Changes in joint laxity associated with the menstrual cycle, with pregnancy, with the post-partum period, and with the menopause
This thesis looks at changes in joint laxity associated with the menstrual cycle,
pregnancy, and the menopause and the potential contribution of female
hormones to that laxity.
A pilot study revealed that there was a potential link between the phases of
the menstrual cycle and the onset of musculo-skeletal injury.
Following an extensive literature search studying the various hormones
involved in the menstrual cycle, and their receptors in musculo-skeletal
tissues, an interesting picture emerged that appeared to support the evidence
evinced in the pilot study. This was particularly so with regard to papers that
attempted to show a link between athletic injury and the phases of the
Four experiments were designed using a Hyperextensometer capable of
examining the range of movement in the first metacarpo-phalangeal joint of
the subject's dominant hand. Women with a normal menstrual cycle, pregnant
women, breast feeding women, and women after the menopause, were all
examined to discover if their hormones had an effect on the mobility of the
-The results of the menstrual cycle study showed that every subject underwent
, an increase in laxity as she progressed throughout the cycle, and that change
was particularly significant in the first phase of the cycle. The pregnancy study
showed that once again all subjects measured showed an increase in joint
laxity as the pregnancy progressed, however this laxity change was neither ,
uniform throughout the pregnancy nor the same from one subject to another.
The majority of subjects however experienced an increase in laxity in the
middle months of their pregnancies. The study found that when comparing
primaparous to multiparous subjects the primaparous group changed earlier.
The post natal study looked at changes in laxity that took place in breast
versus bottle feeding mothers. It failed to draw any significant conclusions
from the data. Finally the menopause study showed that women who take a
hormone replacement retain joint laxity more than a control group.
The implications of these findings were discussed.