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Additively manufactured (AM) biodegradable porous iron-manganese (FeMn) alloys have recently been developed as promising bone-substituting biomaterials. However, their corrosion fatigue behavior has not yet been studied. Here, we present the first study on the corrosion fatigue behavior of an extrusion-based AM porous Fe35Mn alloy under cyclic loading in air and in the revised simulated body fluid (r-SBF), including the fatigue crack morphology and distribution in the porous structure. We hypothesized that the fatigue behavior of the architected AM Fe35Mn alloy would be strongly affected by the simultaneous biodegradation process. We defined the endurance limit as the maximum stress at which the scaffolds could undergo 3 million loading cycles without failure. The endurance limit of the scaffolds was determined to be 90 % of their yield strength in air, but only 60 % in r-SBF. No notable crack formation in the specimens tested in air was observed even after loading up to 90 % of their yield strength. As for the specimens tested in r-SBF, however, cracks formed in the specimens subjected to loads exceeding 60 % of their yield strength appeared to initiate on the periphery and propagate toward the internal struts. Altogether, the results show that the extrusion-based AM porous Fe35Mn alloy is capable of tolerating up to 60 % of its yield strength for up to 3 million cycles, which corresponds to 1.5 years of use of load-bearing implants subjected to repetitive gait cycles. The fatigue performance of the alloy thus further enhances its potential for trabecular bone substitution subjected to cyclic compressive loading. Statement of significance: Fatigue behavior of extrusion-based AM porous Fe35Mn alloy scaffolds in air and revised simulated body fluid was studied. The Fe35Mn alloy scaffolds endured 90 % of their yield strength for up to 3 × 106 loading cycles in air. Moreover, the scaffolds tolerated 3 × 106 loading cycles at 60 % of their yield, Biomaterials & Tissue Biomechanics

In this work, we have developed and characterized a ceramic composite based on a core of directionally solidified calcium zirconate-calcium stabilized zirconia (CZO-CSZ) eutectic composite coated with a bioactive glass-ceramic. The aim is to research new orthopedic implants as an alternative to conventional 3Y-TZP bioinert ceramics. The CZO-CSZ eutectic rods were grown from the melt of rods of CaO-ZrO2 in the eutectic composition using the laser floating zone technique (LFZ). The mechanical results indicated that directional eutectics prepared with this technique exhibited good mechanical strength and significant hardness and toughness. The LFZ technique was also used to melt the bioactive coating previously placed by dip coating on the CZO-CSZ rod surface. Depending on the thickness of the coating and the applied laser power, an alloying or coating process was achieved. In the first case, the coating was diluted with the surface of the eutectic cylinder, leading to the segregation of the calcium zirconate and zirconia phases and the formation of a bioactive phase embedding zirconia particles. In the second case, a layer of ceramic glass was formed, well attached to the eutectic cylinder. These layers were both studied from the microstructural and bioactivity points of view.

Bone cement is used as a mortar for securing bone implants, as bone void fillers or as spacers in orthopaedic surgery. Antibiotic-loaded bone cements (ALBCs) have been used to prevent and treat prosthetic joint infections by providing a high antibiotic concentration around the implanted prosthesis. High antibiotic concentrations are, on the other hand, often associated with tissue toxicity. Controlling antibiotic release from ALBCS is key to achieving effective infection control and promoting prosthesis integration with the surrounding bone tissue. However, current ALBCs still need significant improvement in regulating antibiotic release. In this review, we first provide a brief introduction to prosthetic joint infections, and the background concepts of therapeutic efficacy and toxicity in antibiotics. We then review the current state of ALBCs and their release characteristics before focusing on the research and development in controlling the antibiotic release and osteo-conductivity/inductivity. We then conclude by a discussion on the need for better in vitro experiment designs such that the release results can be extrapolated to predict better the local antibiotic concentrations in vivo.

Hard tissues, such as bone and teeth, are natural composites of collagen nanofibers that are reinforced by inorganic calcium phosphate Nano crystallites, in the form of nanocomposites. The interlocking between these components in hard tissues explains their unique characteristics. Bone is mainly classified into two major types; compact and cancellous depending on the extent of porosity. Fractures in the compact bone can be treated using bone fixation implants, such as rods, screws, and plates, or can be totally replaced by bone implants if complete substitution is required. Cancellous bone, on the other hand, is highly porous and its substitution with synthetic biomaterials is a challenge. The current study investigates the use of 3D printing technology to fabricate 3D porous scaffolds that can be used as substitutes for fractured cancellous bone. Three types of polymers have been investigated because of their classification as bioactive (polyethylene terephthalate); PET), biodegradable (poly(lactic acid); PLA), and bioinert (Acrylonitrile-butadiene-styrene terpolymer); ABS). All polymers were 3D printed into highly porous scaffolds that were further chemically functionalized to enhance their surface properties, hence improve their potential application as bone implants. Both as-printed and chemically functionalized porous scaffolds were characterized for their structure and morphology. Moreover, chemically-treated PET and PLA scaffolds were investigated for their preliminary in vitro performance in a simulated body fluid (SBF) medium, while chemically conditioned ABS scaffolds were used as platforms to grow a biodegradable metalorganic framework (HKUST-1) onto their surfaces. Preliminary results of the current study showed the potential of the chemically functionalized porous scaffolds to be used as implants for the partial and total replacement of defective porous bone.

[EN] A lot of research effort is being made in the field of biomaterials, specifically those ones used for producing bone implants. New methods and materials are being studied in order to match the properties of the tissues that they replace and achieve better integration. One interesting field of research is titanium bone prostheses. Materials used for bone replacing are improving in order to match bone properties and therefore achieve a high osseointegration. Other ways of enhancing this are improving the surface and structure of them, or using biomaterials that can accelerate the formation of new bone material around the implant. The aim of this project is to explore new ways of fabricating novel functionally graded Ti-based implants based on powder metallurgy. This method can be used in order to get a high quality titanium scaffold with graded structural/ mechanical/biological properties that match those of bone, and along with the addition of biomaterials, enhances biointegration, and reduces the chances of implant failure. To conclude, this subject involves the study of new methods to produce easily high quality implants, but also the study of bone formation process and how to enhance it using bioactive compounds. Improving implant’s lifetime and reducing chances of failure will improve many people’s lives.

The growing interest in multi-functional metallic biomaterials for bone substitutes challenges the current additive manufacturing (AM, =3D printing) technologies. It is foreseeable that advances in multi-material AM for metallic biomaterials will not only allow for complex geometrical designs, but also improve their multi-functionalities by tuning the types or compositions of the underlying base materials, thereby presenting unprecedented opportunities for advanced orthopedic treatments. AM technologies are yet to be extensively explored for the fabrication of multi-functional metallic biomaterials, especially for bone substitutes. The aim of this review is to present the viable options of the state-of-the-art multi-material AM for Ti-, Mg-, and Fe-based biomaterials to be used as bone substitutes. The review starts with a brief review of bone tissue engineering, the design requirements, and fabrication technologies for metallic biomaterials to highlight the advantages of using AM over conventional fabrication methods. Five AM technologies suitable for metal 3D printing are compared against the requirements for multi-material AM. Of these AM technologies, extrusion-based multi-material AM is shown to have the greatest potential to meet the requirements for the fabrication of multi-functional metallic biomaterials. Finally, recent progress in the fabrication of Ti-, Mg-, and Fe-based biomaterials including the utilization of multi-material AM technologies is reviewed so as to identify the knowledge gaps and propose the directions of further research for the development of multi-material AM technologies that are applicable for the fabrication of multi-functional metallic biomaterials., Biomaterials & Tissue Biomechanics

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porousand“as-received”c.p. Tisur faces with the aim of improving cellular viability. Nano features were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0◦ to 75◦ degrees, and fluences up to 5.0×1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.

This article is focused on the part of my master´s theses which discusses the corrosion of biodegradable bone implants in solutions which simulate human blood environment. It explains use of Tafel Analysis for corrosion measurements and the way how those measurements were done. At the end of article results are being described and analyzed.

This article is focused on the part of my master´s theses which discusses the corrosion of biodegradable bone implants in solutions which simulate human blood environment. It explains use of Tafel Analysis for corrosion measurements and the way how those measurements were done. At the end of article results are being described and analyzed.

This article is focused on the part of my master´s theses which discusses the corrosion of biodegradable bone implants in solutions which simulate human blood environment. It explains use of Tafel Analysis for corrosion measurements and the way how those measurements were done. At the end of article results are being described and analyzed.

This article is focused on the part of my master´s theses which discusses the corrosion of biodegradable bone implants in solutions which simulate human blood environment. It explains use of Tafel Analysis for corrosion measurements and the way how those measurements were done. At the end of article results are being described and analyzed.

To facilitate examination for osteogenesis and follow up after craniotomy similar head models called phantoms are made. The head phantom should emulate the tissues from a real head. This requires that the realistic head phantom have the same electrical properties as relative permittivity (dielectric constant) and conductivity. Both must be validated and matched for right frequency spectrum. Validation measurements are performed by a coaxial slim probe connected to an Agilent Technologies E8364B network analyzer. The range of frequency measured is from 1 to 50 GHz, but matching will only be processed for 1 to 10 GHz. The resonance frequency for the antenna or sensor, which later will be used, is 2.4 GHz. The end results of the head phantom consists of three different tissues or layers (skin, bone and brain). Cavities will be created in the bone and will act as different defects or stages of re-growing bone. Phantom cube is done for examining the influence of implant in bone. Insertions of cube samples are made to emulate intermediates between implant and bone. Keywords: agar, BMP, body morphogenetic protein, bone implant, brain phantom, craniosynostosis, craniotomy, cube phantom, phantom, re-growing bone, skin phantom, skull phantom, tissue.

The results of experimental study on the macro- and micropreparations of biocomposite bone graft Osteomatrix when replacing the femoral defects in rats using immunohistochemical method and light microscopy are provided. Dynamics of the researches — 3 months. We have studied immunohistochemical and histomorphological features of restructuring bone implants, developed an experimental model for transplantation of bone implants in laboratory animals. Information value of immunohistochemical study for an objective evaluation of bone remodeling rate and its response to the implant has been demonstrated. This method helps to identify reliably osteoinductive proteins, as well as to quantify level of their expression., Представлены результаты экспериментального исследования на макро- и микропрепаратах биокомпозитного костного материала Остеоматрикс при замещении дефектов бедренной кости у крыс с применением иммуногистохимического метода и метода световой микроскопии. Динамика исследований — 3 месяца. Изучены иммуногистохимические и гистоморфологические признаки перестройки костных имплантатов, разработана экспериментальная модель трансплантации костных имплантатов на лабораторных животных. Показана информативность иммуногистохимического исследования для объективной оценки скорости ремоделирования костной ткани и ее реакции на имплантат. Этот метод позволяет достоверно идентифицировать остеоиндуктивные протеины, а также количественно оценить их уровень экспрессии., Наведені результати експериментального дослідження на макро- і мікропрепаратах біокомпозитного кісткового матеріалу Остеоматрикс при заміщенні дефектів стегнової кістки у щурів із застосуванням імуногістохімічного методу та методу світлової мікроскопії. Динаміка досліджень — 3 місяці. Вивчені імуногістохімічні та гістоморфологічні ознаки перебудови кісткових імплантатів, розроблена експериментальна модель трансплантації кісткових імплантатів на лабораторних тваринах. Показана інформативність імуногістохімічного дослідження для об’єктивної оцінки швидкості ремоделювання кісткової тканини та її реакції на імплантат. Цей метод дозволяє вірогідно ідентифікувати остеоіндуктивні протеїни, а також кількісно оцінити їх рівень експресії.

Magnesium alloys have been investigated in different fields of medicine and represent a promising biomaterial for implants due to characteristics like bioabsorbability and osteoinduction. The objective of this study was to evaluate the usability of magnesium as implant material in middle ear surgery. Magnesium implants were placed into the right middle ear of eighteen New Zealand White rabbits. Nine animals were euthanized after four weeks and nine animals after three month. The petrous bones were removed and embedded in epoxy resin. The specimens were then polished, stained and evaluated with the aid of a light microscope. The histological examination revealed a good biocompatibility. After four weeks, a beginning corrosion of the implant's surface and low amount of trabecular bone formation in the area of the stapes base plate was observed. A considerable degradation of implants and obvious bone formation was found three month after implantation. The magnesium alloy used in the present study partly corroded too fast, so that a complete bone reconstruction could not be established in time. The increased osteoinduction on the stapes base plate resulted in a tight bone-implant bonding. Thus, a promising application of magnesium could be a coating of biomaterials in order to improve the bony integration of implants. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

This study aims to establish a mandible fracture model, and to review fracture healing following fixation with a locking miniplate system. Eighteen 2-year-old sheep were divided into three groups of six. Each animal had a single fracture that was anatomically reduced and internally fixed by a single 4-hole plate with two monocortical screws each side of the fracture. The fractures were internally fixed with poorly contoured conventional miniplates or poorly contoured mini-locking plate or well contoured conventional miniplates. Two sheep in each of the three groups were killed at 2, 4 and 8 weeks after surgery. The mandibles were radiographed then decalcified specimens were reviewed microscopically. No clinical difference was observed between the groups. All fractures were at an advanced stage of bony union by 4 weeks. Fracture union appeared radiographically more advanced with the locking plate system. This study established a protocol for simulating a fracture model for the study of fracture healing. A more advanced stage of union was seen for fractures internally fixed with locking plates/screws than with a conventional system. The observations suggest the purported biological benefits of locking miniplate system do exist. © 2013 International Association of Oral and Maxillofacial Surgeons.

Resection of musculoskeletal sarcoma can result in large bone defects where regeneration is needed in a quantity far beyond the normal potential of self-healing. In many cases, these defects exhibit a limited intrinsic regenerative potential due to an adjuvant therapeutic regimen, seroma, or infection. Therefore, reconstruction of these defects is still one of the most demanding procedures in orthopaedic surgery. The constraints of common treatment strategies have triggered a need for new therapeutic concepts to design and engineer unparalleled structural and functioning bone grafts. To satisfy the need for long-term repair and good clinical outcome, a paradigm shift is needed from methods to replace tissues with inert medical devices to more biological approaches that focus on the repair and reconstruction of tissue structure and function. It is within this context that the field of bone tissue engineering can offer solutions to be implemented into surgical therapy concepts after resection of bone and soft tissue sarcoma. In this paper we will discuss the implementation of tissue engineering concepts into the clinical field of orthopaedic oncology.

Bone infection remains a formidable challenge to the medical field. The goal of the current study is to evaluate antibacterial coatings in vitro and to develop a large animal model to assess coated bone implants. A novel coating consisting of titanium oxide and siloxane polymer doped with silver was created by metal-organic methods. The coating was tested in vitro using rapid screening techniques to determine compositions which inhibited Staphylococcus aureus growth, while not affecting osteoblast viability. The coating was then applied to intramedullary nails and evaluated in vivo in a caprine model. In this pilot study, a fracture was created in the tibia of the goat, and Staphylococcus aureus was inoculated directly into the bone canal. The fractures were fixed by either coated (treated) or non-coated intramedullary nails (control) for 5 weeks. Clinical observations as well as microbiology, mechanical, radiology, and histology testing were used to compare the animals. The treated goat was able to walk using all four limbs after 5 weeks, while the control was unwilling to bear weight on the fixed leg. These results suggest the antimicrobial potential of the hybrid coating and the feasibility of the goat model for antimicrobial coated intramedullary implant evaluation.

[no abstract]

The excellent properties of Ti have resulted in its generalised use for bone implants. However, Ti is very stiff in comparison with human cortical bone, and this creates problems of bone weakening and loosening of the implant. This article discusses the mechanical properties (flexural and compressive strength, and stiffness) of porous Ti-6Al-4V specimens developed using the space holder method. These properties are examined relative to the production process parameters: compacting pressure and sintering time, as well as temperature, and the addition of spacer and its particle size. It is seen that when spacer is added, compressive strength decreases with the application of compacting pressure and that these are the most influential parameters. The developed pieces show a closed and unconnected porosity. Small additions of spacer (25 vol.-%) reduce stiffness to around half of that shown by the solid material, and the resulting pieces are strong enough to be used as bone substitute. © 2011 Institute of Materials, Minerals and Mining.

Studies concerning the application of Porites asteroides coral for bone implant purposes have demonstrated the biological viability of its use. As a complement to previous research regarding the development of bone-powder based composite materials which are useful for such applications, this study was aimed at developing a coral powder-based composite material which would be able to satisfy the appropriate structural, mechanical and cytotoxic properties required for its use. A composite material made of coral powder, calcium sulphate powder and water was therefore developed, and its properties were tested in different compositions. The results showed how the resulting composite material had properties which were comparable to those of human cortical bone (from both a structural and mechanical point of view), as well as being non-toxic below a 0.35 mg/ml critical composite material concentration., Diferentes estudios referentes a la aplicación del coral tipo Porites asteroides en implantes óseos han demostrado su viabilidad biológica para este fin. Como complemento a investigaciones previas relacionadas con el desarrollo de un material compuesto a base de polvo de hueso susceptible de osteo-implantación, el propósito de este estudio es desarrollar un material compuesto a base de polvo de coral, que satisfaga las propiedades estructurales, mecánicas y citotóxicas requeridas para ser considerado como un material adecuado para este fin. A partir de esto se desarrolló un material a base de polvo de coral, polvo de sulfato de calcio y agua, y se realizaron los respectivos ensayos en diferentes composiciones del mismo. Los resultados generales muestran que el material compuesto desarrollado posee propiedades comparables a las del hueso cortical humano (desde un punto de vista tanto estructural como mecánico) y adicionalmente no muestra evidencias de citotoxicidad si se utiliza en concentraciones menores a 0.35 mg/ml.

Two common causes leading to bone implant failure are: an insufficient bonding between the implant and surrounding bone and infection. Patients with implant failure often undergo revision surgeries which are costly and painful. Moreover, for patients who receive orthopedic implants after cancerous tissue is removed, it would be beneficial to implant an anti-cancer material that can impede the return of cancerous tissue growth that may develop from cancer cells not removed during surgery. Therefore, the objective of this study was to create a coating material that can: (i) promote healthy, normal bone growth, (ii) inhibit bacterial attachment and (iii) impede cancer growth. To achieve that objective, conventional orthopedic implant materials (such as titanium (Ti), stainless steel and ultra high molecular weight polyethylene) were coated with selenium (Se) nanoclusters. Different coating densities were achieved by varying Se concentration in the reaction mixture. For the first time, Se nanocluster coatings were shown to enhance healthy osteoblast (bone-forming cell) and inhibit cancerous osteoblast proliferation in either separate-culture experiments or co-culture experiments. S. epidermidis (one of the leading bacteria that infect implants) functions were inhibited on materials coated with Se-nanoclusters compared to uncoated materials. Therefore, a new orthopedic implant coating material is introduced here that may be ideal for promoting bone growth and inhibiting cancer and bacteria growth.

Vhledem k celosvětovému stárnutí populace, dochází k častější potřebě opravy pohybového aparátu. V některých případech je proto nutno přejít v konečné fázi k implantaci kostní náhrady. Nejčastěji je pro svoji biokompatibilitu a bioaktivitu využíván hydroxyapatit, který je v kostech přirozeně zastoupen. Využití hydroxyapatitu jako materiálu pro kostní náhrady je omezeno mechanickou stabilitou v porézních systémech. Metoda, při které bylo dosaženo nejlepšího poměru mechanické stability a porozity, se nazývá freeze – casting. Tato metoda využívá tvorbu ledu (v případě vodných suspenzí) ke tvorbě lamelární struktury během kontrolovaného mražení. Dalším krokem je odstranění ledových krystalů lyofilizací. Následně je výsledná porézní lamelární struktura zpevněna slinutím. Změnou složení suspenze nebo podmínek mražení lze dosáhnout různé mezilamelární vzdálenosti, spojení lamel a porozity. V této práci byly připraveny keramické suspenze v objemovém zastoupení hydroxyapatitu 7,5 %, 10 %, 15 % a 20 %, které byly použity při přípravě porézních kostních náhrad metodou freeze – casting. Během mražení byla do struktur implementována 3D mřížka, která posloužila jako šablona pro síť kanálků (v průměru cca 800 mikrometrů). Po lyofilizaci byly následným ohřevem odstraněny z materiálu organické látky, včetně 3D mřížky. Výsledná biokeramická struktura dosáhla porozity víc než 90 % a velmi dobrého poměru mechanické stability a porozity. Implementace 3D mřížky se ukázala být vhodnou metodou pro kontrolovanou tvorbu kanálků s dostatečným rozměrem, sloužící k zvýšení bioaktivity materiálu., Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Vhledem k celosvětovému stárnutí populace, dochází k častější potřebě opravy pohybového aparátu. V některých případech je proto nutno přejít v konečné fázi k implantaci kostní náhrady. Nejčastěji je pro svoji biokompatibilitu a bioaktivitu využíván hydroxyapatit, který je v kostech přirozeně zastoupen. Využití hydroxyapatitu jako materiálu pro kostní náhrady je omezeno mechanickou stabilitou v porézních systémech. Metoda, při které bylo dosaženo nejlepšího poměru mechanické stability a porozity, se nazývá freeze – casting. Tato metoda využívá tvorbu ledu (v případě vodných suspenzí) ke tvorbě lamelární struktury během kontrolovaného mražení. Dalším krokem je odstranění ledových krystalů lyofilizací. Následně je výsledná porézní lamelární struktura zpevněna slinutím. Změnou složení suspenze nebo podmínek mražení lze dosáhnout různé mezilamelární vzdálenosti, spojení lamel a porozity. V této práci byly připraveny keramické suspenze v objemovém zastoupení hydroxyapatitu 7,5 %, 10 %, 15 % a 20 %, které byly použity při přípravě porézních kostních náhrad metodou freeze – casting. Během mražení byla do struktur implementována 3D mřížka, která posloužila jako šablona pro síť kanálků (v průměru cca 800 mikrometrů). Po lyofilizaci byly následným ohřevem odstraněny z materiálu organické látky, včetně 3D mřížky. Výsledná biokeramická struktura dosáhla porozity víc než 90 % a velmi dobrého poměru mechanické stability a porozity. Implementace 3D mřížky se ukázala být vhodnou metodou pro kontrolovanou tvorbu kanálků s dostatečným rozměrem, sloužící k zvýšení bioaktivity materiálu., Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Vhledem k celosvětovému stárnutí populace, dochází k častější potřebě opravy pohybového aparátu. V některých případech je proto nutno přejít v konečné fázi k implantaci kostní náhrady. Nejčastěji je pro svoji biokompatibilitu a bioaktivitu využíván hydroxyapatit, který je v kostech přirozeně zastoupen. Využití hydroxyapatitu jako materiálu pro kostní náhrady je omezeno mechanickou stabilitou v porézních systémech. Metoda, při které bylo dosaženo nejlepšího poměru mechanické stability a porozity, se nazývá freeze – casting. Tato metoda využívá tvorbu ledu (v případě vodných suspenzí) ke tvorbě lamelární struktury během kontrolovaného mražení. Dalším krokem je odstranění ledových krystalů lyofilizací. Následně je výsledná porézní lamelární struktura zpevněna slinutím. Změnou složení suspenze nebo podmínek mražení lze dosáhnout různé mezilamelární vzdálenosti, spojení lamel a porozity. V této práci byly připraveny keramické suspenze v objemovém zastoupení hydroxyapatitu 7,5 %, 10 %, 15 % a 20 %, které byly použity při přípravě porézních kostních náhrad metodou freeze – casting. Během mražení byla do struktur implementována 3D mřížka, která posloužila jako šablona pro síť kanálků (v průměru cca 800 mikrometrů). Po lyofilizaci byly následným ohřevem odstraněny z materiálu organické látky, včetně 3D mřížky. Výsledná biokeramická struktura dosáhla porozity víc než 90 % a velmi dobrého poměru mechanické stability a porozity. Implementace 3D mřížky se ukázala být vhodnou metodou pro kontrolovanou tvorbu kanálků s dostatečným rozměrem, sloužící k zvýšení bioaktivity materiálu., Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Vhledem k celosvětovému stárnutí populace, dochází k častější potřebě opravy pohybového aparátu. V některých případech je proto nutno přejít v konečné fázi k implantaci kostní náhrady. Nejčastěji je pro svoji biokompatibilitu a bioaktivitu využíván hydroxyapatit, který je v kostech přirozeně zastoupen. Využití hydroxyapatitu jako materiálu pro kostní náhrady je omezeno mechanickou stabilitou v porézních systémech. Metoda, při které bylo dosaženo nejlepšího poměru mechanické stability a porozity, se nazývá freeze – casting. Tato metoda využívá tvorbu ledu (v případě vodných suspenzí) ke tvorbě lamelární struktury během kontrolovaného mražení. Dalším krokem je odstranění ledových krystalů lyofilizací. Následně je výsledná porézní lamelární struktura zpevněna slinutím. Změnou složení suspenze nebo podmínek mražení lze dosáhnout různé mezilamelární vzdálenosti, spojení lamel a porozity. V této práci byly připraveny keramické suspenze v objemovém zastoupení hydroxyapatitu 7,5 %, 10 %, 15 % a 20 %, které byly použity při přípravě porézních kostních náhrad metodou freeze – casting. Během mražení byla do struktur implementována 3D mřížka, která posloužila jako šablona pro síť kanálků (v průměru cca 800 mikrometrů). Po lyofilizaci byly následným ohřevem odstraněny z materiálu organické látky, včetně 3D mřížky. Výsledná biokeramická struktura dosáhla porozity víc než 90 % a velmi dobrého poměru mechanické stability a porozity. Implementace 3D mřížky se ukázala být vhodnou metodou pro kontrolovanou tvorbu kanálků s dostatečným rozměrem, sloužící k zvýšení bioaktivity materiálu., Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Práce je rozdělena na 3 hlavní části. V první části je shrnuta teorie dané problematiky. Zde jsou sjednoceny teoretické informace o různých možnostech jednotlivých přístupů. Výsledkem této části je tedy obecný souhrn teoreticky možných postupů vytvoření umělé kostní náhrady, kde ke každému jsou uvedeny jeho výhody a nevýhody. Teoretická část obsahuje také informace, které nakonec v praxi autor nevyužil. Jeho myšlenkou však bylo vytvořit ucelený pohled na problematiku z více úhlů pohledu. Druhá část využívá teoretické poznatky z předchozího souboru informací a na jejich základě definuje kroky potřebné k úspěšnému zvládnutí problematiky 3D tisku kosti. Třetí část se řídí pokyny obou předchozích a zaměřuje se na praktické zhotovení kosti a následné zhodnocení zvolené metody. Jsou zde probrány jednotlivé úkony, které vedly k finálnímu zhotovení kosti. Závěr práce je potom zaměřen na zhodnocení úspěšnosti zvolených postupů a doporučení pro další kroky v budoucnu., The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.

Porézne materiály sú momentálne veľkým objektom záujmu tkanivového inžinierstva. Poskytujú unikátne vlastnosti, ako je bioaktivita, biodegradabilita, osteokonduktivita a vaskularizácia. Veľký potenciál v medicínskych aplikáciách vykazujú najmä keramické porézne sústavy. Kritickým problémom pri poréznych scaffoldoch sú zlé mechanické vlastnosti, a preto sa momentálne využívajú len pri nízko zaťažovaných miestach. Táto práca sa zaoberá prípravou scaffoldov z hydroxyapatitu, pomocou metódy freeze-casting, kde bola aplikovaná nepriama 3D tlač s cieľom dosiahnuť otvorené kanáliky s veľkosťou nad 200 µm . Porovnáva mechanické vlastnosti scaffoldov s rôznou vnútornou štruktúrou a sleduje, aký vplyv má implementácia rôznych typov mriežok na výslednú stabilitu. Boli pripravené scaffoldy s rôznym usporiadaním makro kanálikov vo vnútornej štruktúre, ale mali rovnaké rozmery. 3D mriežka bola implementovaná pred mrazením do formy a táto mriežka bola spekaním odstránená, kde vo výslednom scaffolde ostal len systém kanálikov o rozmeroch najmenej 540-600 µm. Experimentálne bolo zistené, že typ 3D mriežky má vplyv na výslednú mechanickú stabilitu scaffoldu. Pootočenie tejto mriežky nemá významný vplyv na výsledok, len napomáha k praskaniu v smere závitnice. Kombinácia týchto metód vykazuje veľmi dobrú kontrolovateľnosť s riadenými makro kanálikmi vo výslednom scaffolde, a preto je vhodná pre prípravu kostných náhrad s rôznou štruktúrou., Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.

Vhledem k celosvětovému stárnutí populace, dochází k častější potřebě opravy pohybového aparátu. V některých případech je proto nutno přejít v konečné fázi k implantaci kostní náhrady. Nejčastěji je pro svoji biokompatibilitu a bioaktivitu využíván hydroxyapatit, který je v kostech přirozeně zastoupen. Využití hydroxyapatitu jako materiálu pro kostní náhrady je omezeno mechanickou stabilitou v porézních systémech. Metoda, při které bylo dosaženo nejlepšího poměru mechanické stability a porozity, se nazývá freeze – casting. Tato metoda využívá tvorbu ledu (v případě vodných suspenzí) ke tvorbě lamelární struktury během kontrolovaného mražení. Dalším krokem je odstranění ledových krystalů lyofilizací. Následně je výsledná porézní lamelární struktura zpevněna slinutím. Změnou složení suspenze nebo podmínek mražení lze dosáhnout různé mezilamelární vzdálenosti, spojení lamel a porozity. V této práci byly připraveny keramické suspenze v objemovém zastoupení hydroxyapatitu 7,5 %, 10 %, 15 % a 20 %, které byly použity při přípravě porézních kostních náhrad metodou freeze – casting. Během mražení byla do struktur implementována 3D mřížka, která posloužila jako šablona pro síť kanálků (v průměru cca 800 mikrometrů). Po lyofilizaci byly následným ohřevem odstraněny z materiálu organické látky, včetně 3D mřížky. Výsledná biokeramická struktura dosáhla porozity víc než 90 % a velmi dobrého poměru mechanické stability a porozity. Implementace 3D mřížky se ukázala být vhodnou metodou pro kontrolovanou tvorbu kanálků s dostatečným rozměrem, sloužící k zvýšení bioaktivity materiálu., Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.