Gender bias may contribute to sex-based disparity in TKA utilization, outcomes

Delay in treatment for osteoarthritis (OA) of the knee may have a negative influence on function and knee scores of women who undergo total knee arthroplasty (TKA). Initiation of treatment at an earlier stage could have a beneficial effect on knee function in female patients, according to a study presented at the 2009 Annual Meeting in Las Vegas.

Brian S. Parsley, MD, presented the results of the study, “The influence of gender on outcomes of TKA,” which evaluated the differences between male and female TKA patients at the time of surgical intervention. Dr. Parsley’s co-investigators were Roberto Bertolusso, MS; Melvyn Augustus Harrington, MD; and Philip C. Noble, PhD.

TKA underutilized in women?
Osteoarthritis is the most prevalent chronic disease in the United States—affecting more than 59 per­cent of Americans older than age 65—and a greater percentage of women are affected than men. This is particularly true when it comes to OA of the knee: men tend to have a reduced risk, while women—especially those older than age 55—have been shown to have a more severe presentation. This gender difference has been associated with various factors including hormonal influences, cartilage thickness, bony anatomy, femoral-tibial sizing, and patellar Q-angle differences, the researchers point out.

Yet a study published last year found the odds of an orthopaedic surgeon recommending TKA to a male patient was 22 times that for a female patient.

“Gender bias may contribute to the sex-based disparity in the rates of utilization of TKA,” said Dr. Parsley. “At the very least, this disparity may delay the female patient from undergoing surgery until their functional level has experienced further deterioration.”

To assess whether the severity of disease at the time of presentation differs between male and female TKA patients, the investigators carried out a prospectively collected/retrospectively reviewed study of nearly 900 patients. The impact of any gender differences on the patient’s outcome was also evaluated.

The study
Between 1996 and 2007, 890 patients—537 females (60 percent) and 353 males (40 percent)—underwent elective TKA by a single surgeon. A variety of implants—all cemented—were used, with similar distribution between genders. A standardized hyperflexion rehabilitation protocol was utilized in all cases with full weight bearing encouraged immediately postoperatively. Each patient was evaluated preoperatively and postoperatively for range of motion (ROM), Knee Society Score (KSS), and Knee Function Score.

Timing affects outcome
“The timing of presentation is multifactorial, but clearly appears to have an effect on patient outcome,” Dr. Parsley said of the study’s findings.

At the time of surgical intervention, male patients were found to be significantly younger (64.1 yrs) than females (67.1 yrs). Body mass index, preoperative and postoperative ROM, and the change in ROM were similar between groups.

Preoperative KSS scores were equivalent (males, 47.4; females, 46.6), but the male patients demonstrated a significantly greater improvement in postoperative function (90) than female patients (84.5). Knee Function Scores were significantly lower for the female group at presentation (females, 45.2; males, 57.0) and that difference persisted after surgery (females, 63.6; males, 73.1).

“A better understanding of sex and gender differences in the development of OA will allow for improved education of the public on the appropriate timing and treatment of this debilitating disease,” Dr. Parsley said.

“It is also clear that gender biases exist and might have a detrimental effect on outcomes,” he said, adding that “an effort should be made to lessen the burden of this disease and allow for improved functional outcomes.”

The authors report no conflicts of interest with this study.

Carolyn Rogers is a staff writer for AAOS Now. She can be reached at rogers@aaos.org