However, there are still some limitations in our study. First, the
sliding movement used in the friction and wear test was not the
same as the real movement in the artificial joints although the
selected movement has met the test standard of total joint prostheses
(i.e., ASTM F732). Some friction tests of the PVP solutions
will be performed under the physiological loading conditions of
sliding and rolling in the future. Second, whether high PVP concentrations
have serious toxicity for the tissues around artificial
joints should be justified. The PVP solutions with different concentrations
might have different osmotic pressure, and its effect
needs to be analyzed. Third, the time of the wear test in the paper
is a few short compared to the service life of artificial joints in
human body. The wear test with longer time would be developed
where the morphology of wear debris should be characterized as
well as its biological influence.