Artificial joint replacement is a true success achieved by modern medical science. Few technologies have brought such tremendous benefits to patients and society as arthroplasty. However, as with most other surgical procedures, choosing the right indication is critical to achieving a satisfactory outcome. “The concepts of “indications” and “contraindications” actually represent the result of a complex decision-making process that must be carried out by both the physician and the patient. Any medical decision-making process requires careful consideration of the potential risks and benefits of a particular operation, especially in the case of surgery. Both patients and physicians must carefully evaluate the potential outcomes of surgical treatment, and in complex cases, physicians need to use their communication and education skills to inform patients of the risks and benefits of specific surgical procedures so that they can actively participate in the decision-making process. Artificial joint replacement surgery has a time-limited effect, making the elderly the best group to treat. The incidence of osteoarthritis in the elderly population is extremely high, severely affecting their ability to care for themselves and their quality of life. In elderly patients with osteoarthritis and symptoms, joint replacement can be considered for symptomatic relief as long as there are no serious systemic organic pathologies (e.g., severe coronary artery disease, untreated hypertension or diabetes). Except in elderly patients, a 20-30 year life expectancy of the artificial joint should be required. Current artificial joints do not fully meet this requirement. As the implantation time increases, various complications can occur, requiring additional or even multiple revisions or leaving severe disability. Therefore, the indications for arthroplasty should be strictly controlled. Especially in young patients, a cautious approach should be taken. The basic reason for this is that it should be used in cases that are difficult to resolve with other treatments (including surgery). Indications Artificial joint replacement is mainly used for painful joint disease with loss of function that has not been treated surgically or with other surgical treatments. Patients with limited motion without pain, unequal limb length, or radiographs suggesting severe joint damage without significant clinical symptoms are not indications for arthroplasty. 1, joint pain: difficult to control and obviously affect the function of joint pain, is the most important indications for artificial joint replacement. (1) Joint pain due to local injury or disease: secondary osteoarthritis due to various causes is the most common in China, including trauma, dysplasia, uneven joint surface due to soft tissue lesions, abnormal joint alignment, poor limb alignment or joint instability. (2) Primary osteoarthritis: In Europe and the United States, it is the first indication for artificial joint replacement, but in China, it is generally lower than secondary osteoarthritis, but it is still a common indication for hip and knee arthroplasty. (3) Systemic diseases: such as rheumatoid arthritis, lupus erythematosus, etc.. They are often characterized by multiple joint damage, young patients and often severe deformities. Surgery should be performed after the systemic disease is basically under control and should be properly planned in the context of the patient’s condition. Improper scheduling can make the operation and postoperative care difficult. Patients with severe soft tissue contractures and joint deformities often make surgery more difficult. Severe soft tissue contractures and deformities should be corrected first and then the prosthesis should be replaced, except for mild contractures and deformities that can be corrected at the time of prosthesis replacement. If you expect to solve the problem through prosthesis replacement in one phase, it is often difficult to achieve the goal, and will increase the incidence of intraoperative and postoperative complications. Prosthetic replacement of joint and its adjacent bone is an important part of limb preservation therapy for bone tumor, which is often combined with chemotherapy or radiotherapy before and after surgery. The bone and joint are then reconstructed with an artificial prosthesis. Customized prostheses are often used to meet the needs of different cases. 3. Infectious lesions have been listed as a contraindication to surgery in the past. In recent years, there has been an increase in the number of reports of artificial arthroplasty being used in cases where the infection has been controlled, and septic infections have also been treated with antibiotics to remove the lesion, flush it adequately, and then replace it with a prosthesis. There have been many cases of successful one-stage replacement in Europe for patients who have undergone revision surgery due to failed infection, but most authors still advocate surgery more than 1 year after the infection is completely controlled. In Asia, including China, there are already people who have performed one-stage arthroplasty while removing tuberculosis lesions from the bone and joint, and the recent results are good, but the long-term results need to be further observed. Contraindications 1. Local or other sites still have active infection. 2.Poor local skin, soft tissue and blood supply, which may lead to difficulty in closing the incision or soft tissue and skin necrosis in the incision after surgery. 3.Neurogenic arthropathy. 4.Severe osteoporosis. 5. Paralysis of the muscles around the joint, which makes it difficult to maintain the stability of the joint after surgery or to complete the active movement of the joint. 6. Systemic conditions or concomitant diseases that make it difficult to tolerate replacement surgery. 7.Patients with a history of dementia and those with unrealistic expectations.