The human body is like a machine, which gradually wears out or fails with the extension of time, and new parts can be replaced to make the machine work again. The human body is also subject to ageing due to the passage of time, damage due to accidents, and failure due to disease. The replacement of “malfunctioning” parts in the human body with new ones has long been a reality. Some people ask, if the joints of the limbs are damaged, can they also be replaced with new ones? The answer is yes, artificial joints can be inserted into the body to replace joints that have suffered damage and failed. However, the human body is not an ordinary “machine”, the human body has a complex and sophisticated structure, even the best artificial joints can not achieve the structure and function of normal human joints, therefore, when artificial joint replacement, it is necessary to clearly understand when joint replacement is needed? What are the advantages and disadvantages of joint replacement? Is artificial joint surgery complicated and dangerous? What are the possible complications? What do I need to be aware of before and after surgery? As early as 100 years ago, mankind already had the idea of replacing broken joints with artificial joints, but due to the limitations of technology and materials at that time, the progress of artificial joint technology was slow. After the 1940s and 1950s, with the development of science, especially the progress of material science and biomechanics, the research and practical application of artificial joints gradually matured. At present, artificial joint replacement surgery is quite common in developed countries such as Europe and the United States, and there are hundreds of thousands of joint replacement surgeries in the United States every year. In China, artificial joint surgery was carried out in the 1970s, but it was only after foreign artificial joint companies entered the domestic market in the early 1990s that artificial joint surgery gradually took shape on a certain scale. The emergence and continuous development of artificial joints has made the idea of replacing bad joints a reality for the previous generations. Currently, all major joints of the extremities can be replaced with artificial joints, but the most widely used are the hip and knee joints. Most commonly used artificial joint designs are metal alloys or ceramics mated with UHMWPE prostheses and are available in a variety of types, designs, interfaces, and sizes. In the case of artificial hip joints, the connection between the implanted joint prosthesis and the human bone is either biologically fixed or fixed with an adhesive called “bone cement”, the surface of the stem is microporous or covered with a hydroxyapatite coating to facilitate the connection between the prosthesis and the bone, or the head is designed with ceramic to improve wear resistance. In general, new designs and the development and use of new materials are still ongoing. Who needs a joint replacement? In summary, joint replacement can be considered when the joint structure has been destroyed and lost function due to trauma, non-suppurative inflammation, ischemic necrosis, tumors and other pathologies, and other treatments are ineffective or inappropriate. Of course, in specific cases, some relevant factors need to be considered, such as the nature and severity of the lesion, age, physical condition, past medical history, etc. Take the most commonly used hip joint replacement as an example, the cases suitable for hip joint replacement are ① elderly patients with obvious displaced femoral neck fracture; ② ischemic necrosis of the femoral head caused by various reasons, and the hip joint has been destroyed, with obvious clinical pain and functional impairment; ③ serious osteoarthritis caused by various reasons, with serious pain and functional impairment; ④ rheumatoid arthritis and ankylosing spondylitis, with joint pain (4) rheumatoid arthritis and ankylosing spondylitis, with joint pain, deformity, and restricted activities. (5) Dislocation or subluxation of the hip joint caused by various reasons, secondary to osteoarthritis; (6) Osteoarthritis and subluxation or dislocation caused by hip dysplasia; (7) Damage to the hip joint caused by other reasons. After the artificial hip replacement, the patient can recover normal or near-normal standing and walking functions, with pain relief and obvious improvement in quality of life. Recently, a 93-year-old man fell and sustained a fracture of the femoral neck. After the injury, the old man was in pain, did not want to eat or drink, was depressed and was not used to being in bed all day. After the surgery, the old man was able to sit up and walk with the help of crutches in one week. The old man’s mental, dietary and physical strength quickly returned to the state before the fracture. Numerous examples have shown the good efficacy of hip replacement, which can also correct shortening deformities and improve walking gait, allowing elderly patients to avoid long-term bed rest and various complications caused by bed rest. Surface replacement of the knee joint is mainly aimed at elderly patients with severe osteoarthritis of the knee joint and young adults with rheumatoid arthritis, who often have knee deformity, severe pain, difficulty walking or even inability to walk. This procedure removes the deteriorated surface cartilage from the joint and replaces it with a joint prosthesis made of metal alloys and polymer materials, while correcting the joint deformity and restoring normal lower extremity force lines, without removing much bone, but rather preserving as much bone as possible. Therefore, the analogy of surface knee replacement to dentures is somewhat valid, as the surface is replaced, while the foundation of the joint is preserved. After surgery, the patient is able to recover from pain and resume walking soon after rehabilitation and training. Artificial joint replacement surgery has been developed and refined over the last few decades and has become a mature procedure, bringing hope to patients suffering from joint disease. However, there is a risk of complications associated with joint replacement surgery, including wear and tear, loosening, dislocation, infection, deep vein thrombosis, and complications related to the heart, lungs, liver, and kidneys. Many of those who undergo surgery are elderly patients who may themselves have a history of hypertension, coronary heart disease, diabetes, etc., and any surgery is a risk for them. Therefore, a thorough examination and evaluation before surgery and adequate preparation are essential. Close postoperative observation, proper rehabilitation and reasonable functional exercises are important aspects to ensure the success of surgery. Correctly performing the surgery and installing the artificial joint is the key to reducing the complications of the artificial joint and maintaining long-term good results. Artificial joint replacement surgery is a technically demanding task that requires skilled and superior surgical techniques, as well as the ability and experience to correctly select surgical indications and to properly perform preoperative and postoperative management. Therefore, it is advisable to have artificial joint replacement surgery performed in a hospital with a competent joint surgery department and with experienced and skilled surgeons.