My close friend and bicycle riding partner since 1968 had a knee replacement in 2008. He was a serious bike rider (road and mountain) and a very serious and high level practitioner of Yoga. He was in great shape before the knee surgery. Ex ski racer and runner - very bad osteoarthritis.
He had NO choice about the TKR - his worst knee developed Calcium Pyrophosphate Deposition (CPPD) (pseudo gout) which leads to to severe, painful attacks or chronic (long-term) pain and inflammation. Over time, joints may degenerate, or break down, resulting in chronic disability. Medical treatments were of no benefit and he was unable to walk or sleep, even after taking heavy narcotic pain medication.
His TKR solved the CPPD problem but adhesion's (scar tissue build up) have severely limited his ability to bicycle or hike after a full recovery from the surgery. He has had two followup surgeries to remove the adhesion's but still can not pedal with clipless pedals. No person could have possibly worked harder than he did to facilitate his recovery but it just didn't happen.
He does not regret the surgery, he really had not choice, but is very disappointed that his bicycle riding and yoga work is now so limited.
My father was also very active on the bike and hiking trails, at age 75, when he had both knees replaced and was still hiking and riding just before his death at 87. He was very pleased with the long term results and you could hardly tell his knees were not natural.