I had to abandon the Zwift during recovery from the TKR because it was just too competitive for me ... I was always trying to keep up and that resulted in overdoing it multiple times with setbacks in recovery. You may have more restraint than me with Zwift, but it is worth being cautious and pacing according to how your knee is progressing rather than the fellow ahead of you on the Zwift route. Anyway, I am sure you will do fine.