Long-term study shows knee replacements last lifetime for active young adults

A 40-year study by Hospital for Special Surgery (HSS) researchers has found that active young adults who underwent total knee replacement were unlikely to require knee replacement revision in their lifetime, according to a new study shared today in a podium presentation at the American Academy of Orthopaedic Surgeons 2025 Annual Meeting.

As an increasing number of younger adults in their 40s and 50s consider total knee replacement, many wonder how long knee implants last before requiring a revision procedure. The findings from our study-the largest and longest follow-up of patients under 55 undergoing total knee replacement-confirm that young patients can be confident their initial knee implants will allow them to pursue a high level of activity and more than likely last the rest of their lives."

William J. Long, MD, FRCSC, an HSS hip and knee surgeon and the senior author of the study

HSS orthopedic surgeons designed the longitudinal study to track outcomes for patients 55 years of age and younger who had total knee replacements between 1977 and 1992. During that period, they used knee prostheses known as the Insall-Burstein I and Insall-Burstein II-predecessors of implants used today that provide posterior stability. Both designs were conceived and developed at HSS. Previously, the investigators conducted patient follow-ups at 10, 25, and 30 years following surgery.

For this final report, Dr. Long and colleagues analyzed outcomes after 40 years for 81 patients aged 33 to 55 years. The analysis included 107 knees in total. Overall, 70% of patients in the study had no revision procedures in their lifetime. Patients were three to four times more likely to have passed away after 40 years than to have required a revision. Remarkably, among the 49 patients who received the original Insall-Burstein I prostheses, 80% did not have any revision surgeries.

"Considering that today's knee replacements have addressed the pitfalls leading to the majority of revisions for mechanical issues in Insall-Burstein I and Insall-Burstein II implants, these are very reassuring findings," says Dr. Long.

Dr. Long also examined six patients (eight knees) in person, and lead and presenting author Aaron Weinblatt, BA, contacted many more patients by phone. There were no signs of loosening nor were there any changes in symmetry or alignment of the original components. Additionally, patients reported an ongoing improved level of activity after surgery.

This was supported by patient-reported activity data collected for eight patients (10 knees) and measured using the Tegner Activity Scale (TAS). Before undergoing total knee replacement, the average TAS score was only 1.5, indicating they could work in a sedentary job and walk on uneven ground but not hike or backpack. At 40 years, their average TAS score was 2.7, indicating the ability to work in light labor occupations and participate in recreational activities such as swimming and walking in forests.

"Patients requiring a total knee replacement should not delay having surgery," Dr. Long says. "Our study results highlight that those who undergo knee replacement sooner are more likely to maintain a high level of activity that contributes to a healthy, longer-term lifespan."

Dr. Long adds that a previous HSS study published in 2014 at the 30-year follow-up showed that for the small percentage of patients who required revisions, the vast majority were doing well, with an average TAS score of 3.0, a good range of motion and no signs of loosening.