Severe knee flexion contractures are commonly seen in patients with degenerative osteoarthritis, rheumatoid arthritis, or traumatic arthritis due to trauma, and most of these patients require artificial knee replacement surgery. In order to obtain a stable knee with good range of motion and straightness, the patient must be carefully evaluated for soft tissue condition before surgery, and a proper soft tissue balance must be performed in a certain order step by step during surgery to select a suitable prosthesis. At the same time, good targeted postoperative rehabilitation and attention to perioperative patient management are the keys to reducing complications and obtaining satisfactory results.