ACL Injury and the Menstrual Cycle

It has long been known that women have a highly elevated risk for rupture of the anterior cruciate ligament (ACL) in the knee compared to men engaged in the same activity. One of the many theories to explain this risk is that the increase in circulating estrogen and degrease in progesterone during the pre-ovulatory stage of the menstrual cycle reduces the strength of the ligament. A group of researchers from the Nollet Musculo-skeletal System Institute in Paris studied 172 pre-menopausal women (mean age 34 years) with regular cycles who tore their ACL while skiing. The accidents mainly occurred on blue (moderately difficult) slopes at medium speed and the ski bindings did not release in most patients.  The authors found that ACL injury was 2.4 times more likely to occur in a pre-ovulatory phase of the cycle compared to the post-ovulatory phase. This pattern was not affected by the use of oral contraceptives. 

Bottom Line:    The findings suggest that women engaged in risky recreational exercise during the pre-ovulatory stage of their menstrual cycles could decrease their risk of injury by taking special precautions.  In skiing this might involve skiing on less demanding runs and adjusting release bindings to a lower threshold.  Read more about the study published in the June 2013 issue of the journal Orthopaedics and Traumatology, Surgery and Research here.