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Chen X, Lian T, Zhang B, Du Y, Du K, Xiang N, Jung DW, Wang G, Osaka A. Design and Mechanical Compatibility of Nylon Bionic Cancellous Bone Fabricated by Selective Laser Sintering. MATERIALS 2021; 14:ma14081965. [PMID: 33919911 PMCID: PMC8070912 DOI: 10.3390/ma14081965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/03/2021] [Accepted: 04/09/2021] [Indexed: 11/25/2022]
Abstract
In order to avoid the stress shielding phenomenon in orthopedic bionic bone implantation, it is necessary to consider the design of mechanical compatible implants imitating the host bone. In this study, we developed a novel cancellous bone structure design method aimed at ensuring the mechanical compatibility between the bionic bone and human bone by means of computer-aided design (CAD) and finite element analysis technology (specifically, finite element modeling (FEM)). An orthogonal lattice model with volume porosity between 59% and 96% was developed by means of CAD. The effective equivalent elastic modulus of a honeycomb structure with square holes was studied by FEM simulation. With the purpose of verifying the validity of the cancellous bone structure design method, the honeycomb structure was fabricated by selective laser sintering (SLS) and the actual equivalent elastic modulus of the honeycomb structure was measured with a uniaxial compression test. The experimental results were compared with the FEM values and the predicted values. The results showed that the stiffness values of the designed structures were within the acceptable range of human cancellous bone of 50–500 MPa, which was similar to the stiffness values of human vertebrae L1 and L5. From the point of view of mechanical strength, the established cellular model can effectively match the elastic modulus of human vertebrae cancellous bone. The functional relationship between the volume porosity of the nylon square-pore honeycomb structure ranging from 59% to 96% and the effective elastic modulus was established. The effect of structural changes related to the manufacture of honeycomb structures on the equivalent elastic modulus of honeycomb structures was studied quantitatively by finite element modeling.
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Affiliation(s)
- Xuewen Chen
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
- Correspondence: (X.C.); (D.-W.J.); (A.O.); Tel.: +86-136-9886-6192 (X.C.)
| | - Tingting Lian
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Bo Zhang
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Yuqing Du
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Kexue Du
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Nan Xiang
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Dong-Won Jung
- Faculty of Mechanical, Jeju National University, Jeju Island 63243, Korea
- Correspondence: (X.C.); (D.-W.J.); (A.O.); Tel.: +86-136-9886-6192 (X.C.)
| | - Guangxin Wang
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
| | - Akiyoshi Osaka
- School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; (T.L.); (B.Z.); (Y.D.); (K.D.); (N.X.); (G.W.)
- Institute of Engineering, Okayama University, Okayama 700-8530, Japan
- Correspondence: (X.C.); (D.-W.J.); (A.O.); Tel.: +86-136-9886-6192 (X.C.)
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Solitro GF, Mainnemare F, Amirouche F, Mehta A. A novel technique with reduced computed tomography exposure to predict vertebral compression fracture: a finite element study based on rat vertebrae. Med Biol Eng Comput 2018; 57:795-805. [PMID: 30402789 DOI: 10.1007/s11517-018-1918-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 10/21/2018] [Indexed: 10/27/2022]
Abstract
Vertebral compression fractures are a significant clinical issue with an annual incidence of approximately 750,000 cases in the USA alone. Mechanical properties of vertebrae are successfully evaluated through finite element (FE) models based on vertebrae CT. However, clinical drawbacks associated to radiation transmission encouraged to explore the possibility to use selected or reduced portions of the vertebra. The objective of our study was to develop a new procedure to predict vertebral compression fracture from sub-volumes. We reconstructed rat vertebras from micro-CT of thoracic and lumbar groups. Each vertebra was partitioned into three sub-volumes of different axial thickness. FE simulating compression tests were performed on each model to evaluate their failure load and stiffness. Using a power function, a high correlation was found for stiffness and strength. The sub-volume with three fifths thickness had a failure load of 180.7 ± 19.2 N for thoracic and of 209.5 ± 27.4 N for the lumbar vertebra. These values were not significantly different from the values found for the entire vertebra (p > 0.05). Based on our findings, failure loads and stiffnesses obtained with reduced CT scans can be successfully used to predict full vertebral failure. This sub-region analysis and power relationship suggests that one can limit radiation exposure to patients when bone characterization is needed. Graphical abstract Estimated mechanical properties in relation to the extent of the computed tomography reconstruction.
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Affiliation(s)
- Giovanni F Solitro
- Department of Orthopaedics, University of Illinois at Chicago, 835 S. Wolcott Avenue, Room E270, Chicago, IL, 60612, USA.,Department of Orthopaedic Surgery, Louisiana State University Health Science Center of Shreveport, 1501 Kings Hwy, Room 3-317, Shreveport, LA, 71104, USA
| | - Florian Mainnemare
- Department of Mechanical Engineering, ENS Cachan, Université Paris-Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France
| | - Farid Amirouche
- Department of Orthopaedics, University of Illinois at Chicago, 835 S. Wolcott Avenue, Room E270, Chicago, IL, 60612, USA.
| | - Ankit Mehta
- Department of Neurosurgery, University of Illinois at Chicago, 912 S Wood St, Chicago, IL, USA
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Tawara D, Nagura K. Predicting changes in mechanical properties of trabecular bone by adaptive remodeling. Comput Methods Biomech Biomed Engin 2016; 20:415-425. [DOI: 10.1080/10255842.2016.1238077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Daisuke Tawara
- Faculty of Science and Technology, Department of Mechanical and Systems Engineering, Ryukoku University, Otsu, Japan
| | - Ken Nagura
- Research & Development Division, Medical Equipment Section, TAKARA BELMONT Corp., Osaka, Japan
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Blanchard R, Morin C, Malandrino A, Vella A, Sant Z, Hellmich C. Patient-specific fracture risk assessment of vertebrae: A multiscale approach coupling X-ray physics and continuum micromechanics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02760. [PMID: 26666734 DOI: 10.1002/cnm.2760] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 10/14/2015] [Indexed: 06/05/2023]
Abstract
While in clinical settings, bone mineral density measured by computed tomography (CT) remains the key indicator for bone fracture risk, there is an ongoing quest for more engineering mechanics-based approaches for safety analyses of the skeleton. This calls for determination of suitable material properties from respective CT data, where the traditional approach consists of regression analyses between attenuation-related grey values and mechanical properties. We here present a physics-oriented approach, considering that elasticity and strength of bone tissue originate from the material microstructure and the mechanical properties of its elementary components. Firstly, we reconstruct the linear relation between the clinically accessible grey values making up a CT, and the X-ray attenuation coefficients quantifying the intensity losses from which the image is actually reconstructed. Therefore, we combine X-ray attenuation averaging at different length scales and over different tissues, with recently identified 'universal' composition characteristics of the latter. This gives access to both the normally non-disclosed X-ray energy employed in the CT-device and to in vivo patient-specific and location-specific bone composition variables, such as voxel-specific mass density, as well as collagen and mineral contents. The latter feed an experimentally validated multiscale elastoplastic model based on the hierarchical organization of bone. Corresponding elasticity maps across the organ enter a finite element simulation of a typical load case, and the resulting stress states are increased in a proportional fashion, so as to check the safety against ultimate material failure. In the young patient investigated, even normal physiological loading is probable to already imply plastic events associated with the hydrated mineral crystals in the bone ultrastructure, while the safety factor against failure is still as high as five. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Romane Blanchard
- TU Wien-Vienna University of Technology, Institute for Mechanics of Materials and Structures, Karlsplatz 13/202, Vienna 1040, Austria
| | - Claire Morin
- CIS-EMSE, CNRS:UMR 5307, LGF, Ecole Nationale Supérieure des Mines, Saint-Etienne, F-42023, France
| | - Andrea Malandrino
- Institute for Bioengineering of Catalonia, C/Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Alain Vella
- Mechanical Engineering Department, University of Malta, Tal Qroqq, Msida MSD, 2080, Malta
| | - Zdenka Sant
- Mechanical Engineering Department, University of Malta, Tal Qroqq, Msida MSD, 2080, Malta
| | - Christian Hellmich
- TU Wien-Vienna University of Technology, Institute for Mechanics of Materials and Structures, Karlsplatz 13/202, Vienna 1040, Austria
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Amjadi Kashani MR, Nikkhoo M, Khalaf K, Firoozbakhsh K, Arjmand N, Razmjoo A, Parnianpour M. An in silico parametric model of vertebrae trabecular bone based on density and microstructural parameters to assess risk of fracture in osteoporosis. Proc Inst Mech Eng H 2014; 228:1281-95. [DOI: 10.1177/0954411914563363] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Osteoporosis is a progressive bone disease characterized by deterioration in the quantity and quality of bone, leading to inferior mechanical properties and an increased risk of fracture. Current assessment of osteoporosis is typically based on bone densitometry tools such as Quantitative Computed Tomography (QCT) and Dual Energy X-ray absorptiometry (DEXA). These assessment modalities mainly rely on estimating the bone mineral density (BMD). Hence present densitometry tools describe only the deterioration of the quantity of bone associated with the disease and not the affected morphology or microstructural changes, resulting in potential incomplete assessment, many undetected patients, and unexplained fractures. In this study, an in-silico parametric model of vertebral trabecular bone incorporating both material and microstructural parameters was developed towards the accurate assessment of osteoporosis and the consequent risk of bone fracture. The model confirms that the mechanical properties such as strength and stiffness of vertebral trabecular tissue are highly influenced by material properties as well as morphology characteristics such as connectivity, which reflects the quality of connected inter-trabecular parts. The FE cellular solid model presented here provides a holistic approach that incorporates both material and microstructural elements associated with the degenerative process, and hence has the potential to provide clinical practitioners and researchers with more accurate assessment method for the degenerative changes leading to inferior mechanical properties and increased fracture risk associated with age and/or disease such as Osteoporosis.
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Affiliation(s)
| | - Mohammad Nikkhoo
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
- Institute of Biomedical Engineering, College of Medicine and Engineering, National Taiwan University, Taipei, Taiwan
| | - Kinda Khalaf
- Department of Biomedical Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi, UAE
| | | | - Navid Arjmand
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Arash Razmjoo
- Glenn Department of Civil Engineering, Clemson University, Clemson, SC, USA
| | - Mohamad Parnianpour
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
- Department of Industrial & Manufacturing Engineering, University of Wisconsin–Milwaukee, Milwaukee, WI, USA
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Wang W, Baran GR, Garg H, Betz RR, Moumene M, Cahill PJ. The Benefits of Cement Augmentation of Pedicle Screw Fixation Are Increased in Osteoporotic Bone: A Finite Element Analysis. Spine Deform 2014; 2:248-259. [PMID: 27927345 DOI: 10.1016/j.jspd.2014.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 02/03/2014] [Accepted: 03/17/2014] [Indexed: 10/25/2022]
Abstract
STUDY DESIGN Biomechanical study using a finite element model of a normal and osteoporotic lumbar vertebrae comparing resistance with axial pullout and bending forces on polymethylmethacrylate-augmented and non-augmented pedicle screws. OBJECTIVE To compare the effect of cement augmentation of pedicle screw fixation in normal and osteoporotic bone with 2 different techniques of cement delivery. SUMMARY OF BACKGROUND DATA Various clinical and biomechanical studies have addressed the benefits of cement augmentation of pedicle screws, but none have evaluated whether this effect is similar, magnified, or attenuated in osteoporotic bone compared with normal bone. In addition, no study has compared the biomechanical strength of augmented pedicle screws using cement delivery through the pedicle screw with delivery through a pilot hole. METHODS This study was funded by a grant from DePuy Synthes Spine. Normal and osteoporotic lumbar vertebrae with pedicle screws were simulated. The models were tested for screw pullout strength with and without cement augmentation. Two methods of cement delivery were also tested. Both methods were tested using 1 and 2.5 cm3 volume of cement infiltrated in normal and osteoporotic bone. RESULTS The increase in screw pullout force was proportionally greater in osteoporotic bone with equivalent volumes of cement delivered. The researchers found that 1 and 2.5 cm3 of cement infiltrated bone volume resulted in an increase in pullout force by about 50% and 120% in normal bone, and by about 64% and 156% in osteoporotic bone, respectively. The delivery method had only a minimal effect on pullout force when 2.5 cm3 of cement was injected (<4% difference). CONCLUSIONS Cement augmentation increases the fixation strength of pedicle screws, and this effect is proportionately greater in osteoporotic bone. Cement delivery through fenestrated screws and delivery through a pilot hole result in comparable pullout strength at higher cement volumes.
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Affiliation(s)
- Wenhai Wang
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA 19104, USA
| | - George R Baran
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA 19104, USA
| | - Hitesh Garg
- Artemis Health Institute, Sector 51, Gurgaon 122001, Haryana, India
| | - Randal R Betz
- Shriners Hospitals for Children-Philadelphia, 3551 North Broad Street, Philadelphia, PA 19140, USA
| | - Missoum Moumene
- DePuy Synthes Spine, Inc., 325 Paramount Drive, Raynham, MA 02767, USA
| | - Patrick J Cahill
- Shriners Hospitals for Children-Philadelphia, 3551 North Broad Street, Philadelphia, PA 19140, USA.
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A 3D elastic micropolar model of vertebral trabecular bone from lattice homogenization of the bone microstructure. Biomech Model Mechanobiol 2013; 13:53-83. [DOI: 10.1007/s10237-013-0486-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 03/16/2013] [Indexed: 10/27/2022]
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Abstract
We addressed the importance of defining a mechanical testing methodology for the compression of human trabecular bone specimens. In fact, currently there are several protocols to test trabecular bone, but a single, standard and validate method has not been accepted yet. In our work, human femoral epiphyses collected from patients with osteoporosis (fragility fractures) and hip osteoarthritis, submitted to total hip replacement surgery, were used. The aims of our work were to develop a mechanical testing methodology for the compression of trabecular bone specimens taking into account the optimization of bone extrinsic and intrinsic variables, in order to establish a patient bone sample database with clinical, structural and mechanical information. Extrinsic variables, such as the effect of specimen preparation, with particular focus on the dimensions of test specimens, and others associated with the compression test, such as the method employed to determine specimen deformation, and hence strain, were evaluated. Also, a new device used to withhold the specimens was developed and tested by the present authors. Although each specimen showed a unique behaviour, even when comparing compression curves between patients from the same disease group, implicating additional complexity and difficulty in the data analysis, the authors managed to assemble the results in two groups related with a possible difference in the deformation mechanisms occurring after yielding.
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Goda I, Assidi M, Ganghoffer JF. Cosserat 3D anisotropic models of trabecular bone from the homogenisation of the trabecular structure. Comput Methods Biomech Biomed Engin 2012; 15 Suppl 1:288-90. [DOI: 10.1080/10255842.2012.713645] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Kadir MRA, Syahrom A, Öchsner A. Finite element analysis of idealised unit cell cancellous structure based on morphological indices of cancellous bone. Med Biol Eng Comput 2010; 48:497-505. [DOI: 10.1007/s11517-010-0593-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Accepted: 02/24/2010] [Indexed: 12/31/2022]
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Tawara D, Sakamoto J, Murakami H, Kawahara N, Oda J, Tomita K. Mechanical evaluation by patient-specific finite element analyses demonstrates therapeutic effects for osteoporotic vertebrae. J Mech Behav Biomed Mater 2010; 3:31-40. [DOI: 10.1016/j.jmbbm.2009.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2008] [Revised: 03/11/2009] [Accepted: 03/11/2009] [Indexed: 11/25/2022]
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Neal ML, Kerckhoffs R. Current progress in patient-specific modeling. Brief Bioinform 2010; 11:111-26. [PMID: 19955236 PMCID: PMC2810113 DOI: 10.1093/bib/bbp049] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 09/20/2009] [Indexed: 11/13/2022] Open
Abstract
We present a survey of recent advancements in the emerging field of patient-specific modeling (PSM). Researchers in this field are currently simulating a wide variety of tissue and organ dynamics to address challenges in various clinical domains. The majority of this research employs three-dimensional, image-based modeling techniques. Recent PSM publications mostly represent feasibility or preliminary validation studies on modeling technologies, and these systems will require further clinical validation and usability testing before they can become a standard of care. We anticipate that with further testing and research, PSM-derived technologies will eventually become valuable, versatile clinical tools.
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Affiliation(s)
- Maxwell Lewis Neal
- Division of Biomedical and Health Informatics, University of Washington, USA
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Proximal half angle of the screw thread is a critical design variable affecting the pull-out strength of cancellous bone screws. Clin Biomech (Bristol, Avon) 2009; 24:781-5. [PMID: 19699567 DOI: 10.1016/j.clinbiomech.2009.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 07/17/2009] [Accepted: 07/20/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND Screws with strong pull-out strength have been sought for the treatment of cancellous bone. We hypothesized that an obliquely angled screw thread has advantages over conventional vertical thread with a minimal proximal half angle. METHODS Metal and bone screws were made of stainless steel and porcine cortical bone. Their proximal half angle was set at 0 degrees , 30 degrees , or 60 degrees . The screws were inserted into porcine cancellous bone. At 0 degrees , the thread faced the recipient bone vertically. Pullout tests at a rate of 30 mm/min (n=40, each screw type) and microcomputed tomography (n=6) were conducted. FINDINGS The pull-out strength of the screws was maximal at 30 degrees ; 348.8 (SD, 44.1)N with metal and 326.6 (39.4)N with bone. It was intermediate at 0 degrees ; 301.9 (35.9)N with metal and 278.2 (30.6)N with bone. It was minimal at 60 degrees; 126.5 (39.0)N with metal and 174.8 (29.7)N with bone. Cancellous bone was damaged between the threads at 30 degrees , while intact cancellous bone was preserved between the threads at 0 degrees. INTERPRETATION A proximal half angle of around 30 degrees is appropriate because the pullout force is applied to the recipient bone evenly. Commercial cancellous screws can be improved by changing the thread shape to minimize the damage to recipient bone.
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Noninvasive prediction of vertebral body compressive strength using nonlinear finite element method and an image based technique. Phys Med 2009; 26:88-97. [PMID: 19781969 DOI: 10.1016/j.ejmp.2009.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 08/11/2009] [Accepted: 08/15/2009] [Indexed: 11/23/2022] Open
Abstract
Noninvasive prediction of vertebral body strength under compressive loading condition is a valuable tool for the assessment of clinical fractures. This paper presents an effective specimen-specific approach for noninvasive prediction of human vertebral strength using a nonlinear finite element (FE) model and an image based parameter based on the quantitative computed tomography (QCT). Nine thoracolumbar vertebrae excised from three cadavers with an average age of 42 years old were used as the samples. The samples were scanned using the QCT. Then, a segmentation technique was performed on each QCT sectional image. The segmented images were then converted into three-dimensional FE models for linear and nonlinear analyses. A new material model was implemented in our nonlinear model being more compatible with real mechanical behavior of trabecular bone. A new image based MOS (Mechanic of Solids) parameter named minimum sectional strength ((sigma(u)A)(min)) was used for the ultimate compressive strength prediction. Subsequently, the samples were destructively tested under uniaxial compression and their experimental ultimate compressive strengths were obtained. Results indicated that our new implemented FE model can predict ultimate compressive strength of human vertebra with a correlation coefficient (R(2)=0.94) better than usual linear and nonlinear FE models (R(2)=0.83 and 0.85 respectively). The image based parameter introduced in this study ((sigma(u)A)(min)) was also correlated well with the experimental results (R(2)=0.86). Although nonlinear FE method with new implemented material model predicts compressive strength better than the (sigma(u)A)(min), this parameter is clinically more feasible due to its simplicity and lower computational costs. This can make future applications of the (sigma(u)A)(min) more justified for human vertebral body compressive strength prediction.
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Wolfram U, Ole Schwen L, Simon U, Rumpf M, Wilke HJ. Statistical osteoporosis models using composite finite elements: A parameter study. J Biomech 2009; 42:2205-9. [DOI: 10.1016/j.jbiomech.2009.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 05/23/2009] [Accepted: 06/02/2009] [Indexed: 10/20/2022]
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Abstract
Advances in computer power, novel diagnostic and therapeutic medical technologies, and an increasing knowledge of pathophysiology from gene to organ systems make it increasingly feasible to apply multiscale patient-specific modeling based on proven disease mechanisms. Such models may guide and predict the response to therapy in many areas of medicine. This is an exciting and relatively new approach, for which efficient methods and computational tools are of the utmost importance. Investigators have designed patient-specific models in almost all areas of human physiology. Not only will these models be useful in clinical settings to predict and optimize the outcome from surgery and non-interventional therapy, but they will also provide pathophysiologic insights from the cellular level to the organ system level. Models, therefore, will provide insight as to why specific interventions succeed or fail.
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Gefen A, Portnoy S, Diamant I. Inhomogeneity of tissue-level strain distributions in individual trabeculae: Mathematical model studies of normal and osteoporosis cases. Med Eng Phys 2008; 30:624-30. [PMID: 17697794 DOI: 10.1016/j.medengphy.2007.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 06/28/2007] [Accepted: 07/02/2007] [Indexed: 11/25/2022]
Abstract
Little is known about the distributions of mechanical strains and stresses in individual trabeculae of cancellous bone, despite evidence that tissue-level strains affect the metabolism of bone. Recently, micro-finite element (micro-FE) studies have provided the first insights into the mechanical conditions in trabeculae, and suggested that osteoporotic cancellous bone experience higher and substantially less-uniform strains with respect to healthy cancellous bone. We may therefore ask whether the inhomogeneity of bone tissue strains is predominantly a consequence of micro-architectural differences between trabeculae, or is it mostly caused by the curvatures of each individual trabecula. Accordingly, the objectives of the present study were to determine the contribution of the shape of a trabecula to the intra-trabecula strain inhomogeneity, and to determine potential differences in intra-trabecula strain inhomogeneities between normal and thinner, osteoporotic-like trabeculae. We employed our previously reported generic single-trabecula model, which is a mathematical representation of the shape of a trabecula based on statistical analyses of mammalian trabecular dimensions. The single-trabecula model was loaded axially and in bending, and strain distributions were calculated for individual trabeculae as well as for "populations" of trabeculae, formed by assigning different trabecular thickness values in the trabecular model, in order to represent the distributions of trabecular shapes in normal and osteoporotic bones. We found that when subjected to equivalent loads, thinner, osteoporotic-like individual trabeculae and populations of thin trabeculae developed substantially greater strain inhomogeneities compared with normal trabeculae. We conclude that the intra-trabecula strain inhomogeneities are likely to be an important factor contributing to the overall increased strain inhomogeneity in osteoporotic cancellous bone, as previously observed in micro-FE studies.
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Affiliation(s)
- Amit Gefen
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.
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