For the study, researchers assessed 1,757 primary cruciate (ligament behind the knee)-retaining TKRs performed between 1975 and 1989 at the Center for Hip and Knee Surgery.
Researchers evaluated 128 patients who were living at the 20 year follow-up.
The study found that 95 patients could walk at least five blocks, 48% of the patients reported unlimited walking, and there were no implant failures after 20 years.
Study author John Meding said that the research refutes any perception that the importance of a well-functioning TKR diminishes over time because of an overall declining functional status.