The indicated alloy is subjected to the following heat treatment methods: We compared the mechanical environment in the in-lay and on-lay collar configurations, through metrics of reconstruction safety, osseointegration potential, and risk of long-term bone resorption due to stress-shielding. doi:10.1097/00003086-199201000-00014, Jeys, L. M., Kulkarni, A., Grimer, R. J., Carter, S. R., Tillman, R. M., and Abudu, A. A = 192.65 [W/m2] x 30 [m2] = 5779.55 W. The information contained in this website is for general information purposes only. Calculate the rate ofheat fluxthrough a wall 3 m x 10 m in area (A = 30 m2). To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. Bone and Jt. Loosening of EPRs is associated with loss of cortical bone, initially at the point of contact between the bone and the collar of the prosthesis, then progressing along the stem (Mumith et al., 2017). This VOI was then eroded to consider B) the first two layers of bone elements extending radially from the implant, and then C) only the first layer of elements in contact with the implant. doi:10.1016/j.medengphy.2006.10.014, Toogood, P. A., Skalak, A., and Cooperman, D. R. (2009). Description of the loads and constraints applied to simulate level walking. Ti6Al4V J. Biomechanics 36, 897904. Front. An element-specific calculation was possible as for each PFR model we had built a corresponding isotopological intact model. Material WebSteel vs Titanium Steels Steels are ironcarbon alloys that may contain appreciable concentrations of other alloying elements. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Modeling three-dimensional-printed trabecular metal structures with a homogenization approach: Application to hemipelvis reconstruction. Few studies have investigated the mechanical environment surrounding the collar and stem in endoprosthetic reconstruction. For vapors, it also depends upon pressure. A modified method for assigning material properties to FE models of bones. In the implanted models we simulated immediate post-operative conditions. Frontiers | Does a novel bridging collar in endoprosthetic However, the in-lay design seemed to offer a slight advantage also in this case, as the decrease of resorption risk was more marked, and more uniform around the collar interface, while the whole lateral aspect in the on-lay design remained at risk of resorption. This plastic rod has a cross-sectional area of 1 cm2. With increasing strain rate, there is an increase in modulus (material behaves in a more brittle manner). Bone and Jt. Supervision: ES and FT. Project administration: ES. Differences in strain with respect to intact conditions were localized at the inner bone-PFR interface, being more marked in the collar-bone interface and levelling off moving distally (longitudinal strain maps in Supplementary Appendix S1). Ti6Al4V Crystal Structure. The Youngs modulus derived from this experiment is 71 GPa for stresses between 500 and 800 MPa. FIGURE 3. BONE Jt. Perren award 2014: Safety factor of the proximal femur during gait: A population-based finite element study. Ultimate tensile strength of Ti-6Al-4V Grade 5 titanium alloy is about 1170 MPa. (2005) because it is rather simple, yet validated against loads from instrumented prostheses, and already used in preclinical testing of joint prosthesis (Martelli et al., 2011a). In t (2013). Elastic properties of the titanium alloy Ti-6Al-4V 78, 513. We realize that the basics in the materials science can help people to understand many common problems. With these composite systems, it is often convenient to work with anoverall heat transfer coefficient,known as aU-factor. Atlas of individual radiographic features in osteoarthritis, revised. Ti6Al4V The mechanical environment is hypothesised to be further optimised with an in-lay collar and thereby maximising ECBB at the implant-bone interface. Bone and Jt. doi:10.1016/S0021-9290(03)00257-4, Biemond, J. E., Aquarius, R., Verdonschot, N., and Buma, P. (2011). 119, 228231. J. Biomechanics 40, 23182323. Static coefficient of friction between stainless steel and PMMA used in cemented hip and knee implants. 30, 444453. doi:10.1016/j.joca.2006.11.009, Bayraktar, H. H., Morgan, E. F., Niebur, G. L., Morris, G. E., Wong, E. K., and Keaveny, T. M. (2004). Typical physical properties for Ti6Al4V. Bone from the cortex at this site grows out and over the collar of the prosthesis. Steel vs Titanium - Comparison - Pros and Cons A is the cross-sectional surface area or the cross-section perpendicular to the applied force. In words, the density () of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. Themelting pointof a substance is the temperature at which this phase change occurs. Feel free to ask a question, leave feedback or take a look at one of our articles. J. J. Biomechanical Eng. 2) You may not distribute or commercially exploit the content, especially on another website. Stainless Steel vs Titanium Alloy Comparison Pros and Phys. K,[12][13] which contributes to its relatively poor machinability. Proc. The in-lay collar demonstrated more uniform load transfer into the bone with a more physiological pattern, and the predictions of bone apposition were double than with an on-lay collar. Large-sliding contact elements accurately predict levels of boneimplant micromotion relevant to osseointegration. However, as i) the maximum value arose in a small location close to an edge and ii) we neither modelled the fine details of the geometry (e.g., fillets, which may decrease stress concentration) nor the trabecular titanium surface (which may instead increase stress concentration especially if residual stresses are not relieved), the final conclusions about prosthesis safety should be left to experimental fatigue testing. To permit an element-by-element comparison of implanted and intact conditions, we built six corresponding intact models, isotopological to PFR models in the part where the PFR is inserted into the diaphysis. It has a chemical composition of 6% aluminum, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium. Recognized as the most popular titanium alloy, Ti6Al4V occupies almost a half of the market share of titanium products used in the world today. A finite element study. There have been no reported studies investigating the overall mechanical environment around the stem and collar using a complete proximal femur constructed into a validated femur model. This study in combination with excellent short-term clinical data would suggest that a fully porous in-lay collar design could significantly increase the survivorship of endo-prosthetic replacements. To compensate for the defeaturing of the anti-rotational features we defined a local cylindric reference system and implemented an orthotropic coefficient of friction, increasing the circumferential coefficient to 0.9, and leaving the axial and transversal ones to 0.3. Inst. As expected, peak stresses occurred at the taper junction surfaces and at the distal collar-bone interface, but were maintained at relatively low levels. doi:10.1016/S0026-0657(06)70603-8, Burr, D. B., Milgrom, C., Fyhrie, D., Forwood, M., Nyska, M., Finestone, A., et al. Given that the PFR interface with bone happens in the diaphysis, we complemented these metrics adding two parameters measured on the diaphyseal bone cortex, i.e., cortical thickness and estimated periosteal radius. doi:10.1016/j.medengphy.2011.05.010, Morgan, E. F., Bayraktar, H. H., and Keaveny, T. M. (2003). WebThe use of materials (i.e., Ti6Al4V) with Youngs modulus higher than those of natural tissues generally cause stress shielding effects, bone atrophy, and implant loosening. Classification of failure of limb salvage after reconstructive surgery for bone tumours: A modified system including biological and expandable reconstructions. Conversely, in D-PFR the on-lay collar showed larger contact area at the collar-bone interface, so that the overall area in contact was similar for both models. 208, 108113. D-PFR models showed not alerting levels of micromotions all over the interfaces, both for the in-lay and on-lay configurations. Contours of the whole femur were identified through segmentation of the original CT data (Mimics 21, Materialise NV, BE) and then used to obtain a mathematical representation of the surfaces (Geomagic Studio v.7, Raindrop Geomagic Inc., United States). Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. Auger Recombination Coefficient. These results show that the ultrasonic properties of Ti6Al4V alloys are closely J. Ti6Al4V doi:10.1007/s11999-014-4116-6, Dean, B. J. F., Matthews, J. J., Price, A., Stubbs, D., Whitwell, D., and Gibbons, C. M. L. H. (2012). doi:10.1007/s11999-008-0473-3, Torbert, J. T., Fox, E. J., Hosalkar, H. S., Ogilvie, C. M., and Lackman, R. D. (2005). Frictional and bone ingrowth properties of engineered surface topographies produced by electron beam technology. Res. theorised that longer resection in PFRs was protective as the mechanical offset decreases with greater resection length, which may explain the reduced stresses in the distal femur (Unwin et al., 1996). Principal strains never exceeded damage thresholds, although some concern was raised by unusual strain peaks in the medial part of the on-lay collar-bone interface. In this study, the ultrasonic resonance parameters of Ti6Al4V alloys under different heat treatments are measured by an impedance analyzer. Although there are no published reports for the in-lay design, two of the authors of this study have been using the in-lay design for the last 5years and to date and have observed zero cases of aseptic loosening in a series of over 100 PFRs. (2008). In general: Most materials are very nearly homogeneous, therefore we can usually writek = k (T). doi:10.1302/0301-620X.99B2.BJJ-2016-0584.R1, Myers, G. J. C., Abudu, A. T., Carter, S. R., Tillman, R. M., and Grimer, R. J. The PFRs in this study have a modular concept, therefore: the proximal reconstruction (P-PFR) was assembled with a femoral neck component, directly linked to the collar and stem (which are also two separate components, assembled through a taper junction); a shaft was added to achieve the mid-diaphyseal reconstruction (M-PFR); two shaft components were used to realize the distal reconstruction (D-PFR). *Correspondence: Enrico Schileo, enrico.schileo@ior.it, Advanced pre-clinical and pre-surgical assessment of musculo-skeletal medical devices, View all 21, 956962. doi:10.1016/j.jbiomech.2004.05.022, Henderson, E. R., OConnor, M. I., Ruggieri, P., Windhager, R., Funovics, P. T., Gibbons, C. L., et al. elastic modulus Writingoriginal draft: GF, ES, DS, JS, and BK. Clin. Where: E is Young's modulus, usually expressed in Pascal (Pa) is the uniaxial stress. doi:10.1016/j.medengphy.2016.12.007, Grimer, R. J., Aydin, B. K., Wafa, H., Carter, S. R., Jeys, L., Abudu, A., et al. Titanium alloy material properties (Ti6Al4V, Youngs modulus 110 GPa, Poissons ratio 0.36) were assigned to PFR elements. doi:10.1097/01.blo.0000179735.37089.c2, Unwin, P. S., Cannon, S. R., Grimer, R. J., Kemp, H. B., Sneath, R. S., and Walker, P. S. (1996). Also, validated models from which the modelling procedure was taken had used linear elastic materials. P-PFR and M-PFR models of the in-lay configurations showed a smoother contact interaction, with no regions exceeding alert values and a more uniform distribution of micromotions over the stem, likely thanks to the larger area in contact. J. Microstructure evolution and mechanical properties FIGURE 6. doi:10.1016/S0021-9290(00)00140-8, Ward, W. G., Johnston, K. S., Dorey, F. J., and Eckardt, J. J. Clinical Orthopaedics and Related Research NA, 3144. The study examined different reconstruction lengths with the PFR and compared the mechanical environment between the two collar types. However, failure in the long-term use of Ti6Al4V implants may occur as a result of the stress shielding effect which caused by the difference elastic modulus between the implant and the bone. doi:10.1243/09544119JEIM728, Martelli, S., Taddei, F., Cristofolini, L., Schileo, E., Rushton, N., and Viceconti, M. (2011b). respectively, are presented. Themelting pointalso defines a condition in which the solid and liquid can exist in equilibrium. A lack of osseointegration can lead to stress shielding whereby more of the stress is transferred from the collar of the implant into the tip of the stem. J. Arthroplasty 14, 102107. J. Biomechanics 41, 24832491. This research was partially funded by Adler Ortho S.p.A in the frame of a grant from the Italian Ministry of Enterprises (MISE) (Grant Mise n. R.0001826, 28/06/2021). Some of our partners may process your data as a part of their legitimate business interest without asking for consent. Elastic Modulus 33, 12031211. International), 145153. doi:10.1007/s00402-010-1218-9, Bram, M., Schiefer, H., Bogdanski, D., Kller, M., Buchkremer, H., and Stver, D. (2006). It is calculated by the ratio of stress value to its corresponding strain value. Other studies have highlighted the rate of aseptic loosening ranges from 2.9% to 28.6% after four to 10years (Unwin et al., 1996; Torbert et al., 2005). 131, 711718. TABLE 3. (2011b): i) the percentage of interface area in contact under load and the interfacial sliding micromovements to quantify the risk of short-term aseptic loosening (risk thresholds set at 50m for implant-cement (Zhou et al., 1989) and 150m for implant-bone interfaces (Pilliar et al., 1986) respectively); ii) the longitudinal, principal and circumferential (hoop) bone strains around the implant to quantify the risk of bone failure (damage thresholds set at 0.73% for tensile and hoop strains, at 1.04% for compressive strains (Bayraktar et al., 2004); iii) the Von Mises equivalent stress on the whole PFR to verify its fatigue safety (fatigue limit set to 400 MPa as a conservative estimate from the data in Long and Rack, (1998)); iv) a strain-energy based indicator of possible positive (apposition) or negative (resorption) bone remodelling around the collar-bone interface. Validated models are available only from microCT images in specific mice breeds, which have limited genetic (and age) variability, contrarily to humans. As muscles are usually successfully reattached to metal surfaces or adjacent tissues at the end of the surgical reconstruction trying to reproduce their original position, attachment locations were kept also in the PFR models. However, there were obvious drops when the pore size of the porous scaffold was around 600 m. However, there is a larger difference in terms of yield point, strength, and total elongation. However, Ti6Al4V alloy has higher Youngs modulus compared with human bone. The thermal conductivity of Ti-6Al-4V Grade 5 titanium alloy is 6.7 W/(m.K). Clin. Received: 09 December 2022; Accepted: 09 May 2023;Published: 05 June 2023. Cement elements were assigned a Youngs modulus The validated modelling procedure adopted neglects bone anisotropy, while the mechanical response of cortical bone of the femoral diaphysis, where the studied reconstructions insist on, is acknowledged to be anisotropic. Densityis defined as themass per unit volume. Melting point of Ti-6Al-4V Grade 5 titanium alloy is around 1660C. However, there were obvious drops when the pore size of the porous scaffold was around 600 m. 15, A1A56. Breaking Strength Compression. The average of hardness and Young's modulus of the RHEACs obtained by the NanoBlitz 3D method were 11 GPa and 219.2 GPa, International Hellenic University, Greece. 467, 876885. Osteoarthr. The major load is applied, then removed while still maintaining the minor load. Introduction: Limb-salvage surgery using endoprosthetic replacements (EPRs) is frequently used to reconstruct segmental bone defects, but the reconstruction longevity is still a major concern. Surg. Bone Jt. Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids. doi:10.1016/j.medengphy.2007.05.006, Heller, M. O., Bergmann, G., Kassi, J.-P., Claes, L., Haas, N. P., and Duda, G. N. (2005). 95, 15691575. Endoprosthetic reconstructions: Results of long-term followup of 139 patients. WebThe results revealed that the contact angle with water, compressive strength, and elastic modulus of the Ti6Al4V alloy porous scaffolds decreased gradually with the increase of pore size. Titanium alloys have very high corrosion resistance and strength-to-density ratio, the highest of any metallic element. Orthop. "The Design and Application of Titanium Alloys to U.S. Army Platforms -2010", Standard Specification for Wrought Titanium-6Aluminum-4Vanadium Alloy for Surgical Implant Applications (UNS R56400), "Titanium Alloy Ti 6Al-4V Technical Data Sheet", "AZoM Become a Member Search Search Menu Properties This article has property data, click to view Titanium Alloys - Ti6Al4V Grade 5", https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119296126.ch169, https://en.wikipedia.org/w/index.php?title=Ti-6Al-4V&oldid=1152854710, Creative Commons Attribution-ShareAlike License 3.0, Implants and prostheses (wrought, cast or by Additive Manufacturing (, Parts and prototypes for racing and aerospace industry. No use, distribution or reproduction is permitted which does not comply with these terms. Percentage of area in contact under load and maximum sliding micromotion at bone-implant and stem-cement interfaces. WebThe results revealed that the contact angle with water, compressive strength, and elastic modulus of the Ti6Al4V alloy porous scaffolds decreased gradually with the increase of pore size. The heat transfer characteristics of a solid material are measured by a property called thethermal conductivity, k (or ), measured inW/m.K. In bone sarcoma, advances in chemotherapy have led to prolonged life expectancy meaning that reconstructions must be long-lasting if they are to avoid multiple revision operations (Grimer et al., 2016). For each reconstruction length one in-lay and one traditional on-lay collar model was built and compared. Surg. Surg. Surg. doi:10.1007/s11999-010-1454-x, Speirs, A. D., Heller, M. O., Duda, G. N., and Taylor, W. R. (2007). Author DS is an employee of Adler Ortho S.p.A. An accurate estimation of bone density improves the accuracy of subject-specific finite element models. FIGURE 5. All reconstructions were virtually implanted in a single femur, carefully chosen to represent the average of the population that may receive a PFR. doi:10.1007/s00264-011-1332-5, Farfalli, G. L., Boland, P. J., Morris, C. D., Athanasian, E. A., and Healey, J. H. (2009). Ti6Al4V is widely used in implants in the fields of orthopedics and dentistry due to its high compressive strength and good biocompatibility. The Rockwell C test is performed with a Brale penetrator (120diamond cone) and a major load of 150kg. Ti6Al4V Orthop. Future research could model in more detail ingrowth throughout the porous collar. Trauma Surg. (2016). 0> texture and phase content show decisive effect on elastic modulus. Estimated percentage volumes of bone around (In-lay) or just below (On-lay) the collar region that are likely to undergo bone resorption, homeostasis or apposition according to the strain energy density criterion adopted. That is, the penetration depth and hardness are inversely proportional. For structural applications, material properties are crucial and engineers must take them into account. In vivo measurement of human tibial strains during vigorous activity. This indicator was evaluated considering bone volumes of interest around the collar, as depicted in Table 4. WebModulus of Elasticity: 27195 ksi: 187.5 kN/mm: Modulus of Rigidity: 10196 ksi: 70.3 kN/mm: Density: 0.286 lb/in 3: 7.920 g/cm 3: Relative Strength: Medium: Fatigue Applications: Good: Rockwell Hardness: C35-45: Conductivity: 2: Typical Surface: B Predicting the position of the femoral head center. Note thatFouriers lawapplies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases. To what extent can linear finite element models of human femora predict failure under stance and fall loading configurations? 28, 6873. Extensive risk analysis of mechanical failure for an epiphyseal hip prothesis: A combined numericalexperimental approach. Assuming one-dimensional heat transfer through the plane wall and disregarding radiation, theoverall heat transfer coefficientcan be calculated as: The overall heat transfer coefficientis then: U = 1 / (1/10 + 0.15/6.7 + 1/30) = 6.42 W/m2K, The heat flux can be then calculated simply as: q = 6.42 [W/m2K] x 30 [K] = 192.65 W/m2, The total heat loss through this wall will be: qloss= q . doi:10.2106/JBJS.F.01324, Kamath, A. F., Lewallen, D. G., and Hanssen, A. D. (2015). Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. Although these implants are widely used the rate of complications for any reason remains five to ten times higher than rates seen following routine total joint arthroplasties (Parvizi et al., 2007; Coathup et al., 2015). A direct validation against experimental data for the studied prosthetic configuration could not be produced. Study on mechanical properties and permeability of elliptical Mech. Half of the whole VOI around the sleeve collar was predicted at risk of resorption. Bone Jt. Phys. Young's modulus Full contact maps for each PFR configuration can be found in Supplementary Appendix S1. In the comparison of existing experimental results, the elastic modulus and yield strength of the gyroid bone scaffold designed by Ataee et al were 1465~2676 MPa and 44.9~56.5 MPa, respectively , which were close to the elastic modulus of trabecular bone. Results were analysed to compare the mechanical environment in the in-lay and on-lay collar configurations, deriving metrics of post-operative reconstruction safety/osseointegration potential, and of long-term bone resorption due to stress-shielding. 99-B, 276282. A 10-node tetrahedral mesh was generated, setting an average element edge length of 1.5mm on the surface (HyperMesh 21, Altair Engineering, Inc., United States). To permit femoral bending, the femoral head centre was constrained to move along the biomechanical axis of the femur that ideally joins the hip (femoral head) centre with the knee centre. (A) details of the procedure to simulate cement interdigitation with porous bone. WebThe results revealed that the contact angle with water, compressive strength, and elastic modulus of the Ti6Al4V alloy porous scaffolds decreased gradually with the increase of pore size. We did not develop or implement a model of the bone remodelling process. Nonetheless, the larger area in contact in the in-lay collar translated in a more even distribution of load in the in-lay stem, so that larger in-lay than on-lay stem portions were in contact with cement. Remodelling tendency results are summarised in Table 4 and Figure 6. Visual maps of estimated bone resorption, homeostasis or apposition in the volume of interest around (In-lay) or just below (On-lay) the collar region. (2017). It is an intensive property; therefore its value does not depend on the size of the test specimen. Continue with Recommended Cookies. The indicator of bone remodelling tendency was defined (Martelli et al., 2011b) as: S = strain energy density per unit of mass. There are several limitations to this study. Is endoprosthetic replacement of the proximal femur appropriate in the comorbid patient? [13], The alloy is vulnerable to cold dwell fatigue. doi:10.1302/0301-620x.78b1.0780005, Valente, G., Pitto, L., Schileo, E., Piroddi, S., Leardini, A., Manfrini, M., et al. The effect of aging on the shape of the proximal femur. WebYoung's modulus describes the relative stiffness of a material, which is measured by the slope of elastic of a stress and strain graph. Virtual implantation of all PFR cases (in-lay and on-lay collar configurations for proximal, mid-diaphyseal and distal reconstructions) was performed on CT data, with the aim to prioritise the best possible fit of prosthetic and intact femoral head centre and hence maximise the similarity of lever arms in the intact and implanted configurations (Figure 2D). The analysis was carried out using a fully validated FE model simulating an instance during a high intensity functional activity. Endoprosthetic replacement of the distal femur for bone tumours. Biomaterials: chapter 4 homework Phys. Conceptualization: FT and ES. Surg. An average estimate of physiological loads during walking was obtained from the work of Heller et al. Eng. In brief, a hip reaction force is applied (at the femoral head centre), equilibrated by muscle forces from abductor and tensor fascia latae (acting at the greater trochanter), and vastus lateralis (acting on the proximal femur diaphysis) (Figure 4). It has a density of roughly 4420 kg/m3. It is significantly stronger than commercially pure titanium (grades 1-4) due to its possibility to be heat treated. Ti6Al4V alloy, also known as Ti64, is an + titanium alloy with high strength, low density, high fracture toughness, excellent corrosion resistance and superior biocompatibility [ 1, 2 ]. (B) details of contact interfaces for the in -lay and on-lay designs, representing bonded interfaces within the PFR (Ba), and frictional interfaces between in-lay collar and bone (Bb), on-lay collar and bone (Bc), and stem and cement (Bd). doi:10.1016/j.jbiomech.2014.08.024, Schileo, E., DallAra, E., Taddei, F., Malandrino, A., Schotkamp, T., Baleani, M., et al. Res. A new hip epiphyseal prosthesis: Design revision driven by a validated numerical procedure. Bone 18, 405410. 700-3500 Kg/cm2. The effect of bone growth onto massive prostheses collars in protecting the implant from fracture. These were accounted for in the contact model (Section 2.4.4 below). (1996). Clin. Titanium alloys in total joint replacementA materials science perspective. 20 Articles, Clinical Orthopaedics and Related Research NA, This article is part of the Research Topic, https://doi.org/10.3389/fbioe.2023.1120430, https://www.frontiersin.org/articles/10.3389/fbioe.2023.1120430/full#supplementary-material. Discussion: In summary, the models corroborate the hypothesis that an in-lay collar, by realising a more uniform load transfer into the bone with a more physiological pattern, creates an advantageous mechanical environment at the bone-collar interface, compared to an on-lay design. Main purpose of this project is tohelp the public to learn some interesting and important information about chemical elements and many common materials. doi:10.2106/00004623-200405000-00010, Coathup, M. J., Batta, V., Pollock, R. C., Aston, W. J., Cannon, S. R., Skinner, J. We and our partners use cookies to Store and/or access information on a device. Eng. The difference of elastic modulus between bone and titanium alloy may evoke clinical problems because of stress shielding. Lin Chen 1, Xiaowei Zhang 1, Yueyi Wang 1, Xuanhong Hao 1 and Hongxi Liu 1. Youngs modulus is equal to the longitudinal stress divided by the strain. The thin layer of trabecular titanium covering the surface of the on-lay collar was not assigned specific reduced properties because: i) its thinness hinders a real effect on the overall resistant section of the collar; ii) its osteoconductive and osteointegrating effects are likely due to its surface organisation rather than to the reduction of the elastic modulus towards a bone-like material, as trabecular titanium cells produced by the same manufacturer for custom made 3D reconstructions showed an effective elastic modulus of 97GPa (i.e., not far from that of the bulk alloy) when mechanically tested (La Barbera et al., 2019). Specimens with martensitic microstructure (samples without heat treatment) show higher yield point and tensile strength, but lower elongation. We intended to simulate a short term post-operative condition, where osseointegration is still to be achieved. on Ti6Al4V Lattice Structures Manufactured by 1) You may use almost everything for non-commercial and educational use. FIGURE 4. (2017) used a finite element model to describe load transfer at the collar-bone interface and confirmed that the stem-collar junction is the region subjected to the highest stresses and crucially that the stresses are greatest when there was no ECBB onto the collar; the authors concluded that this would promote stem fracture under normal walking loads.
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