2002 - University of Washington Bone and Joint Sources

Experimental Group
Table 2: Results of ACL Mechanical Testing.
levels between the control and
experimental groups suggest that the
rats in the placebo group underwent an
ovulatory cycle while the experimental
group had more stable estrogen and
progesterone levels as is typical of cycles
under oral contraceptive control. Our
results show that rats having
undergone 12 oestrus cycles regulated
by oral contraceptive steroids vs those
that have undergone 12 oestrus cycles
without exogenous steroids have
different ACL response to mechanical
stress. Specifically the hormone treated
rats had significantly increased ACL
stretch prior to failure than controls.
There was, however, no significant
difference in peak load before failure or
energy to failure. The increased stretch
prior to failure may be due to a higher
concentration of type 3 collagen vs type
1 collagen as was found by Liu et al in
their studies of acute estrogen exposure.
In contrast to Slaugtherbeck et al we
did not find that the ultimate load to
failure was different between our two
N, N/mm and mJ
600
500
400
300
200
100
0
Results of Specimen Loading
p