Intermountain Press Release

Salt Lake City—Orthopedic surgeons at LDS Hospital late Tuesday became only the second team in the world to implant the first 'gender-specific' artificial knee that has been designed specifically for women.

The Gender Solutions knee, manufactured by Zimmer, is the first artificial knee replacement shaped to fit the unique anatomy of the female knee. The U.S. Food and Drug Administration just approved it for use in the United States.

"The surgery went very well and the patient is recovering nicely," says LDS Hospital orthopedic surgeon Kim Bertin, M.D., who implanted the artificial knee.

The patient, Rosemarie Brinkerhoff of Lovelle, Wyoming, will soon be discharged from LDS Hospital. "I'm very grateful to Dr. Bertin and LDS Hospital for the wonderful care that I've received. I feel very fortunate to be able to benefit from this advanced technology."

The design of the Gender Solutions knee is based on three distinct and scientifically documented shape differences between women's and men's knees. In designing the knee, researchers used a sophisticated and highly detailed map of the female knee using three-dimensional computed tomography (CT) imaging. All other implants now being used for total knee replacement are based upon an average between the size of women's and men's knees. Mounting research shows that the anatomical structure of the female knee is very different than the male knee. Meeting the knee replacement needs of female patients is about implant shape, not size, says Dr. Bertin.

Nearly two-thirds of the more than 400,000 annual knee replacement patients are women, according to the National Center for Health Statistics, and the numbers continue to increase each year. Research shows that while both women and men vastly underuse knee replacement, women are three times less likely than men to undergo the procedure, although they suffer from more knee pain and resulting disability.

LDS Hospital orthopedic surgeons also played a role in the design of the new Gender Solutions' knee. A growing body of research indicates that a woman's knee is not simply a smaller version of a man's knee. The differences involve the bones, ligaments and tendons in the joints, says Dr. Bertin. "Because women's knees are shaped differently than men's it makes perfect sense to design knee implants with women in mind, particularly considering that women are by far the majority of the knee replacement patients," he says.

Dr. Bertin says the new artificial knee implant addresses three key differences of a woman's knee:

1. Narrower Shape, Proportioned to Female Anatomy: When determining the appropriate-sized implant, surgeons measure the end of the femur from front to back and from side to side. Women's knees typically are narrower from side to side, and are more trapezoid-shaped, whereas men's knees are more rectangle-shaped. Surgeons typically choose the implant size based on the front-to-back measurement, which is key in allowing the knee to move and flex properly. However, an implant that fits a woman's knee from front to back often will be too wide from side to side, leading to the implant overhanging the bone and potentially pressing on, or damaging, surrounding ligaments and tendons, possibly causing pain. The Gender Solutions artificial knee is proportionally contoured to the entire bone to provide a more precise fit.
2. Thinner Shape: The bone in the front of a woman's knee is typically less prominent than in a man's knee. Therefore, when a traditional implant is used to replace the damaged bone, the joint may end up feeling and functioning better than before surgery but may still feel "bulky," which may result in pain and decrease optimal function. The new knee is thinner in shape in the front so the knee replacement more appropriately matches the natural female anatomy.
3. More Natural Tracking: The angle between the pelvis and the knee affects how the kneecap tracks over the end of the femur as the knee moves through a range of motion. Women tend to have a different angle than men due to their specific shape and contour. Historically, implants have been designed based on an average between the size of women's and men's knees, and therefore, the traditional artificial knee may tend to track at an angle that leads to a woman's knee feeling "unnatural" as it moves. The new knee implant is designed to accommodate the different tracking angle and function more like a woman's natural knee.

The knee joint is composed of three bones: the end of the femur (thighbone), the top of the tibia (shinbone) and the patella (kneecap), which are all held together by tendons and ligaments and cushioned by cartilage. Knees can become painful, due to arthritis, injury and infection, which cause deterioration of the cartilage. When the cartilage is gone, the bones of the knee grind against each other, wearing away and typically causing severe pain. Total knee replacement involves removing the portion of bone that is damaged and resurfacing the knee with metal and plastic implant.