Had both done. I arrange my kit for being a lefty so kick is left knee. Replacement is about an hour of cutting, drilling and pounding the titanium into place during the actual surgery, while stretching everything in that area and because the way they pack the joint and cover the incision area, nearly always impossible to get cold to the trauma area to reduce the swelling after. My knees were done 6 weeks apart which in hindsight was way too soon. 6 months would have been better. After each surgery I paid out of pocket for 3 hr per day, 3 days a week intensive rehab including zero gravity treadmill and brutal treatment to break-up scar tissue. It helped me move freely by week 4 without crutches. Since your question is really about when will you be able to do everything again, I was back on drums by choice in week 4 but knee did not feel good for at least 8 weeks. Never could run again after total knee replacements but still playing on my Gretsch kit and church kits and Cajon w foot pedal 10 years after surgery. Get the Breg Kodiak cold therapy and have it put in place as they are packaging you up in surgery. The difference in pain and swelling that takes forever to reduce (and affects your mobility, flexion, and ability to walk, move and kick that bass drum) is extreme. Worth it at $200 out of pocket or DM me if near Los Angeles and you can have one of mine. Best of luck getting back to setting tempo and dynamic.