There has been a significant increase in the number of knee revision cases in recent years, and one of the most important reasons for this is the dramatic increase in the number of primary total knee replacements. Another factor is that the number of patients undergoing knee replacement is getting younger and younger, and patients are gradually accepting TKA as a surgical procedure to meet their high activity level. There is another factor that cannot be ignored – weight, which is particularly evident in Western countries. KurtzS and others have predicted that the increase in the number of knee revision surgeries in the United States will be substantially greater than the number of primary total knee replacements/primary total hip replacements/hip revision surgeries. The large number of knee revision cases is a challenge to the surgeon’s surgical skills and a huge impact on the socio-economic structure of each country. To analyze the causes of knee revision, we must first distinguish between the concepts of early and late revision. Early knee revisions are those that occur within 2 years of the patient’s initial knee arthroplasty. Patients with early knee revisions usually complain of pain, swelling of the periarticular skin, joint instability, and limited joint motion. Early knee revision is generally related to surgical technique, while late revision is mostly related to the prosthesis itself.MayleJrRE, MortazaviSM and other scholars made a more detailed analysis, they found that the first cause of early knee revision is infection, and the other causes include poor alignment of the prosthesis, joint instability, or problems with the patellofemoral joint. The causes of late knee revision include factors such as aseptic loosening of the prosthesis, joint instability and infection. The causes of knee revision can be summarized in a limited number of ways, but they manifest differently in different patients. In the case of knee instability, for example, a patient may have instability of extension alone, instability of flexion alone, or instability of extension and flexion at the same time. Factors contributing to knee instability in turn include many aspects, such as insufficient posterior lateral Offset, knee line elevation, or ligament injury. In summary, identifying the cause of the revision is the first step to a successful knee revision. With the wide variety of causes of knee revision, it is especially important to clarify the preoperative diagnosis and develop a revision plan. The operator should focus on the individual patient’s condition and complaints. The operator can ask questions about pain and joint stability as entry points, and collect the patient’s key complaints, focusing on the reasons for the patient’s initial total knee replacement, lower extremity strength, joint stability, and the surgical approach and type of prosthesis used for the initial total knee replacement. After the history has been collected, the surgeon needs to do a thorough clinical examination. It is important to determine the condition of the knee collateral ligaments; are they stable or unstable? If unstable, is it full extension knee instability/moderate flexion knee instability/full flexion knee instability? The operator also checks the active and passive mobility of the patient’s knee to determine the function of the patient’s knee extension device. The presence of scar tissue around the knee, the extent of scar tissue coverage and local skin conditions are also important in the selection of revision surgery. Next, the operator evaluates the patient’s weight-bearing radiographs, including full-length orthopantomograms of the lower extremity and axial patellofemoral radiographs, which allow the operator to determine the position of the prosthesis, the presence of loosening, and the presence of osteolysis. For a very small number of patients, we also need to do a CT scan or other auxiliary tests. Before proceeding with formal revision surgery, the operator must identify the cause of prosthesis implant failure. The surgeon obtains a conclusive diagnosis based on the patient’s history, clinical examination, and analysis of x-rays. The surgeon also considers the surgical approach, the expected extent of the surgical incision, and prosthetic factors (the need for preparation of wedge-shaped pads, restrictive prostheses, long-stemmed prostheses, etc.). Prior to revision, the surgeon also asks two questions: 1. “Will the patient’s knee function be improved by revision?” 2, “How high are the patient’s expectations of the procedure and what state will the patient achieve postoperatively to be satisfied?” . The surgeon must consider all the questions thoroughly and formulate a clear plan for the revision before proceeding with the knee revision.