• Posted March 5, 2026

Testosterone Therapy Could Mean Trouble For Knee Replacement Patients, Study Warns

Testosterone therapy is booming in the U.S., but it might bring higher risks for people undergoing knee replacement surgery, a new study says.

Patients who took testosterone within a year of their surgery had a higher risk of infection, blood clots, kidney damage, pneumonia and knee instability after the procedure, researchers reported this week at a meeting of the American Academy of Orthopaedic Surgeons in New Orleans.

“With more people taking this hormone than ever, and (knee replacement) surgeries expected to exceed 1 million per year by 2030, we wanted to dive deeper into the question of testosterone’s post-surgical effects,” senior researcher Dr. Brian Chalmers said in a news release. He’s an orthopedic surgeon at the Hospital for Special Surgery in New York City.

Testosterone replacement prescriptions have increased from 7.3 million in 2019 to more than 11 million in 2024, researchers said in background notes.

Both men and women take the hormone to aid healthy aging, build muscle and bone, and improve sex drive, researchers said in background notes.

For the new study, researchers tracked more than 13,000 people who received a total knee replacement, directly comparing those on testosterone therapy with those not taking the hormone.

Results showed that within 90 days of surgery, people taking testosterone had higher rates of blood clots in the lungs (1.6% versus 1.2%); pneumonia (3.3% versus 1.9%); kidney injury (4.2% versus 2.9%); and sepsis (1.9% versus 1.1%).

Higher rates of health problems remained one year out from surgery, including blood clots in the lungs (2.6% versus 2%); deep vein thrombosis (4.5% versus 3.3%); cardiac events (3% versus 2.4%); pneumonia (6% versus 4%); kidney injury (7.9% versus 5.2%); and sepsis (2.4% versus 0.9%).

There also was an increased risk of problems with the new joint, results showed. Patients had higher rates of joint infections, bone fractures, implant loosening, knee instability and follow-up knee surgery as far as five years out.

Testosterone has been linked with higher risks for blood clots, but more research is needed to better understand how the hormone might interfere with knee replacement surgery, researchers noted.

“Studies also suggest that testosterone influences the way our bones naturally rebuild themselves over time,” researcher Arsen Omurzakov, a third-year medical student at Weill Cornell Medical College in New York City, said in a news release.

“Testosterone levels may also affect the immune system and the microbiomes that affect the immune system, healing and other key functions in the body,” researcher Argen Omurzakov, a third-year medical student at Case Western Reserve University in Cleveland, added.

The Omurzakovs are twin brothers who have collaborated on new studies throughout their medical training.

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

Harvard Medical School has more on how testosterone affects health.

SOURCE: American Academy of Orthopaedic Surgeons, news release, March 2, 2026