Orthopedic biomaterials ceramics

Although ceramics are brittle, they have created wide interest in their applications as orthopedic biomaterials due to chemical composition similar to bone, the major constituent for which is inorganic minerals (Sommerfeldt and Rubin, 2001). Research also demonstrated the capacity of bioactive ceramics to stimulate new bone formation... 

In spite of these investigations, many reports in the literature demonstrate that these nanoapatite ceramics are not always osteoinductive and, furthermore, do not possess mechanical properties similar enough to bone for sustained osseointegration (Muller-Mai el al., 1995 Doremus, 1992 Du et al., 1999 Weng et al., 1997), criteria necessary for increased orthopedic and dental implant efficacy. Moreover, mechanisms of osteoinduction of calcium phosphate ceramics are not clear and seem to depend on specific nanoapatite material properties (such as surface properties and crystallinity) and the animal tested (i.e., dog versus rabbit). Undoubtedly, the incidental cases of calcium phosphate biomaterial-induced osteogenesis indicate promise in... 

ASD Report (2013) Biomaterials Market by Products (Polymers, Metals, Ceramics, Natural Biomaterials) and Applications (Cardiovascular, Orthopedic, Dental,... 

Marketsandmarkets (2012) Bio-Implants Cardiovascular, Spine, Orthopedics, Trauma, Dental Ceramics, Biomaterial, Alloys, Polymers, Allo/Auto/Xenografts, Synthetic. Report code MD-1190, Press release, September 2012. 

Transparency Market Research (2014) Biomaterials Market for Implantable Devices (Material Type - Metals, Polymers, Ceramics and Natural, Applications - Cardiology, Orthopedics, Dental, Ophthalmology and Others) - Global Industry Analysis, Size, Share, Growth, Trends and Forecast, 2013 - 2019. 

The 2001 recall has not, however, dampened the general enthusiasm for ceramic materials in orthopedics. Alumina is currently the ceramic material of choice for orthopedic applications, either for articulations with UHMWPE or for use in COC alternate bearings. Starting at the end of 2002, a new alumina composite material (BIOLOX Forte CeramTec, Plochingen, Germany) has been available as a femoral head material (Merkert 2003). This ceramic composite, consisting of 75% alumina matrix, is reinforced by 25% zirconia. The improved strength of this new ceramic composite, in comparison with alumina and zirconia, is summarized in Table 6.2. Clinical studies are still needed to determine the effectiveness and reliability of this new biomaterial. 

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). 

The world of biomaterials is diverse, encompassing ceramics and metals used for orthopedic implants (already discussed in Chapters 2 and 3), to artificial heart valves, blood vessel stents, and contact lenses. This sectiOTi will delve into those biomaterials apphcations that utihze soft polymeric-based materials. 

Due to their tunable degradability, biocompatibility, processibility, and versatility, polymeric biocomposites are principal materials investigated for the development of synthetic bone scaffolds, cements, and composites (Porter et al., 2009). As previously defined, a polymeric biocomposite is composed of two or more bulk biomaterials (at least one a polymer) of different phases intended for use in the body. There are an unfathomable number of biocomposites that fit this broad criterion. Classic polymeric biocomposites for orthopedic applications are composed of a solid, synthetic ceramic phase that is osteoconductive or -inductive (Sepulveda et al., 2002) and a biocompatible polymer that was at one stage a liquid. 

Nanocomposites in orthopedic tissue engineering mimic the complex nanoarchitecture of natural bone, muscle, cartilage, and tendon tissue, providing a novel and practical approach to tissue regeneration. All ceramic, polymer, and metallic matrix nanocomposites offer a wide range of properties with different chemical and mechanical features they also exhibit indispensable bioactivity. There is a great potential to improve current biomaterials and nanocomposite scaffolds for musculoskeletal tissue regeneration. However, the variety of different chemical elements and structures of nanocomposites make it difficult to predict unknown outcomes of exposure to musculoskeletal tissue. More research is clearly needed to fully understand favorable nanocomposite chemistries for musculoskeletal tissue. 

Starting in lune 2000, a new alumina matrix nanocomposite material (BIOLOX Delta, CeramTec, Plochingen, Germany) has been available as a femoral head material [101]. This ceramic biomaterial is now broadly used across the orthopedic industry in both femoral heads and acetabular liners. According to the manufacturer, more than 320,000 femoral heads and 160,000 acetabular inserts have been implanted on a worldwide basis as of 2008 [106]. The primary advantage of this alumina matrix composite is its increased strength, fracture toughness, and wear resistance relative to alumina (Table 6.2) [112]. 

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