Women wait longer to pursue knee-replacement surgery than men do

Jan 10 2008

Is getting new knees on your list of New Year's resolutions? Research at the University of Delaware indicates that women wait longer to pursue knee-replacement surgery than men do.

By postponing surgery until they can no longer stand the pain, these women may also risk putting their mobility, and quality of life, on hold indefinitely, according to Lynn Snyder-Mackler, Distinguished Alumni Professor in UD's Department of Physical Therapy and a certified sports physical therapist and athletic trainer.

“Doctors typically tell patients to wait to have knee replacements until they just can't stand the pain any longer,” Snyder-Mackler said. “Our research shows that's bad advice--and worse for women than it is for men--because your level of function going into surgery generally dictates your level of function after surgery,” she noted.

Snyder-Mackler led the research team for the study, which was funded by a $1,125,000 million grant from the National Institutes of Health. Her collaborators included Stephanie Petterson, who earned her doctorate in physical therapy and was a postdoctoral researcher at UD and is now a senior lecturer at the University of East London, and Drs. Leo Raisis and Alex Bodenstab, orthopedic surgeons at First State Orthopaedics in Newark, Del.Stephanie Petterson.

At UD's Physical Therapy Clinic in McKinly Laboratory, 229 candidates for total knee replacements, including 95 men and 126 women with osteoarthritis, were evaluated and compared to 44 healthy men and women who matched them in gender, age and body-mass index. Each subject took part in a series of standard physical tests such as stair climbing and the distance covered in a six-minute walk.

The strength of the participants' quadriceps--the major thigh muscle that extends and straightens the knee--and range of motion of the knee also were assessed at the UD clinic, which handles more than 300 visits by patients each week.

While the men generally were stronger and had more knee function than the women, the test results showed a much greater degree of physical disability in the female knee-replacement candidates compared to the males in the group.

“The women afflicted with osteoarthritis were at a much more advanced stage than the men with the disease,” Snyder-Mackler said. “The women all had painful end-stage osteoarthritis, where the cushion of cartilage padding the knee bones has completely deteriorated and you basically have bone hitting against bone.”

Why are women waiting so long before pursuing surgery?

Snyder-Mackler says there may be a number of reasons. Perhaps women can bear pain better than men, or a woman's world increasingly revolves around the home as we age, or it could be that women are just trying to follow doctor's orders.

“Osteoarthritis of the knee is the most common cause of disability among Americans. It's a disease of age that affects more women than men on a 60-40 basis,” Snyder-Mackler said. “Physicians generally have advised patients to wait as long as they can before pursuing knee replacements, with the thinking that it is a once-in-a-lifetime surgery that should last an average of 20 years. However, delaying surgery can limit the quality of life of patients because how they function before surgery indicates their performance afterward.”

Women need to become more educated about the risks and benefits of knee-replacement surgery, Snyder-Mackler said, and heed the warning signs of serious problems.

“When you feel profound buckling and weakness in your knee when climbing stairs, that is a major problem. You compensate--eventually, you may come downstairs only once a day,” Snyder-Mackler said. “As a result, you become sedentary and that's not good for your health. Earlier intervention can help preserve your mobility and quality of life.”

The research is one of two UD studies led by Snyder-Mackler and reported in the Journal of Bone and Joint Surgery.

In a related study, Snyder-Mackler worked with Dan Ramsey, assistant professor of exercise and nutrition science at the University of Buffalo, and UD colleagues Kristin Briem, physical therapist, and Michael Axe, clinical professor of physical therapy, to determine the effectiveness of “unloader” knee braces in reducing pain and improving function in osteoarthritis patients.

The research, which also was supported by the National Institutes of Health, showed that these braces actually promote pain relief by diminishing muscle contractions rather than by “unloading” or separating the joints. Such knee braces may provide an inexpensive treatment option for some osteoarthritis patients.

Snyder-Mackler says she has always been interested in research on knee injuries, and in providing solutions to improve people's lives.

“I've always had a burning desire to bring evidence to bear on clinical problems--that's always been really important to me,” Snyder-Mackler said. “There are real people at the end of the research loop--patients, physical therapists and physicians, and the patients' families.”