The Experts below are selected from a list of 1689 Experts worldwide ranked by ideXlab platform
C P Duncan - One of the best experts on this subject based on the ideXlab platform.
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gap filling and enhanced Osteoconduction associated with alendronate coated porous tantalum
Orthopaedic Proceedings, 2018Co-Authors: Winston Y Kim, K Duan, R Wang, D S Garbuz, B A Masri, C P DuncanAbstract:Introduction Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was to develop an experimental model which would simulate the clinical revision hip scenario and to determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model. Methods Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections. Results The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124%, 232% and 170% respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls. Discussion Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects.
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enhanced Osteoconduction and defect filling associated with alendronate coated porous tantalum
Orthopaedic Proceedings, 2009Co-Authors: Winston Y Kim, K Duan, R Wang, D S Garbuz, B A Masri, C P DuncanAbstract:Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was to develop an experimental model which would simulate the clinical revision hip scenario and determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model. Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections. Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls. Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects.
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enhanced gap filling and Osteoconduction associated with alendronate calcium phosphate coated porous tantalum
Journal of Bone and Joint Surgery American Volume, 2008Co-Authors: D S Garbuz, Winston Y Kim, K Duan, R Wang, B A Masri, Thomas R Oxland, Helen M Burt, C P DuncanAbstract:ABSTRACTBackground:Porous tantalum has been shown to be effective in achieving bone ingrowth. However, in some circumstances, bone quality or quantity may be insufficient to allow adequate bone ingrowth. We hypothesized that local delivery of alendronate from porous tantalum would enhance the abilit
John E. Davies - One of the best experts on this subject based on the ideXlab platform.
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bone healing and the effect of implant surface topography on Osteoconduction in hyperglycemia
Acta Biomaterialia, 2014Co-Authors: Elnaz Ajami, Vanessa C Mendes, Rahim Moineddin, E Mahno, Spencer Bell, John E. DaviesAbstract:Dental implant failures that occur clinically for unknown reasons could be related to undiagnosed hyperglycemia. The exact mechanisms that underlie such failures are not known, but there is a general consensus that bone growth is compromised in hyperglycemia. Nevertheless, contradictory findings exist related to peri-implant bone healing in hyperglycemia. We hypothesized that hyperglycemia delays early bone healing by impeding Osteoconduction, and that the compromised implant integration due to hyperglycemia could be abrogated by using nanotopographically complex implants. Thus we undertook two parallel experiments, an osteotomy model and a bone in-growth chamber model. The osteotomy model tracked temporal bone healing in the femora of euglycemic and hyperglycemic rats using micro computed tomography (microCT) analysis and histology. The bone in-growth chamber model used implant surfaces of either micro- or nanotopographical complexity and measured bone–implant contact (BIC) using backscattered electron imaging in both metabolic groups. Quantitative microCT analyses on bone volume, trabeculae number and trabeculae connectivity density provided clear evidence that bone healing, both reparative trabecular bone formation and remodeling, was delayed in hyperglycemia, and the reparative bone volume changed with time between metabolic groups. Furthermore, fluorochrome labeling showed evidently less mineralized bone in hyperglycemic than euglycemic animals. An increased probability of Osteoconduction was seen on nano-compared with microtopographically complex surfaces, independent of metabolic group. The nanotopographically complex surfaces in hyperglycemia outperformed microtopographically complex surfaces in euglycemic animals. In conclusion, the compromised implant integration in hyperglycemia is abrogated by the addition of nanotopographical features to an underlying microtopographically complex implant surface.
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discrete calcium phosphate nanocrystalline deposition enhances Osteoconduction on titanium based implant surfaces
Journal of Biomedical Materials Research Part A, 2009Co-Authors: Vanessa C Mendes, Rahim Moineddin, John E. DaviesAbstract:We sought to assess the ability of nanotopographically complex titanium surfaces to accelerate Osteoconduction. For this, 130 miniature bone ingrowth chambers (called “T plants”), fabricated from either commercially pure titanium (cpTi) or titanium alloy (Ti6Al4V or Ti64), with microtopographically complex surfaces were used in the study, of which 50 were further modified by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanoparticles that superimposed a nanotopographic complexity on each implant surface. Thus, four experimental groups were generated (cpTi, cpTi-DCD, Ti64, and Ti64-DCD), and the Tplants were implanted bilaterally in the femora of Wistar rats for 9 days. After harvesting, the femora were trimmed, and multiple-mounted samples were embedded in PMMA. The blocks produced were ground and block faces observed by back-scattering electron imaging (BSEI) at different planes through the chambers. Osteoconduction was assessed, as a function of bone-implant contact, on a total of 1087 BSEI micrographs and submitted to rigorous statistical analyses. Our results showed both the important effects of anatomic location on bone ingrowth and the significant increase in Osteoconduction (p < 0.001) as a function of the enhanced surface nanotopography obtained by the CAP nanocrystals. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
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Osteoconduction on, and Bonding to, Calcium Phosphate Ceramic Implants
MRS Proceedings, 1995Co-Authors: D. M. Dziedzic, I. H. Savva, David Wilkinson, John E. DaviesAbstract:AbstractCalcium phosphate ceramic blocks of three different densities, porous, intermediate and dense, were prepared by tape casting (total = 18), and implanted in the femora of 9 Wistar rats for 1 to 3 weeks. Following fixation, the tissue was prepared for examination by scanning electron microscopy (SEM) of freeze fractured specimens, or back-scattered electron imaging (BSEI) of polymethylmethacrylate (PMMA) embedded, undecalcified, sections. The results demonstrated that while all ceramics were osteoconductive, the 93 % dense implants showed no evidence of bone bonding as judged by the plane at which specimens separated or cracked during preparation for microscopy. The porous ceramics, on whose surfaces both multinucleated cells and osteoid tissue were observed at all implantation times, exhibited less bone contact than the other two groups. Both SEM and BSEI showed that there was bone growth into the microporosity of both intermediate and porous ceramics, pore size range 1−2μ m, to a depth of about 6μm. The latter corresponds to the thickness of natural bone lamellae. In all implants examined, de novo bone formed on the ceramic surface by the initial production of a biological cement-line like interfacial extracellular matrix. The results clearly show that Osteoconduction and bone-bonding are distinct mechanistic phenomena. While we assume the former to be a consequence of protein adsorption events culminating in anchorage of osteoblasts to the implant surface, the latter is the result of mechanical interdigitation of the extracellular matrix, produced by osteoblasts, with the microtopography of the implant surface.
L D Bellincampi - One of the best experts on this subject based on the ideXlab platform.
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potential of an ultraporous β tricalcium phosphate synthetic cancellous bone void filler and bone marrow aspirate composite graft
European Spine Journal, 2001Co-Authors: Erik M Erbe, Jeffrey G Marx, Theodore D Clineff, L D BellincampiAbstract:Autogenous cancellous bone is considered to be the best bone grafting material. Autogenous bone grafts provide scaffolding for Osteoconduction, growth factors for osteoinduction, and progenitor stem cells for osteogenesis. However, the procurement morbidity, limited availability, and expense associated with the use of autogenous bone grafts are significant disadvantages. Allografts and xenografts lack the osteoinduction and osteogenesis properties of autogenous bone, and they introduce the potential for both transferring disease and triggering a host immune response. Synthetic bone grafts [hydroxyapatite or tricalcium phosphate(TCP)], while good platforms for Osteoconduction, lack any intrinsic properties of osteoinduction and osteogenesis. A composite graft that combines synthetic scaffold with autogenous osteoprogenitor cells from bone marrow aspirate (BMA), a low-morbidity procedure, could potentially deliver the advantages of autogenous bone grafts without the disadvantages. A new ultraporous β-TCP construct, engineered using solution-derived nano-particle technology, may prove to be an ideal carrier for BMA in such a composite. The unique, interconnected macroporosity, mesoporosity, and microporosity of this synthetic cancellous bone void filler allows it to wick in cells and nutrients via enhanced capillarity. Preliminary canine data support this expectation, demonstrating bone formation that suggests good penetration of cells and nutrients. These results suggest that BMA cells, absorbed into such a scaffold, may remain viable, thereby potentially making such a composite a true synthetic replacement for autogenous cancellous bone.
Tadashi Kokubo - One of the best experts on this subject based on the ideXlab platform.
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Osteoconduction of porous ti metal enhanced by acid and heat treatments
Journal of Materials Science: Materials in Medicine, 2013Co-Authors: Toshiyuki Kawai, Takashi Nakamura, Shunsuke Fujibayashi, Mitsuru Takemoto, Haruhiko Akiyama, Seiji Yamaguchi, Deepak K Pattanayak, Kenji Doi, Tomiharu Matsushita, Tadashi KokuboAbstract:Bone ingrowth into porous Ti metal is important for stable fixation of Ti metal implants to surrounding bone. However, without surface treatment this is limited to only a thin region of the outer surface of the Ti metal. In the present study, a porous Ti metal with a porosity of ~60 % and interpore connections of 70–200 micrometers in diameter was investigated in terms of its chemical and heat treatments, by implanting it into rabbit femur for periods varying from 3 to 12 weeks. The porous Ti metal subjected to heat treatment at 600 °C after H2SO4/HCl mixed acid treatment showed the largest bone ingrowth in comparison with those subjected to no treatment, only acid treatment, and only heat treatment even at an early stage after implantation, and remained as such even 12 weeks after implantation. Their bone ingrowths were well interpreted in terms of apatite-forming abilities of the Ti metals in body environment. Their apatite-forming abilities did not depend upon their surface roughness nor type of crystalline phase, but upon the positive surface charge.
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bone like tissue formation on a biomimetic titanium surface in an explant model of Osteoconduction
Journal of Biomedical Materials Research Part A, 2009Co-Authors: Juliane Isaac, Sabine Loty, Ahmad A Hamdan, Tadashi Kokubo, Ariane Berdal, J M SautierAbstract:The clinical use of titanium in dental and orthopedic applications is limited. Over recent years, implant surfaces have undergone numerous modifications to enhance bone integration. In this study, we experimented a bioactive titanium using a simple chemical and moderate heat treatment that led to the formation of a bone-like apatite layer on its surface in simulated body fluids. We used a bone explant model to demonstrate that cells can migrate from the explants and subsequently differentiate to form a mineralized nodular structure. Furthermore, these cells expressed alkaline phosphatase, bone sialoprotein, osteocalcin and the transcription factor, Runx2. Using this model of Osteoconduction, we showed that bioactive titanium bonds directly to bone, while pure titanium cannot. These findings show the importance of implant surface composition in promoting osteogenic cell differentiation and subsequent apposition of the bone matrix, allowing strong bonds to form. This model could be particularly beneficial to closely mimic bone formation adjacent to endosseous implants. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
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bioactive bone cements containing nano sized titania particles for use as bone substitutes
Biomaterials, 2005Co-Authors: Koji Goto, Shuichi Shinzato, Tadashi Kokubo, Masami Hashimoto, Masakazu Kawashita, Jiro Tamura, Shunsuke Fujibayashi, Takashi NakamuraAbstract:Three types of bioactive polymethylmethacrylate (PMMA)-based bone cement containing nano-sized titania (TiO2) particles were prepared, and their mechanical properties and osteoconductivity are evaluated. The three types of bioactive bone cement were T50c, ST50c, and ST60c, which contained 50 wt% TiO2, and 50 and 60 wt% silanized TiO2, respectively. Commercially available PMMA cement (PMMAc) was used as a control. The cements were inserted into rat tibiae and allowed to solidify in situ. After 6 and 12 weeks, tibiae were removed for evaluation of osteoconductivity using scanning electron microscopy (SEM), contact microradiography (CMR), and Giemsa surface staining. SEM revealed that ST60c and ST50c were directly apposed to bone while T50c and PMMAc were not. The Osteoconduction of ST60c was significantly better than that of the other cements at each time interval, and the Osteoconduction of T50c was no better than that of PMMAc. The compressive strength of ST60c was equivalent to that of PMMAc. These results show that ST60c is a promising material for use as a bone substitute.
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Osteoconduction of bioceramics in normal and osteopenic rats comparison between bioactive and bioinert ceramics
Journal of Applied Biomaterials, 1992Co-Authors: Yasushi Iwashita, Takashi Nakamura, Takao Yamamuro, Ryuichi Kasai, Toshiaki Kitsugi, Hideo Okumura, Tadashi KokuboAbstract:Rats with experimental osteopenia, which was induced by resecting both ovaries and sciatic nerves (OVX + NX), were used to evaluate Osteoconduction of an apatite and wollastonite-containing glass-ceramic (designated A-W.GC) and an alumina ceramic. The bone mineral densities (BMDs) of the femurs were measured by dural energy X-ray absorptiometry (DEXA) and determination of the ash weight. Twelve weeks after the first operation, when the BMDs in the OVX + NX groups were about 20% less than that in the sham-treated groups (Sham), the bioceramics were implanted into the proximal tibiae. The bone mineral masses around the implants in the proximal tibiae were evaluated by histological examination of undecalcified specimens and DEXA. Both types of implants in the OVX + NX groups showed less reactive bone than those in the Sham groups. However, a histomorphological study revealed that the direct contact area between bone and implant was larger with bioactive ceramic A-W.GC than with the bioinert alumina ceramic even under osteopenic conditions while two types of ceramic made no difference on the bone at distance from the implant. The direct contact area with A-W.GC did not show any difference between the Sham and the osteopenic OVX + NX groups. The bioactive ceramic A-W.GC appears to have good osteoconductivity solely on its surface even under osteopenic conditions.
Franz E Weber - One of the best experts on this subject based on the ideXlab platform.
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the optimal microarchitecture of 3d printed β tcp bone substitutes for vertical bone augmentation differs from that for Osteoconduction
Materials & Design, 2021Co-Authors: Chafik Ghayor, Indranil Bhattacharya, Franz E WeberAbstract:Abstract Synthetic bone substitutes are used for regeneration of bone defects and for vertical or horizontal bone augmentation. With the development of new manufacturing methodologies such as additive manufacturing, not only can the outer shape of a scaffold (the macroarchitecture) be personalized, but also the microarchitecture, defined as the distribution of material within the scaffold, can be designed and optimized for bone ingrowth. Our study assessed the optimal pore-based microarchitecture for Osteoconduction in comparison to vertical bone augmentation. Histological analysis of the samples from an Osteoconduction and a bone augmentation model showed that the best microarchitecture to achieve vertical bone augmentation contained pores of 1.7 mm diameter and differed from the optimal microarchitecture for Osteoconduction, which contained pores of 1.2 mm diameter. The extent of vertical bone augmentation correlated with increasing pore diameter. Moreover, the differences between the microarchitectures were highly significant for Osteoconduction, but less significant for vertical bone augmentation. Thus, our results suggest that the microarchitectures of the scaffolds in vertical bone augmentation and in bone regeneration of a defect are crucial determinants of the depth of bone ingrowth and the area of bony regeneration. However, the microarchitecture appears to be more crucial in Osteoconduction.
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microporosities in 3d printed tricalcium phosphate based bone substitutes enhance Osteoconduction and affect osteoclastic resorption
International Journal of Molecular Sciences, 2020Co-Authors: Chafik Ghayor, Indranil Bhattacharya, Tsehsiang Chen, Mutlu Ozcan, Franz E WeberAbstract:Additive manufacturing is a key technology required to realize the production of a personalized bone substitute that exactly meets a patient's need and fills a patient-specific bone defect. Additive manufacturing can optimize the inner architecture of the scaffold for Osteoconduction, allowing fast and reliable defect bridging by promoting rapid growth of new bone tissue into the scaffold. The role of scaffold microporosity/nanoarchitecture in Osteoconduction remains elusive. To elucidate this relationship, we produced lithography-based osteoconductive scaffolds from tricalcium phosphate (TCP) with identical macro- and microarchitecture, but varied their nanoarchitecture/microporosity by ranging maximum sintering temperatures from 1000 °C to 1200 °C. After characterization of the different scaffolds' microporosity, compression strength, and nanoarchitecture, we performed in vivo studies that showed that ingrowth of bone as an indicator of Osteoconduction significantly decreased with decreasing microporosity. Moreover, at the 1200 °C peak sinter temperature and lowest microporosity, osteoclastic degradation of the material was inhibited. Thus, even for wide-open porous TCP-based scaffolds, a high degree of microporosity appears to be essential for optimal Osteoconduction and creeping substitution, which can prevent non-unions, the major complication during bone regeneration procedures.
