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ACL Injury and Hormones
Ross A. Hauser, M.D.
Though males and females have the same musculoskeletal structures, there are
some unique differences that actually make female athletes more prone to injury.
In regard to skeletal differences, males usually have wide shoulders and narrow
hips, whereas a female generally has a wide pelvis in relation to the width of
her shoulders. This wider pelvis is necessary for childbirth. This wider pelvis
is stabilized by the
sacroiliac
ligaments
in the back and the
pubic symphysis
and
pubic ligaments in the front. It is these ligament structures that are
stressed and account for the significant back pain that occurs in 50 percent of
women who are
pregnant.
This wider pelvis in females leads to an increased inward slant of the thigh
and, therefore, an increased Q-angle of the knee. The Q-angle, a measurement of
the angle created by the line from the anterior superior iliac spine and the
patella, and the line from the patella to the tibial tubercle, is normally less
than 12 degrees. An increased Q-angle produces excessive lateral forces on the
quadricep's mechanism and abnormal tracking of the patella. This is one of the
reasons why
chondromalacia patella or
patellofemoral syndrome is more common in
women. (Hutchinson, M. Knee injuries in female athletes. Sports Medicine. 1995;
19:288-302.)
As stated above, a female's thighs tend to slant inward towards the knees more
than a male's. This puts additional strain on a woman's hips and their
ligamentous support. This is one of the reasons that the majority of the 120,000
hip replacements done each year are in women. Females also have a wider carrying
angle of the elbows. This is similar to the Q-angle of the knee. This wider
angle places additional stress on the medial elbow stabilizers, namely the
ulnar
collateral ligaments, which are usually the culprits when a female athlete has
medial
elbow pain.
Body composition is also different between males and females. The average body
fat content of the female is approximately 26 per-cent, compared with that of
the male at 14 percent. The female has a lower lean body mass indicating less
muscle mass. The greater muscle mass in males is due to the predominant effect
of the androgen
hormones, whereas
estrogen, predominant in females, results in
increased body fat. As it turns out, this difference in hormones is key to
understanding why female athletes are more easily injured and repair more slowly
than their male counterparts.
Testosterone stimulates
fibroblastic
proliferation, whereas
estrogens, especially estradiol, inhibits it.(Liu, S.
Estrogen affects the cellular metabolism of the
anterior cruciate ligament. A
potential explanation for female athletic injury. American Journal of Sports
Medicine. 1997; 25:704-709.)
It is for this primary reason that female athletes can benefit from
Prolotherapy
for their
sports injuries. Estrogen makes a woman a woman, but they have a
definite negative effect when it comes to healing sports injuries.
Females also have a smaller proportion of muscle in relation to body size
because of the hormonal differences. Having less muscle tissue means there is
less muscle to stabilize the joints if the ligaments are injured. This causes
more stress to be placed on injured ligaments in women than in men, because
women do not have as much muscle back-up. This is another reason for female
athletes to become familiar with the local
Prolotherapist.
Females, compared to males, have a lower metabolic rate, the rate of conversion
of food to energy under conditions of total rest. This appears to be related to
the greater lean body mass of the male and the greater proportion of adipose
tissue in the female. This could be one explanation why females heal sports
injuries slower than men and why more of them develop
chronic pain, and need
operations such as hip replacements.
The Hormone Factors
Walk into any chronic pain clinic and who do you see? You see women.
Caring
Medical and Rehabilitation Services in Oak Park is no different. About three out
of every four patients coming for Prolotherapy are woman. Why are the women
getting most of the
arthritis and needing the majority of the artificial joint
replacements? It is easy to explain when you take into account the hormone
factor.
The dominant hormone in males is testosterone. Testosterone is very anabolic,
which means that it stimulates the growth or repair of tissues. Men have about
10 times the amount of testosterone as women. This is why they have a sex drive
that is about 10 times as strong as women do. It is also the reason why, on
average, men are 33 percent stronger than women. Males are stronger because of
their increased muscle mass due to testosterone. When males perform strength
training, they develop increased strength and increased muscle size due to
hypertrophy of the muscles. This hypertrophy is due to the effect of
testosterone. Females performing strength training gain increased strength with
relatively less muscle hypertrophy. This is because females have significantly
less testosterone. If a woman shows up at the Olympics looking like a man, the
other athletes will accuse her of using anabolic hormones like testosterone. The
complaint is justified. When a woman does weight strength training, she will get
stronger, but she cannot turn herself into a body shaped like a man because the
hormones are just not there.
Recent epidemiological studies have recognized a significantly higher anterior
cruciate ligament (ACL) injury rate in female athletes as compared with male
athletes in sports such as basketball, hand-ball, gymnastics, and soccer. (Gray,
J. A survey of injuries to the anterior cruciate ligament of the knee in female
basketball players. International Journal of Sports Medicine. 1985; 6:314-316.;
Nilsson, S. Soccer injuries in adolescents. American Journal of Sports Medicine.
1978; 6:358-361.; Slauterbeck, J. The incidence of anterior cruciate ligament
tears in men and women collegiate soccer players Orthop. Trans. 1996; 20:259.;
Whiteside, P. Men's and women's injuries in comparable sports. Physician and
Sports Medicine. 1980; 8:130-136.) Although various causes of this phenomenon
have been postulated, including differences in ligament or muscle strength,
conditioning, endurance, anatomy, and training techniques, the most plausible
appears to be the hormone factor.
Unique to the female athlete is her exposure to a constantly changing hormonal
milieu throughout her reproductive years. For most of her life, the female
athlete is exposed to rhythmic variation in either endogenous hormones during a
regular menstrual cycle or exogenous hormones via
oral contraceptives.
It has been only recently that it was discovered that there are estrogen
receptors on the fibro-blasts of the human ACL, suggesting that female sex
hormones may have an effect on the structure and composition of this ligament.
Dr. Stephen Liu and associates, at the UCLA School of Medicine, made this
discovery and went the next step to find out exactly how estrogen affects
ligament growth. They investigated the effects of 17B-estradiol on the cellular
proliferation and
collagen synthesis of
fibroblasts derived from the rabbit
anterior cruciate ligament. Measuring 3H-thymidine and 14C-hydroxyproline
incorporation assessed fibroblast proliferation and collagen synthesis,
respectively. They found that collagen synthesis was significantly reduced with
increasing local estradiol concentration. Declining collagen synthesis was first
noted at a 17B-estradiol concentration of 0.025 ng/ml. Within physiologic levels
of estrogen (0.025 to 0.25 ng/ml), collagen synthesis was reduced by more than
40 percent of control, and at pharmacological levels of 2.5 and 25 ng/ml, as
typically occurs in female atheletes taking birth control pills or estrogen
replacement therapy, by more than 50 percent of control. A significant reduction
of fibroblast proliferation was also observed with increasing estradiol
concentrations.
These results are startling. Estrogen, the female hormone, dramatically inhibits
fibroblasts. These fibroblasts are what make the collagen that makes up the
ligaments and
tendons, which are injured during sports. Estrogen was shown in
the above study to inhibit the fibroblastic growth and thus collagen formation
in a dose-dependent manner.
The more estrogen a woman has, the more inhibition will occur. This has direct
effects for all women taking birth control pills. Birth control pills have
pharmacological levels of estrogen, which are far in excess of a woman's normal
production. The simplest way for a female athlete, who is on artificial
estrogen, to overcome sports injuries, is to stop taking them. Inevitably, women
are placed on birth control pills because of menstrual irregularities, which are
easily treated with natural medicine techniques including diet manipulation and
nutritional supplements. At Caring Medical and Rehabilitation Services in Oak
Park, we perform
Diet Typing and hormonal testing on our patients. The
female athletes inevitably come up essential fatty acids deficient. This means
they need to injest more good fats in their diets in the form of omega-3 fatty
acids as is found in fish oils. They are encouraged to drink cod liver oil and
eat more fish. Better kinds of fats are also found in nuts and seeds, flaxseed
oil, and olive oil. Just this mild change in diet is typically all that is
needed to get rid of menstrual cramps and other menstrual irregularities.
Sometimes, however, more sophisticated dietary manipulation, herbal
supplementation, or other natural medicine techniques may be needed.
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