Biomedical Engineering Reference
In-Depth Information
7.1 Introduction
Bone defects and malformation, caused by trauma, infection, tumor resec-
tion, congenital deformity, and physical and pathological degeneration, rep-
resent a major concern for orthopedic surgeons. According to the Office of
the U.S. Surgeon General, bone diseases affect 10 to 12 million people in the
United States and there are approximately 1.5 million fractures reported in
the United States every year (Shane 2010). Within the European Union, it is
estimated that a bone fracture occurs every 30 seconds as a consequence of
osteoporosis (Compston 1999) and in China over 3 million individuals per
year are estimated to suffer from bone defects or injury; figures that only
superficially describe the enormous impact of such injuries on the quality
of life of individuals and health care costs carried by society (Kesheng et al.
2006). Considering this data, we can see that bone repair and regeneration
can solve a serious problem for human beings.
Bone tissues have a native potential for self-healing; however, many
patients, especially those with critical size defects or poor bone quality, still
require surgical treatments. However, due to lack of donor tissue and pos-
sible donor site morbidity, surgical treatment is not a perfect choice. Bone tis-
sue engineering represents a promising alternative to generate new bone for
any desired size and shape, and is the current therapeutic concept for bone
defect healing. One of the commonly accepted definitions of tissue engineer-
ing was proposed by Langer and Vacanti in 1993: “an interdisciplinary field
that applies the principles of engineering and life sciences toward the devel-
opment of biological substitutes that restore, maintain, or improve tissue
function or a whole organ.” Tissue engineering is a multidisciplinary field
in which physicians, engineers, and scientists seek to provide novel solu-
tions for orthopedic surgery in an effort to overcome the previously men-
tioned disadvantages. The extensively recognized key elements for bone
tissue engineering and morphogenesis are osteogenic cells, osteoconductive
scaffolds or extracellular matrices (ECM), and osteoinductive growth factors
under mechanical microenvironment (Figure 7.1).
Great progress has been made using bioactive materials for bone tis-
sue repair and regeneration has as a result of the scientific efforts aimed
at improving the tissue-material response after implantation. The extent
of bone regeneration could be enhanced by using appropriate bioactive
materials. According to the present classifications, we can generally sepa-
rate it into inorganic and organic materials. Inorganic biomaterials such as
hydroxyapatite, tricalcium phosphate, bioactive glasses, and silicate ceram-
ics produce tenacious bonds with hard tissue by reacting with physiologic
fluids. However, stiff and brittle characteristics make it difficult to form into
complex shapes. On the other side, composite polymers are easily fabricated
into complex structures, but they are too weak to meet the demands of sur-
gery and the
in vivo
physiologic environment (Boccaccini and Blaker 2005).
Search WWH ::
Custom Search