Female Knee No Different – Says New Study

Do the smaller, thinner (at the front) prosthetic knees designed for women work any better than non-gender specific components? Alexander Sah, M.D., and John Dearborn, M.D., orthopedic surgeons at the Dearborn-Sah Institute for Joint Restoration decided to find an answer to that question. They investigated how women (who make up 60% of all TKR—total knew replacement—patients) functioned with a leg component designed specifically for them.

The investigators powered their study with more than 1, 900 total knee replacement surgeries in women between 2006 and 2010. In more than 1, 500 of the procedures the surgeon had implanted femoral components, or parts imitating the leg bone from the hip to the knee, that were specifically designed for women.

The researchers also looked at 771 knee replacement surgeries performed on women between 2002 and 2006 before gender-specific parts were created. By looking at patients’ X-rays that capture images of non-uniform parts of the body, researchers focused on how well the new knees fit the host bone in patients.

The researchers evaluated patients’ pain levels, range of motion and function after surgery. They found that patients with the gender-specific knee had the same functional and range-of-motion improvements as those who received the standard knee. Although the female-specific part had less overhang than the standard knee, knee flexion and kneecap movement was the same in both groups.

“The variation in femoral anatomy between males and females has initiated interest in femoral prosthesis design changes, ” the researchers wrote. “While component overhang can be minimized intra-operatively, and is reflected radiographically, outcomes are not improved based on objective measurements.”

Rates of lateral release of the kneecap, a surgical procedure to realign the kneecap, were also comparable to those measured in standard knees at 6.7% and 5.8%, respectively. The outcome of their study was that a prosthetic knee made especially for women undergoing knee replacement surgery brought the same knee bend and functional improvements as standard knees not specific to gender. Sah and Dearborn presented their study at the 2013 Annual Meeting of the American Academy of Orthopaedic Surgeons.