Three-Dimensional Finite Element Analysis of Surface Mesh Model of Human Tibia Bone

 

K. Pradeep1, V. E. Jayanthi1*, K. Hemalatha2, K. Adalarasu3, M. Jagannath4

1PSNA College of Engineering and Technology, Dindigul, Tamil Nadu, India

2Dhanalakshmi Srinivasan Engineering College, Perambalur, Tamil Nadu, India

3SASTRA Deemed to be University, Thanjavur, Tamil Nadu, India

4Vellore Institute of Technology (VIT), Chennai, Tamil Nadu, India

*Corresponding Author E-mail: jayanthi.ramu@gmail.com

 

ABSTRACT:

The tibia bone or shank bone is the bigger and stronger of the two bones in the leg below the knee in vertebrates, and it associates the knee with the ankle bones. 3D model is proposed to improve the performance of non-linear analysis in tibia deformation from 2D DICOM Computer Tomography image. Materialize Interactive Medical Image Control System (MIMICS) software is used to develop surface mesh 3D model of tibia bone. Material properties, boundaries conditions and self-weight of the body are the elements used in Finite Element Analysis (FEA) to analyze the nodal solution of displacement, stress and strain using ANSYS software. Proposed model is able to estimate and analyze the displacement, von Mises stress and von Mises strain values of tibia bone by applying various static loads conditions. The results are helpful to develop a rapid prototype (RP) Model of mimic natural bone using bioactive synthetic ceramics material.

 

KEYWORDS: Finite Element Analysis, Material Interactive Medical Image Control System (MIMICS), ANSYS, Tibia Bone, Rapid Prototype Model.

 

 


INTRODUCTION:

A bone graft is an invasive technique applied to fix fractures in bones and joints. Transplantation of bone tissue called bone graft which helps in fixing bones when they are damaged from joints issue. Bone grafting is frequently used to augment bone healing and growth of bone in the fracture site during surgery to reconstructing or replacing skeletal defects have been described by Gazdag et al1. Surgical strategies include bleeding, contagion and responses to anaesthesia. Bone grafts convey the dangers of surgical methodology furthermore with ache, bulge, nerve damage and inflammation. Computer modelling method for developing a three-dimensional bone graft structure is introduced. Geometric and Computer Aided Design (CAD) based computer modelling approaches are carried out by Lal et al2.

 

The alternative treatment for bone graft is implantation of bone by removal of fractured bone. Various parameters are needed to analyse before the implantation is replaced during surgery. The parameters like displacement, von Mises stress, von Mises strain are measured from three-dimensional (3D) image acquired from cone-beam Computed Tomography (CT) scanner but it is more expensive.

 

Materialize Interactive Medical Image Control System (MIMICS) is an intuitive tool for the perception and division of 3D image from 2D-DICOM image from CT and MRI imaging modality. The object (s) to be visualized as well as delivered is characterized precisely by medical professionals and technical knowledge isn't vital for making 3D model representations of medical objects using MIMICS. MIMICS software used for diagnosis, surgical and dental strategies planning. In this way, medical doctors can analyse and decide the well ordered strategy in the actual stage with a computer3. Operation planning and rehearsals are carried out by MIMICS. The software is very flexible to interface the Rapid Prototyping (RP) model for building distinctive gives a consistent work process stage and thus change from Computer Tomography (CT) and Magnetic Resonance Imaging (MRI) data into 3D models is simpler. 3-Matic software used to increase and enhance the quality of triangles (diminishing or expanding the quantity of triangles) using meshing technique4.

 

Arrangement of new prosthesis on a patient requires estimating the correct dimension of a patient’s body. Such estimation includes different parameters and henceforth an exact technique is required. Artistic rendering utilizing manual measurements estimations includes significant time, exertion and cost and are also prone to error. Three-dimensional model based ANSYS software provides a better alternative measurement for the artistic rendering. Finite Element Analysis (FEA) is utilized to assess a stresses developed in the tibia bone under different static load conditions and material properties. Analysis of stress dispersion is clarified by Teixeira et al5. considering 100N load with the arrangement of the most exterior planes of the models, which demonstrates a minimal bone length of 4.2 mm.

 

Prosthetic bone implants are fabricated to approximately replicate a patient's original bone6. Rapid Prototyping (RP) is utilized for 3D printing or prosthesis creation. Nano crystal aggregate and collagen are the properties of 3D structural cancellous bone. To mimic the cancellous bone properties need Rapid Prototyping (RP) type model using bioactive synthetic material. Calcium ion (Ca2+)-implanted titanium and Hydroxyapatite (HA) are broadly utilized biocompatible ceramic material in medicine, yet essentially for contact with bone tissue, because of its similarity to mineral bone7.

 

The paper is organised with following sections, Section 2 describes the steps involved in tibia bone analysis and implantation. Section 3 discussed the results of the proposed system. The work is concluded in Section 4.

 

MATERIAL AND METHODS:

In traditional practices scanned images are diagnosed with the help of film photography. The various steps to convert CT or MRI scanned 2D DICOM image data into 3D image are: Segment the data to get Region of Interest (ROI), Convert the segmented data into 3D model and Export the model into different configurations as required for additionally preparing like Finite Element Analysis or Rapid Prototyping. Block diagram of the proposed technique to obtain the Finite Element Analysis of surface mesh 3D model tibia bone using MIMICS and ANSYS software is shown in Figure 1.

 

 

 

Input Image and Density Segmentation:

MIMICS V14.12 information tool is used for effective analysis. 2-D DICOM Computer Tomography image size of 48 cross sectional layers with 0.6 mm thickness is taken as input image for the conversion of 3D model. Initially, Region of Interest (ROI) is chosen from the input image using segmentation process based on the measurement of the distance of any cavity, area and bone length. Secondly, segmented ROI from 2D DICOM CT image is imported into MIMICS package, where the entire slices is get loaded and converted into 3D data model (Axial, Coronal and Sagital view).

 

MIMICS V14.12 is used for the selection of Region of Interest (ROI) in the given input image using segmentation process based on the measurement of the distance of any cavity, area and bone length. Editing operation is manually carried out based on density mask to reconstruct the bone separately in the bone structure.

 

Re-Meshing:

Three-dimensional modelling of tibia bone is re-meshed using 3-matics platform. The gap between bones ordinarily involved by cartilages and sinovial liquid are not segmented in ROI. The cartilages are displayed independently in a CAD system permits to separate the posterior region. The important factor to be considered in Finite Element Analysis is to assign a different material property based on the kinematic constraints8. The created essential 3D models are then exported as geometrical records for a 3-matic platform and afterward permitted to 3D geometrical operations. The small holes in the 3D model are considered as bad triangles. Triangular mesh is carried out to increase the quality of triangles by reducing the bad triangles in the bone is called triangular reduction. Cavity fill operations at the density masks are likewise acknowledged to accomplish independent and smoother primary 3D models.Poly lines are created to permit the utilization of the “Cavity Fill from Polylines” tool, in order to easier way of eliminating internal voids. In region growing process geometrical separation is happen by the way of disconnecting the adjacent mask is named as volume mesh as shown in the Figure 2.

 

Region growing operations are performed in all slices present in the CT scan image. Volume Meshing is done to increment and enhance the quality of triangles in 3-matic platform. Volume mesh is generated by assigning material properties to get realistic simulation result. If 3D structure is not well defined then the error is occurred, while applying load in ANSYS software. In region growing process tibia 3D structure is well defined. Surface mesh is performed to improve the strength of 3D volume mesh structure and it is shown in the Figure 3. Segmented tibia bone is modeled in 3D data image and then re-meshed in 3-matic platform is shown in Figure 4.

 

Figure 1: Block diagram of three-dimensional finite element analysis of surface mesh model tibia bone using MIMICS and ANSYS software.

 

Figure 2: Volume mesh of human tibia bone 3D model image.

 

 

Figure 3: Surface mesh of human tibia bone 3D model image.

 

 

Figure 4: Re-meshed 3D model of human tibia bone in 3-Matic platform.

 

Finite Element Analysis:

To test the execution of Re-meshed 3D Model, the 3D model is import to ANSYS software. ANSYS software required lower and upper limit of 250 Hounsfield units (HU) and 2000 Hounsfield units (HU) of volume soft tissues to isolate bone from the bone structure. Load, material property and boundary condition are applied to calculate the Displacement, von Mises stress and von Mises strain values of tibia bone using FEA. The stress and strain calculation of different load is important for implementation of Rapid Prototyping (RP) model. Performance of Rapid Prototyping (RP) model is increased, while increasing the implant bone diameter; stress and strain is clearly described by Ding et al9. FEA in ANSYS software is utilized for testing the mechanical behavior of the tibia bone and it is used for posterior validation with experimental values before surgical procedure.

 

RESULTS AND DISCUSSION:

Prevalence of occurrence of injury is common to the lower extremities because of the road accidents, especially, during the collision of a vehicle and pedestrian. This situation brings out fractures of long bones, injuries to the knee and ankle10. FEA report is helpful to known the in performance of biomechanical test and orthopedic conclusions before surgery procedures. Finite element analysis is carried out using ANSYS software. Titanium material is considered for measuring the mechanical properties. Initially, 10N load is applied to the human tibia bone to measure the corresponding displacement, stress and strain, the values are listed in Table 1 and their structural view are shown in Figure 5 (a), 5(b) and 5(c).

 

Table 1: Finite element analysis report of measured parameters.

Nodal solutions after the applied load of 10 N

Parameter

Tibia

Displacement (m)

29.681

von Mises stress (pa) max

242.12

von Mises strain (pa) max

0.0334

 

Figure 5: (a) Displacement vector sum of human tibia bone.

 

Figure 5: (b) von Mises strain of human tibia bone.

 

Figure 5: (c) von Mises stress of human tibia bone.

 

For validation and verification the mechanical responses of the model is basement to design and develop an implanted plate for fractured tibia bone and tested for various load conditions11. Various load such as 10 N, 50 N, 100 N, 150 N, 200 N, 250 N, 300 N are applied to 3D model of tibia bone to measure all three parameters and their results are listed in Table 2. From this analysis, the stress and strain value are same but their displacement is varies with respect to the load. From the review, different materials have their own stress and strain value. If the load changes then displacement would change but stress and strain remains constant.

 

Table 2: Finite element analysis report of measured parameters with applied loads.

Displacement vector sum for various load conditions

Load conditions applied (N)

Displacement (max) of tibia bone (mm)

50

14.85

100

26.98

150

46.25

200

61.75

250

74.84

300

86.60

CT image were used to obtain the finite element (FE) models of human tibia bones and its effects on tibia structure and properties of materials in the case of stance phrase running. MIMIC V14.12 and ANSYS software’s are used to construct the 3D tibia models. Hyper mesh V.12 software is used to create the FE model and stress distribution was analyzed by ANSYS V14.5 software in the tibia bones12. The main causes of long term bone fracture, bone restoration, developed stresses and contact conditions at the bone can be easily investigated by FEA. Surface meshing is used to reconstruct stable 3D FE models of tibia bone. Equilateral triangles to the 3D models of bone and generation of surface mesh from automatic re-meshing operation done by MIMICS and FEA. The size of the 3D triangles reduced and their quality is improved by some other operations. For every bone in human body having different material properties because human bones are made up of compact and spongy bones. In MIMIC, properties of materials calculated from gray values of CT data are assigned based on uniform method. Finite element model of the 3D volumetric meshed and materials of bone converted into ANSYS V14.0 under different conditions. Tibia bone structure is very typical and equally distributed in all the directions13. The distribution of the stresses on tibia bone can be carried out by FE analysis. If the body weight load is increased automatically contact and compressive stresses will be increased14.

 

CONCLUSION:

The texture information of tibia bone is analyzed by 3D model for implantation of abnormal tibia bone. MIMICS V14.12 information tool is used for converting Region of Interest (ROI) of 2D DICOM CT scanner image into 3D mesh image in the form of surface mesh. Nodal solution is required for implanting any kind of bone. ANSYS software package is used for non-linear analysis of displacement, von Mises stress and von Mises strain. Methodology discussed in this paper is the foundation in development of implantation of abnormal tibia bone by applying the different load conditions. This helps to develop a rapid prototype implant of human tibia bone.

 

ACKNOWLEDGEMENT:

The authors would like to thank all researchers contributed their study in field of biomechanics and modelling.

 

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

 

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Received on 10.03.2018         Modified on 19.04.2018

Accepted on 20.05.2018        © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(7): 2752-2756.

DOI: 10.5958/0974-360X.2018.00508.5