Biomedical Engineering Reference
In-Depth Information
tion of better biomaterials for various academic, clinical and industrial interests.
In order to describe the numerous promising applications of nanostructured
biomaterials, this chapter will begin by addressing why nanomaterials may be
the next generation of improved implants to regenerate tissues and organs. It will
cover a variety of medical applications for different tissues and provide some
specific examples of recent developments and practical applications of
nanomaterials in the clinical and industrial setting. This chapter will finish on
how nanostructured biomaterials can be efficiently used to combat current
challenges in tissue engineering and artificial organ implantation, pointing out
future prospects of nanostructured biomaterials in the medical arena.
9.2 Nanostructured biomaterials for bone
applications
9.2.1 Background of orthopedics
Bone tissue engineering is one of the oldest research areas in all of organ
replacement. Specifically, in 1923, the first hip replacement surgery was con-
ducted [23, 24]. Clearly, since then, various bone implants (such as for healing
bone fractures, repairing defects and reconstructing joints) have been routinely
inserted increasing the quality of life for millions of people. The National Center
for Health Statistics (NCHS) reported that there were more than 1 039 000 bone
fractures in 2004 [25]. Moreover, the American Academy of Orthopedic
Surgeons reported that in the US, from 1999 to 2003, there was a 19.7% increase
in hip replacement surgeries up from about 274 000 procedures (including
168 000 total hip replacements and 106 000 partial hip replacements) to more
than 328 000 procedures (including 220 000 total hip replacements and 108 000
partial hip replacements) [26].
Although bone implants have improved the quality of life for numerous
patients, it is important to note that conventional bone implant materials, such as
titanium and titanium alloys used for fixation devices for repairing bone
fractures and artificial joint replacements to treat osteoarthritis, still have many
shortcomings. For example, in just the US, nearly 11% of all hip replacements
(36 000 revisions out of 328 000 replacements) and 8% of all knee replacements
(33 000 revisions out of 418 000 replacements) failed in 2003 [26]. The number
of revisions is increasing steadily. From October 1, 2005 to December 31, 2006,
51 345 total hip replacement revisions were conducted and the most common
causes of these revisions included: instability/dislocation, mechanical loosening,
infection, etc., as shown in Fig. 9.2 [27]. In addition, the lifetime of current
artificial joint implants is only about 10±15 years on average [28], so younger
and more active patients (such as those men under 60 and women under 55
years) who receive artificial joint replacements will inevitably need more than
one revision surgery in their lifetime.
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