NANOMATERIALS FOR IMPROVED ORTHOPEDIC AND BONE TISSUE ENGINEERING APPLICATIONS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 208

nanomaterials has motivated wide investigation for their applications in orthope-
dic implants. Further investigation of the infl uence of nanoparticulate wear debris
on bone cell health is necessary to effectively minimize osteolysis as well as fully
realize the benefi ts of nanotechnology in orthopedic implant/applications [34,35].
7.2.2.3 Other Complications (Wear of Articulating Surfaces, Fractures,
etc.). The relative motion of some orthopedic implants is impossible to avoid
and the resulting mechanical load is extremely large (especially at the articulating
surface of hip or knee implants). The more active and young the patients receiv-
ing orthopedic implants, the higher the risk of articulating bearing surface wear
and periprosthetic fractures [36]. In fact, wear of articulating bearing surfaces has
commonly evoked our attention. From the basic mechanical viewpoint, adhesive
wear, abrasive wear, third body wear, wear fatigue and corrosion are fi ve major
mechanisms causing wear of articulating bearing surfaces [37]. Modifi cation of
polyethylene and substitution of metal-metal or ceramic-ceramic bearings for
polyethylene may both help to improve the wear-resistant property of implant
materials.
Several investigations have revealed that periprosthetic femoral fractures
accompanied with total hip replacements are more common after revision surger-
ies than after primary replacements [40,41]. So with the increasing number of
revision surgeries, it is expected that periprosthetic femoral fractures will become
more common than before. Since mechanical properties (including strength,
toughness, and ductility) of implant materials are closely related to the above
complications and have infl uences on the long-term success of an orthopedic
implant, synthesizing various orthopedic implant materials which biomimic the
mechanical properties of natural bone is rather desirable.
It should be realized that each previously mentioned complication for ortho-
pedic implants are widely related to each other. That is, the high rate of implant
fractures is usually accompanied by a loose implant [38,39]; loosening of implants
can also be caused by osteolysis or infl ammation; wear particle generation (see
section 7.2.2.2) and infl ection [5] often coexist with wear of articulating surfaces.
Therefore, reducing the infl uence of one complication may have positive effects
on preventing other complications and fi nally improving the long-term success of
orthopedic implants.
7.3 NANOMATERIALS FOR IMPROVED ORTHOPEDIC AND BONE
TISSUE ENGINEERING APPLICATIONS
Nanomaterials are materials with basic structural units, grains, particles, fi bers or
other constituent components in the range of 1-100 nm [42]. Compared to respec-
tive conventional micron-scale materials, they can exhibit enhanced mechanical
properties, cytocompatibility, and electrical properties which make them suitable
for orthopedic implants. Next, the research investigating the use of nanomaterials
in the orthopedic tissue engineering fi elds is extensively reviewed.