Minimally invasive pain-free knee replacement technology Knee replacement has been criticized by patients for long postoperative pain recovery period. In surgical elective surgery, 75.5% of patients are concerned about postoperative pain, 92% of patients urgently need postoperative analgesia, 80% of patients report inadequate analgesia, and more than 50% of patients still have pain 72 hours after surgery. The ideal analgesic method is the combined application of multi-modality, multiple stages (preoperative, intraoperative, postoperative), multiple routes (peripheral local, spinal level, supraspinal level), multiple drugs (opioids, non-steroidal anti-inflammatory drugs, local anesthetics, etc.), and multiple modalities to meet the original intention of analgesia and to achieve both perfect analgesia and minimize its adverse effects. Causes of pain 1. excessive stretching of the surgical incision, excessive release of soft tissues 2. prolonged tourniquet, swelling of the limb 3. mismatch of prosthesis placement, irritation of soft tissues 4. hematoma irritation 5. rehabilitation exercises: in terms of surgical incision, QS technique is used to significantly reduce bleeding, swelling and pain. Reduction of quadriceps injury Protection of the knee extension device, which facilitates early landing. Achieve the purpose of early down to the ground and early rehabilitation. 2 days later down to the ground, 7 days later without walker, one week later easy walking, 2 weeks later start to walk freely, can train up and down stairs. Perfect hemostatic measures The open tourniquet after the installation of the arthroplasty helps to identify the bleeding points and allows for complete soft tissue hemostasis, the bone surface is closed with bone wax, and the postoperative joint cavity trauma is sprayed with hemostatic powder. The absence of obvious bleeding points can be confirmed intraoperatively. Intra-articular cocktail application Cocktail is prepared intraoperatively; Ropivacaine 180mg, Keflex 25mg, Epinephrine 0.25mg, Morphine 3-5mg, Betamethasone 1mg, Gentamicin 160,000 units; finally, saline is added and mixed to 100ml. The method of use is critical. In the early stage, the self-control pump was used, which conflicted with the drainage tube. It led to drug loss; later it was changed to soft tissue injection. It was found that posterior joint capsule injection tended to cause ankle joint swelling. Subcutaneous injection caused poor wound healing. Changed to suprapatellar capsule as primary and medial and lateral as secondary. Remaining intra-articular infiltration. The drainage tube was developed after 12h. Effectiveness was significantly improved. The agent can sustain analgesia for 1-2 weeks, with some patients rebounding in pain at one week and some at 2 weeks. So it has to be covered by oral anti-inflammatory and analgesic drugs. Some patients still have pain after one month. Continuation of the drug can be considered.