ACL tears linked to women's running style
From www.JSOnline.com
Milwaukee Journal Sentinel
InteliHealth
June 07, 1999
Baltimore - A puzzle for doctors: Why do female athletes tear their anterior cruciate ligaments more often than male athletes? ACL tears, which can end a promising athletic career and usually require surgical repair, occur during sudden stops and turns, or during an awkward landing, such as when a basketball player jumps up and lands on another player's foot.
Women athletes are three to four times more likely than men to tear this ligament.
A new study, which was presented at the American Academy of Orthopaedic Surgeons in California in early February, videotaped athletes. Researchers saw that women run differently than men, and as result, they rely more on the quadriceps muscles in the front of the knee, rather than the hamstrings in back. Men run in a more crouched position, while women's knees and hips are straighter.
Edward G. McFarland, M.D., director of the Division of Sports Medicine and Shoulder Surgery for the Johns Hopkins Medical Institutions, explains in this InteliHealth interview why this difference in posture might be the answer to the puzzle.
InteliHealth: Do you find this explanation plausible?
Dr. McFarland: I think it's probably right; women don't run the same as men in many sports. Women tend to run more upright than men when they run. Two recent studies show that women do indeed have different body mechanics than men when they run. They don't have as much flexion in the knee when they do cutting maneuvers, and they put more stress on the inside of the knee when changing direction. One of these studies was on recreational athletes so it may not extrapolate to highly-trained female athletes.
IH: Is there anything structurally different in female knees?
Dr. McFarland: That's controversial, but I don't think that it will prove to be a major factor. There is not much one can do about one's bone structure.
IH: So why the greater numbers of ACL tears in women?
Dr. McFarland: There are three factors: One, it's probably the way they run; two, it's the way they use muscles around the knee when running; and three, there may be some inherent laxity or loosening of the knee which is different than in men. Some people suggest the ACL is more likely to tear at certain times of the menstrual cycle, which may relate to the hormonal milieu, but those studies aren't conclusive. Exercises that increase muscle tone around the knee might prove helpful.
IH: Can you change the way women run - or at least young girls?
Dr. McFarland: I think so. If you look at women's basketball now versus 20 years ago, the women used to run in a much more upright posture. I think women's sports have changed in terms of their athleticism. Their techniques are approaching that of men. There will always be some differences due to physiology, but women also have made great gains.
IH: If women use their quadriceps more than the hamstrings, why would that make a difference?
Dr. McFarland: We don't know exactly how or why these ligaments tear with sudden decelerating pivots. If the knee is not
guarded correctly, it shifts. There have been people who have suggested you can train the muscles to contract when you cut. But I don't see how - that would have to be an instantaneous, unconscious reaction. Recently there was an article in the Clinical Journal of Sports Medicine about a study of women in the NCAA. They looked at women's and men's soccer and basketball. The study found no difference in the ACL rate no matter what level the athletes were playing at. Although women had more tears than men, the rates were the same for Division I, II, and III. That would infer that skill is not involved as a factor in these injuries. It's hard to say what is skilled and unskilled. This study needs to be repeated for high school and higher caliber athletes to have more meaning.
IH: Is there an age-related component to these injuries?
Dr. McFarland: ACLs occur in people when they're active; so it's usually between 15 and 25. With skiers you can see them at any age group.
IH: I have an 11-year-old girl who plays basketball and soccer and lacrosse. Is there anything I can do?
Dr. McFarland: There are enough studies that show the higher rate of knee ligament injuries in women is real - the question is how do you do anything about it? I personally think as women's athleticism increases over time, the gap is going to close. Others suggest it's the hormonal difference or some inherent laxity that predisposes women to injury. Another option is to avoid sports that put the ACL at risk.
IH: Do braces help prevent ACL tears?
Dr. McFarland: The answer is no. Not even the braces used by football players are necessary in most cases - and are controversial, by the way. They protect the medial ligament but not the anterior cruciate ligament. Bracing is not currently recommended for prophylaxis or to prevent knee injuries in non-contact sports. Probably the only thing to do for prevention is stay in shape, and have players do quadriceps and hamstring strengthening as part of their fitness program.
Copyright The Johns Hopkins University, 1999. All rights reserved. This interview is not intended to provide advice on personal medical matters, nor is it intended to be a substitute for consultation.