Men have a higher level of function before and after total knee replacement surgery

According to the Agency for Healthcare Research and Quality, more than 600,000 knee replacements are performed in the U.S. each year. In 2012, 393,345 women and 237,896 men underwent TKR, most often to alleviate the pain and immobility associated with late-stage arthritis. While research has looked at the anatomic differences between the knees of men and women, the higher levels of arthritis in women versus men, and the utilization of TKR among men and women, there has been little study on how gender influences the level of function before and after surgery.

In this study, researchers identified and studied 287 TKR patients at seven different institutions between 2005 and 2007. All of the patients were between the ages of 21 and 80 at the time of surgery and a body mass index <40 g/m². All of the patients except two had a diagnosis of end-stage arthritis. The patient group included 108 men (112 knees) with a mean age of 67, and 170 women with a mean age of 66. All of the patients were evaluated preoperatively and at the following six points following surgery: six weeks, three months, one year, two years, five years and seven years. A Kaplan-Meier assessment gauged implant survival, and quality of life measurements were taken at three and four years post-surgery. During each evaluation, researchers measured knee function, range of motion, extremity activity and overall health.

At five years post-surgery, implant survival was 100 percent for men and 99.1 percent for women. Range of motion also was nearly identical between genders. Functional scores were consistently higher for the men versus women: preoperatively, 57.1 versus 51; postoperatively at six weeks, 63.7 versus 51.5; at three months, 83.1 versus 74.3; at two years, 90 vs. 81.6; at five years, 90.1 vs. 82.9; and at seven years, 96 vs. 79.5. Men also recovered faster within the six week recovery time after surgery; however, both genders had almost identical improvement in mean knee score function (improvement from presurgical levels) at five years.

"Our data supports that while both genders benefit from TKR, men have higher levels of function and activity both prior to and after TKR compared to women," said lead study authors Jeffrey J. Cherian, DO and Michael A. Mont, MD. "These functional outcome differences are most likely due to many factors (including biologic/genetic) and highlight the need for further research related to the role of gender of both the patient and the surgeon in the decision making process of TKR, sex-based biological differences in functional recovery capacity, and whether sex/gender based pre- and postoperative rehabilitation protocols are warranted."