Materials Science and Technology IX
Materials Research and Application II
Recent Development in Machining, Materials and Mechanical Technologies II
Advanced Materials and Engineering Materials VI
Mechanics of Masonry Structures Strengthened with Composite Materials II
Advanced Materials and Processes of Metalworking II
Orthopedic Biomaterials - From Materials Science to Clinical Applications
Symposium on Materials Science and Engineering
High Technology: Research and Applications 2016
21st Symposium on Composites
Analysis of Damage Features and Failures for Structural Materials and Parts
Advances on Manufacturing and Material Sciences
Engineering Tribology and Materials
Orthopedic Biomaterials - From Materials Science to Clinical Applications
摘要: In the last decades, very significant advances have been made for what concerns bone and joint substitution and in the repair and regeneration of bone defects. Though some strong requirements are still to be met, biomaterials for these purposes have known an impressive evolution, for what concerns their mechanical behaviour, their bioresorbability and finally their capability to generate new bone tissue in a stable way in long periods. The validation of such materials necessarily depends on a suitable characterization of their properties. In this article a brief review of some works in this field, carried out by the authors’ research group, is presented. It was shown in particular how advanced experimental methods, such as synchrotron radiation µCT and synchrotron radiation diffraction can offer very important information, can be not only complementary methods to more standard techniques (electron microscopy, X-ray diffraction), but can also offer the possibility to measure parameters that cannot be obtained otherwise.
摘要: Considering its functions (support, protection, assisting in movement and storage of minerals), the bone is an essential organ for the human body and the bone trauma/damages have a great impact on the human body functionality. For that reason a variety of biomaterials are studied for potential applications in bone regeneration or substitution. Bone substitution materials, with similar chemical composition to that of natural bone, and specifically those obtained by processes which mimic the natural bone formation in vivo, has been shown to be among the best. In this study, using a process of co-precipitation of calcium phosphate precursors on a mixture of biopolymers (chitosan, collagen, hialuronic acid) and magnetic nanoparticles (magnetite functionalized with chitosan), biodegradable biomimetic scaffolds have been obtained. In order to study their chemical structure, the biodegradable scaffolds have been characterized by Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the biodegradable scaffolds, studied using scanning electron microscopy (SEM) indicated a macroporous morphology, which influenced the retention of simulated biological fluids. A direct relationship between the scaffolds’ degradation rate and the concentration of the polymeric phase has been observed. The in vitro cytocompatibility tests indicate that the prepared scaffolds are biocompatible and assure and adequate mediums for osteoblasts.
摘要: The lack of meniscal tissue increases the risk of early cartilage degeneration. Classic treatment includes suturing and partial menscectomies, total meniscectomies being abandoned. Modern treatments are based on the implantation of special scaffolds that replace some of the lost meniscal tissue. This paper reviews the basic principles of modern treatment of the menisci and it includes a retrospective study, in which a total of 10 patients (7 men and 3 women, mean age: 28.28 (21-38)) were enrolled. All patients had previous surgery and were subjected to arthroscopic treatment with a biodegradable scaffold (Actifit®). They received KOOS (Knee Injury and Ostheoarthritis Outcome Score), Lysholm and Tegner score. The Tegner score was not very useful in determining the success or failure of the surgery. The Lysholm and KOOS score results improved at the 1-year follow-up. The results of the scores that the patients filled out, showed an improvement in their preoperatively knee related problems. The Actifit® scaffold is safe and effective in treating meniscal defects.
摘要: The history of acrylic bone cement comprise a long period of time, Sir John Charnley being considered the founder of modern artificial joint replacement, as he started to develop the cementing in the late 1950s. Acrylic bone cements (ACB) are polymer-ceramic composites based on polymethyl metacrylate (PMMA), widely used in orthopaedics as suture materials and fixation devices. The main features of these materials are: 1) biocompatibility and ability to support new bone growth (osteoconductive) and 2) bioactivity (ability to form a calcium phosphate layer on its surface). The main function of the cement is to serve as interfacial phase between the high modulus metallic implant and the bone, thereby assisting to transfer and distribute loads. During years of follow up, cemented prosthesis with acrylic bone cements (ABC) demonstrated a good primary fixation and load distribution between implant and bone, along with the advantage of fast recovery of the patient. However, several problems are still persisting, as the orthopedic acrylic bone cements have to meet several medical requirements, such as low values of maximum cure temperature in order to avoid thermal necrosis of the bone tissue during the setting time, appropriate setting time (so that cement does not cure too fast or too slowly) and high values of compressive strength in order to withstand the compressive loads involved by normal daily activities. Generally, the improvement mechanical properties can be realized in three directions: 1) by searching alternative material to PMMA acrylic bone cements; 2) chemical modification of PMMA; and 3) the reinforcement of PMMA by adding different bioactive particles, antimicrobials, vitamins. The aim of this rewiew is to explore the development of bone cements in the last decade, to highlight the role of bone cement additives with respect to mechanical properties and limitations of polymethylmethacrylate in orthopaedic surgery. The behavior of antibiotic-loaded bone cement is discussed, compared with other alternative additives including nanofillers, together with areas of research that are now open to explore new insights and applications of this well known biomaterial.
摘要: Biodegradable magnesium-based alloys shows good prospects in their use as biodegradable orthopedic materials. The aim of this study is to demonstrate good biocompatibility and lack of local and systemic toxicity of some experimental implants made by magnesium alloy type Mg-Ca 0,8 [%wt]. The study was conducted by implanting some experimental pins made by magnesium alloy type Mg-Ca 0,8 [%wt] in bone, proximal femur and intramedullary tibia, and in thigh muscle of the rabbits. Also, we follow the evolution of blood levels of Mg, Ca, blood counts, liver and kidney function. The evolution of the experience animals was followed for 6 weeks by radiologic imaging, and taking blood samples. After 6 weeks, we obtain after euthanasia of animal experience the harvest blood samples, and musculoskeletal tissue samples for histopathological examination. The histopathology results have not demonstrated peri-implant cytotoxicity, bone and muscle cells being viable. Fibrosis at tissue implant border was minimal showing a good integration. There were no pathological increases in blood levels of Mg and Ca, or changes in blood counts, as well as no change in renal or hepatic function. All this experimental results demonstrates that the magnesium alloy type Mg-Ca 0,8 [%wt] represent a promising solution in orthopedic surgery, proving to be safe, with a high degree of biocompatibility, and without toxic effects.
摘要: The manner of studying of the fracture modes could be done through fractography. Fractography is the study of fracture surface morphologies and it gives an insight into damage and failure mechanisms, underpinning the development of physically-based failure criteria. In composites research it provides a crucial link between predictive models and experimental observations. Fractographic methods are routinely used to determine the cause of failure in all engineering structures, especially in product failure and the practice of forensic engineering or failure analysis. In material science research, fractography is used to develop and evaluate theoretical models of crack growth behavior. One of the aims of fractographic examination is to determine the cause of failure by studying the characteristics of a fracture surface. Different types of crack growth produce characteristic features on the surface, which can be used to help identify the failure mode. The overall pattern of cracking can be more important than a single crack, however, especially in the case of brittle behavior materials. Initial fractographic examination is commonly carried out on a macro scale utilizing low power optical microscopy and oblique lighting techniques to identify the extent of cracking, possible modes and likely origins. When it is needed to identify the nature of failure, an analysis at high magnification is required and scanning electron microscopy (SEM) seems to be the best choice. The problem of fracture behavior of biometallic materials is a real one, being well and repeatedly presented in literature. Variations in alloy compositions can lead to subtle differences in mechanical, physical, or electrochemical properties. However, these differences are minor compared with the potential variability caused by differences in fabrication methodology, heat treatment, cold working, and surface finishing, where surface treatments are particularly important for corrosion and wear properties. The aim of this paper, therefore, is to summarize the different types of metals and alloys used as biomaterials, the corrosion of metals in the human body, and different failure damages of metallic implants.
摘要: Metallosis is an adverse event developed in relation with an orthopedic implant. It was brought into attention by metal on metal total hip arthroplasty. Lately, cases were diagnosed in total knee, total elbow, and spinal surgery. Metallic debris - released because of wear or corrosion - start an inflammatory response in a chronic condition. Beside local effects, systemic effects are also described; among them toxic effects, neurological and psychiatric, alteration in thyroid and heart function, skin rushes and discoloration. Diagnosis is helped by x-ray examination but is based on fluid aspiration with ions level determination and histological examination. Osteolysis phenomena induced by metallosis may compromise bone ingrowth and promote implant loosening; as result bone stock may be compromised. The cases we present have a particular development pattern; each of them was initiated as a result of atypical behavior of the implants. Two of them necessitated bone grafting in order to replace the reduced bone stock and all three required revision surgery. The cases emphasize the diagnosis methodology and the possible complications encountered during orthopedic implant surgery.
摘要: Open wounds treatment is very often a challenge for both the physician and patient. They require long term complex treatment with surgical debridement, dressing changing, additional therapies including expensive medication, with a high risk of failure. The most difficult to treat are the diabetic wounds and those that are associated with advanced arterial disease. In these special cases, the peripheral vascularization is severely impaired and the complications are imminent. Sixteen patients were selected from those appearing to our hospital departments of orthopedic and plastic surgery. Inclusion criteria included patients with a recurrent mixed fibrotic and granular wound base following trauma or diabetes, in which NPWT was indicated, without exclusion criteria. Patients enrolled were treated with regularly scheduled NPWT dressing change and using of a collagen scaffold. Patients were followed until healing, with visual representations of wound progression and time to full healing recorded. Both applications of these therapies appeared to accelerate the wound healing by clearing degenerative fibrous tissue and expediting wound granulation without additional complication. Some of the patients were healed partially and plastic surgery techniques were applied. Use of collagen scaffolds in conjunction with negative pressure wound therapy in the care of complex wounds is a reliable and effective method combining both the new granular tissue formation capacity of the scaffold to hold osteoblasts. In our experience, we have noticed that the patients benefit greatly when collagen scaffolds is combined with NPWT. It is our belief that this combination therapy combines the molecular clearing of non-viable collagen with the wound granulation necessary to advance complex wounds in healing.
摘要: Acute dislocation of the patella is a very common injury of the knee. In more than 90% of the cases the medial patellofemoral ligament (MPFL) is injured. Reconstruction of the MPFL has become a popular soft tissue procedure, which reduces hospitalization and the rehabilitation period. Bioabsorbable materials, in form of screws and anchors are ideal for soft fixation to bones in orthopedics. We would like to present our experience and short-term results after MPFL reconstruction with semitendinous autograft and bioabsorbable fixation devices. 10 patients were involved in this study with PF joint instability, who underwent to MPFL reconstruction. In order to evaluate the functional outcome of the procedure we applied the Tegner Lysholm scoring system before and after 3 Months of surgery. MPFL reconstruction significantly improved the functionality of the PF joint. Gender distribution of the studied group was: 7 female with an average age of 25 5,03 SD and 3 male patients with an average age of 29 1 SD. The key for the success in MPFL reconstruction is the positioning of the femoral tunnel, followed by an isometric tensioning of the graft. Bioabsorbable materials reduce inflammatory, and foreign body response facilitating biointegration of the autograft.