Metallic implants in the human body are widely used in surgery, and th
eir corrosion and degradation processes are being extensively investig
ated around the globe. As with other structural components, possible m
echanisms of failure in orthopaedic implants are: mechanical fracture,
wear and corrosion, or, more importantly, combinations of these facto
rs. Many implants are exposed to high loads and intense wear, which, a
s a consequence of the patient's movements, are repeated an immense nu
mber of times. The consequent degradative effect on the metals is grea
tly increased by the fact that the surrounding body-fluid environment
is corrosive. Considering the high human cost of revisional surgery an
d the fact that even ''small'' amounts of corrosion products released
into the body tissue are unacceptable, it is clear that the nature and
distribution of corrosion products released into the body from orthop
aedic implants remains an important issue. Modular implants are being
developed, and fretting corrosion/wear are potential degradation probl
ems. They play a deleterious role in the degradation process of the ar
ticulating implants by producing fretting debris, which can be detrime
ntal to body tissues and will significantly reduce the performance of
the implants. Therefore, this paper reviews the mechanisms of fretting
and fretting fatigue that accelerate the fatigue failure of orthopaed
ic implants, and also presents a state-of-the-art review of the invest
igations carried out by many workers on this subject.