Some people can participate in a sport for years, and never
damage their ACL. Others have had three or four ACL reconstructions. What
determines susceptibility?
You are female. This is not a
sexist statement. Statistics don’t lie. If you are female, you are
probably asking “Why Me?” The following factors contribute to a woman’s
susceptibility to ACL injury:
“Q” Angle: The Q angle refers to the quadriceps
angle, or the angle between the hip and the knee. Since it is steeper in women,
they are more prone to having the kneecap slide, thereby causing injury.
Less
Androgen: Having less androgen means
that women are often less prone to developing large muscles. Muscle fiber helps
protect the joints and connective tissue. Female athletes are subject to the
same torque forces in their knee as men. If the muscle is not strong enough to
protect the joint, the kneecap will be even more prone to sliding.
Jump
Landing Tactics: Women do not bend their knees as much as men when landing
from a jump. This increases knee joint pressure.
Pivoting
Tactics: Women turn and pivot in a more erect position. Bending at the knee
and hip reduces ACL stress.
Quadricep/Hamstring
Imbalance: Women use their quads more then their hamstrings when landing
and changing direction. As the quadriceps contract, the hamstrings will stretch
and relax. A stretched muscle produces less force. If the knee is not
sufficiently flexed, there will be increased force on the shinbone. This can cause an ACL tear. It’s extremely
important to realize that anyone, male or female, whose quadriceps are
significantly stronger than their hamstrings, may be highly susceptible to ACL
injury!
Narrow
Intercondylar Notch: This is a controversial theory, but worth examining.
The intercondylar notch is at the end of the thigh. . This is where the
anterior and posterior cruciate ligaments form an x. It has been speculated
that since women have a narrow notch, it predisposes them to ACL injury.
Estrogen
and Joint Laxity: The female hormones
often give women natural joint and muscular flexibility. Unfortunately, this
often leads to hyper mobility. The current trend towards extreme yoga practices
that encourage contortion, as opposed to functional, dynamic flexibility may be
one of the key reasons that women are suffering more ACL injuries. Keep in
mind, there has been no study whatsoever that has successfully concluded that
pre-sport stretching prevents injury, but many studies have demonstrated that
excessive pre-activity stretching can actually cause injury. In 1988, a Swedish
study of 108 female soccer players demonstrated that the players were more
susceptible to injury during the premenstrual and menstrual stages of their
cycles. It’s interesting to note that injuries were reduced when oral
contraceptives were administrated.