Functionally graded materials (FGMs)
are emerging materials systems,
with structures and compositions gradually changing in a particular
direction. Consequently, the properties of the materials gradually
change in the desired direction to achieve particular nonhomogeneous
service demands without abrupting the compositional and behavioral
interface at the macroscale. FGMs have been found to have high potential
as orthopedic implants; because the functional gradient can be adapted
in such a manner that the core of FGM should be compatible with the
density and strength of bone, interlayers can maintain the structural
integrity and outermost layers would provide bioactivity and corrosion
resistance, thus overall tailoring the stress shielding effect. This
review article discusses the typical FGM systems existing in nature
and the human body, focusing on bone tissue. Further, the reason behind
the application of these FGMs systems in orthopedic implants is explored
in detail, considering the physical and biological necessities. The
substantial focus of the present critical review is devoted to two
primary topics related to the usage of FGMs for orthopedic implants:
(1) the synthesizing techniques currently available to produce FGMs
for load-bearing orthopedic applications and (2) the properties, such
as mechanical, structural, and biological behavior of the FGMs. This
review article gives an insight into the potential of FGMs for orthopedic
applications.