The Knee Needs of Girls

Knee replacement implants for women no different than standard

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Women considering a new knee have a choice: a standard knee replacement designed for either gender or a knee that's made just for the ladies. 

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, according to new research presented at a conference.

Though women's prosthetic knees are smaller and thinner than the standard implant, the findings showed that women see improved knee function with whatever new knee is given to them.

"Work with a physical therapist after knee replacement."

Alexander Sah, MD, and John Dearborn, MD, orthopedic surgeons at the Dearborn-Sah Institute for Joint Restoration, investigated how women who underwent total knee replacement (TKR) surgeries functioned with a leg component designed specifically for women.

Female knee implants are narrower, thinner at the front and angle differently than the standard prosthetic knee used in TKR surgeries for all genders. Women make up 60 percent of all TKR patients, according to researchers.

The study included more than 1,900 total knee replacement surgeries in women between 2006 and 2010. 

More than 1,500 of the procedures involved female flex femoral components, or parts imitating the leg bone from the hip to the knee, that were specifically made for women.

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' radiographs, or 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.

They also evaluated patients' pain levels, range of motion and function after surgery.

Patients with the gender-specific knee had the same functional and range-of-motion improvements as those who received the standard knee, researchers found.

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," researchers wrote in their report.

"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 similar in gender-specific knees and in standard knees at 6.7 percent and 5.8 percent, respectively.  

The study was presented March 21 at the 2013 Annual Meeting of the American Academy of Orthopaedic Surgeons. The findings have not yet been published in a peer-reviewed journal.

Reviewed by: 
Review Date: 
April 3, 2013
Last Updated:
April 4, 2013