(Reuters Health) - Patients having knee replacement surgery sometimes hope to regain or improve their sexual activity afterward, but that doesn’t always happen, a new study finds.

A year after surgery, about 40% of patients said their expectations of sexual activity weren’t met, researchers report in Clinical Orthopaedics and Related Research.

“Patients generally have high expectations towards the results of a prosthesis and expect to remain active despite their age, which also includes sexual activity,” said study leader Rita Harmsen of Leiden University Medical Center in the Netherlands.

“Sexual activity is important to quality of life for men and women alike, however, sexual issues are not easily discussed -- not in daily life, not in the consultation room, not by specialists, not by patients,” she told Reuters Health by email. “After surgery, effective instructions (about how to safely resume) are missing, and surgeons are not aware of hidden questions.”

Harmsen and colleagues analyzed data for more than 800 patients scheduled for total knee replacement in 2012-2015 at seven hospitals in The Netherlands. Patients ranked their preoperative expectations and postoperative fulfillment on a 5-point scale.

Before the knee replacement surgery, about half of patients expected better sexual activity after recovery. Men were more likely to have expectations for postoperative sexual activity, particularly men under age 60. About 46% of men expected “back to normal” sexual activity, compared with 32% of women. For both genders, anticipation decreased with age.

Overall, about 58% reported fulfillment of their expectations after surgery, which was nearly equal for men and women. Fulfilment was slightly lower in higher age groups for both genders. Women under age 65 experienced fulfillment more often than men of the same age.

Importantly, those in better health before surgery were more likely to report better sexual activity after surgery. And patients who experienced greater health improvements after surgery reported fulfilled or exceeded sexual expectations as well.

“At the same time, about 40%, or two out of five patients, experienced unfilled expectations,” Harmsen said. “These results can be very disappointing.”

A limitation of the study is that preoperative expectations and postoperative fulfillment were each measured with just one survey question, the study authors wrote. Future studies should interview patients and their partners to understand what the expectations were and why they’re unfulfilled after surgery, Harmsen said. Difficulties may be related to age, insufficient rehabilitation, or the mobility of the knee after surgery, which can limit certain sexual positions. Patients may need education about comfortable and safe sexual positions after knee replacement, she added.

“As surgeons, we do not address this aspect often enough, and it’s important to set realistic expectations after surgery,” said Dr. Antonia Chen of Brigham and Women’s Hospital in Boston, Massachusetts. Chen, who wasn’t involved with this study, is the director of research for arthroplasty services.

In addition, longer studies may show whether it takes more than a year after surgery for patients to return to normal sexual activity levels or meet their expectations, she said.

“Patients who undergo total knee replacements have overall improved physical function after surgery,” she told Reuters Health by email. “However, it is worthwhile to have a discussion prior to surgery with your surgeon about sexual activity expectations so that you can better understand the likelihood of having your expectations met or potentially tempering expectations after surgery.”

SOURCE: bit.ly/2qrBwqI Clinical Orthopaedics and Related Research, online November 1, 2019.