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March 6, 2007 > Innovative Knee Replacements Designed for Women

Innovative Knee Replacements Designed for Women

As a teenager, Colleen Crawford's life revolved around competitive sports, ranging from gymnastics to skiing and everything in between. Then, at age 19, she tore her anterior cruciate ligament (ACL), the major stabilizing ligament of the knee. It was the first of many injuries that eventually destroyed her knee.

"Over the next six years, I had five different surgeries for sports injuries," she recalls. "By the time I was 25, I had no cartilage left in my knee - it was bone rubbing on bone. Then I had another 'clean-up' surgery done when I was 35. I was in so much pain, I couldn't participate in sports. Even walking was difficult. People kept suggesting a knee replacement, but I was apprehensive, so I put it off until last summer at age 41."

A friend who runs physical therapy rehabilitation clinics referred her to orthopedic surgeon Dr. John Dearborn at Washington Hospital's Center for Joint Replacement. "I asked him all sorts of questions," she says. "I wanted a knee that would last and one that would be strong enough to allow me to take part in sports again. He recommended a new knee implant, called the Zimmer Gender Knee, which is designed specifically for women. It just made sense to me."

According to the U.S. Centers for Disease Control and Prevention, more than 400,000 Americans a year have knee replacement surgery, and more than 60 percent of those are women. Since the time modern knee implants were introduced in the early 1970s, all the designs were based on average measurements of both men and women, which often resulted in poorly fitting implants for women.

"Men and women - quite obviously - have different anatomies," Dr. Dearborn explains. "The end of a woman's femur - the thigh bone - is shaped differently from a man's, with the side-to-side width narrower than a man's for a given anterior-posterior dimension. The aspect ratios are totally different. The standard design for the knee implant which we attach to the end of the femur was adequate for a lot of people, but in women, if you got the right size implant for the anterior-posterior width, it was often too wide from side to side."

"We were always compromising, either accepting an implant that 'overhangs' the bone or one that was undersized in one way or another," explains Dr. Dearborn. "The Zimmer Company studied the anatomy of the female femur and designed a knee implant that fits women better."

In addition to a more slender profile and contoured shape, the Gender Knee also takes into account the fact that a woman's shape generally results in a different angle between the hip and the knee. "Because women's hips are wider, the femur comes down at a sharper angle, which affects how the kneecap slides over the femur," Dr. Dearborn says. "The gender-specific knee aligns better to the way the female kneecap tracks."

Since the introduction of the Gender Knee in April, Dr. Dearborn has used it in approximately 250 knee-replacement surgeries so far, including some in men. "No two bodies are exactly alike," he notes, "and it turns out that this new implant works better for about eight percent of men, too."

As for Crawford's surgery, Dr. Dearborn had no doubt the Gender Knee was the right choice. "Colleen definitely has classic female bone dimensions," he says. "Plus, she is a high-level athlete, and it's even more important to have an implant fit properly when you're very physically active."

Crawford is definitely pleased with the results. "Knee surgery is not fun to go through, but the results are awesome," she says. "I was up and walking around by the second day. Now I'm back to skiing, kickboxing and jogging on the treadmill. I've got my life back - without the pain."

Dr. Dearborn notes that knee replacement surgery is recommended only for treatment of advanced arthritis and other conditions that can't be treated by other means such as anti-inflammatory medications, injections, physical therapy or arthroscopic surgery.

For more information regarding Washington Hospital's Center for Joint Replacement, call (888) 494-7003 or visit, click on "Services & Programs" and select "Center for Joint Replacement" from the drop down menu.

For more information about the Zimmer Gender Knee, visit their Web site at





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