الفهرس 
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Abstract
Introduction : A biomaterial is any substance (other than drugs), natural or synthetic, that treats, augments, or replaces any tissue, organ, and body function. The properties of materials are governed by their structure, determined by the way their constituent atoms are bonded together. Mechanical requirements must be taken into consideration when choosing materials for biomedical applications. Material strength (tensile or compressive), stiffness, fatigue endurance, wear resistance, and dimensional stability should be considered with respect to the end use of the prosthetic device to ensure its success. Conclusion : The mechanical properties (e.g., strength, modulus, and fatigue limit) of metals makes them desirable choices for many load-bearing biomedical prostheses applications. Metals are susceptible to degradation by corrosion, a process that can release by-products (such as ions, chemical compounds, and particulate debris) that may cause adverse biological responses. Ceramics are attractive biomaterials because they can be either bioinert, bioactive, or biodegradable; however, they have serious drawbacks because they are brittle and have low tensile strength. polymers have much lower strengths and moduli but they can be deformed to a greater extent before failure. Consequently, polymers are generally not used in biomedical applications that bear loads (such as body weight). Ultra-high-molecular-weight polyethylene is an exception, as it is used as a bearing surface in hip and knee replacements. The properties of polymers depend on the composition, structure, and arrangement of their constituent macromolecules. Biodegradable polymers had been widely used in the last decade specially in sport medicine but, it still have drawbacks which must be dealt with by continuing research and biotechnology to gain optimal performance. Medical research continues to explore new scientific frontiers for diagnosing, treating, curing, and preventing diseases at the molecular/genetic level. With this newfound knowledge, there will be further need for innovative formulations and/or modifications of existing materials, for novel materials, and for nontraditional applications of biomaterials, such as in tissue engineering. Promising developments include the use of engineered tissues, regenerative bioactive materials, gene therapy and nanophase materials. In addition to new challenges and opportunities, some of the unresolved issues (primarily, biocompatibility) of the past and present will also need to be addressed in the future.