Knee Implants Still Work If You’re Obese, Don’t Need To Be Gender Specific

knee implants still work in obese

Three important new studies on knee implants — also known as total knee replacement (TKR) — were presented Wednesday at the 2013 annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) taking place this week in Chicago. Two encouraging studies suggested that TKR can be just as successful in obese as in normal weight patients — although it will cost more time and money for the heavier patients.

A third study suggested that women don’t need special “female” implants to have a good result.

Chances are that there’s a knee replacement coming to you or to someone you care about. The Journal of the American Medical Society stated last September that the number of knee replacements performed has more than doubled since 1991. They predicted that 3.5 million of the surgeries will be performed every year by 2030.

At the same time, the obesity rate is also growing. The Centers for Disease Control and Prevention (CDC) said that over one-third of American adults are already obese. Although some groups are harder hit by the epidemic than others, there was no state that had an obesity rate less than 20 percent.

Needless to say, orthopedic surgeons are feeling the pressure to find out if obese patients can safely enjoy the benefits of knee replacement surgery. One study, led by Mayo Clinic’s Dr. Hilal Maradit-Kremers, reviewed the records of 8,000 patients who underwent the surgery between 2000 and 2008, breaking them into eight groups depending upon their body mass index (BMI) and health conditions.

Being heavier increased the cost and recovery time of the surgery, adding up to several hundred dollars more per procedure, because doctors have to bring extra technical skills to work around the extra weight.

A second, related study performed in Singapore on 301 patients who got knee implants showed that surgeons didn’t have to spend any more time performing the surgery on the obese patients — but the patients themselves had to spend more time in the hospital recovering.

However, lead study author Dr. Chin Tat Lim pointed out that obese patients ultimately had just as good an outcome as the normal weight patients. “Obesity does not negate good surgical outcome in total knee arthroplasty,” he said.

Although you may associate getting knee replacement surgery with hard-hitting male athletes who play football or other sports, it’s an issue that faces women as well. In fact, women now receive 60 percent of all knee implants, sparking surgeon Dr. Alexander P. Sah and his team to see if special narrower implants designed for women really worked better.


They reviewed over 1900 women between 2006 and 2010 who got the gender-specific implants and compared them to over 770 women who got TKR from 2002 to 2006 before the devices were in common use. Both groups had the same amount of relief of pain and improvement in mobility.

“Benefits of using the gender-specific component may not be detectable by current measures, or may not exist at all,” said Dr. Sah.

With knee implants and total knee replacements on the rise, it’s good to know the doctors are always looking for ways to make them even better.

[marathon runners photo courtesy Aaron Fulkerson and Flickr]