All patients who need an artificial knee replacement are concerned with the same question: What material is my artificial knee made of? How long will it last? Do I need to “save it”? This question starts with the material of the artificial knee. Modern artificial knees are made of high-tech cobalt-chromium-molybdenum alloy and ultra-high polymer polyethylene lining. There is an analysis of the life span of artificial prostheses, Harvard University’s Bioengineering Laboratory has done a study: they will simulate the artificial joint mounted on a cadaver in biological solution, under a gravity load of 60 kg to simulate the movement of the human body, in the equivalent of 10 years of movement, the polyethylene liner wear is only 0.2 mm. This means that it would take 100 years to reach a level of wear of 5 mm that would break the liner! Of course, laboratory tests are not the same as real human motion, which is multifaceted and diverse; and no doctor or patient can be as accurate as a tester. When these objective influences are removed, the effective survival of the prosthesis in the real human body is 25-30% of the laboratory results, and even then, the effective life of the prosthesis is 25-30 years! Therefore, the use of artificial joints is like driving a car. Under normal circumstances, if no accidents occur, they can be used for many years, even more than 20 or 30 years without problems. If you drive a car under overload, the car may be scrapped before it reaches the end of its useful life. We have followed up the replacement of domestic artificial joints more than ten years ago, and more than 90% of the patients are still using them. Therefore, artificial joints made with today’s high-tech concepts and materials should theoretically have a life expectancy of at least 20 years if they are properly installed. However, patients with high body weight, high activity levels and osteoporosis are prone to premature wear and loosening of the artificial joint. Of these, osteoporosis is the biggest enemy of artificial joint replacement. I always tell my patients: Artificial joint replacement is like making a house door; the doctor is a very good craftsman and can make a perfect door; the prosthesis is like imported high-grade hinges with a long life span, but if the wood used to make the door rots after a few years, the door will be deformed and the hinges will fall off before they reach their effective life span. Therefore, patients who have received artificial joint replacements must prevent osteoporosis and exercise and maintain them under the constant guidance of their doctors. The lifelong follow-up system for patients who have received artificial knee replacements in the department I preside over: annual reviews to check the condition of the prosthesis, check the status of bone density, and provide targeted guidance and treatment according to the patient’s condition.