Birth Control Pills May Keep Knee Injury-Free
Canadian Study Suggests Birth Control Pills Help Prevent Knee Ligament Tears
Nov. 18, 2004 -- Women taking birth control pills have greater knee stability than those not using birth control pills, according to a Canadian study.
Women are four to eight times more likely to injure their knees than men, say the McGill University researchers, who included Paul Martineau, MD, chief resident in the orthopaedic division of McGill University Health Centre.
"Female athletes are expected to suffer over 30,000 serious knee injuries in a given year," write Martineau and colleagues in a recent issue of the Clinical Journal of Sport Medicine.
Differences in the alignment of the hip and leg, muscle strength, and hormones all play a role in increasing a woman's risk of knee injury.
One of the worst knee injuries -- rupturing the anterior cruciate ligament (ACL) -- occurs two to eight times more often in female athletes than male athletes, say the researchers.
Though interventional programs have improved muscle strength to help knee stability, little can be done to address differences in the female anatomy that place women at risk of injury.
Since past research has shown that female hormones may affect ligament composition, the synthetic hormones in birth control pills may help make knees steadier, say Martineau and colleagues.
The current study looks at the effects of birth control pills in increasing joint ligament stability. Birth control pills stabilize the normal hormonal fluctuations that occur in the menstrual cycle.
Their findings are based on 78 female McGill athletes who were about 20 years old. Forty-two participants were taking birth control pills; on average, they had taken the pills for about three years.
None of the participants had hormonal imbalances or previous knee injuries.
The researchers examined the women's knees using an arthrometer, a device that gauges loose-jointedness.
Participants taking birth control pills had less loose-jointedness in their knees than those not taking birth control pills.
The researchers call for further studies to find out if greater knee stability seen with birth control pills translates into fewer ACL injuries.