scholarly journals Multiscale Design and Multiobjective Optimization of Orthopedic Hip Implants with Functionally Graded Cellular Material

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Sajad Arabnejad Khanoki ◽  
Damiano Pasini
Keyword(s):  
Bone Resorption ◽  
Relative Density ◽  
Titanium Implant ◽  
Functionally Graded ◽  
Interface Instability ◽  
Interface Failure ◽  
Bone Implant ◽  
Multiscale Mechanics ◽  
Cellular Microstructure ◽  
Dense Titanium

Revision surgeries of total hip arthroplasty are often caused by a deficient structural compatibility of the implant. Two main culprits, among others, are bone-implant interface instability and bone resorption. To address these issues, in this paper we propose a novel type of implant, which, in contrast to current hip replacement implants made of either a fully solid or a foam material, consists of a lattice microstructure with nonhomogeneous distribution of material properties. A methodology based on multiscale mechanics and design optimization is introduced to synthesize a graded cellular implant that can minimize concurrently bone resorption and implant interface failure. The procedure is applied to the design of a 2D left implanted femur with optimized gradients of relative density. To assess the manufacturability of the graded cellular microstructure, a proof-of-concept is fabricated by using rapid prototyping. The results from the analysis are used to compare the optimized cellular implant with a fully dense titanium implant and a homogeneous foam implant with a relative density of 50%. The bone resorption and the maximum value of interface stress of the cellular implant are found to be over 70% and 50% less than the titanium implant while being 53% and 65% less than the foam implant.

Multiscale Design and Multiobjective Optimization of Orthopaedic Cellular Hip Implants

2011 ◽  
Author(s):  
Sajad Arabnejad Khanoki ◽  
Damiano Pasini
Keyword(s):  
Finite Element ◽  
Bone Resorption ◽  
Multiobjective Optimization ◽  
Relative Density ◽  
Homogeneous Medium ◽  
Unit Cell ◽  
Interface Stress ◽  
Optimization Strategy ◽  
Interface Failure ◽  
Nsga Ii

A multiscale design and multiobjective optimization procedure is developed to design a new type of graded cellular hip implant. We assume that the prosthesis design domain is occupied by a unit cell representing the building block of the implant. An optimization strategy seeks the best geometric parameters of the unit cell to minimize bone resorption and interface failure, two conflicting objective functions. Using the asymptotic homogenization method, the microstructure of the implant is replaced by a homogeneous medium with an effective constitutive tensor. This tensor is used to construct the stiffness matrix for the finite element modeling (FEM) solver that calculates the value of each objective function at each iteration. As an example, a 2D finite element model of a left implanted femur is developed. The relative density of the lattice material is the variable of the multiobjective optimization, which is solved through the non-dominated sorting genetic algorithm II (NSGA-II). The set of optimum relative density distributions is determined to minimize concurrently interface stress distribution and bone loss mass. The results show that the amount of bone resorption and the maximum value of interface stress can be reduced by over 70% and 50%, respectively, when compared to current fully dense titanium stem.

scholarly journals Influence of calcium ion-modified implant surfaces in protein adsorption and implant integration

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Eduardo Anitua ◽  
Andreia Cerqueira ◽  
Francisco Romero-Gavilán ◽  
Iñaki García-Arnáez ◽  
Cristina Martinez-Ramos ◽  
...  
Keyword(s):  
Protein Adsorption ◽  
Titanium Implant ◽  
Volume Density ◽  
Bone Implant ◽  
The Mean ◽  
Intervention Costs ◽  
Medial Section ◽  
Post Implantation

Abstract Background Calcium (Ca) is a well-known element in bone metabolism and blood coagulation. Here, we investigate the link between the protein adsorption pattern and the in vivo responses of surfaces modified with calcium ions (Ca-ion) as compared to standard titanium implant surfaces (control). We used LC–MS/MS to identify the proteins adhered to the surfaces after incubation with human serum and performed bilateral surgeries in the medial section of the femoral condyles of 18 New Zealand white rabbits to test osseointegration at 2 and 8 weeks post-implantation (n=9). Results Ca-ion surfaces adsorbed 181.42 times more FA10 and 3.85 times less FA12 (p<0.001), which are factors of the common and the intrinsic coagulation pathways respectively. We also detected differences in A1AT, PLMN, FA12, KNG1, HEP2, LYSC, PIP, SAMP, VTNC, SAA4, and CFAH (p<0.01). At 2 and 8 weeks post-implantation, the mean bone implant contact (BIC) with Ca-ion surfaces was respectively 1.52 and 1.25 times higher, and the mean bone volume density (BVD) was respectively 1.35 and 1.13 times higher. Differences were statistically significant for BIC at 2 and 8 weeks and for BVD at 2 weeks (p<0.05). Conclusions The strong thrombogenic protein adsorption pattern at Ca-ion surfaces correlated with significantly higher levels of implant osseointegration. More effective implant surfaces combined with smaller implants enable less invasive surgeries, shorter healing times, and overall lower intervention costs, especially in cases of low quantity or quality of bone.

Alkali-Modified Titanium Surface Stimulating Formation of Bone-Implant Interface

2007 ◽  
Vol 361-363 ◽  
pp. 749-752
Author(s):  
J. Strnad ◽  
Jan Macháček ◽  
Z. Strnad ◽  
C. Povýšil ◽  
Marie Strnadová
Keyword(s):  
Titanium Implant ◽  
Surface Characteristics ◽  
Healing Time ◽  
Machined Surface ◽  
Implant Surface ◽  
Bone Implant ◽  
Bone Response ◽  
Modified Surface ◽  
The Difference ◽  
Titanium Implant Surface

This study was carried out to assess the bone response to alkali-modified titanium implant surface (Bio surface), using histomorphometric investigation on an animal model. The mean net contribution of the Bio surface to the increase in bone implant contact (BIC) with reference to the turned, machined surface was evaluated at 7.94 % (BIC/week), within the first five weeks of healing. The contribution was expressed as the difference in the osseointegration rates ( BIC/'healing time) between the implants with alkali modified surface (Bio surface) and those with turned, machined surface. The surface characteristics that differed between the implant surfaces, i.e. surface morphology, specific surface area, contact angle, hydroxylation/hydration, may represent factors that influence the rate of osseointegration.

The Microtomographic Evaluation of Marginal Bone Resorption of Immediately Loaded Scalloped Design Implant With Various Microthread Configurations in Canine Mandible: Pilot Study

2010 ◽  
Vol 36 (5) ◽  
pp. 357-362 ◽  
Author(s):  
Young-Seok Park ◽  
Seung-Pyo Lee ◽  
Chong-Hyun Han ◽  
Joo Hyun Kwon ◽  
Young-Chul Jung
Keyword(s):  
Pilot Study ◽  
Bone Resorption ◽  
Bone Loss ◽  
Titanium Implant ◽  
Marginal Bone Loss ◽  
Future Studies ◽  
Preliminary Study ◽  
Type 3

Abstract This study was undertaken to evaluate the effect of microthread geometry of scalloped design implant on marginal bone resorption. Four types of scalloped design titanium implant specimens were prepared. The type 1 implant had a machined scalloped collar, type 2 had a sandblasted and acid-etched scalloped collar, type 3 had horizontal microthreads, and type 4 had parabolic microthreads, which are parallel with the scalloped conical margin. Two implants of a type were randomly installed immediately after extraction in the mandible of a beagle dog. Definitive prostheses were delivered immediately after surgery. After 12 weeks of healing, the dog was sacrificed and microtomography was performed. Type 4 specimens showed a marginal bone loss pattern definitively analogous to the scalloped margin. In this preliminary study, microthread geometry affected the marginal bone resorption pattern of scalloped design implants. However, additional specimens and more controlled conditions should be applied in future studies to confirm these results.

Functionally Graded Dental Implant and its Effect on Bone Remodeling

2008 ◽  
Vol 47-50 ◽  
pp. 1035-1038 ◽  
Author(s):  
Daniel Lin ◽  
Qing Li ◽  
Wei Li ◽  
Michael V. Swain
Keyword(s):  
Dental Implant ◽  
Bone Remodelling ◽  
Early Stage ◽  
Titanium Implant ◽  
Functionally Graded ◽  
Critical Problem ◽  
Long Term Effect ◽  
Graded Material ◽  
Bio Compatibility

Currently, titanium dominates the dental implant materials due to its strength and bio-inerrability. The use of titanium implant had demonstrated considerable surgical success. However, researchers are spontaneously pursuing better materials to achieve better osseointegration in the early stage of implantation. Recently, dental implants based on functionally graded material (FGM) were introduced in pursuit for the goal of enhanced bio-compatibility. The concept for FGM dental implant is that the property would vary in certain pattern to match the biomechanical characteristics required at different regions in the oral bone. However, mating properties do not necessarily guarantee better osseointegration and bone remodelling. There is no existing report available on the long-term effect of FGM dental implant on its hosting bone tissues. This paper aims at exploring this critical problem by using computational bone remodelling technique. The magnitude of bone remodelling due to use of FGM implant is identified over a healing period of four years. Comparisons were made between titanium and various FGM designs, the interesting differences were observed and the optimum FGM design was suggested based on the remodelling results.

Finite element analysis of gradient lattice structure patterns for bone implant design

2020 ◽  
Vol 11 (4) ◽  
pp. 535-545
Author(s):  
Asliah Seharing ◽  
Abdul Hadi Azman ◽  
Shahrum Abdullah
Keyword(s):  
Finite Element Analysis ◽  
Relative Density ◽  
Mechanical Behaviour ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Element Analysis ◽  
Bone Implant ◽  
Content Type ◽  
Octet Truss ◽  
Structure Patterns

PurposeThe objective of this paper is to identify suitable lattice structure patterns for the design of porous bone implants manufactured using additive manufacturing.Design/methodology/approachThe study serves to compare and analyse the mechanical behaviours between cubic and octet-truss gradient lattice structures. The method used was uniaxial compression simulations using finite element analysis to identify the translational displacements.FindingsFrom the simulation results, in comparison to the cubic lattice structure, the octet-truss lattice structure showed a significant difference in mechanical behaviour. In the same design space, the translational displacement for both lattice structures increased as the relative density decreased. Apart from the relative density, the microarchitecture of the lattice structure also influenced the mechanical behaviour of the gradient lattice structure.Research limitations/implicationsGradient lattice structures are suitable for bone implant applications because of the variation of pore sizes that mimic the natural bone structures. The complex geometry that gradient lattice structures possess can be manufactured using additive manufacturing technology.Originality/valueThe results demonstrated that the cubic gradient lattice structure has the best mechanical behaviour for bone implants with appropriate relative density and pore size.

scholarly journals MODELING PULL-OUT TEST OF DENTAL IMPLANTS

2003 ◽  
Vol 15 (04) ◽  
pp. 133-142 ◽  
Author(s):  
ANNA DOLLAR ◽  
KEVIN P. MEADE
Keyword(s):  
Continuous Distribution ◽  
Singular Integral Equations ◽  
Analytical Techniques ◽  
Relative Displacement ◽  
Interface Failure ◽  
Bony Tissue ◽  
Bone Implant ◽  
Pull Out ◽  
Edge Dislocations ◽  
Quantities Of Interest

The objective of this paper is to investigate bone-implant interface failure using analytical techniques of fracture mechanics. The implant usually is anchored to the surrounding bone by growth of bony tissue into the surface of the implant. A mechanical interlock is formed between the implant and the bone. Plane strain conditions are imposed. By using a continuous distribution of edge dislocations to represent interfacial debonding, the problem reduced to a system of singular integral equations that was solved numerically using standard collocation techniques. Quantities of interest are the extent of the debonded zone, the relative displacement between the implant and the bone and the stresses at the bone-implant interfaces, all of which depend on the load in a nonlinear fashion.

scholarly journals Anodisation Increases Integration of Unloaded Titanium Implants in Sheep Mandible

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Warwick J. Duncan ◽  
Min-Ho Lee ◽  
Tae-Sung Bae ◽  
Sook-Jeong Lee ◽  
Jennifer Gay ◽  
...  
Keyword(s):  
Titanium Implant ◽  
Titanium Implants ◽  
Implant Stability ◽  
Bone Implant ◽  
Implant Stability Quotient ◽  
Phosphate Ions ◽  
Surface Control ◽  
Bone Implant Contact ◽  
The Subject ◽  
Clinically Significant

Spark discharge anodic oxidation forms porous TiO2films on titanium implant surfaces. This increases surface roughness and concentration of calcium and phosphate ions and may enhance early osseointegration. To test this, forty 3.75 mm × 13 mm titanium implants (Megagen, Korea) were placed into healed mandibular postextraction ridges of 10 sheep. There were 10 implants per group: RBM surface (control), RBM + anodised, RBM + anodised + fluoride, and titanium alloy + anodised surface. Resonant frequency analysis (RFA) was measured in implant stability quotient (ISQ) at surgery and at sacrifice after 1-month unloaded healing. Mean bone-implant contact (% BIC) was measured in undemineralised ground sections for the best three consecutive threads. One of 40 implants showed evidence of failure. RFA differed between groups at surgery but not after 1 month. RFA values increased nonsignificantly for all implants after 1 month, except for controls. There was a marked difference in BIC after 1-month healing, with higher values for alloy implants, followed by anodised + fluoride and anodised implants. Anodisation increased early osseointegration of rough-surfaced implants by 50–80%. RFA testing lacked sufficient resolution to detect this improvement. Whether this gain in early bone-implant contact is clinically significant is the subject of future experiments.

3D Printing of Parts with Intra-Layer Variable Density

2019 ◽  
Vol 799 ◽  
pp. 288-293
Author(s):  
Angelos Vassilakos ◽  
John Giannatsis ◽  
Vasilios Dedousis
Keyword(s):  
3D Printing ◽  
Relative Density ◽  
Internal Structure ◽  
Variable Density ◽  
Functionally Graded ◽  
Density Values ◽  
Time Part ◽  
Innovative Potential ◽  
Short Time ◽  
Complex Parts

3D Printing can be considered as one of the most innovative manufacturing processes of our time. Part of the innovative potential of 3D Printing is associated with the production of geometrically complex parts in a relatively short time. In the present paper, a methodology for the production of parts with complex internal structure and intra-layer density variability (ILDV) is presented. The proposed methodology may be used to produce structures composed by two materials, such as functionally graded parts and composites. The variability of the internal structure and composition is captured through voxel modeling, where at each voxel a unique relative density value for each material is assigned. These relative density values are then translated to predefined extrusion paths, which the 3D printer follows for the construction of layers composed by one or two materials. Representative cases and examples of parts with ILDV are presented and discussed.

scholarly journals Porous architected biomaterial for a tibial-knee implant with minimum bone resorption and bone-implant interface micromotion

2018 ◽  
Vol 78 ◽  
pp. 465-479 ◽  
Author(s):  
Amirmohammad Rahimizadeh ◽  
Zahra Nourmohammadi ◽  
Sajad Arabnejad ◽  
Michael Tanzer ◽  
Damiano Pasini
Keyword(s):  
Bone Resorption ◽  
Bone Implant
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