scholarly journals Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jun Fu ◽  
Ming Ni ◽  
Jiying Chen ◽  
Xiang Li ◽  
Wei Chai ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Bone Defect ◽  
Cancellous Bone ◽  
Acetabular Bone ◽  
Fea Model ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Von Mises ◽  
Von Mises Stresses

Purpose. The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones.Methods. The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N).Results. The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment.Conclusions. The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

scholarly journals Stress analysis of a Burch-Schneider cage in an acetabular bone defect: A case study

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Katrien Plessers ◽  
Hans Mau
Keyword(s):  
Bone Defect ◽  
Long Term Results ◽  
Element Analysis ◽  
Large Defect ◽  
Acetabular Bone ◽  
Acetabular Bone Defect ◽  
Increased Risk ◽  
Acetabular Bone Defects ◽  
Von Mises ◽  
Von Mises Stresses

Burch-Schneider cages are often used for the treatment of acetabular bone defects. In several clinical studies these cages have shown good mid- to long-term results. However, a higher failure rate has been reported in large Paprosky IIIB defects compared with smaller Paprosky II-IIIA defects. This study aims to investigate the effect of cage support on cage failure by means of finite element analysis. The Von Mises stresses in both the implant and the bone are analyzed for a Burch-Schneider cage used in the following scenarios: (1) a large acetabular bone defect, (2) a small acetabular bone defect and (3) a large acetabular bone defect in combination with a reinforcement plate. The results show that implant and bone stresses are higher in the large defect (99th percentile of 146.6 and 73.5 MPa respectively) than in the small defect (99th percentile of 43.9 and 47.9 MPa respectively). Adding a reinforcement plate to posteriorly support the cage decreases the stresses but not fully compensates for the missing bone support (99th percentile of 93.1 and 55.3 MPa respectively). Since high stresses cause an increased risk for fatigue failure and implant loosening, sufficient implant support is required to reduce the risk of cage failure.

scholarly journals Acetabular Bone Defect in Total Hip Arthroplasty for Crowe II or III Developmental Dysplasia of the Hip: A Finite Element Study

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yinqiao Du ◽  
Jun Fu ◽  
Jingyang Sun ◽  
Guoqiang Zhang ◽  
Jiying Chen ◽  
...  
Keyword(s):  
Bone Defect ◽  
Developmental Dysplasia ◽  
Von Mises Stress ◽  
Acetabular Cup ◽  
Acetabular Bone ◽  
Fea Model ◽  
Acetabular Bone Defect ◽  
The Stability ◽  
Von Mises ◽  
Different Diameters

Background. The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect in Crowe type II or III developmental dysplasia of the hip (DDH), which could evaluate the stability of the acetabular cup with different types of bone defects, different diameters of femoral ceramic heads, and the use of screws and analyze the stress distribution of screws. Methods. The FEA model was based on the CT scan of a female patient without any acetabular bone defect. The model of acetabular bone defect in total hip arthroplasty for Crowe II or III DDH was made by the increasing superolateral bone defect area of the acetabular cup. Point A was located in the most medial part of the acetabular bone defect. A 52 mm PINNACLE cup with POROCOAT Porous coating was implanted, and two screws (the lengths were 25 mm and 40 mm) were implanted to fix the acetabular cup. The stability of the acetabular cup and the von Mises stress of point A and screws were analyzed by a single-legged stance loading applied in 1948 N (normal working). The different diameters of the femoral ceramic head (28 mm, 32 mm, and 36 mm) were also analyzed. Results. The von Mises stress of point A was gradually increased with the increasing uncoverage values. When the uncoverage values exceeded 24.5%, the von Mises stress of point A without screws increased significantly, leading to instability of the cup. Screws could effectively reduce the von Mises stress of point A with uncoverage values of more than 24.5%. However, the peak von Mises stress in the screws with the uncoverage values that exceeded 24.5% was considerably increased. The diameter of the femoral ceramic head had no significant effect on the von Mises stress and the stability of the acetabular cup. Conclusions. We recommend that uncoverage values of less than 24.5% with or without screw is safe for patients with Crowe II or III DDH.

scholarly journals In Vivo Reconstruction of the Acetabular Bone Defect by the Individualized Three-Dimensional Printed Porous Augment in a Swine Model

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jun Fu ◽  
Yi Xiang ◽  
Ming Ni ◽  
Xiaojuan Qu ◽  
Yonggang Zhou ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Bone Defect ◽  
Bone Ingrowth ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Acetabular Bone ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Matching Degree

Background and Purpose. This study established an animal model of the acetabular bone defect in swine and evaluated the bone ingrowth, biomechanics, and matching degree of the individualized three-dimensional (3D) printed porous augment. Methods. As an acetabular bone defect model created in Bama miniswine, an augment individually fabricated by 3D print technique with Ti6Al4V powders was implanted to repair the defect. Nine swine were divided into three groups, including the immediate biomechanics group, 12-week biomechanics group, and 12-week histological group. The inner structural parameters of the 3D printed porous augment were measured by scanning electron microscopy (SEM), including porosity, pore size, and trabecular diameter. The matching degree between the postoperative augment and the designed augment was assessed by CT scanning and 3D reconstruction. In addition, biomechanical properties, such as stiffness, compressive strength, and the elastic modulus of the 3D printed porous augment, were measured by means of a mechanical testing machine. Moreover, bone ingrowth and implant osseointegration were histomorphometrically assessed. Results. In terms of the inner structural parameters of the 3D printed porous augment, the porosity was 55.48 ± 0.61 % , pore size 319.23 ± 25.05   μ m , and trabecular diameter 240.10 ± 23.50   μ m . Biomechanically, the stiffness was 21464.60 ± 1091.69   N / mm , compressive strength 231.10 ± 11.77   MPa , and elastic modulus 5.35 ± 0.23   GPa , respectively. Furthermore, the matching extent between the postoperative augment and the designed one was up to 91.40 ± 2.83 % . Besides, the maximal shear strength of the 3D printed augment was 929.46 ± 295.99   N immediately after implantation, whereas the strength was 1521.93 ± 98.38   N 12 weeks after surgery ( p = 0.0302 ). The bone mineral apposition rate (μm per day) 12 weeks post operation was 3.77 ± 0.93   μ m / d . The percentage bone volume of new bone was 22.30 ± 4.51 % 12 weeks after surgery. Conclusion. The 3D printed porous Ti6Al4V augment designed in this study was well biocompatible with bone tissue, possessed proper biomechanical features, and was anatomically well matched with the defect bone. Therefore, the 3D printed porous Ti6Al4V augment possesses great potential as an alternative for individualized treatment of severe acetabular bone defects.

Reconstruction of Paprosky type III Acetabular Defects by the Three-dimensional Printed Porous Augment: Techniques and Clinical Outcomes of 18 Consecutive Cases

2020 ◽  
Author(s):  
Jun Fu ◽  
Ming Ni ◽  
Xiang Li ◽  
Wei Chai ◽  
Libo Hao ◽  
...  
Keyword(s):  
Clinical Outcomes ◽  
Bone Defect ◽  
Three Dimensional ◽  
Acetabular Bone ◽  
Type Iii ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
The Mean ◽  
Acetabular Defects

Abstract Background and Purpose: A major challenge posed by primary and revision total hip arthroplasty (THA) is the management of severe acetabular bone defect. Previous surgical techniques have certain limitations in the anatomical reconstruction and accurate match of severe acetabular defects. Until now, reports are scanty on the clinical outcomes of acetabular reconstruction by the three-dimensional (3D) printed porous augments in bone defect patients. This study reported the clinical outcomes of reconstruction of Paprosky type III acetabular defects by 3D printed porous augments.Methods: 18 patients with Paprosky type III acetabular defects receiving reconstructive surgery by 3D printed porous augments were included in current study. Their data, including general information, intra-operative findings, imaging results, functional scores and complications were retrospectively analyzed.Results: The mean follow-up time lasted 33.3 ± 2.0 (24-56) months. The average limb-length discrepancy (LLD) was 31.7 ± 4.2 (3-59) mm preoperatively, 7.7 ± 1.4 (1-21) mm postoperatively (p<0.0001) and 7.5 ± 1.2 (0-18) mm at the latest follow-up. The mean vertical position of hip center of rotation (HCOR) from the inter teardrop line changed from preoperative 50.7 ± 3.9 (23.3-75.3) mm to postoperative 22.9 ± 1.9 (10.1-40.3) mm (p<0.0001), with the latest follow-up revealing an HCOR of 22.3 ± 1.7 (11.0-40.5) mm. Follow-up study showed that no hip had radiolucencies and radiological loosening of the acetabular components and augment. The average HHS improved from 40.3 ± 4.5 (10.5-71) before operation to 88.4 ± 1.9 (75-97) at the last follow-up (p<0.0001). Moreover, follow-up exhibited that no periprosthetic joint infection, hip dislocation, fracture and re-revision occurred. Conclusion: Surgical treatment of Paprosky type III acetabular defect with 3D printed porous augment was simple, achieved good match between porous augment and the defect bone surface and the acetabular component, ideally restored LLD and HCOR after operation, significantly improved HHS score and attained good early clinical outcomes. It is a promising personalized solution for patients with severe acetabular bone defect.

Evaluation of Optimal Taper of Immediately Loaded Wide-Diameter Implants: A Finite Element Analysis

2013 ◽  
Vol 39 (2) ◽  
pp. 123-132 ◽  
Author(s):  
Momen A. Atieh ◽  
Reza A. Shahmiri
Keyword(s):  
Finite Element ◽  
Cancellous Bone ◽  
Strain Distribution ◽  
Immediate Loading ◽  
Stress Strain ◽  
Wide Diameter ◽  
Mandibular Molar ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Molar Extraction

This study aimed to evaluate the effects of different tapering angles of an immediately loaded wide-diameter implant on the stress/strain distribution in bone and implant after implant insertion in healed or fresh molar extraction sockets. A total of 10 finite element (FE) implant-bone models, including 8.1-mm diameter implant, superstructure, and mandibular molar segment, were created to investigate the biomechanical behavior of different implant taper angles in immediate and delayed placement conditions. The degrees of implant taper ranged from 2° to 14°, and the contact conditions between the immediately loaded implants and bone were set with frictional coefficients (μ) of 0.3 in the healed models and 0.1 in the extracted models. Vertical and lateral loading forces of 189.5 N were applied in all models. Regardless of the degree of implant tapering, immediate loading of wide-diameter implants placed in molar extraction sockets generated higher stress/strain levels than implants placed in healed sockets. In all models, the von Mises stresses and strains at the implant surfaces, cortical bone, and cancellous bone increased with the increasing taper angle of the implant body, except for the buccal cancellous bone in the healed models. The maximum von Mises strains were highly concentrated on the buccal cortical struts in the extracted models and around the implant neck in the healed models. The maximum von Mises stresses on the implant threads were more concentrated in the non-tapered coronal part of the 11° and 14° tapered implants, particularly in the healed models, while the stresses were more evenly dissipated along the implant threads in other models. Under immediate loading conditions, the present study indicates that minimally tapered implants generate the most favorable stress and strain distribution patterns in extracted and healed molar sites.

scholarly journals The sensitivity of contact stresses in the mandibular premolar region to the shape of Zirconia dental implant: A 3D finite element study

2018 ◽  
Vol 24 (2) ◽  
pp. 55-63 ◽  
Author(s):  
Duraisamy Velmurugan ◽  
Masilamany Santha Alphin ◽  
Benedict Jain AR Tony
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cortical Bone ◽  
Transition Region ◽  
Dental Implant ◽  
Cancellous Bone ◽  
Contact Stresses ◽  
Thread Profile ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Background: Implant thread profile plays a vital role in magnitude and distribution of contact stresses at the implant-bone interface. The main goal of this study was to evaluate the biomechanical effects of four distinct thread profiles of a dental implant in the mandibular premolar region. Methods: The dental implant represented the biocompatible Zirconia material and the bone block was modelled as transversely isotropic and elastic material. Three-dimensional finite element simulations were conducted for four distinct thread profiles of a dental implant at 50%, 75%, and 100% osseointegration. An axial static load of 500 N was applied on the abutment surface to estimate the stresses acting within the bones surrounding the implant. Results: Regions of stress concentration were seen mostly along the mesiodistal direction compared to that in the buccolingual direction. The cortical bone close to the cervical region of the implant and the cortical bone next to the first thread of the implant experienced peak stress concentration. Increasing the degree of osseointegration resulted in increased von-Mises stresses on the implant-cortical transition region, the implant-cancellous transition region, the cortical bone, and the cancellous bone. Conclusion: The results show that the application of distinct thread profiles at different degrees of osseointegration had significant effect on the stresses distribution contours in the surrounding bony structure. Comparing all four thread profiles, a dental implant with V-thread profile induced lower values of von-Mises stresses and shear stresses on the implant-cortical transition region, implant-cancellous transition region, cortical bone, and cancellous bone.

EFFECT OF ANTERIOR IMPLANT POSITION ON BIOMECHANICAL PERFORMANCE IN THE MAXILLARY ALL-ON-FOUR TREATMENT: A 3-D FINITE ELEMENT ANALYSIS

2021 ◽  
Author(s):  
Taygun SEZER ◽  
Kerem Kilic ◽  
Emir Esim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Bone Tissue ◽  
Cancellous Bone ◽  
Principal Stresses ◽  
Element Analysis ◽  
Central Tooth ◽  
Von Mises ◽  
Von Mises Stresses

In the all-on-four concept, the positions of both posterior and anterior implants can affect stress distribution. The aim of this study was to examine the effect of the position of anterior implants on stress distribution in the implant, the bone around the implant, and prosthetic components in the resorbed maxilla using the all-on-four concept. All-on-four designs were prepared with three different anterior implant positions in a fully edentulous maxilla. Anterior implants were placed axially in the central incisor area in model 1, in the lateral incisors area in model 2, and in the canine area in model 3, forming three groups. The von Mises and principal stresses in the bone tissue and the von Mises stresses in the implant and prosthetic components were evaluated by three-dimensional finite element analysis. There were more stresses on the cortical bone than cancellous bone. The stresses on the bone tissue and implant components were generally concentrated around the posterior implant, whereas the stresses on the prosthetic components were generally concentrated in the anterior region. Changing the anterior implant positions from the central tooth to the canine tooth reduced the stress on the bone around the implant. The highest von Mises stresses occurred in the prosthetic superstructure in all models, whereas the lowest stresses occurred in the cancellous bone. Changing the position of the anterior implants from the central tooth to the canine area in the maxillary all-on-four concept created a favourable stress distribution.

A Finite Element Analysis of the Human Temporomandibular Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu
Keyword(s):  
Finite Element ◽  
Temporomandibular Joint ◽  
Reaction Force ◽  
Element Model ◽  
Contact Stresses ◽  
Element Analysis ◽  
Tensile Stresses ◽  
Reaction Forces ◽  
Von Mises ◽  
Von Mises Stresses

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.

scholarly journals A FEA-Based Methodology to Predict the Osteotome Wear Status during Nasal Bone Surgical Operations

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 855 ◽  
Author(s):  
G. Skordaris ◽  
F. Stergioudi ◽  
A. Boumpakis ◽  
D. Stergioudi ◽  
H. Behrbohm
Keyword(s):  
Fatigue Strength ◽  
Nasal Bone ◽  
Bone Geometry ◽  
Test Results ◽  
Surgical Instrument ◽  
Preventive Replacement ◽  
Fea Model ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Surgical Operations

A FEA-based methodology was developed in order to predict the wear status of an osteotome (surgical instrument) during its use in a lateral nasal bone osteotomy considering its fatigue strength. The latter parameter was determined by appropriate FEM-evaluation of the perpendicular impact test results. For the simulation of the surgical procedure, two scenarios were examined: (i) when utilizing a brand new osteotome and (ii) when utilizing an already used osteotome characterized by decreased fatigue strength. The actual nasal bone geometry used in the FEA model was obtained from a high-resolution, maxillofacial, computed tomography (CT) scan of a single patient. In both cases examined, depiction of fracture patterns for the osteotome and the nasal bone were obtained. The wear of a new osteotome and an already used osteotome was also calculated and compared. The developed von Mises stresses in both the osteotome and nasal bone were depicted. The proposed methodology allowed an accurate prediction of the critical number of impacts that the osteotome can receive during the lateral nasal osteotomy which is followed in all rhinoplasties. Based on the developed methodology, a preventive replacement of the osteotome before its extensive fracture can be determined, thereby minimizing the risk of postoperative complications.

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