Women's Health: Female knee replacement sparks debate

A new artificial knee designed specifically for women is stirring up controversy among orthopedic surgeons, with some saying the device will lead to better outcomes for women after knee replacement surgery, while others are deriding it as nothing but marketing.

The Gender Solutions High-Flex Knee was introduced last year by U.S. company Zimmer. The device takes into account differences in the shape and size of the end of the thigh bone between men and women. It is intended for people who have worn out their knee joint due to arthritis.

Dr. Richard Booth, chief of orthopedic surgery at Pennsylvania Hospital in Philadelphia and principal developer of the knee, says the new implant design is appropriate for 60 per cent of women (typically, more petite women) and 10 to 15 per cent of men.

"What's best about this gender concept is that we're going to an era now of sophistication and customization that we've never reached before. This is an evolution that's become a revolution," Booth said during a panel discussion at a recent orthopedics meeting in San Diego.

"There is no question this whole problem is geared around marketing hype," countered Dr. Merrill Ritter, professor of orthopedic surgery at Indiana University in Indianapolis. He said his own review of 7,300 standard knee replacements revealed equally excellent results in both sexes. "None of this data supports the gender-specific total knee replacement. Ladies and gentlemen, make your call, but do it with data, not marketing."

In the ensuing discussion, panelists acknowledged women may not do as well as men after joint replacement, but there are other factors besides implant design involved. "If you look at females overall, they start out with more pain preoperatively and lower scores preoperatively (and) they wait longer to have their joint replacement," said Dr. John Callaghan of the University of Iowa in Iowa City. Other researchers at the meeting noted women's obesity rates and fat distribution around the knees may be additional factors to consider.

Dr. Robert Bourne, chairman of orthopedics at the University of Western Ontario in London, says cost could be a major issue with the new implant in this country. "These knees cost over $1,000 more. And considering we only pay about $2,000 for an implant, that's a huge impact.

"It's a brilliant marketing ploy, because 60 per cent of the knees done are in women, and women think that if they go to some other manufacturer, they're not getting a knee that'll fit women, which isn't true. And you've never heard any outcome data that they've had better results. There's nothing. It's all marketing."

Bourne says Canadian joint replacement registry data has so far revealed no differences in outcomes between knee implants, possibly because subtle differences are dwarfed by the overall improvement in knee pain and function. But he notes only about 85 per cent of people are extremely satisfied with their joint replacement. "So there is room for improvement."