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This paper reports the unusual ion sorption of zinc ions to the structure of solution-precursor plasma-sprayed hydroxyapatite coatings studied via X-ray photoelectron and Raman spectroscopy techniq...

Application of artificial neural networks for optimization of plasma spraying parameters was considered. Artificial neural networks were used to select realistic parameters of titanium and hydroxyapatite powder coating of titanium products. For titanium coatings, the optimal arc current was found to be 380-450 A; optimal spraying distance, 100-150 mm; optimal titanium powder dispersity, 40-90 μm. Similar optimal ranges were obtained for hydroxyapatite coatings. The goal of the optimization wais to maximize the coating adhesion to the substrate and to improve its porosity.

Hydroxyapatite (HA) coated carbon/carbon composites (CC) is a potential material for orthopedic application because of the combination of good biocompatibility and mechanical properties. In this work, we synthesize a tree-planting interface which is composed of holes formed by micro-oxidized CC substrates and carbon nanotubes (CNTs) to achieve a high bonding strength of HA coating. The holes include annular gaps between carbon fiber and pyrolytic carbon, as well as irregular holes formed by oxidized pyrolytic carbon. The CNTs can grow inside the holes and extend into the HA coating. As a result, the bonding strength of HA coating with tree-planting interface achieves 11.14 ± 0.78 MPa. It increases by 181.3% comparing with the HA coating on CC without interface (3.96 ± 0.30 MPa). The in-vitro bioactivity evaluated by the response of mesenchymal stem cells (MSCs) shows promotions of cell proliferation and cell activity with increasing culture time. After applied with tree-planting interface, the HA coating with strong bonding and good bioactivity may be applied in orthopedic field in the future.

Composite scaffolds obtained by the combination of biodegradable porous scaffolds and hydroxyapatite with bone regeneration potential are feasible materials for bone tissue engineering. However, most composite scaffolds have been fabricated by complicated procedures or under thermally harsh conditions. We have previously demonstrated that hydroxyapatite coating onto various substrates under a thermally mild condition was achieved by erbium-doped yttrium aluminum garnet (Er: YAG) pulsed laser deposition (PLD). The purpose of this study was to prepare a polycaprolactone (PCL) porous scaffold coated with the hydroxyapatite by the Er: YAG-PLD method. Hydroxyapatite coating by the Er: YAG-PLD method was confirmed by morphology, crystallographic analysis, and surface chemical characterization studies. When cultured on PCL porous scaffold coated with hydroxyapatite, rat bone marrow-derived mesenchymal stem cells adhered, spread, and proliferated well. The micro-CT and staining analyses after the implantation of scaffold into the critical-sized calvaria bone defect in rats indicate that PCL porous scaffold coated with hydroxyapatite demonstrates accelerated and widespread bone formation. In conclusion, PCL porous scaffold coated with hydroxyapatite obtained by the Er: YAG-PLD method is a promising material in bone tissue engineering.

Objectives: Titanium implants are regarded as a promising treatment modality for replacing missing teeth. Osteointegration and antibacterial properties are both desirable characteristics for titanium dental implants. The aim of this study was to create zinc (Zn)-, strontium (Sr)-, and magnesium (Mg)-multidoped hydroxyapatite (HAp) porous coatings, including HAp, Zn-doped HAp, and Zn-Sr-Mg-doped HAp, on titanium discs and implants using the vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) technique. Methods: The mRNA and protein levels of osteogenesis-associated genes such as collagen type I alpha 1 chain (COL1A1), decorin (DCN), osteoprotegerin (TNFRSF11B), and osteopontin (SPP1) were examined in human embryonic palatal mesenchymal cells. The antibacterial effects against periodontal bacteria, including Porphyromonas gingivalis and Prevotella nigrescens, were investigated. In addition, a rat animal model was used to evaluate new bone formation via histologic examination and micro-computed tomography (CT). Results: The ZnSrMg-HAp group was the most effective at inducing mRNA and protein expression of TNFRSF11B and SPP1 after 7 days of incubation, and TNFRSF11B and DCN after 11 days of incubation. In addition, both the ZnSrMg-HAp and Zn-HAp groups were effective against P. gingivalis and P. nigrescens. Furthermore, according to both in vitro studies and histologic findings, the ZnSrMg-HAp group exhibited the most prominent osteogenesis and concentrated bone growth along implant threads. Significance: A porous ZnSrMg-HAp coating using VIPF-APS could serve as a novel technique for coating titanium implant surfaces and preventing further bacterial infection.

Purpose The purpose of this study is to obtain an effective implant with porous structures on its surface, named porous-surfaced implant, which helps to improve the overall stability of the implant and promote the combination of implant and alveolar bone. Design/methodology/approach Porous-surfaced implants with a porosity of 16%, 21%and 32% were designed and the effect of porosity on the strength of the implant was analyzed by ABAQUS software. Porous-surfaced implants with different porosity were printed by selective laser melting and the surface morphology was observed. Animal experiments of implants with porous structures and coating were carried out in healthy beagle dogs. The experimental group was treated with hydroxyapatite coating and the control group was not treated. Bone volume (BV) and total volume (TV) of the implant surface of the experimental group and control group were calculated by Skyscan CTvol software. Findings With the increase of porosity of porous-surfaced implants, the neck stress of the porous-surfaced implants increased and their strength decreased. In addition, in animal vivo experiments, the ratio value of BV to TV of the porous-surfaced implants was between 55.38% and 79.86%, which was the largest when the porosity of porous-surfaced implants was 16%. The internal and surrounding bone formation content of porous-surfaced implants with hydroxyapatite coating was higher than porous-surfaced implants without coating. Originality/value The results of this study show that the pores on the surface of implants can be filled with the new bone and porous-surfaced implants with 16% porosity provide better space for the growth of new bone. The porous structures with hydroxyapatite coating are beneficial to the growth of new bone around implants. The results of this study are helpful to improve the overall stability of implants and to promote the combination of implant and alveolar bone.

The surface of titanium (Ti) dental implants must be modified to improve their applicability, owing to the biological inertness of Ti. This study aims to use sandblasting as a pretreatment method and prepare a hydroxyapatite (HA) coating on Ti to improve its biocompatibility and induce bone bonding and osteogenesis. In this paper, sandblasted Ti discs were coated with α-tricalcium phosphate (α-TCP) via Er:YAG pulsed laser deposition (Er:YAG-PLD). An HA coating was then obtained via the hydrothermal treatment of the discs at 90 °C for 10 h. The surface characteristics of the samples were evaluated by SEM, SPM, XPS, XRD, FTIR, and tensile tests. Rat bone marrow mesenchymal stem cells were seeded on the HA-coated discs to determine cellular responses in vitro. The surface characterization results indicated the successful transformation of the HA coating with a nanorod-like morphology, and its surface roughness increased. In vitro experiments revealed increased cell attachment on the HA-coated discs, as did the cell morphology of fluorescence staining and SEM analysis; in contrast, there was no increase in cell proliferation. This study confirms that Er:YAG-PLD could be used as an implant surface-modification technique to prepare HA coatings with a nanorod-like morphology on Ti discs.

Excellent osseointegration of biomaterial is very important for the stability of dental implants in clinical field. Much has been learned about this concept and significant improvements on the design and surface modification of implants have been done in the implant dentistry.

Hydroxyapatite (HA) coating was deposited on commercially pure Ti to improve its biocompatibility as a biomedical implant material. The HA layer was deposited by the electrophoretic deposition (EPD) method. The processing parameters controlled the HA structure. In this research, the applied voltage was varied 20, 30, and 40 V to optimize a free-crack layer. The current output during EPD at 20 V was in the order of 10-5 A/cm2. A higher current density in the order of 10-4 A/cm2 was obtained at 30 and 40 V. The coating formed at 20 V was relatively free of crack. A high number of cracks began to observe in the layer formed at 30 V, while only a few cracks were revealed on the layer formed at 40 V. The average thickness of the HA layer increased slightly with applied voltage. The thickness was approximately 40±5 µm, as observed by an optical microscope. The optimum voltage to produce a thick HA layer with a small number of cracks was at 40 V.

Metallic implants are extensively used to treat a spectrum of orthopaedic related disorders. Among the metals, titanium and its alloys are considered most excellent and indispensable material for the production of orthopaedic implants regarding their sterling mechanical properties and exceptional biocompatibility. Recently, rapid progress in developing non-toxic titanium-based alloys with modulus similar to that of human bone has inspired researchers globally. Thus, many studies have focused on titanium alloys, their heat treatment processes and several processing technologies. Additive manufacturing has been designed to enhance their mechanical properties tailored towards biomedical applications. Inarguably, the need to further improve on the implant’s biocompatibility with bodily environment for optimum service life is of great importance. Hence, hydroxyapatite coating provides an improvement as demonstrated by in vitro as well as in vivo studies. The present article critically reviews, based on recent scientific literatures, the progress made thus far in the development of titanium-based alloys, additive manufacturing processes and their heat and surface treatments tailored towards biomedical applications.

Dogs underwent high-frequency automated tibia lengthening with the Ilizarov apparatus over a 1.8-mm hydroxyapatite-coated intramedullary titanium wire. Daily distraction was 3.0 mm with a fraction of 0.125 mm/h and continued ten days. The regenerate was well vascularized, had zonal structure and was of normal or hyperplastic type to the end of distraction. Osteogenesis was fast and complete. The wire served for both mechanical and biological reinforcement of the bone callus and provided reduction of external fixation time. Mean consolidation time with the apparatus on the limb was 13.83±4.02 days. Overall, external fixation index was 10.5 days/cm and 4.8 days/cm in the consolidation phase.

This study aims to investigate the effect of the electrophoretic deposition process (EPD) of natural HA (extracted from bovine bones) with various particle size on Ti-29Nb-13Ta-4.6Zr (TNTZ) coating surfaces. HA particles were refined from bovine bone powders using planetary ball mill and then sieving to separate the particle based on its size. The maximum size according to sieving mesh size is #25 µm, #63 µm and #125 µm. The coating process was conducted by using EPD apparatus with voltage and time process 10V and 5 minutes, respectively, for each sample. The coating layer morphology was observed with Stereo Microscopy, Scanning Electron Microscopy (SEM) and the thickness was measured with Thickness Gauge. The result shows that the size of the particle determines the coating layer characteristics. The best of HA coating quality according to the implant coating standard is obtained for the 25 µm particle size with the surface coverage is 99%. The thickness is 121 µm and the ratio of chemical composition Calcium and Phosphor Ca/P) is 1,49%. These may be concluded that, on the point of view physical characteristics, natural HA from bovine bone has potential enough as a coating layer to improve the bioactivity implant for biomedical application. However, the mechanical characteristic of the layer is still needed to determine the strength of coating layer for avoiding delamination during application.

Hydroxyapatite (HA) is potentially used as a coating material for titanium alloys to improve their bioactivity and then enhancing the osseointegration characteristic of metal implants for orthopedic application. Electrophoretic Deposition (EPD), one of the coating methods that is widely applied for coating metal because of its simplicity and relatively low cost, is chosen for coating metal implants. HA coating layer quality can be controlled by adjusting applied voltages and coating time of the EPD process. However, the optimum voltage and exposing time has not yet been known for new type titanium implant such as Ti-12Cr and TNTZ. This work is, therefore, focusing on the effect of applied voltage and coating time on the mass growth, HA coating thickness, and surface coverage that can be produced on the surfaces of both alloys, and also on the conventional titanium alloy, Ti6Al4V, for comparison. The result of this work showed that there is a significant influence of the titanium alloy type on the HA layer performances. However, it is necessary to choose a suitable voltage and to expose time for producing a sufficient coating layer that meets the standard of orthopedic implants.

Finite element analysis (FEA) has been proven to be a precise and applicable method for evaluating dental implant systems. This is because FEA allows for measurement of the stress distribution inside of the bone and various dental implant designs via simulation analysis during mastication where such measurements are impossible to perform in-vitro or in-vivo experiment. That is why the relationship between implant design and load distribution at the implant bone interface is a crucial issue to understand. This research study focuses on a static simulation and bonding strength for PLA/HA coating on V thread design of dental implant using three-dimensional finite element. The average masticatory muscle that involves in human biting such as X, Y and Z direction will be used to simulate force with load condition of 17.1N, 114.6N and 23.4N respectively. Based on result obtained, the coated dental implant model is more compatible than uncoated model due to lower maximum stress which is reduce about 16%. The coated model also shows lower deformation and higher bonding strength. Outcomes from this research provide a better understanding of stress distribution characteristics that would be useful in order to improve design of dental implant thread and evaluation of the PLA/HA bonding strength applied.

Both tensile and shear adhesion strength tests were performed to evaluate interfacial strength between hydroxyapatite coatings on titanium alloy substrates subjected to anodization and heat treatment prior to deposition as well as post-deposition heat treatment. Results of the tensile adhesion strength tests were influenced by the size of the blasting media and the processing of pre- and post-heat treatments but not influenced by anodization. The finite element method (FEM) analysis of stress distribution during the shear adhesion strength test was also performed to evaluate the degree of stress singularity. The results show that the stress singularity parameters were dominant factors of stress distribution in the stress singularity fields, and they were also expected to influence the “essential” interfacial strength. In addition, the size of the blasting media had the same influence on the shear and tensile adhesion strength tests. This suggests the possibility of estimating tensile adhesion strength using the results of shear adhesion strength.

Composite materials with a biologically active coating are created. The morphology of a newly formed surface is studied by scanning electron microscopy, as well as the Brunauer–Emmett–Taylor method. The adhesive strength of the hydroxyapatite coating is determined by centrifugal separation. As a result of the studies, the most promising method of deposition, the best shape of the coating material and the optimal porosity of the titanium scaffold are established.

Titanium and its alloys are standard for orthopedic prosthetic devices, due to their good mechanical properties and biocompatibility. However, bioactivity on the implant surface needs to be improved to achieve an optimal osseointegration process. Metal implants are often coated by hydroxyapatite because they have a chemical composition and crystal structure similar to apatite in the human skeletal that suitable for bone reconstruction. The focus of this research is on surface treatment designed to promote better biological responses through hydroxyapatite layers. Also combining the acid etching treatment of Ti-6Al-4V and the electrophoretic coating process of the hydroxyapatite to obtain stronger mechanical interlocking interface. Hydrofluoric-Acid treatment conducted in various time. Then, coated with nanosized hydroxyapatite through electrophoretic deposition at 15V voltage for 10 minutes. Scanning Electron Microscopy and Contour measurements were performed to show the surface topography indicating the formation of surface contours with increasing surface roughness parameters in accordance with the time of the etching process. The contours on the surface of the substrate induce the mechanical interlocking of the surface so that the results of hydroxyapatite deposition optimal at the time of etching 5 minutes

Background. There are many strategies for modifying the surface of implants to create optimal conditions for the development of bone tissue. At the same time, the question of correlation of the effect of surface roughness or surface chemical composition on cell activity or osteogenesis processes remains open. Objective. The study of cellular mechanisms of osseointegration using cell cultures that occur after implantation of implants with a different type of alloy and the nature of their surface. Methods. To analyze the adhesion and cell proliferaiton, the resazurin reduction method was used, scanning electron microscopy was used to determine the distribution of cells on the sample surface and the type of cell interaction with surface. Results. Cell adhesion is observed in all studied groups, and the degree of cell adhesion is directly related to the presence of hydroxyapatite on the surface. A growing trend in the proliferation of osteoblasts is noted, while fibroblast proliferation slows down from the 3rd to the 7th day. At the same time, slow cell proliferation occurs on the surface of the implants without modification, and the percentage the reduction of resazurin does not exceed 23.5%. It should be noted that there is no difference between the types of alloys, which proves the predominance of the influence of surface topography on the proliferative activity of osteoblasts. Scanning electron microscopy on the 7th day revealed the presence of osteoblasts and fibroblasts in all studied samples. However, in the absence of hydroxyapatite, the cells are unevenly located on the surface of the sample, they are large in size and have long processes that do not have a clear orientation, and on the surface with hydroxyapatite coating there is a higher cell growth density, which predominantly has 2 processes and oriented in the same direction. Conclusion. The use of hydroxyapatite coating significantly increases the ability of cells to adhere to the surface of the implant. The presence of calcium and phosphorus mainly stimulates the proliferation of osteoblastic dipheron cells and almost does not affect the ability of fibroblasts to proliferate., Актуальность. Существует множество стратегий модификаций поверхности имплантатов для создания оптимальных условий для развития костной ткани. При этом остается открытым вопрос о корреляции влияния шероховатости или химического состава поверхности на активность клеток или процессы остеогенеза. Цель. Изучение клеточных механизмов остеоинтеграции с применением культур клеток, происходящих после вживления имплантатов с различным типом сплава и характером их поверхности. Методы. Для анализа адгезии и динамики роста клеток использовали метод редукции резазурина, а для определения распределения клеток на поверхности образца и типа взаимодействия клеток с поверхностью – метод растровой электронной микроскопии. Результаты. Адгезия клеток наблюдается во всех исследуемых группах, причем степень их адгезии имеет прямую связь с наличием на поверхности гидроксиапатита. Отмечается растущий тренд пролиферации остеобластов, в то время пролиферация фибробластов замедляется с 3-х по 7-е сутки. При этом на поверхности имплантатов без модификации происходит медленная пролиферация клеток, а процент роста редукции резазурина не превышает 23,5%. Следует заметить, что разница между типами сплавов отсутствует, что доказывает преобладание влияния топографии поверхности на пролиферативную активность остеобластов. Растровая электронная микроскопия на 7-е сутки выявила наличие остеобластов и фибробластов на всех исследуемых образцах. Однако при отсутствии гидроксиапатита клетки неравномерно расположены на поверхности образца, отличаются большими размерами и наличием длинных отростков, не имеющие четкой ориентации, а на поверхности с гидроксиапатитным покрытием отмечается более высокая плотность роста клеток, которые преимущественно имеют 2 отростка и ориентированные в одном направлении. Итог. Использование гидроксиапатитного покрытия значительно повышает способность клеток к адгезии на поверхности имплантата. Наличие кальция и фосфора преимущественно стимулирует пролиферацию клеток остеобластического диферона и почти не влияет на способность фибробластов к пролиферации., Актуальність. Існує безліч стратегій модифікацій поверхні імплантатів для створення оптимальних умов для розвитку кісткової тканини. При цьому залишається відкритим питання щодо кореляції впливу шорсткості чи хімічного складу поверхні на активність клітин чи процеси остеогенезу. Мета. Вивчення клітинних механізмів остеоінтеграції із застосуванням культур клітин, що відбуваються після вживляння імплантатів з різним типом сплаву та характером їх поверхні. Методи. Для аналізу адгезії та динаміки росту клітин використовували метод редукції резазурину, а для визначення розподілу клітин на поверхні зразка та типу взаємодії клітин з поверхнею - метод растрової електронної мікроскопії. Результати. Адгезія клітин спостерігається у всіх досліджуваних групах, при чому ступінь їх адгезії має прямий зв’язок з наявністю на поверхні гідроксиапатиту. Відзначається зростаючий тренд проліферації остеобластів, в той час проліферація фібробластів уповільнюється з 3-ї до 7-ї доби. При цьому на поверхні імплантатів без модифікації відбувається повільна проліферація клітин, а відсоток зростання редукції резазурину не перевищує 23,5%. Слід зауважити, що різниця між типами сплавів відсутня, що доводить переважання впливу топографії поверхні на проліферативну активність остеобластів. Растрова електронна мікроскопія на 7-му добу виявила наявність остеобластів та фібробластів на всіх досліджуваних зразках. Проте за відсутності гідроксиапатиту клітини нерівномірно розташовані на поверхні зразка, відрізняються більшими розмірами та наявністю довгих відростків, які не мають чіткої орієнтації, а на поверхні з гідроксиапатитним покриттям відмічається значно вища щільність росту клітин, які переважно мають 2 відростки, орієнтовані в одному напрямі. Підсумок. Використання гідроксиапатитного покриття значно підвищує здатність клітин до адгезії на поверхні імплантату. Наявність кальцію та фосфору переважно стимулює проліферацію клітин остеобластичного диферону та майже не впливає на здатність фібробластів до проліферації.

Hydroxyapatite (HA) was obtained from eggshells using selective thermal treatment. The properties like mechanical strength, biocompatibility and adhesion of hydroxyapatite were enhanced by adding titanium oxide (TiO2) and aluminum oxide (Al2O3) in two different compositions (HA-10TiO2-10Al2O3 (H10T10A) and HA-20TiO2-20Al2O3 (H20T20A)). Mechanical performance of the detonation sprayed H10T10A and H20T20A hybrid ceramic powders on AISI 304L SS steel were estimated by pin-on-disc apparatus. A load of 110 N was applied constantly over the pin which slides a linear distance of 2700 m at a linear velocity of 1 m/s at atmospheric temperature. The present investigation shows that the specific wear rate of bare AISI 304L SS was 8.23 × 10−5 mm3/N-m, while those of H20T20A and H10T10A coatings were 0.402 and 0.844 × 10−5 mm3/N-m respectively. The coatings and coating powders were characterized by SEM, XRD and FT-IR, XRD techniques respectively. The results showed that H20T20A coating has higher wear resistance in comparison to HA10T10A.

Highlights • Septic arthritis of the hip joint is relatively uncommon in adults. • Ag-HA implants have not been used in two-stage total hip arthroplasty. • Ag-HA implants may be used in two-staged total hip arthroplasty., Introduction Septic arthritis of the hip joint in adults is a rare and potentially devasting disease. To the best of our knowledge, there have been no reports of two-stage total hip arthroplasty (THA) for the treatment of septic arthritis of the hip joint with a cementless hip implant that has antibacterial properties. Presentation of case We present a case of two-stage THA with a thermal-sprayed silver oxide-containing hydroxyapatite coating (Ag-HA) implant to treat septic arthritis of the hip joint with hip osteoarthritis in an 80-year-old woman. There was no complication or recurrence at 28 months follow-up after 2nd-stage operation. Discussion Ag-HA implants were found to have antibacterial activity within the subcutaneous tissues and bone, osteoconductive properties, and no adverse reactions in vivo. Moreover, no adverse events due to silver were reported in a clinical or radiographic study. Conclusion To further reduce infection after two-staged THA for septic arthritis of the hip joint, antibacterial implants, such as an Ag-HA implant, may be used.

We study the influence of the voltage (100–180 V) of plasma-electrolytic oxidation on the formation of hydroxyapatite coatings on VT1-0 commercially pure titanium in alkaline electrolytes (hydroxyapatite + 1 M potassium hydroxide). We analyze the physical and chemical characteristics of hydroxyapatite coatings (phase composition, thickness, porosity, and surface roughness) and establish the conditions of formation of coatings for which the ratio Ca/P is close to the values typical of biological hydroxyapatite.

Prosthetic joint infection (PJI) is one of the most devastating complications that can occur following total hip and total knee arthroplasty. Despite the remarkable advances that have been made in surgical techniques and implant technology, the incidence of PJI has remained largely unchanged over the past two decades. One approach that has been described in the literature to minimize the risk of PJI has been the use of silver-coated prostheses. Silver has been reported to have antimicrobial properties when added to a variety of orthopaedic materials including bone cement, hydroxyapatite coatings and wound dressings. Silver is also being increasingly used as a surface coating for endoprostheses used for reconstruction around the hip and the knee with the specific aim of reducing the incidence of prosthetic joint infection. Despite the increasing adoption of this technology, the use of silver coatings remains controversial. The optimal method for preparation and the thickness of the coating, as well as the mechanism(s) of action in reducing the incidence of PJI, are unclear. The issue of silver toxicity is also an important consideration. This paper provides an overview of the use of silver coatings in reconstructive orthopaedics, as well as the types available and techniques used to coat endoprostheses. We also review the basic science as well as the clinical applications of silver coatings in the prevention of PJIs.

Artificial material such as stainless steel (SS) is widely used for orthopaedic applications owing to its superior properties, ease of fabrication and lower cost. However, in the body environment, stainless steel can leach toxic elements such as nickel and chromium. To prevent this, a hydroxyapatite (HAp) coating having chemical characteristics very similar to the human bone was deposited on a medical-grade UNS S31254 austenitic stainless steel by a Low-velocity oxy-fuel spray gun (LVOF). The coating was characterised by using a field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscope (FTIR). The adhesion strength, microhardness and corrosion behaviour were studied using the Tensometre, Vickers microhardness tester and potentiodynamic polarisation with electrochemical impedance spectroscope. The bacterial adhesion and bioactivity of the coating were also evaluated. The LVOF sprayed HAp coating has shown better corrosion resistance, higher bioactivity and higher hardness than the uncoated steel. The presence of tricalcium phosphate, octa-calcium phosphate (OCP) and tetra-calcium phosphate (TTCP) was found in the coating. LVOF sprayed HAp coating is also found suitable in lowering the bacterial adhesion on the steel substrate.

Few reports have evaluated the use of hydroxyapatite (HA) coating in SL-MIA-type stems in total hip arthroplasty (THA). Here, we compared early femoral bone remodeling after total hip arthroplasty using the SL-PLUS MIA stem with and without hydroxyapatite coating. From February 2012 to March 2017, 132 patients (150 hips) (HA group: 48 patients [52 hips], non-HA group: 84 patients [98 hips]) underwent THA with an SL-PLUS MIA stem. The mean follow-up duration was 3.7 years (standard deviation 1.2, range: 1.0–6.1). The Harris Hip Score (HHS), postoperative bleeding volume measurements and plain radiographs were used for clinical and radiological follow-up evaluations. Peri-prosthetic bone mineral density changes were measured by dual-energy X-ray absorptiometry. At 1 year, the HHS improved from 44.4 points preoperatively to 89.2 points postoperatively and from 44.5 points to 89.7 points in the HA and non-HA groups, respectively. At 1 year postoperatively, subsidence (≧ 3 mm) occurred in 0% and 8.2% of the HA and non-HA groups, respectively. Stress shielding (≧ Grade 3) occurred in 0% and 6% of the HA and non-HA groups, respectively. The radiolucent line was significantly smaller in the HA than in the non-HA group. There was no significant difference in the bone mineral density distribution in the two groups. Addition of HA to the SL-MIA stem can help enhance the initial fixation and early osseointegration. Further studies are required on the long-term effects of adding HA to reduce stress shielding of the proximal area of the stem.

Aluminium-free Mg–4Zn–4Sn–0.6Ca–0.5Mn alloys, with similar mechanical properties to natural bone, were produced and used as substrates for electrophoretic deposition (EPD) of hydroxyapatite (HA) po...

The lack of bioactivity of titanium (Ti) is one of the main drawbacks for its application in biomedical implants since it can considerable reduce its osseointegration capacities. One strategy to overcome this limitation is the coating of Ti with hydroxyapatite (HA), which presents similar chemical composition than bone. Nonetheless, most of the strategies currently used generate a non-stable coating and may produce the formation of amorphous phases when high temperatures are used. Herein, we proposed to generate a Ti-HA composite coating on Ti surface to improve the stability of the bioactive coating. The coating was produced by cold gas spraying, which uses relatively low temperatures, and compared to a Ti coating. The coating was thoroughly characterized in terms of morphology, roughness, porosity and phase composition. In addition, the coating was mechanically characterized using a tensile loading machine. Finally, biological response was evaluated after seeding SaOS-2 osteoblasts and measuring cell adhesion, proliferation and differentiation. The novel Ti-HA coating presented high porosity and high adhesion and bond strengths. No change in HA phases was observed after coating formation. Moreover, osteoblast-like cells adhered, proliferated and differentiated on Ti-HA coated surfaces suggesting that the novel coating might be a good candidate for biomedical applications. info:eu-repo/semantics/acceptedVersion

The goal of the present contribution is to show what is the effect of Ag addition on in vitro bioactivity and degradation characteristics of hydroxyapatite (HAP) in simulated body fluid (SBF), Dulbecco's Modified Eagle's medium (DMEM) and phosphate buffer solution (PBS) over a period of immersion at 37 ± 0.5 °C ranged from 1 to 21 days. Also, the corrosion investigations in all three media were carried out at 37 ± 0.5 °C. The results showed that the coatings behaviour is modulated with respect to the testing media and indicated that the Ag addition into hydroxyapatite has enhanced the general behaviour of HAP by either preventing and/or reducing dissolution of the HAP in SBF and DMEM solutions, while in PBS media the Ag addition contributed to a very slow degradation of hydroxyapatite. Thus, it can be said that the Ag addition into HAP enhances the overall chemical stability and behaviour in acellular media.

Plasma-sprayed hydroxyapatite (HA) coatings have been widely utilized in load-bearing titanium alloy implants. In this study, Mg, Sr co-substituted HA ((Mg, Sr)-HA) nano-scale powders have been synthesized, which are further used to prepare (Mg, Sr)-HA coatings on Ti-6Al-4V alloys in order to improve the biological functions. The average size of (Mg, Sr)-HA nano particles is ∼75 nm. The average bonding strength for (Mg, Sr)-HA coating and samples after heat treatment at 500 °C or 600 °C for 3 h are 26.17 ± 2.11 MPa, 36.07 ± 4.48 MPa and 37.07 ± 2.95 MPa, respectively. There is a significantly increase of bonding strength likely due to low residual stress after heated treatment. MC3T3-E1 cells show a high proliferation rate when cultured with (Mg, Sr)-HA coating extract compared to the normal culture medium, which also exhibit large extension and deposition of extracellular matrices when adhered on the coating surfaces. Thus, these (Mg, Sr)-HA coatings show high bonding strength and improved biological functions, which offer promising future applications in the fields of orthopedics and dentistry.

The treatment of osteochondral defects in joint cartilage remains challenging due to its limited repair capacity. This study presents a metallic osteochondral plug with hydroxyapatite (HA)-coated cap edges for improved implant-tissue contact. The hypothesis was that improved attachment prevents from synovial fluid-influx and thereby avoids osteolysis and resulting implant instability. In total, 24 female, adult sheep were randomized into three groups. All animals received an Episealer®-implant in the medial condyle of the right knee. The implants were coated with two different HA versions or uncoated (control group). After 12 weeks, the implant-tissue connections were analysed radiologically and histologically. In general, the groups with the coated cap edges showed a better quality of tissue connection to the implant. The occurrence of gaps between tissue and implant was more seldom, the binding of calcified and hyaline cartilage to the cap was significantly better than in the uncoated group. A histomorphometrically measured lower amount of void space in these groups compared to the group with the uncoated edges confirmed that. The hypothesis of a tighter cartilage bone contact was confirmed. The HA coating of the implant’s cap edges resulted in better adherence of cartilage to the implant, which was not previously reported. In conclusion, this led to a better contact between implant and cartilage as well as neighbouring bone. In clinical routine, joint fluid is aggressive, penetrates through cartilage rifts, and promotes osteolysis and loosening of implants. The observed sealing effect will act to prevent joint fluid to get access to the implant–tissue interfaces. Joint fluid is aggressive, can cause osteolysis, and can, clinically cause pain. These effects are liable to decrease with these findings and will further the longevity of these osteochondral implants.

The optimization of the anodization process of Ti substrate for in situ synthesis of hydroxyapatite/titanium oxide composite coatings on titanium substrate was accomplished. The anodization was performed under 30, 60 and 90 V cell voltage, and the morphology of treated surface, as well as linear and surface roughness, were analysed by field emission-scanning electron microscopy, atomic force microscopy and roughness tester. It was shown by linear and surface roughness analyses that titanium anodized under 60 V has the highest roughness, whereas at 90 V the flattening of the surface occurs. As the highest surface roughness results emerged at 60 V, the novel process of composite anHAp/TiO2 coating synthesis, which comprises simultaneous processes of TiO2 formation and HAp deposition, as well as HAp impregnation within TiO2 surface layer, was performed at this voltage. Ti substrate surface was completely covered by composite coating, with no visible cracks. The adhesion quantified according to ASTM D3359-02 standard is considerably improved with respect to the coatings obtained by cathaphoretic processes, with no need of subsequent sintering. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172060]

Chitosan is a cationic polymer that forms polymerized membranes upon reaction with anionic polymers. Chitosan−carboxymethyl cellulose (CMC) capsules are drug delivery carrier candidates whose mechanical strength and permeability must be controlled to achieve sustained release. In this study, the capsules were prepared from chitosan−γ-glycidoxypropyltrimethoxysilane (GPTMS)−CMC. The mechanical stability of the capsules was improved by crosslinking the chitosan with GPTMS. The capsules were then coated with hydroxyapatite (HAp) by alternately soaking them in calcium chloride solution and disodium hydrogen phosphate solution to prevent rapid initial drug release. Cytochrome C (CC), as a model drug, was introduced into the capsules via two routes, impregnation and injection, and then the CC released from the capsules was examined. HAp was found to be deposited on the internal and external surfaces of the capsules. The amount of CC introduced, and the release rate were reduced by the HAp coating. The injection method was found to result in the greatest CC loading.

This study aims at experimentally revealing the effects of damages/fractures in HAp coating layer of acetabular cups on loosening behavior of the acetabular cups. Aseptic loosening is occurred due to degradation of fixing force of acetabular cups by biological effects or mechanical loading. However, effects of mechanical loading on loosening behaviour have not been observed yet. In order to simulate cyclic loading conditions of gaits, a testing system which can load entire components of joint including acetabular cups and stem parts was designed. Moreover, by applying two positions of AE sensors during fatigue testing, it was possible to observe the damage behavior of HAp coating. AE measurement detected different failure modes of HAp coating, which were locally occurred at an edge part of the acetabular cup due to stress singularity at that region. In the cases of changing fixation angles, even though damages in simulated cancellous bone surrounding acetabular cups were less occurred, extents of rotational displacements were compatible with the one in an original fixation angle.

Biomaterials are natural or synthetic materials that are used in human body and are materials to evaluate, treat, support or replace any tissue, organ, or function of the body. Due to its favorable biocompatibility and mechanical properties, HA-coated metal-based implants are used in the orthopedic surgery operations. For this purpose, sol-gel synthesized nano sized HA powders were produced. Ti6Al4V alloy was coated with hydroxyapatite(HA) by using the sol–gel method. Surface morphologies, thermal, mineralogical properties and bioactivity of the coatings were examined and the characterization of the coatings was performed by using DTA-TG, XRD, SEM, and EDX.

Objective We developed a silver-containing hydroxyapatite (Ag-HA) coating to prevent periprosthetic joint infection (PJI). Methicillin-resistant Staphylococcus aureus (MRSA) is the main PJI-causing bacteria. Previously, we had reported the combined effect of Ag-HA coating and vancomycin (VCM) on MRSA biofilm formation 24 h after MRSA inoculation. In this study, we investigated the time-dependent efficacy of Ag-HA coating and VCM on MRSA biofilm formation on Ti discs in vitro by three-dimensional confocal laser scanning microscopic analysis. Results For the Ti VCM and HA VCM groups, the total biofilm volumes per area at 96 h after MRSA inoculation were significantly larger than those at 48 h after MRSA inoculation, respectively (p p p

The CentPillar stem (Stryker Orthopaedics), an anatomical short stem, was designed to match the proximal femoral canal shape in both patients with normal hips and those with developmental dysplasia of the hip (DDH). The long-term outcomes of the CentPillar stem was examined herein.In total, 222 hips that underwent total hip arthroplasty using the CentPillar stem were analyzed. DDH was the main reason for surgery (79.3%). Implant survivorship was assessed using Kaplan-Meier analysis. For radiographic evaluation, stress shielding was assessed using the Engh classification. For functional evaluation, patients' ability to perform deep hip bending activities (sit on the floor, squat, and sit straight) was assessed.During a median follow-up of 13.1 years, 2 stem revisions were performed (aseptic loosening and late hematogenous periprosthetic infection), and the overall cumulative implant survival rate was 99.0% at 15 years. In the radiographic evaluation, grade3 stress shielding was found in only one hip. More than 80% of the patients were able to perform each of the three deep hip bending activities.Good fixation at the proximal part of the femur was obtained, and the implant survival rate of the CentPillar stem was excellent during a long-term follow-up.

The morphology, crystal orientation, phase composition and other details of the resulting coating were characterized by means of SEM, XRD, FT-IR and so on. Then, a discussion was conducted about the growth mechanism of HA under the context of magnetic field. According to the research results, the magnetic fields of different intensities have impact on the morphology and crystal orientation of the hydroxyapatite coating to some extent. Additionally, the effect of high magnetic field is found to be more significant.

Weak osteogenic activity affects the long-term fixation and lifespan of titanium (Ti) implants. Surface modification along with a built-in porous structure is a highly considerable approach to improve the osteoinduction and osseointegration capacity of Ti. Herein, the osteoinduction and osteogenic activities of electrochemically deposited (ED) nanoplate-like, nanorod-like and nanoneedle-like hydroxyapatite (HA) coatings (named EDHA-P, EDHA-R, and EDHA-N, respectively) were evaluated in vitro and in vivo by comparison with those of acid/alkali (AA) treatment. The results revealed that the apatite forming ability of all nanostructured EDHA coatings was excellent, and only 12 h of soaking in SBF was needed to induce a complete layer of apatite. More serum proteins adsorbed on EDHA-P than others. In cellular experiments, different from those on EDHA-R and EDHA-N, the cells on EDHA-P presented a polygonal shape with lamellipodia extension, and thus exhibited a relatively larger spreading area. Furthermore, EDHA-P was more favorable for the enhancement of the proliferation and ALP activity of BMSCs, and the up-regulation of OPN gene expression. Based on the good biological performance in vitro, EDHA-P was selected to further evaluate its osteoinduction and osteogenic activities in vivo by comparison with AA treatment. Interestingly, a greater ability of ectopic osteoinduction was observed in the EDHA-P group compared to that in the AA group. At the osseous site, EDHA-P promoted more bone on/ingrowth, and had a higher area percentage of newly formed bone in the bone-implant interface and inner pores of the implants than in the AA group. Thus, a nanoplate-like HA coating has good potential in improving the osteoinductivity and osteogenic activity of porous Ti implants in clinical applications.

The production of hydroxyapatite (HAP) composite coatings has continuously been investigated for bone tissue applications during the last few decades due to their significant bioactivity and osteoconductivity. Herein, we highlight the recent experimental and theoretical progresses on HAP coatings, which may bridge the existing gap between theory and practice. The experimental studies mainly deal with electrochemical (EC) and electrophoretic (EP) deposition for the synthesis of nano-HAP in the form of coatings. Additionally, the biocompatible coating method for the fabrication of HAP composite coatings, the plasma spraying (PS) technique, and its mechanism are discussed in this review. Furthermore, the adhesion strength, mechanical, tribological and electrochemical phenomena of HAP composite coatings are critically analyzed. Their ameliorated bactericidal activity is also discussed to recognize the possibility of substituted HAP coatings from a clinical perspective. In addition, computational studies on the HAP system are explored in this report, including the first-principles density functional theory, ab initio modeling and molecular dynamics simulations. Thus, the main significance of this review is to present a collective discussion on the structural features, interfacial mechanics and binding aspects by experimental and theoretical investigations for HAP-based biomaterials, which can provide clear insights for the future research related to orthopedic applications.

Nanotechnology is a very attractive tool for tailoring the surface of an orthopedic implant to optimize its interaction with the biological environment. Nanostructured interfaces are promising, especially for orthopedic applications. They can not only improve osseointegration between the implant and the living bone but also may be used as drug delivery platforms. The nanoporous structure can be used as a drug carrier to the surrounding tissue, with the intention to accelerate tissue–implant integration as well as to reduce and treat bacterial infections occurring after implantation. Titanium oxide nanotubes are promising for such applications; however, their brittle nature could be a significantly limiting factor. In this work, we modified the topography of commercially used titanium foil by the anodization process and hydrothermal treatment. As a result, we obtained a crystalline nanoporous u-shaped structure (US) of anodized titanium oxide with improved resistance to scratch compared to TiO2 nanotubes. The US titanium substrate was successfully modified with hydroxyapatite coating and investigated for bioactivity. Results showed high bioactivity in simulated body fluid (SBF) after two weeks of incubation.

Implantasi menggunakan material titanium Ti-6Al-4V ELI masih memiliki keterbatasan yaitu osseointegrasi yang rendah karena bersifat kurang bioaktif. Hidroksiapatit digunakan sebagai bahan pelapisn meningkatkan bioaktivitas material dan ikatan material dengan jaringan tulang. Material Ti-6AL-4V ELI (kepingan) dilapisi dengan hidroksiapatit menggunakan metode electrophoretic deposition, dengan variasi voltase (5,8, dan 11 volt) selama 5 menit dan variasi waktu deposisi (5,8, dan 11 menit) dengan voltase 8 volt. Pengujian kekasaran dan kekuatan adhesi lapisan hidroksiapatit pada permukaan material dilakukan secara kualitatif. Hasil penelitian yang diperoleh menunjukkan bahwa metode EPD dapat digunakan untuk melapisi material Ti-6Al-4V ELI dengan hidroksiapatit. Massa partikel penyusun lapisan hidroksiapatit relatif dipengaruhi oleh perlakuan waktu deposisi karena terdapat perubahan ketebalan lapisan. Akan tetapi, susunan partikel relatif dipengaruhi oleh daya yang mengakibatkan migrasi partikel yang akan berpengaruh terhadap ikatan lapisan pada permukaan material. Perlakuan voltase 8 volt selama 5 menit menghasilkan kekasaran pemukaan material dilapisi hidroksiapatit Ra 0,88 dan kerusakan lapisan setelah cross cut tape test adalah 2,25% yang berarti lapisan mengalami adhesi dengan baik pada permukaan material. Dengan masa hidroksiapatit relatif tinggi (0,3 mg), lapisan tersebut menutupi permukaan material titanium dengan baik (surface coverage 82,1%) memiliki ketebalan rata-rata (73,3 μm). Hasil yang diperoleh diharapkan sesuai untuk aplikasi biomedis.

Surface modification of orthopedic and dental implants has been demonstrated to be an effective strategy to accelerate bone healing at early implantation times. Among the different alternatives, coating implants with a layer of hydroxyapatite (HAp) is one of the most used techniques, due to its excellent biocompatibility and osteoconductive behavior. The composition and crystalline structure of HAp allow for numerous ionic substitutions that provide added value, such as antibiotic properties or osteoinduction. In this article, we will review and critically analyze the most important advances in the field of substituted hydroxyapatite coatings. In recent years substituted HAp coatings have been deposited not only on orthopedic prostheses and dental implants, but also on macroporous scaffolds, thus expanding their applications towards bone regeneration therapies. Besides, the capability of Q4 substituted HAps to immobilize proteins and growth factors by non-covalent interactions has opened new possibilities for preparing hybrid coatings that foster bone healing processes. Finally, the most important in vivo outcomes will be discussed to understand the perspectives of substituted HAp Q5 coatings from a clinical point of view.

In the present study, the corrosion resistance and bioactivity of AZ91HP magnesium alloy were improved by plasma spraying hydroxyapatite (HA) coating. X-ray diffraction measurements indicated that the coating formed amorphous and little β-Ca3 (PO4)2 besides of HA. The corrosion resistance and bioactivity of the coating and magnesium alloy in simulated body fluid were investigated using immersion test. The coating showed lower corrosion rate and better bioactivity than magnesium alloy. The coating significantly improved the hydrophilicity of Mg alloy. The prothrombin time of the coating was 18 s, and the prothrombin time of Mg alloy was 11 s, so the coating had better anticoagulant activity.