The present study has several limitations that must be
addressed. First, although the statistical power of the
present sample is adequate, caution must be taken in
generalizing the present results. The small number of
women studied may not represent the greater population
of patients with knee OA and TKA. Second, the present data
cannot be generalized to men because our population was
composed strictly of women. Third, the lack of a no-exercise
control group must be noted. One could argue that operated
patients (OKG), fearing a new surgery if the exercise fails,
may give more attention to the exercise program and could
improve in a second evaluation even without the proposed
exercises. However, previous studies with only TKA
subjects showed no improvement in functional performance
in no exercise or standard physical therapy control groups,
suggesting that the fear of a new operation would not
improve these variables (4,7,14). Moreover, the total or
partial restoration of OKG functional performance, lowerlimb
loading distribution and balance levels to those of
healthy older women performing the same exercise program
reinforces the benefits of resistance training among
older women with TKA and OA in the contralateral knee.
Fourth, the 12 deg/sec assumption in case of falling does
not represent the real value of center of gravity sway during
the unilateral stance test; rather, this value is a recommendation
from the manufacturer for research and clinical
purposes. Moreover, the fact that all OKG women failed to
complete the 3 repetitions of the unilateral stance test
without loss of balance resulting in falls before training and
that only 2 women failed to complete 1 repetition (but were
able to complete the other 2 repetitions) after training, which
resulted in a significant improvement in average unilateral
stance time after training, shows that unilateral stance
balance was improved during follow-up in OKG women.
Finally, the follow-up period was rather short, warranting
additional studies with a no-exercise control group; in
particular, long-term follow-up focused on analyzing end
points such as radiographic evaluation of disease progression
or second TKA may offer additional compelling
evidence for the validity of the present resistance training
program.