What is the abdominal wall component separation technique? The component separation technique (CST) is a technique for repairing the abdominal wall that may be used to increase abdominal volume, reduce abdominal wall tension, and is useful for repairing defects in the midline region of the anterior abdominal wall. The essence of the CST approach is to cover the abdominal wall defect by the detachment of the abdominal wall muscle gliding, in other words, the abdominal wall defect is repaired by its own muscle tissue. The abdominal wall repaired and reconstructed by this technique has the protection of a muscular layer. This is important to maintain the normal physiological function of the abdominal wall. This surgical approach dates back to 1985 or earlier Component Separation Technique and Hernia or Abdominal Wall Defects” is listed in thousands of articles on PubMed, mostly in recent years, indicating the increasing importance of this technique in the repair and reconstruction of abdominal wall defects. The most important components of the anterior abdominal wall are the muscles and fascia, in terms of muscles, the two longitudinal rectus abdominis muscles and their three lateral flattened layers, from superficial to deep, the external oblique abdominal muscles, the internal oblique abdominal muscles and the transverse abdominal muscles. The fascias between the muscles of the anterior abdominal wall do not fuse with the tendon membrane to form three longitudinal “lines”, the central one being the abdominal self line and the two sides being the meniscus respectively. There is no nerve or blood vessel penetration in the superficial layer of the semilunar line. The rectus abdominis muscle has a relatively independent blood supply from above and below it, and the nerves that govern muscle movement also run deep on both sides of the muscle. Based on this structural feature, three separate longitudinal “lines” can be surgically dissected to separate the muscles, while affecting their blood flow and function. In the study of the relationship between the anterior abdominal wall structures and abdominal circumference, it was found in autopsies that a relatively non-vascular plane exists between the external and internal oblique abdominal muscles, and that the complex of the rectus abdominis and its anterior sheath can slide and push about 10 cm toward the midline after separation from the posterior sheath. In other words, this separation through the muscles without gliding to enlarge the abdominal circumference is used to repair and reconstruct the defect in the abdominal wall. The surgical principle and indications of the tissue structure separation technique The surgical principle of CST is to increase the area of the abdominal wall by using the bit and glide between the muscles of the anterior abdominal wall, which is achieved by incising both halluxes in order to separate and unfold the three layers of muscles of the anterior lateral wall and the posterior rectus abdominis sheath. Thus, this technique avoids the more complex operations such as the transfer of the muscle quitting myocutaneous flap at the entry point. The tenet of CST is that defects in the abdominal wall can be covered by relying on the abdominal wall’s own muscle tissue, which is essential to preserve and maintain the original function of the abdominal wall. Since CST repair is achieved mainly by the separation of the abdominal wall muscles on both sides moving towards the middle. Therefore, the indications for CST are mainly for repairing defects in the middle part of the anterior abdominal wall. Tissue separation technique operation steps: 1, the choice of incision Generally choose a longitudinal straight incision, in order to facilitate adequate separation without revealing; around the umbilicus (if necessary, the umbilicus can be removed). 2, the extent of separation of the subcutaneous tissue of the abdominal wall muscle Adequate separation of the anterior sheath of the rectus abdominis muscle and the surface of the tendon membrane of the external oblique abdominal muscle, both sides up to the anterior axillary line, the upper edge to the subxiphoid process, and the lower edge to the pubic symphysis. 3, determine the size of the abdominal wall defect and muscle separation range Firstly, measure and determine the size of the abdominal wall defect, then decide the length of the meniscus incision according to the extent of the abdominal wall defect; if the defect is small, only one side of the meniscus can be incised. 4, meniscus incision and muscle separation The meniscus of one side was incised first, and the separation was performed between the avascular plane between the external and internal oblique abdominal muscles, and then pulled toward the midline; the same was done on the opposite side. The abdominal wall muscles are slid through the above separation to determine if it is sufficient to cover the abdominal wall defect. 5, posterior rectus abdominis auxiliary incision If incision of both sides of the semilunar line still can not obtain satisfactory muscle flaps for the closure of the abdomen, the peritoneum can be separated from the midline, that is, behind the white line of the abdomen, to both sides, turning up the rectus abdominis muscle, longitudinal incision of the posterior sheath of the rectus abdominis muscle. To make the rectus abdominis muscle flattening step to obtain 2-4cm range of motion. 6, re-strengthening of the abdominal wall By separating the abdominal wall muscles without gliding, the abdominal circumference is expanded and the defect of the abdominal wall is repaired, however, this separation without gliding also thins the muscles of the abdominal wall. Therefore, it is often necessary to reinforce the muscles with artificial material (patch) in front of and behind the muscle, a process called re-strengthening of the abdominal wall. There are three ways of re-enforcement, i.e., patch placed in front of the muscle, patch placed behind the muscle, and absorbable material placed after the muscle level is mostly chosen. 7, the placement of subcutaneous drainage tubes and layer by layer suture abdominal wall Operational considerations: 1, the size of the incision itself can not be too large (about 12 cm), but the gap between the skin, subcutaneous tissue not muscle fascia can be separated by pulling the hook, but, the separation surface must be large, to reach the desired extent. 2, pay attention to the depth when cutting the semilunar line, so as not to cut and damage the motor nerve innervating the rectus abdominis muscle. When incising the posterior sheath of the rectus abdominis muscle, care should be taken to protect the blood vessels supplying the rectus abdominis muscle. Due to the large subcutaneous tissue separation surface, intraoperative drainage must be placed to avoid postoperative formation of subcutaneous fluid and the development of infection. Technically, the drainage should be adequate, and drainage tubes can be placed on both sides separately. The best choice of drainage tube is an 8-10 gauge ventricular drainage tube (made of silicone) to facilitate unobstructed drainage.