Osteonecrosis of the femoral head (ONFH) is divided into two categories: traumatic and non-traumatic, the latter mainly caused by long-term heavy application of corticosteroids, alcohol abuse and abnormal blood function. The disease has a high disability rate and is a serious threat to human health, and has become a hot spot of global public concern. Li Zirong reported that new cases of ONFH in China range from 150,000 to 200,000 per year, and the cumulative cases requiring treatment range from 5 to 7.5 million. The ministries of health in Japan and the United States have classified this disease as an unsolved intractable disease and invested heavily in research, but there are still many challenges to be solved. At present, the treatment of ONFH is still a major problem in orthopedics. Only the correct grasp of treatment principles, for each stage using the appropriate method, in order to obtain the best results. Patients with osteonecrosis are mostly young, so the preservation of their own femoral head should be considered first. At present, early cases take conservative treatment, such as: Chinese medicine to activate blood circulation and remove blood stasis, lipid-lowering drugs, hyperbaric oxygen, blood purification, intervention, magnetic therapy, etc. 1.Large body surgical treatment: According to the international osteonecrosis staging standard of the World Society for Research in Osteocirculation (ARCO), for those with stage 0~II-A, borehole decompression is feasible. for those with stage II-B~III-B, osteotomy or bone grafting, including bone grafting with vascular tips, is applicable. For stage III-C and above, artificial hip arthroplasty can be considered. Many factors can affect the outcome and prognosis of surgery. The extent of the lesion plays a decisive role in the prognosis, and the greater the extent, the worse the prognosis. The prognosis is worse for central and lateral lesions than for medial lesions. Patients with systemic diseases, such as systemic lupus erythematosus and organ transplantation, have a poor prognosis and should be considered for artificial hip replacement. However, the long-term outcome of either cemented or uncemented hip arthroplasty for ONFH is poorer than that for other diseases. Artificial hip arthroplasty is suitable for: (1) elderly patients; (2) bilateral lesions reaching international osteonecrosis stage III-C or above; (3) severe pain affecting joint function. 2.Minimally invasive technology for P:The concept of Minimally InvasiveTechnique was introduced in recent times. Minimally invasive means a small invasion or injury to the living body (mainly refers to human). Minimally invasive surgery technique refers to the surgery performed by arthroscopy, intervertebral discoscopy, laparoscopy, thoracoscopy, etc., and the surgery performed by small incision and micro-injury. It is also customarily called “minimally invasive surgery”, i.e., minimally invasive surgery. The connotation of “minimally invasive surgery” should include two aspects: first, small incisions, and second, minimal surgical damage, especially the latter. Small incisions have the advantage of being aesthetically pleasing. However, if the incision is small and the internal damage is large, it cannot be called “minimally invasive surgery”. So, now the minimally invasive surgery used to treat ONFH basically includes at least 3 aspects: ① high-tech means, innovative efficacy: through small incisions to apply gene therapy, tissue engineering, etc. for the prevention and treatment of ONFH. ②Small surgery: the original has been carried out small incision surgery, such as: drilling decompression, etc. (③Major surgery developed into minimally invasive surgery: such as simple removal of necrotic bone plus bone grafting under arthroscopy, minimally invasive artificial hip joint replacement, etc. (1) Gene therapy: attention has been paid to the use of bone marrow stem cells for gene therapy and tissue engineering. the pathogenesis of ONFH is associated with a variety of genes, and there have been some animal experiments and clinical studies of gene therapy to compensate for positive cytokines and their receptors to treat ONFH. e.g., Zhang Ye, Zeng Bingfang et al. (2004) reported that transfection of pCDNA3-Ang-1 plasmid with liposome-mediated In vitro isolated and cultured rabbits (bonemesenchymalstemcells, BMSCs), complexed with tricalcium phosphate (TCP) ceramics, repaired rabbit liquid nitrogen frozen femoral head necrosis. Yang Cao, Yang Shuhua, Du Jingyuan et al. (2004) reported that basic fibroblast growth factor (bFGF) eukaryotic expression plasmid pCD rbFGF was mixed with collagen or vascular endothelial growth factor eukaryotic expression plasmid pCDhVEGF165 200 μg was mixed with collagen and implanted into the necrotic rabbit femoral head, respectively. New bone was formed in the femoral head 8 weeks after surgery, which promoted the repair of femoral head necrosis. All of these can be accomplished by applying minimally invasive techniques. (2) Tissue engineering: Li Zirong (2004) reported that for stage II and early stage III femoral head necrosis with necrosis volume greater than 15%, a minimally invasive technique (i.e., incision of 5-7 cm) was used to remove the necrotic bone under navigation guidance, and the own bone marrow (250-300 ml) was separated from the stem cells using a cell separator, and then, together with osteogenic material (artificial bone) as a carrier, was punched into the necrotic bone This method is used to preserve the joint by removing the bone marrow (250-300ml), separating the stem cells with a cell separator, and then inserting the bone material (artificial bone) as a carrier into the necrotic bone removal area to allow new blood vessels and bone to grow in. This method has an excellent rate of 85% (stage II) and 50% (stage III), thus enabling some patients to postpone or avoid artificial joint replacement. For femoral head necrosis between early and mid-stage, a new bone grafting material compounded with bone growth factor and autologous bone marrow stem cells is implanted into the osteonecrosis area by open surgery. It can stimulate new bone formation and increase the mechanical support to the subchondral bone, effectively preventing further collapse of the femoral head. The trauma is slight, the incision is only 3~5cm, and it does not damage the blood circulation of the joint capsule, and the joint movement function is good. It is of great value in the treatment of early femoral head necrosis in young patients. (3) Drilling decompression: Drilling decompression is also called core decompression, core decompression and medullary core decompression. It is effective in only 60% of cases. (4) Bone grafting: Through a small incision on the lateral aspect of the greater trochanter, a channel is drilled to reach under the cartilage of the femoral head and implant free fibula, or a compression implant (autogenous cancellous bone) is placed. Osteotomies in combination with arthroscopy have also been reported. However, the clinical results of these bone grafting methods (not with blood transported bone) remain to be further observed. (5) Small-incision, minimally invasive total hip arthroplasty has been performed in many hip centers in the United States through small incisions. The reason for the increasing popularity of this procedure is that it is expected to become more popular due to the significant improvement in the patient’s joint function. Patients are able to regain function and comfort sooner and better. At 6 weeks postoperatively, few people are using an assistive device. At 10 weeks postoperatively, the patient’s single limb status has returned to 90% of normal. This is attributed to the small surgical incision and very minimal damage to the periarticular muscles, allowing for a rapid recovery of muscle strength and joint function postoperatively. Most physicians prefer a single posterior lateral incision (Sculco, 2001; Dorr, 2002; Hartzband, 2002). Most physicians in this country are also happy to use a single postero-lateral incision. The posterolateral single incision must be located at the posterior edge of the greater trochanter. The muscles incised through this incision are mainly the gluteus maximus, and the short external rotators are released from the posterior aspect of the hip at the femoral attachment, without separating the gluteus medius and superior gluteus maximus muscle fibers passing through the area of the nerve. The small incision does not significantly increase the difficulty of the procedure, and it usually takes only one hour to complete the procedure from skin incision to wound closure. A special set of retractors and grinding drills are necessary. The indications for minimally invasive surgery should be strictly selected: the patient should be moderately fat and thin, the acetabular cup should be non-cemented, and the femoral prosthesis can be non-cemented or cemented. The following cases are not suitable for this surgery: obesity, especially developed muscles, ankylosing spondylitis involving the hip joint, acetabular dysplasia, hip dislocation requiring special treatment of the acetabulum, soft tissue release, advanced femoral head necrosis with huge bone redundancy in the acetabulum or inside the femoral head, etc. It is difficult to perform this surgery. The surgeon should have rich experience in total hip arthroplasty, otherwise it is easy to damage important nerves and blood vessels, and the placement of the prosthesis may also be problematic. In addition, it is worth mentioning the surgical navigation system, which can greatly reduce the trauma of surgery by decompression and removal of necrotic bone under the guidance of minimally invasive surgical navigation system. The surgical navigation system can be used in minimally invasive surgery for artificial hip replacement to significantly improve the accuracy of prosthesis placement. The error of placing the acetabular cup can be within 1º, and the abduction angle can be accurately maintained at 45º and the anterior tilt angle at 20º, thus avoiding the poor prosthesis position due to the small visual field of the minimally invasive surgery.