Orthopedic substitutions

As shown in Table 18.1, bone is a lightweight (low density) material. Most of the orthopedic substitutions currently used, such as steel, titanium, and alumina, are much denser than bone. Comparatively, CBPC materials come close to the density of compact bone. 

The development of biomechanical models derived from continuum formulations for transport of water and charged species in porous media has been carried out for various soft tissues [1-3] and implemented using finite element models (FEMs) [4-8], Such models provide quantitative views of the response of these complex structures that is especially useful in the study of orthopedic, vascular, ocular, and soft tissue substitutes developed by tissue engineering. In this paper a formulation and FEM are described that incorporate and extend these works in a very general model that identifies physical material properties and allows transient analyses of both natural and artificial soft tissue structures. 

Polylactides are made from lactic acid and are used for orthopedic repair materials. They can be absorbed by the body and are used for the treatment of porous bone fractures and joint reconstruction. Dextran is a substitute for blood plasma in medicine. It is produced by fermentation of saccharose by Leuconostoc mesenteroides microorganisms. After the fermentation is completed (about 24 h), the cell mass is separated and the dextran is precipitated by addition of ethanol to the liquid phase. 

It has exceptionally good optical properties its transparency has made it a popular substitute for glass in apphcations where breakage must be avoided (plexiglass). It has a variety of industrial uses including automotive parts and glazings. PMMA was the first implanted synthetic polymeric biomaterial it was used as a hip prosthesis in 1947 (see USP XVIII, The Pharmacopia of the USA, (18th Revision), US Pharmacopoeia Convention, Inc., Rockville, MD, 1 September 1980). PMMA is currently used in orthopedic applications, as bone cement, and in intraocular lenses. 

ScHONiNG and Koch (1975) performed a randomized study on the incidence of anaphylactoid reactions to five plasma substitutes in orthopedic patients. Each... 

Laurencin, C.T., Khan, Y. 2009. Bone graft substitute materials eMedicine Orthopedic Surgery. Available at http //emedicine.medscape.com/article/1230616-... 

However, some other orthopedic implantable medical devices including carbon fiber have shown successful results. Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) has been reviewed by Li et al. [13] to assess properties, technical data, and safety in orthopedic applications. CFR-PEEK may be an ideal material as it has a modulus very similar to bone and an ability to withstand prolonged fatigue strain. It can also be manufactured to match the modulus of both cortical and cancellous bone densities. This review shows no breakdown over time, while CFR-PEEK is readily accepted by the body. One reported study done by Steinberg et al. [48] makes a comparison between commercially available devices and CFR-Peek substitutes for wear/debris. The wear/debris was assessed based on the amount of the debris generated... 

As new technologies and advances in robotics and bone substitutes guide the way to less-invasive surgical interventions, health care experts predict that many more orthopedic procedures will be performed in outpatient settings or result in overnight hospital stays and that fewer procedures will involve extended stays in the hospital. As demand for orthopedic surgeons increases, hospitals are likely to form alliances and partnerships with other hospitals so... 

The successful tests of BIOVERIT I and II allowed the glass-ceramics to be applied as biomaterials for bone substitution in human medicine. More than 850 implants have been successfully applied (up to 1992) in orthopedic surgery, especially different types of spacers (Schubert et al., 1988) and in head and neck surgery, especially middle ear implants (Fig. 4-27) (Beleites and Rechenbach, 1992). 

Shord, E. C. 1999. Coralline bone graft substitutes. Orthopedic Clinics of North America 30 599-13. 

Natural bone is made of 60% of inorganic calcium phosphate minerals. " To this end, many researchers have developed synthetic bone substitutes based upon ceramics to better mimic the natural composition of bone. Ceramics have been widely used for orthopedic and dental applications, and have been used... 

CPCs are widely used as bone substitutes and for augmentation in orthopedic applications due to their close resemblance to the mineral component of natural bone. CPCs are a powder phase of calcium and/or phosphate salts. 

Moreover, a rarmber of different prosthetic devices based on PLA have been developed in orthopedic fixation or as bone substitution materials. The choice of this PLA polymer is... 

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