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WHAT WOMEN KNEED
Female patients find improved comfort in specially-contoured prosthetic device
By Sandy Kleffman

WALNUT CREEK - For more than 30 years, orthopedic surgeons have performed knee replacements with implants designed for the average person. But some surgeons began to notice a problem: The prosthesis, which comes in several sizes, often does not fit women well. Now a growing number of orthopedists are using a new model made with a woman's bone structure in mind. Some say it leads to greater comfort and a more natural feel.

"This is the nicest new thing to happen in total knees in the past 10 years," said Dr. Douglas Lange, an orthopedic surgeon for the John Muir Health system. "It does seem to make a difference. "Isn't it surprising," he added, "that for all those years, we just assumed that a woman's knee was a smaller version of a man's?" It is not.

Women's knees are anatomically different. They are narrower, the bone in front is less prominent, and the knee cap or patella "tracks" differently. While the muscle tends to pull the knee cap straight up and down in a man, it pulls slightly to the side in a woman because of her wider pelvis. Each year in the United States, more than 400,000 people undergo knee replacements. Two-thirds of them are women.

Orthopedists recommend the surgery when arthritis or a sports injury wears down the cartilage in the knee to the point that it becomes painful and difficult to move, and other means of resolving the problem have failed. A surgeon will then install a metal and plastic joint to better cushion the knee.

To make the old-style implant fit better, Lange often found he needed to use a smaller size and remove more bone from a woman's knee, or the implant would slightly overhang the bone, which can irritate soft tissue. After the surgery, some women complained that their knee felt tight or thicker than usual. "Surgeons had noticed that the bulkiness was something women were aware of," Lange said. With the new model, "there is a sense of comfort," he said. "The knee does look more natural. People aren't talking about that tight feeling on the front of their knees."

Not everyone is on board with the new design, however. Dr. Kevin Bozic, an orthopedic surgeon who specializes in knee replacement and is an assistant professor at UCSF, doesn't use the women's model. He argues that no one has proven it makes a difference. "I don't see it as a significant advance," he said. "I see it more as a marketing tool." Bozic said expertise and the number of surgeries an orthopedist performs play a bigger role in the outcome. "It really has more to do with the surgical technique that you use than the type of implant," he said.

Yet Lange remains a believer. He does about 300 total joint replacements a year, two-thirds of which are knee replacements. A few months ago, Lange became one of the first people in the area to use the gender-specific model manufactured by Zimmer. He receives no remuneration from the firm.

Elaine Josephian, an 85-year-old Moraga resident, said she has been pleased with the outcome of her surgery using the women's model. Osteoarthritis had worn down the cartilage in her knee so that it became painful to get around. Her recovery from the surgery was faster than she expected. "I walked in here with a walker one week after I had the surgery," she said. "The second week, I came in just using a cane."  Now, she uses neither. A casual observer would be hard-pressed to notice anything unnatural about her gait. During a recent visit to Lange, she bent her knee back at nearly a 145 degree angle without discomfort. "It's quite flexible," she said.

The surgery, which typically costs about $18,000, is not for everyone. People should first attempt more conservative means of easing pain and improving mobility, including anti-inflammatory medicine, cortisone shots, lubricant injections, braces, physical therapy and exercise, Lange said. But when those methods fail, "there comes a point when the symptoms and the frustration exceed our sense of humor," he said. "We run out of gas. We get impatient. We're frustrated. Our lifestyle has been diminished. We're not enjoying our lives." That is the time to consider surgery, Lange said.

Knee replacement is not a good option for some people, including those who are prone to infections, have serious heart disease, poor immunity or a history of vascular disease. "Some people are simply too fragile," Lange said. But other patients tell him the surgery gave them their life back. One elderly woman in a board and care facility was told she would have to move because she needed a walker to get to the lunch room and the facility did not allow walkers. After the surgery, she could get around without one and remain in the home. Lange said he is surprised no one developed a woman's model sooner. "Men and women are different and we've all known that," he said, "but it took awhile for scientists to get it."

The physicians of Muir Orthopaedic Specialists believe good medical care is a result of mutual understanding, respect and trust. In today's fast paced world, we recognize the importance of communication and spend as much time as possible to provide information explaining condition and treatment options so that our patients can make informed decisions about their care.

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