Thank you, Klara. Your article makes a lot of sense. You know what is best for you. I am sorry about knee replacement. However, I pray for success for the outcome of your surgery. Some folks older than you do very well after surgery, rehab, & physical therapy. My friend's Ortho told her to take liquid collagen & curcumin before & after her surgery every day. She is 74 & has been on two travel adventure tours. Her surgery was three years ago. She lives in Arizona Senior living. You look like 55 not 67. Don't stress, you are smart & God will be there for you. Blessings. Stay safe.