Severe tissue injuries of the lower leg are often accompanied by tibial fractures and soft tissue defects, and improper treatment can cause necrotic defects and infection of the tibia, severe tibial bone outgrowth and infection with long and difficult treatment cycles, or even eventually have to be treated by amputation, and it has been considered a major problem in traumatic orthopedics [1]. In fact, in most of the cases referred to microsurgery, there are often already varying degrees of tissue infection, and it is a challenge to repair the tissue defect while avoiding further infection and necrosis of the tissue. To solve this problem, from July 2007 to October 2010, the author applied the partial open tissue flap transplantation method to treat 55 cases of open tibial osteonecrosis bone infection and achieved satisfactory results, which are summarized as follows. I. Clinical data 1, general data 55 cases in this group, including 36 male cases and 19 female cases. Age 19-56 years old, average 39 years old; tissue defect site: 13 cases of upper tibia, 41 cases of middle and lower tibia, and 1 case of full-length tibia. Traumatic features: 5 cases of simple bone exposure necrosis, 50 cases of open bone infection bone defects, different degrees of blackened necrosis of exposed bone, different degrees of inflammatory secretions in the trauma, and the presence of submerged necrotic tissue cavities, the boundaries of necrotic tissue were not easy to determine [Figure 2]; the length of bone exposure was up to 25 cm and the shortest 7 cm. treatment plan: 2 cases applied local tipped island flap, 25 cases applied anastomosis The treatment plan: 2 cases of localized tipped island flap, 25 cases of free tissue flap with anastomosis, 49 cases of free anterolateral femoral (muscle) flap, 5 cases of iliac flap and 1 case of fibula flap combined with anterolateral femoral (muscle) flap. 2, surgical methods (1) Preoperative preparation: preparation of the trauma surface: potential cavity open and without limited abscess, good growth of fresh granulation on the trauma surface, and no pus outflow during daily cleaning and dressing change. Preparation of vessels in the affected area: Combine with clinical data to initially determine the vascular condition of the affected area, paying particular attention to venous conditions. If necessary, the vascular condition of the lower leg trunk should be clarified by ultrasound Doppler, MRA or angiography, and the ipsilateral or bridging graft, end-to-end anastomosis or end-to-side anastomosis or vascular bridging anastomosis should be selected according to the vascular condition of the lower leg. In other cases, tissue flaps were selected according to the recipient area. (2) Surgical method: flap design requirements: the size of the bone flap should be comparable to the extent of the defective bone, and the area of the flap should be such that it completely covers the major structures in the trauma such as bone, tendon, blood vessels and nerves, but it is not necessary to completely cover the entire trauma. If the arterial caliber is thick, the end-lateral anastomosis is preferred. If the accompanying veins are small and the donor veins are large, the thick superficial veins should be dissected for backup. For bone flap grafting, the broken end of the recipient bone should be cleared to fresh bone, repeatedly rinsed, tissue flap grafting: routinely cut each tissue flap according to the design, retaining sufficient length of vascular tip, transplanting the tissue flap in the recipient area, and fixing the bone block with a kerfing needle; the flap covers the main trauma, including bone, tendon, vascular nerve, etc., suturing most of the flap, not suturing the part near the deep trauma or more necrotic tissue, retaining 1~2 The flap was not sutured in the part near the deep trauma or with more necrotic tissues, and an open window of 1~2 places was reserved. 3.Results All the tissue flaps were viable, and the survival rate reached 100%. One case of deep tissue infection occurred, which healed after debridement and opening of the wound. The residual trauma was closed at 3-6 weeks after surgery. One case of osteonecrosis of the long tibial segment was completely healed after a second debridement of the necrotic tissue at 6 months postoperatively. Twenty-two cases were followed up for 6 months to 1 year after surgery, with satisfactory long-term follow-up results and complete healing of the wounds. The donor area recovered satisfactorily, leaving a linear scar. The advantages and disadvantages of partial open tissue flap grafting and surgical indications Tibial fractures are prone to osteonecrosis and defects, especially when accompanied by bone infection, and treatment is more difficult. However, in clinical practice, the author found that the calf wound is not a single cavity, and because the tissue flap does not completely fill the cavity, the tissue flap covering the wound will artificially divide the wound into several relatively independent cavities, affecting the effect of flushing and drainage, which may also be one of the reasons for recurrent infections. In addition, the use of continuous irrigation and drainage requires the patient to be bedridden, which some patients may not be able to adhere to. Severe tissue trauma often involves both anterior and posterior soft tissues of the lower leg, leaving a large area of trauma, which requires a large area of tissue flap to be cut and is highly traumatic. The author’s use of partial open tissue flap grafting can solve these disadvantages. The so-called partial open free graft refers to the tissue flap covering the main area of the trauma, other areas or parts of the area without tissue coverage, and the trauma cavity is connected to the outside world with a certain range of open areas. The disadvantage is that the requirement for postoperative wound cleaning and dressing changes is high, and improper treatment may lead to limited infection or even osteomyelitis formation. It is also important to master the indications for surgery. Generally speaking, inflammatory trauma with fresh granulation growth, fresh trauma with deep tissue necrosis, subterranean cavity prone to limited infection, bone exposure and/or bone defect with varying degrees of bone necrosis, and exposed internal fixation without endograft removal are all suitable for partial open tissue flap repair. Especially for those with bone exposure, timely tissue coverage is of great value to the patient’s psychology, bone repair and nutrition. 2, the clinicopathological characteristics of the tissue in the trauma cavity after tissue flap transplantation Clinical observation shows that after the tissue flap covers the trauma, the smaller gap can be filled by the growing granulation tissue in time, and after about 2 weeks, the tissue flap and the trauma completely heal. First, the necrotic bone of the long segment of cortical bone could not heal with the tissue flap tissue, and even six months after surgery, an inflammatory reactive zone was still seen between the tissue flap tissue and the necrotic bone, but the necrotic bone had been resorbed to form a scattered bone sheath, and the new bone healed on its deep surface, with inflammatory tissue between the two, and the flap and bone healed in the area without the necrotic bone sheath. As seen in [Figure 3b], the resorption of necrotic bone is synchronized with the formation of new bone, and within 6 months, the bone replacement growth is completed, and the small necrotic cortical bone and cancellous bone can be directly resorbed and replaced. In principle, if a local island flap can be selected for repair, a free tissue flap graft is not necessary. Small inflammatory trauma and bone exposure can generally be repaired by local island flaps [3]. In large inflammatory trauma and bone outgrowth, or even osteonecrotic defects, the corresponding anastomotic vascularized composite tissue flap must be selected for repair [4]. Iliac flaps or bifold fibular flaps are chosen for bone defects of less than 8 cm, and longer bone defects are chosen for combined fibular flap plus anterolateral femoral flap grafting. The single fibula is indeed small compared to the tibia, but after about 2 years of functional exercise, the grafted fibula can be significantly thickened and the circumference and strength of the bone can approach that of the tibia. The anterolateral femoral flap can be cut flexibly according to the needs of the recipient area, and the position of the flap is placed in the trauma cavity and the exposed bone, which is conducive to enhancing tissue resistance to infection and increasing the speed of local tissue healing. 4.Surgical points and postoperative precautions (1) Select the appropriate open area, which is related to the ability to achieve sufficient effective drainage, and place it in the area directly connected to the trauma cavity and easy to drain. (2) In principle, the tissue flap should be completely sutured to the wound edge on at least 2 sides, and the deep wound should be filled as tightly as possible with soft tissue. (3) In order to obtain adequate blood supply, the disconnection time of bridge-type tissue flap graft should be more than 6 weeks, and at least 1/2 of the tissue flap edge should be completely sutured to the wound edge. (4) Promptly clean and change the medication after surgery, usually 1~2 times daily to ensure the relative cleanliness of the wound cavity and to avoid infection caused by fluid accumulation. One patient in our group developed acute intra-medullary infection due to untimely dressing change, which was cleared twice and took 3 months to heal. (5) Because of more tissue fluid exudation in the first to second week after surgery, the nutritional intake of patients is more demanding, and nutrients such as amino acids are supplemented intravenously when necessary. (6) Pay attention to postoperative rehabilitation treatment, after the grafted tissue flap is stabilized, promptly get out of bed, which can improve their general physique and increase patients’ confidence, which is conducive to limb function recovery.