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Porous degradable metallic biomaterials are attracting considerable attention as promising bone implant materials. Recently, the interest in developing new biomaterials with enhanced performance stimulates the widespread development of fabricating techniques for porous metals. In this work, the recent progress and novel trends on preparation methods of metallic foams for biomedicine were systematically reviewed. The common synthesis methods for porous Mg, Fe, Zn, and their alloys intended for orthopedic applications are comprehensively discussed and compared. The advantages and disadvantages of relevant manufacturing strategies are evaluated. While the modern techniques enable fabrication of complex porous structures and customized shapes, the cost-effective and easy controllable approach are major benefits of traditional methods. Main structural characteristics and properties of biomaterials fabricated using different routes are also presented. Furthermore, the future research directions and current challenges are mentioned. The ambition of this review article is to provide useful guidelines for researchers to choose suitable manufacturing technique to prepare materials with desired structural topology and mechanical, and degradation properties.

Titanium implants have been widely used as one of the most effective treatments of bone defects. However, the lack of osteogenesis and bacteria-resistant activities result in high infection and loosening rates of titanium implants. Anodic oxidation could easily construct titanium dioxide nanotubes (TNTs) array on the surface of titanium, and the rough surface of TNTs is beneficial to the growth of osteoblast-related cells on the surface. And TNTs could be excellent drug carriers because of their single-entry tubular hollow structure. In this review, we aim at detailing the application of TNTs as drug carriers in the field of bone implants. Starting from the topography of TNTs, we illustrated the biological activity of the TNTs surface, the drugs for loading in TNTs, and the controlled and responsive release strategies of drug-loaded TNTs, respectively. At the end of this review, the shortcomings of TNTs as the drug carrier in the field of bone implants are discussed, and the development direction of this research field is also prospected.

Millions of people suffer from bone loss and diseases each year, which give rise to bone-related medical treatments. Multi-material coatings composed of Silicon Substituted Hydroxyapatite (Si-HA) and Silver Substituted Hydroxyapatite (Ag-HA) potentiated its usage as an ideal bone implant material with favourable biological response and antibacterial properties, respectively. Each patient has different conditions (e.g. bone ages, bone density, position, and infection status) and specific bone implant requirement, thus requiring specific designs of Si-HA and Ag-HA bone implant material ratios. In this paper, a recommender system which took advantage of Wide&Deep recommendation architecture and DenseNet architecture was provided and a semi-supervised training process was utilized to recommend appropriate bone implant material ratio (Si-HA:Ag-HA) for each patient to improve the bone disease treatment and recovery. The proposed recommendation system could achieve high accuracy ( $$92.2\%$$ ) and efficiency (using only $$10\%$$ of labeled data) on test dataset, which could be potentially utilized in future clinical usages and provide doctors with decision support to make better clinical decisions.

As two promising biomaterials for bone implants, biomedical metals have favorable mechanical properties and good machinability but lack of bioactivity; while bioceramics are known for good biocompatibility or even bioactivity but limited by their high brittleness. Biocermets, a kind of composites composing of bioceramics and biomedical metals, have been developed as an effective solution by combining their complementary advantages. This paper focused on the recently studied biocermets for bone implant applications. Concretely, biocermets were divided into ceramic-based biocermets and metal-based biocermets according to the phase percentages. Their characteristics were systematically summarized, and the fabrication methods for biocermets were reviewed and compared. Emphases were put on the interactions between bioceramics and biomedical metals, as well as the performance improvement mechanisms. More importantly, the main methods for the interfacial reinforcing were summarized, and the corresponding interfacial reinforcing mechanisms were discussed. In addition, the in vitro and in vivo biological performances of biocermets were also reviewed. Finally, future research directions were proposed on the advancement in component design, interfacial reinforcing and forming mechanisms for the fabrication of high-performance biocermets.

Diaphyseal defects of canine tibia bones were replaced with bioactive cylindrical mesh implants made of Ti–6Al–4V titanium alloy. Bone−implant units were cut with a precision cutter using abrasive cutting discs (thickness, 0.76 mm; rotational speed, 2000 rpm; feed rate, 12 mm/min for sample 1 and 5 mm/min for samples 2–4). Tissues were found to suffer thermal damage at a disc feed rate of 12 mm/min; 72.6% of tissues in the projection of the defect cavity were found to be unsuitable for histological examination. At a feed rate of 5 mm/min, thermal damage or significant mechanical damage to the tissues was not observed. Thus, at the stage of preparation of samples of titanium–containing bone−implant units for the assessment of osseointegration, the degree of tissue preservation, under otherwise identical conditions, depends on the cutting tool feed rate.

Purpose The aim of this study was to assess the biomechanical properties of intact vertebra augmented using a local osteo-enhancement procedure to inject a triphasic calcium sulfate/calcium phosphate implant material. Methods Twenty-one fresh frozen human cadaver vertebra (Th11–L2) were randomized into three groups: treatment, sham, and control (n = 7 each). Treatment included vertebral body access, saline lavage to displace soft tissue and marrow elements, and injection of the implant material to fill approximately 20% of the vertebral body by volume. The sham group included all treatment steps, but without injection of the implant material. The control group consisted of untreated intact osteoporotic vertebra. Load at failure and displacement at failure for each of the three groups were measured in axial compression loading. Results The mean failure load of treated vertebra (4118 N) was significantly higher than either control (2841 N) or sham (2186 N) vertebra (p p Conclusions This biomechanical study shows that a local osteo-enhancement procedure using a triphasic implant material significantly increases the load at failure and displacement at failure in cadaveric osteoporotic vertebra.

Tantalum is a refractory metal with a melting point of 2996°C but it offers outstanding biocompatibility for bone implant applications. In this study, the selective electron beam melting (SEBM) process was used for the first time to fabricate both dense and fine lattice tantalum structures. The use of 90-ppm-oxygen Ta powder for SEBM ensured excellent ductility of the as-printed fine Ta lattice implants with strut diameter of just 350 μm. The as-printed dense Ta samples (99.90%) achieved tensile ductility of 45% compared with the minimum requirement of 25% by ISO 13782 and the reported 2% fabricated by SLM using 1800-ppm-oxygen Ta powder. Since 2016, 27 clinical applications have been achieved in China using the custom-designed and SEBM-printed Ta implants by the authors of this study. All these Ta implants (mostly Ta lattice structures) have performed satisfactorily in patients’ bodies so far. Three selected clinical applications, Ta lattice hip, fibula and femur implants, are briefly discussed in this article.

After more than 5 decades of research, the failure of bone implants is still poorly understood. The aging population makes it increasingly urgent to solve this issue. Among the reasons for failure, catastrophic brittle fracture can be directly related to the implant material and fabrication and deserves more attention. Indeed, clinically available implants do not sufficiently reproduce the hierarchical and heterogeneous microstructural organization of our natural bones, ultimately failing at replicating their mechanical strength and toughness. Nevertheless, recent advances in additive and advanced manufacturing have opened new horizons for the fabrication of biomimetic bone implants, challenging at the same time their characterization, testing, and modeling. This critical review covers selected recent achievements in bone implant research from a materials standpoint and aims at deciphering some of the most urgent issues in this multidisciplinary field. Nanyang Technological University Accepted version H. L. F. acknowledges financial support from Nanyang Technological University with the Start-Up grant M4082382.050.

Introduction The BAHA (bone-anchored hearing aid) Attract is a magnetic transcutaneous bone conduction device anchored into the temporal bone. The standard surgical technique for BAHA Attract is a multi-tools time-consuming process, which requires a large cutaneous incision. The objective of this study is to describe and test the feasibility of a minimally invasive pocket (MIP) technique for Magnet Bone Implant Hearing Aid (MBIHA) with a modified magnet of BAHA Attract without fixation and without any tissue reduction. We use a 3-cm vertical skin incision and a subperiosteal pocket. Method A study of 10 patients with conductive or mixed hearing loss who benefited from a MBIHA using the MIP technique is presented. The pure tone average (PTA) (dB) for air-conduction thresholds and the speech recognition threshold (SRT) (dB) in speech audiometry in quiet are calculated. The Entific Medical Systems (EMS) questionnaire and the postoperative clinical outcomes are realized. Results We found a significant improvement of 33.8 dB on average for the PTA and 44.8 dB for the SRT with MBIHA at 3 months, compared with unaided situation. No implant was removed or displaced after 2 years of follow-up. The skin condition remains intact in all the cases. Conclusion The minimally subperiosteal pocket surgical technique MIP without fixation and with tissue preservation for the MBIHA is safe, rapid and effective for patients with conductive or mixed hearing loss. It opens new perspectives of development and modify conventional concept in magnetic coupling of bone-conducted device.

A method of surgical treatment of midshaft clavicular fractures and a compression interlocking nail for osteosyn-thesis of the clavicle were developed. Strength characteristics of various bone−implant−bone systems in osteosyn-thesis of midshaft clavicular fractures were compared. It was shown that none of the tested fixation techniques provides stability under conditions of axial loading comparable to that of an intact clavicle. The developed design can be recommended as a method of choice for osteosyn-thesis of midshaft clavicular fractures, as it demonstrated strength characteristics comparable to those of other systems.

β-Ti alloys are known for their very low Young’s modulus, excellent physical properties, and biocompatibility, hence they are considered as attractive metallic materials for long-term bone implant applications. However, β-Ti alloys are poor wear resistant and typically bioinert materials, thus their surfaces need to be modified to have wear resistant and bioactive properties. In this paper, an overview is given to the available surface functionalization techniques to improve the biological properties of β-Ti alloys. Mechanical, physical, chemical, and electrochemical treatments, as well the immobilization of bio-functional molecules are discussed. Bioactivity, biocompatibility, haemocompatibility, wear and/or corrosion, behaviour of the β-Ti alloys can be improved using a proper surface modification technique, by altering the surface composition and topography or removing the undesired material from the alloy surface.

Si3N4ceramics show excellent characteristics of mechanical and chemical resistance in combination with good biocompatibility, antibacterial property and radiolucency. Therefore, they are intensively studied as structural materials in skeletal implant applications. Despite their attractive properties, there are limited data in the field about in vitro studies of cellular growth on ceramic implant materials. In this study, the growth of bone cells was investigated on porous silicon nitride (Si3N4) ceramic implant by using electrochemical impedance spectroscopy (EIS). Partial sintering was performed at 1700 °C with limited amount of sintering additive for the production of porous Si3N4scaffolds. All samples were then sterilized by using ethylene oxide followed by culturing MG-63 osteosarcoma cells on the substrates for in vitro assays. At 20 and 36 h, EIS was performed and results demonstrated that magnitude of the impedance as a result of the changes in the culture medium increased after incubation with osteosarcoma cells. The changes are attributed to the cellular uptake of charged molecules from the medium. Si3N4samples appear to show large impedance magnitude changes, especially between 100 and 1 Hz. Impedance changes were also correlated with WST-1 measurements (36 h) and DAPI results.

The effects of Fe, Si, and O additions on the mechanical properties of some biomedical TNTZ β-Ti alloys were analyzed to reveal the dissimilarities arising between TNTZ alloys variants as benchmark alloys, and the same alloys with additions of Fe, Si, and/or O; because the Ti-6Al-4V alloy is still widely used in medical applications, data for this alloy are also reported. The mechanical properties of the analyzed alloys correspond to the post-solution-treated condition. Considering the biomedical use of these alloys for low-cost, load-bearing bone implants, the additions of Fe, Si, and O showed a generally beneficial effect on the modulus of elasticity (maintained at approximately 75 GPa), strength (values of yield stress at approximately 1000 MPa), and ductility; the main practical result is that all the analyzed alloys showed an elastic modulus lower than that of the Ti-6Al-4V alloy. The addition of O and the co-addition of Fe-O in TNTZ β-Ti alloys seems to produce the best combination of bio-mechanical characteristics.

Nitinol, being a shape memory and super elastic alloy, is used in medical industry. Surface modification of nitinol helps to reduce the nickel ion leaching in physiological environment. The purpose of this study is to modify the nitinol surface by the silanization technique and to conduct a comparative investigation with the bare nitinol in the aspect of leaching of nickel ion, hemocompatibility, and in vivo animal response. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy studies confirmed the addition of organofunctional alkoxysilane molecules through the silanization process. The histological study showed the presence of adequate number of osteoblasts in silanized nitinol. The fluorochrome labeling study depicted more new bone formation (8 and 21% higher) in silanized nitinol specimens than bare one at one and three months postoperatively. Radiology and SEM study also proved the better performance of silanized samples. The cumulative in vivo results indicate its suitability as the potential bioimplant in various orthopedic surgical uses.

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting (EBM(®)), using an Arcam EBM(®) A2X machine.

Metastatic disease is the principal cause of prostate-cancer-related mortality. Our ability to accurately recapitulate the spread of prostate cancer to bone - the most common site of metastasis - is critical to the development of novel metastasis-directed therapies. Several translational models of prostate cancer bone metastasis have been developed, including animal models, cell line injection models, 3D in vitro models, bone implant models, and patient-derived xenograft models. The use of these models has led to numerous advances in elucidating the molecular mechanisms of metastasis and innovations in targeted therapy. Despite this progress, current models are limited by a failure to holistically reproduce each individual element of the metastatic cascade in prostate cancer bone metastasis. In addition, factors such as accurate recapitulation of immunobiological events and improvements in tumour heterogeneity require further consideration. Knowledge gained from historical and currently used models will improve the development of next-generation models. An introspective appraisal of current preclinical models demonstrating bone metastases is warranted to narrow research focus, improve future translational modelling, and expedite the delivery of urgently needed metastasis-directed treatments.

Experimental approaches have been widely used to investigate the bone–implant interfacial strength of anterior lumbar interbody fusion (ALIF) devices. However, improper design of experimental jigs and inconsistencies in cadaveric specimens might significantly impede the evaluation of different ALIF device designs. Therefore, this study aimed to investigate and compare various test setups in terms of their feasibility for conducting pullout tests on ALIF devices. Three types of pullout test setups for evaluating the interfacial strength of the ALIF devices were investigated. Then, finite element models of the L4–L5 segment with different ALIF device designs were developed and numerical analysis was performed. Finally, the results from all the pullout test setups were compared with those obtained from numerical analysis. The results indicated that the quasi-material and boundary pullout test setup (QMBPTS), which considered the effects of the composite material of the test specimens and mimicked the lumbar posterior element’s anatomy and loading mechanism, revealed a more realistic bone failure pattern and interfacial pullout strength compared with the general pullout test setup and the quasi-boundary pullout test setup. The finite element models could accurately predict the experimental results obtained using the QMBPTS. It was confirmed that QMBPTS is a feasible and inexpensive pullout test setup for evaluating the bone–implant interfacial pullout strength of ALIF devices. Both the experimental and numerical approaches could provide useful information for designing a biomechanical experiment to solve bone–implant loosening problems.

Results of a computer simulation of the elastic properties of α+β- and β-titanium alloys, used for medical purposes, within the framework of the molecular-dynamics method are presented. It is shown that β-titanium alloys are best suited for the use as bone implants because of their small moduli of elasticity. The advisability of the use of the molecular-dynamics method for the study of the elastic properties of titanium alloys, serving as bone implants, is demonstrated.

Micro machining has growing number of applications in various industries such as biomedical, automotive, aerospace, micro-sensor, micro-actuator and jewelry industries. Small-sized freeform titanium parts are frequently needed in the biomedical applications, especially in the implantations such as mini-blood pumps and mini left-ventricular assist devices, finger joint replacements and small bone implants. Most of the small-sized titanium parts with freeform geometries are machined using micro ball-end milling before polishing and other surface treatments. Decreasing the cycle time of the machining parts is important for the productivity. In order to reduce the cycle time of the roughing process in the micro ball-end milling, this paper investigates the implementation of a previously developed force-based feedrate scheduling (FFS) technique on micro milling of freeform titanium parts. After briefly introducing the instantaneous micro milling forces in micro ball-end milling of titanium parts with freeform surfaces, the FFS technique is implemented in the rough machining of a freeform titanium surface to demonstrate the cycle time reduction potentials via virtual micro milling simulations.

Mg-5.6Zn-0.5Zr alloy (ZK60) tends to degrade too rapid for orthopedic application, in spite of its natural degradation, suitable strength and good biocompatibility. In this study, Nd was alloyed with ZK60 via laser melting method to enhance its corrosion resistance. The microstructure features, mechanical properties and corrosion behaviors of ZK60-xNd (x = 0, 1.8, 3.6, 5.4 wt.%) were investigated. Results showed that laser melted ZK60-xNd were composed of fine ɑ-Mg grains and intermetallic phases along grain boundaries. And the precipitated intermetallic phases experienced successive changes: divorced island-like MgZn phase → honeycomb-like T phase → coarsened and agglomerated W phase with Nd increasing. It was worth noting that ZK60-3.6Nd with honeycomb-like T phase exhibited an optimal corrosion behavior with a corrosion rate of 1.56 mm year-1. The improved corrosion behavior was ascribed to: (I) dense surface film caused by the formation of Nd2O3 hindered the invasion of immersion solution; (II) the three-dimensional honeycomb structure of intermetallic phases formed a tight barrier to restrain the propagation of corrosion. Moreover, ZK60-3.6Nd exhibited good biocompatibility. It was suggested that ZK60-3.6Nd was a preferable candidate for biodegradable bone implant.

New technological approaches based on biocompatible nanocomposites with hydroxyapatite (HA) and collagen matrix are described. Optimal conditions of HA synthesis in collagen fibers and its use in bone implants are discussed.

Increasing evidence shows that magnetic fields and magnetic responsive scaffolds can play unique roles in promoting bone repair and regeneration. This article addresses the synergistic effects of magnetic scaffolds in response to external magnetic fields on the bone regeneration in situ. Additionally, the exploration of using magnetic scaffolds as tools in the bone implant fixation, local drug delivery and mimicking microenvironment of stem cell differentiation are introduced. We also discussed possible underlying mechanisms and perspectives of magnetic responsive scaffolds in the bone repair and regeneration.

Efficacy of the use of bone implants and their reparative capacity are determined by the implant frame architecture. The implant should provide optimal ratio of porosity and pore size intended to maintain intensive pullulation of bone tissue. The goal of this work was to describe methods of formation of porous structure in ultrahigh molecular weight polyethylene (UHMWPE). The UHMWPE materials are intended for use in maxillofacial surgery. The following parameters of UHMWPE were estimated in this work: volume porosity, pore size, and mechanical characteristics of porous samples as functions of manufacturing procedures. Pore size was found to be determined by water-soluble filler, whereas mechanical characteristics depended on working pressure.

Like most bone deficits, mandibular segmental defects may result from surgical reconstruction due to congenital deformity, tumor resection, other pathologies, senescence, trauma, or infection. The goals of mandibular reconstruction are to restore the mandible’s function and normal appearance. Clinical methods to restore the mandible typically rely on bone replacement using some combination of bone tissue transfer and metal implants. This paper reviews the safety, design, and efficacy of metal implants in general and specifically for the repair of mandibular segmental defects. These problems include implant incorporation, implant failure mechanisms (e.g., stress concentration, stress shielding), corrosion and toxicity, infection, and muscle re-attachment. Finally, this paper presents the use of porous nickel-titanium (NiTi) implants for the repair of skeletal defects through the example of mandibular segmental defects. Resorbable magnesium, and porous and non-porous NiTi, immobilization hardware are also discussed. These materials provide new options which may better match the material properties, and if they can be 3D printed, better match the shape of surrounding host tissue. These advances might reduce engrafted bone and metal implant failure and restore musculoskeletal function for the long term. Patient-specific hardware and grafting strategies might prove to be useful tools in determining both the patient’s appearance and functional outcome following reconstructive musculoskeletal surgery.

In order to simulate the osseointegration of bone implants, a bio-active interface theory is necessary. The thin bone-implant interface layer is described by the Drucker- Prager plasticity model. The formulation of bone mineral density depends on the local mechanical environment. For the simulation of the osseointegration of bone implants a bio-active interface theory is suggested. A thin bone-implant interface layer is described by a Drucker-Prager plasticity model. An evolution rule for the bone mineral density is for- mulated in dependency of the local mechanical environment. The time dependent ingrowth is modeled by a hardening rule which modifies the Drucker-Prager yield-surface cone in the principle stress state in dependency of the local bone min- eral density. The osseointegration process is limited by the violation of a so called micromotion threshold. This rela- tive motion in the implant-bone interface is computed by dynamic loads of daily motion activity. For parameter stud- ies on detailed 3D models model reduction techniques are introduced. The applicability is demonstrated on a hip-joint prosthesis which is in clinical usage.

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is one of the most attractive materials for bone implants due to its compositional and biological similarity to native tissues. Bone is an inorganic–bioorganic composite material consisting mainly of collagen proteins and HAp, and its properties depend intimately on its nano-scale structures.

A worldwide search is now underway for materials which are suitable for introducing into the human body for purposes of diagnostics, medical treatment, or replacement of bone tissue. Physicians are especially interested in ceramic materials whose chemical composition is close to that of natural bone tissue. This is a ceramic based on calciumphosphate compounds, primarily hydroxyapatite (HAP) — a material which is identical to the biomineral of human bones. Together with biocompatibility and bioactivity, materials for bone implants must exhibit bioresistance (resistance to dissolution in the body) or bioresorbability (capability of gradually or completely dissolving in water in the body as the new bone accumulates) depending on the medical treatment being used.

Corrosion resistance of high quality sintered compacts made of the Co-Cr-Mo alloy powder in manufacturing bone implants has been investigated. The samples met the characteristic mechanical requirements for this kind of implants, but the increased density of the porous material turned out to be crucial in the improvement of their corrosion resistance. It seems that the rotary cold repressing (RCR) of sintered compacts could be a very advantageous alternative to the single or multiple matrix pressing. The influence of cold repressing and the subsequent heat treatment of sintered compacts made of the Co-Cr-Mo powder on the changes of their density, microstructure, and corrosion resistance was investigated in this work.

In the course of the research described in this paper a prototype assembly system for the automated fabrication of customized, biodegradable bone implants for tissue engineering applications has been developed. This work is part of a collaborative effort between the Handling Laboratory (hLab) of Fachhochschule Vorarlberg and the Bone Tissue Engineering Center (BETC) of Carnegie Mellon University. Bone implants are built up using thin layers of highly porous, biodegradable polymer scaffold materials. These layers can be seeded with cells prior to assembly. The main focus of this work is robotic handling of the prefabricated polymer layers. Additional components that are addressed include the cutting of contoured polymer layers from sheetstock and the assembly of the 21/2 dimensional layers to form 3D bone implants. Cutting tests have been performed to assess different cutting technologies. Assembly tests with mechanical connectors and fibrin adhesive have also been conducted. These components are integrated within a robot cell to demonstrate overall system feasibility.

Osteoinduction is the process by which osteogenesis is induced. It is a phenomenon regularly seen in any type of bone healing process. Osteoinduction implies the recruitment of immature cells and the stimulation of these cells to develop into preosteoblasts. In a bone healing situation such as a fracture, the majority of bone healing is dependent on osteoinduction. Osteoconduction means that bone grows on a surface. This phenomenon is regularly seen in the case of bone implants. Implant materials of low biocompatibility such as copper, silver and bone cement shows little or no osteoconduction. Osseointegration is the stable anchorage of an implant achieved by direct bone-to-implant contact. In craniofacial implantology, this mode of anchorage is the only one for which high success rates have been reported. Osseointegration is possible in other parts of the body, but its importance for the anchorage of major arthroplasties is under debate. Ingrowth of bone in a porous-coated prosthesis may or may not represent osseointegration.

With the aim of developing an ideal bone graft, a new bone grafting material was developed using deglued bone, chitosan and gelatin. Deglued bone (DGB) which is a by-product of bone glue industries and has the close crystallographic similarities of hydroxyapatite was used as main component in the preparation of bone implant. Chitosan was prepared from the exoskeleton of prawn (Pinaeus indicus, family Crustaceae) which is a by-product of seafood industries. Chitosan gives toughness to the product and do not allow the DGB particles to wither away when the implant is placed in the defect. Gelatin was used as binder for the preparation of DGB-chitosan composite. The DGB, chitosan and DGB-chitosan-gelatin composite, which were prepared in the laboratory, were analysed for their physicochemical properties by infrared spectroscopy, X-ray diffraction and scanning electron microscopy studies.

Aim of the study For more than twenty years the IMZ-system has been in clinical use, since 1995 modified as IMZ-TwinPlus. The aim of this prospective clinical trial was to analyse the success of the latter implant system, which is an automatically threading cylindrical titanium screw with a deep structured surface (Fa. FRIATEC AG, Mannheim, BRD). Investigated parameters were the peri-implant situation of the soft tissues, the bone loss and the rate of implant failure after a maximum period of 4.5 years of clinical use. Material and methods From 1995-2000 sixty-eight patients were provided with a total of 278 IMZ TwinPlus screw implants for various indications (mainly alveolar ridge atrophy). 191 implants were inserted without any, 35 implants with a loco-regional and another 52 implants after comprehensive reconstructive osteoplastic surgery. 38 patients with 155 implants were re-examined using a standardised protocol to evaluate peri-implant hard- and soft tissue situation as well as the patient's subjective assessment of the treatment. Results With a maximum of 54 months the mean observation period was 30 months. The implant failure rate has risen to 6% so far (n = 18 in 12 patients). Two patients bearing 7 implants have passed away. One patient with 4 implants was lost to follow up. 249 implants were still under function at examination, thus the in situ rate was 91%. The Kaplan-Meier survival rate after 54 months proved 91%. Discussion To our knowledge there are at present no other data published on the survival rate of the IMZ TwinPlus implant system. The results of this study evaluate a survival rate similar to the classical IMZ cylinder implant and other implant systems for the analysed observation period. Conclusions After a maximum observation period of 4.5 years the IMZ TwinPlus implant system showed results in the range of other well-established implant systems. Designed to resist rotation of the superstructure the IMZ TwinPlus screw implant widens the range of indications in comparison to the classical IMZ cylinder implant system.

Bone reconstruction can be performed with an autogeneic graft from various donor regions. Osteoconductive and osteoinductive bone substitutes originate from substances of diverse chemical and morphological types and can have a synthetic or a biological derivation. Alongside autogeneic bone transplants and allogenic and xenogeneic bone implants, alloplastic bone replacements of synthetic or semi-synthetic origin are being used for defect reconstruction. In an animal model in rabbits five bone substitutes and one autogeneic graft were surgically incorporated into identical bone defects (10times 10 mm in size) in six anatomically defined regions of the skull. With scintigraphic and histological methods, the metabolic dynamics of the bone is examined as it reacts to the transplantation of autogeneic bone or to implanted bone replacement material.

The methods of fabricating porous materials are reviewed. The optimum methods of fabricating porous materials from calcium phosphates, including materials for use as bone implants, are demonstrated.

Titanium implants were inserted in transgenic mice overexpressing bovine growth hormone. Four weeks after insertion the implants were cut out en bloc with the surrounding bone. The undecalcified specimens were cut and ground to a thickness of approximately 10 μm. Histomorphometry demonstrated significantly more direct bone to metal contact for the transgenic mice than for the non-transgenic littermates. The results indicate that endogenous high levels of bovine growth hormone result in improved early bone-implant integration. This study indicate that it may be possible to systemically administrate growth hormone in man, in the early healing in phase, to improve implant integration.

Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which removed the organic and sintered the HA. The synthetic scaffolds were prepared by freeze-casting HA powders, using different solid loadings (20–35 vol.%) and cooling rates (1–10°C/min). Both types of scaffolds were infiltrated with polymethylmethacrylate (PMMA). The porosity, pore size, and compressive mechanical properties of the natural and synthetic scaffolds were investigated and compared to that of natural cortical and cancellous bone. Prior to infiltration, the sintered cancellous scaffolds exhibited pore sizes of 100 – 300 μm, a strength of 0.4 – 9.7 MPa, and a Young’s modulus of 0.1 – 1.2 GPa. The freeze-casted scaffolds had pore sizes of 10 – 50 μm, strengths of 0.7 – 95.1 MPa, and Young’s moduli of 0.1 –19.2 GPa. When infiltrated with PMMA, the cancellous bone- PMMA composite showed a strength of 55 MPa and a Young’s modulus of 4.5 GPa. Preliminary data for the synthetic HA-PMMA composite showed a strength of 42 MPa and a modulus of 0.8 GPa.

Fourteen titanium porous-coated implants with a cylindrical shape (length 22 mm and diameter 5±0.3 mm) were prepared. Bead size was 250–350 μm. Seven implants were plasma-sprayed with hydroxyapatite and the other seven remained uncoated. Implants, both hydroxyapatite-coated and uncoated, were randomly selected and press fitted longitudinally into the proximal femoral cancellous bone bilaterally in seven dogs. After 12 weeks the dogs were euthanized and push-out and histomorphometric backscattered electron microscopy studies were carried out. No statistical differences in the mechanical tests were observed. Comparing hydroxyapatite-coated versus uncoated implants, the histomorphometric results showed statistical significance in the percentage of bone (p=0.01); and in bone index, ratio between bone ingrowth and bone ongrowth (p=0.01). The size of the bone implant interface was smaller in the hydroxyapatite applied to spherical bead titanium porous coatings were demonstrated. These morphological and histomorphometric results support the concepts involved with the use of hydroxyapatite as a coating for uncemented porous prosthetic devices.

Template-assisted electrohydrodynamic atomization (TAEA) spraying deposition, a recently developed and an electric-driven jet-based technique has been used to prepare bioactive surface topography on titanium (Ti). Nanometer-scaled SiHA (nanoSiHA), which closely resembles the bone mineral, has been synthesized and deposited on Ti surfaces with a range of patterns, such as pillars and tracks. A human osteoblast (HOB) cell model has been used to evaluate the in vitro cellular responses to nanoSiHA deposition. alamarBlue™ assay showed that nanoSiHA patterns are able to encourage the attachment and growth of HOB cells in comparison to those of nanoSiHA coating. The preferential growth of HOB cells was found along and across the track, HOB cells were also found to stretch between two tracks. Image analysis of HOB cell responses to the size of nanoSiHA pattern showed that the length of HOB cells was proportional to the gaps between the tracks until reaching the maximum length of 110 μm. The results indicate that the distance between the structures is paramount over the width. Our study will pave the way to control and guide cellular responses for new generation of bone implants.

This article reports that cadaver bones can replace injured or diseased bone, but up to a third of these grafts fail because they cannot repair microscopic cracks from normal wear and tear, unlike living bone. Resurrecting dead bones could give patients an option to amputation. Molecular immunologist Edward Schwarz of the University of Rochester and his colleagues compared mice that had healthy and dead bone implants and found that living bone significantly expresses two genes involved in blood vessel growth and old bone reabsorption. The researchers incorporated these genes into a freeze-dried virus, which they coated onto dead femur bone grafts. The genes induced the body to supply blood to the dead bone, thereby revitalizing it. New bone formation did not occur uniformly on graft surfaces, but the team found other genes that might improve the approach's efficacy.

Acoustic and mechanical tapping methods forin vivo assessment of the interfaces of bone implants are experimentally compared using implant models made of metal and glass. The former (AcT method) is based on the measurement of the frequency and amplitude of the vibration of a sample induced by a tapping needle. The latter (MeT method) is based on the measurement of the time during which a tapping rod is contacted with a sample. The following results were found. The vibration of a sample induced in the MeT test is very different from that induced in the AcT test; the former is much larger in the maximum amplitude and much lower in the main frequency than the latter, although both are of damped type. Nevertheless, a discrimination between hard and soft interfaces by each test is almost equally clear. It depends on load directions to some extent, reflecting a mechanical difference of the interface and/or the surrounding bone. The MeT test appears to be more sensitive than the AcT test for implant models surrounded by a thin compact bone. For implant models surrounded by a thick compact bone, however, the former is a little less sensitive than the latter.

The applicability of an acoustoelectric technique to thein vivo assessment of the interfacial mechanical states for various bone implants has been shown by usingex vivo models. It has been found that the signal taken from an implant depends on the surrounding bone and the implant material to some extent as well as on the interfacial state.[/p]

In degenerative and posttraumatic osteoarthritis of the knee joint pain is a major indication for correctional osteotomy. In additon, the degree of arthrosis, axis deviation, range of motion and derangement of ligaments must be considered. In the cases reviewed supracondylar femur osteotomy, extraligamentar and high interligamentar osteotomy of the tibial head were utilized for correction. High tibial osteotomies were performed without using stabilizing plates. Autologous as well as homologous bone implants were added as needed. From the results presented we conclude, that the different methods of correctional osteotomies are equivalent, as long as the axis deviation, which is present in most cases, is corrected into a physiological valgus position. About 3/4 of the patient operated upon were improved as far as pain, range of motion and weigthbearing are concerned. Regression of the arthrotic structural changes could be demonstrated in a few cases only.

We have investigated the role of defatted, decalcified xenogenic bone implants composited by impregnation with fresh autologous marrow in bridging large cortical defects. Diaphyseal cortical implants were obtained from orthopaedic operations on humans and from guinea pigs and prepared by treatment with acetone, 0.6 M HCl and ethanol. The composited graft was used to bridge a 3 cm defect in the diaphysis of the ulna of rabbits. Periodic investigations were made clinically, radiographically and histologically and by tetracycline, fluorescence studies up to 20 weeks. Abundant new bone formation was observed in 85.7% of composited human xeno-autografts and in 83.3% of composited guinea pig xeno-autografts. New bone formation was seen in 13.3% of noncomposited xeno-implants. No appreciable antigenicity was observed either clinically or histologically in the grafts. The high degree of success obtained justifies further studies on implants composited by fresh autologous marrow and offers hope for the enhancement of new bone formation clinically, particularly in reconstructive operations for significant skeletal defects. We feel that the osteo-inductive potential of autologous marrow was responsible for the healing of the defects aided by the better internal milieu provided by defatted decalcified xeno implant.

A new process is described for preparing dense, polycrystalline hydroxylapatite. This material has close to theoretical density and is free of fine pores and second phases. The best material has an average compressive strength of 917 MN m−2 (133×103 psi), and polished samples have an average tensile strength of 196 MN m−2 (28.4×103 psi). The material is highly translucent, and the degree of translucence depends upon processing conditions. The relationship between processing variables and microstructure, strength, and translucence is described. This dense hydroxylapatite has good promise for bone implants and dental applications.

A method for the preparation of bone samples containing metallic implants is presented. Technics are detailed for samples to be analyzed by mechanical, microradiographical and microangio-graphical means, and by tetracycline labeled fluorescent and polarized light microscopy.

Gamma radiation used to sterilize organic bone matrix totally destroys the bone inductive capacity and thus leads to a less desirable bone implant.