In the past, severe osteoarthritis eventually led to joint disability, while the current artificial joint surgery can enable patients to relieve joint pain and restore joint movement. In advanced stages of osteoarthritis, severe degeneration of joint cartilage, joint deformity, and restricted movement seriously affect the patient’s daily life; joint replacement can be used for those who do not respond well to general treatment. Joint replacement improves the quality of life for elderly patients while extending their lives, while for younger patients joint replacement enables them to actively participate in social life and work, and the age range of artificial joints (total hip and total knee replacement) has been widened compared to the past. Frailty is a characteristic of older patients, and many people are concerned that it will affect the outcome of the surgery, but numerous clinical results have confirmed that it does not affect the outcome; moreover, the greater the functional limitation, the better the postoperative improvement. Patients who undergo artificial joint surgery usually have severe x-ray damage to the diseased joint that is ineffective with non-surgical treatment. Artificial joint surgery has an excellent outcome for both pain and disability, and most patients have a good prognosis for long-term improvement in symptoms and physical function. Surgery is significantly more effective than fusion or osteotomy, and the cost is very worthwhile and effective compared to most other treatments for chronic disease. Early complications of arthroplasty, such as infection and deep vein embolism, are low, and joint dislocation has decreased from about 7% in the past to about 3%.