Class I ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Custom Made ◽  
Root Position ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Background Stress concentration may cause bone resorption even lead to the failure of implantation. This study was designed to investigate whether a certain sagittal root position could cause stress concentration around maxillary anterior custom-made root-analogue implants via three-dimensional finite element analysis. Methods The von Mises stresses in the bone around implants in different groups were compared by finite element analysis. Six models were constructed and divided into two groups through Geomagic Studio 2012 software. The smooth group included models of unthreaded custom-made implants in Class I, II or III sagittal root positions. The threaded group included models of reverse buttress-threaded implants in the three positions. The von Mises stress distributions and the range of the stresses under vertical and oblique loads of 100 N were analyzed through ANSYS 16.0 software. Results Stress concentrations around the labial lamella area were more prominent in the Class I position than in the Class II and Class III positions under oblique loading. Under vertical loading, the most obvious stress concentration areas were the labial lamella and palatal apical areas in the Class I and Class III positions, respectively. Stress was relatively distributed in the labial and palatal lamellae in the Class II position. The maximum von Mises stresses in the bone around the custom-made root-analogue implants in this study were lower than around traditional implants reported in the literature. The maximum von Mises stresses in this study were all less than 25 MPa in cortical bone and less than 6 MPa in cancellous bone. Additionally, compared to the smooth group, the threaded group showed lower von Mises stress concentration in the bone around the implants. Conclusions The sagittal root position affected the von Mises stress distribution around custom-made root-analogue implants. There was no certain sagittal root position that could cause excessive stress concentration around the custom-made root-analogue implants. Among the three sagittal root positions, the Class II position would be the most appropriate site for custom-made root-analogue implants.

On the Effect of Screw Preload on the Stress Distribution of Mandibles During Segmental Defect Treatment Using an Additively Manufactured Hardware

2016 ◽  
Author(s):  
Amirhesam Amerinatanzi ◽  
Narges Shayesteh Moghaddam ◽  
Ahmadreza Jahadakbar ◽  
David Dean ◽  
Mohammad Elahinia
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Fixation Device ◽  
Element Analysis ◽  
Porous Niti ◽  
The Finite Element Analysis ◽  
Low Stiffness ◽  
Von Mises

The most common method for mandibular reconstructive surgery is the use of a Ti-6Al-4V fixation device and a fibular double barrel graft. This highly stiff fixation hardware (E = 112 GPa) often shields the bone graft (E = 20 GPa) from carrying the load, which may result in bone resorption. Highly stiff Ti-6Al-4V fixation hardware is also likely to concentrate stress in the fixation plate or at screw threads, possibly leading to hardware cracking or screw pull-out. As a solution for that, we have proposed and studied the effect of using a low stiffness, porous NiTi fixation device [1–4]. Although the stress in the fixation device is increased, using such low stiffness fixation hardware, is preferable to have an even higher stress on the graft in order to minimize the risk of resorption or hardware failure. We assume that preloading screws allows them to better engage the fixation hardware with the plate and the surrounding bone and causes an increased von Mises stress. The fixation device can be patient-specific and additively manufactured, such that the shape would match the outer surface of the cortical bone. In this study, we modeled a healthy cadaver mandible via CT-derived 3D surface data. The mandible was virtually resected in the molar region (M1−3). The model simulated the result of reconstructive surgery under the highest chewing loading regime (i.e., 526 N on first right molar tooth [5, 6]) where reconstruction was done with either Ti-6Al-4V fixation hardware or patient specific, stiffness-matched, porous NiTi fixation hardware. The calibration of the material properties for this simulation was done using experimentally obtained data (DSC and compression tests) of Ni-rich NiTi bulk samples. The analyzed term in the finite element analysis was stress distribution in the cortical and cancellous bone. Porous NiTi fixation devices were also produced using Selective Laser Melting (SLM) using the geometry of the aforementioned cadaver mandible. In this paper we have studied the effect of additional torque or preload on the performance of the fixation plates. The finite element analysis demonstrated that applying a preload to the screws increased the stress on the bone. Under similar levels of applied preload, the porous NiTi fixation device showed an increased level of von Mises stress in the bone, particularly in the graft. Additionally, the analysis indicated the higher level of stress on the bone surrounding the screws for the case of using NiTi, which could contribute to increasing screw stability. The fabricated patient-specific fixation hardware not only matched the shape of cortical bone but also contained the level of porosity that defines the appropriate modulus of elasticity.

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