After a knee replacement, patients usually have 10-15 years of use. Clinical statistics show that most patients have an artificial joint that lasts 10-15 years, and some patients are able to make the artificial joint last even longer, up to 20 years, if their muscles are well maintained and they exercise properly. If the patient is less active and the muscles are not exercised well, the life expectancy of the artificial joint will be significantly shorter, even less than 10 years. Knee replacement surgery is primarily indicated for severe osteoarthritis of the knee, as well as traumatic arthritis, where the patient presents with an inversion deformity, valgus deformity, or limited flexion and extension. Joint replacement can restore lower extremity strength, remove joint pain and limited motion. After joint surgery, patients should be rehabilitated to strengthen the muscles of the lower extremities to enhance the stability of the joint and to further extend the life of the patient’s artificial joint.