V. Post-transplantation and femoral head necrosis 1. Post-implantation of severed limbs (fingers): At present, the technology of limb replantation is becoming more and more mature, including bone scaffold reconstruction, blood circulation reconstruction, vascular anastomosis, nerve repair and so on. Experimental research and clinical observation show that hyperbaric oxygen can improve the oxygen supply to the amputated limb, promote vascular proliferation, reduce thrombosis and prevent postoperative infection, which can increase the success rate of amputated limb replantation by 30%. 2, skin graft (ischemic): hyperbaric oxygen is an important treatment method to improve the survival rate of skin flap after surgery, which can accelerate capillary proliferation, promote the formation of collateral circulation, improve the blood supply of skin flap graft area, prevent infection, and make the wound surface fresh and alive. Our department has already verified in animal experiments and clinical practice that hyperbaric oxygen can significantly increase the viable flap area up to 50%. 3. Ischemic femoral head necrosis: The incidence of femoral head necrosis has gradually increased in recent years, and the long-term use of large doses of hormones is an important reason, and some patients have unclear etiology. Hyperbaric oxygen therapy can improve microcirculation ischemia, unblock the microvessels near the hip joint, increase the collateral circulation and improve the nutrition of the femoral head, so that the necrotic bone is gradually absorbed, or the osteoblasts proliferate and promote the formation of new bone. In our clinic (including the SARS period), we have adopted the method of hyperbaric oxygen therapy combined with drug therapy to improve the cure rate and improvement rate of ischemic femoral head necrosis, especially for the stage I and II femoral head necrosis, the effect of hyperbaric oxygen therapy is good.