Research shows that women suffer more sports-related injuries to the knee than do men. Injuries to the anterior cruciate ligament (ACL) are three to four times more likely among female athletes.
The reasons for this difference is difficult to explain, but several theories were mentioned in an article in the July issue of Running & Fit News (Vol. 18, No. 7).
The first theory relates to the bone structure differences between men and women. A recent study, reported at an American College of Sports Medicine meeting, compared the bone structure differences using the skeletons of 100 men and 100 women. Researchers found that the female knee had a smaller joint surface, which makes it more susceptible to injury.
Other studies have focused on the differences between the hip width of men and women and the angle of the femur, the upper leg bone, to the knee joint, which might increase the stress on the joint more in women.
A third study, reported at the annual meeting of the American Academy of Orthopedic Surgeons, suggested that women run and perform other athletic movements in a more upright position than men. This study suggested that the more upright position causes the quadriceps, the front muscles of the leg, to dominate the hamstrings, the back muscles. A less upright position, used by men, activates the hamstrings to a greater extent and may provide more protection for the ACL.
Other experts believe that the higher injury rate for women is simply a matter of conditioning: Men train for leg strength more and for a longer period of time than women.
A final reason may relate to the hormone estrogen. In an interesting study, researchers looked at the effect of estrogen on ligament cells and found that ligament cells did not grow as well in the presence of estrogen. The effect enables the pelvis to loosen adequately for childbirth but may result in making the knee less stable.
So what should women do to help stabilize the knee? All of the studies suggested basically the same thing: Women should protect themselves with intelligent training aimed at a balance of strength and flexibility, especially in the muscles that surround the knee.
Garth Fisher is director of the Human Performance Research Center at Brigham Young University.