Until only recently, knee replacements - although available in different sizes -- had been gender-neutral and didn't take into account the differences between male and female anatomy.
The result? A traditional knee implant was often too wide for a woman, resulting in pain and compromised function for some. Women often still had some difficulty getting out of a chair or climbing stairs.
Now, for women needing a knee replacement due to pain or limited mobility, a newly available knee implant designed specifically for women has a narrower and thinner shape. The design of the new implant is based on CT imaging that mapped female knees to make knee replacements more proportioned to the female anatomy.
Women have a wider pelvis than men, which changes the angle of the knee joint, and that a woman's kneecap is thinner than a man's. Lenox Hill orthopaedic surgeon Dr. Giles Scuderi, who was part of a team of surgeons that developed the advanced knee replacement, is in the vanguard of using this first female-specific knee implant. The implant - called the Gender Solutions High-Flex Knee received clearance from the FDA earlier this year.
Because it is shaped more like a woman's natural knee, it allows more natural motion. With a narrower and thinner shape, it permits more natural tracking ability (that is, improved ability of the knee cap to glide over the femoral portion of the prosthesis).
About 300,000 knee replacements are performed each year in the United States. About two-thirds of the patients are women.
There are three basic design characteristics that make this new implant more suitable for women.
Narrower shape, proportioned for women. When determining the proper sized implant for the knee, surgeons measure the femur from front to back and side to side. Women's knees are typically more trapezoid-shaped whereas men's knees are more rectangle-shaped. Prior to the High-Flex Knee, implants that fit women from back to front were too wide, posing a risk to surrounding ligaments and tendons.
Thinner shape. The bone in front of a woman's knee is typically less prominent than in a man's knee. When a traditional implant is used to replace damaged bone, the joint may end up feeling "bulky," which could result in pain and less optimal function. The front of the High-Flex Knee is thinner in shape and matches the female anatomy.
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 the range of motion. Women tend to have a different angle than men because their shape and contour. The new knee was designed to accommodate the different tracking angle.
Additional benefits include a less invasive replacement procedure, less disruption of tissue surrounding the knee and because of a proper fit, it's more cosmetically appealing.
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