Thank you for your question regarding when you should undergo knee replacement after your arm lift surgery. I would allow you at least 4 to 6 weeks to heal from your arm lift surgery. During that time, your body will need to replace some of the blood loss during the arm lift procedure. Though there won't be much blood loss, your body will need some time to recoup from the surgery. Before your knee surgery, you will have to have your blood tested again. Also, about six weeks allows your arms to heal enough to rely on your upper arm strength and body to assist your legs with their recovery. Of course, this is advice from an experience board-certified plastic surgeon. It would help if you were asking your orthopedic surgeon what they suggest. Good Luck. I hope this helps to answer your question regarding when you can have knee surgery after your arm lift surgery. Sincerely, Dr. Katzen. (“Verified” Plastic Surgeon, President of the American Society of Bariatric Plastic Surgeons, certified by the American Board of Plastic Surgery, Fellow of the International Society of Aesthetic Plastic Surgery, American College of Surgery, and International College of Surgery, and member of the American Society of Plastic Surgery, American Academy of Cosmetic Surgery and RealSelf Hall of Fame.)