Nasal septum correction surgery is one of the most common rhinologic procedures in otorhinolaryngology-head and neck surgery. Its surgical approach has evolved over the past 100 years and is divided into three stages: subtotal nasal septal resection, submucosal resection, septal correction and septoplasty. Submucosal resection is able to meet the correction of various types of septal deviation and is still widely used today. However, is the septum correction surgery really the best nowadays? Is septoplasty the same as septum correction surgery? With the introduction and development of nasal endoscopy in the 1970s, the development of endoscopic septum correction surgery was promoted. The treatment of nasal septal deviation under direct endoscopic vision provides a clear operative field and expands the indications for traditional surgery. However, the ensuing problem is the prevalence of excessive removal of the septal stent. Although these procedures can correct the deviated septum and relieve the symptoms, the large area of nasal septal cartilage and bone is removed, resulting in the absence of the main septal scaffold, making the septal mucosa too loose and oscillating, and can lead to slow deformation of the nose, such as saddle nose, overly wide nasal dorsum, collapse of the supra-apical region, and septal perforation. Biomechanical analysis of nasal septal deviation production How to correct various forms of nasal septal deviation while preserving the nasal septal cartilage and normal bone structure scaffolding and avoiding complications by relieving the stress relationship that leads to nasal septal deviation is still a topic well worth exploring. From the perspective of bone growth and development, the cranial bone completes its development earlier, while the nasal septal cartilage completes its development later, i.e., the nasal septal cartilage is still growing when the frontal bone is completed with the maxilla and palate. Therefore, the upper and lower part of the nasal septum is fixed and will form an upper and lower stress relationship because it cannot be lengthened, which is mainly concentrated in the connection area between the weaker nasal septal cartilage and the peripheral bones and is probably the most important factor in the formation of nasal septal deviation. In addition, the nasal septum is composed of several bones or cartilages, and the growth of each part is unbalanced. As shown in Figure 1, the septum is cartilaginous at the beginning, and then begins to partially ossify. The lower plastron, maxillary nasal crest, and palatine process are the first to ossify; while the posterior part of the nasal septum gradually ossifies forward, the order of ossification is from the cephalic to the caudal side. When the posterior and inferior septal vertical plates and the plow bone and palatine process of the maxilla are ossified and fixed, the cartilaginous portion is still extending and growing. Therefore the tension caused by this uneven development acts mainly on the anterior, inferior and posterior three lines of the nasal septal cartilage, i.e. at the intersection with the ossified part, forming three core areas of stress, forming a protrusion, and in severe cases a crest, the momentum, causing severe deviation. As shown in Figure 2, the first tension curve: between the caudal end of the square cartilage and the medial foot of the greater pterygoid cartilage of the nasal columella, forming an anterior deviation; the second tension curve: where the septal cartilage joins the vertical plate of the sieve bone, forming a high deviation; the third tension curve: where the square cartilage meets the plow bone, the nasal crest of the maxilla and the nasal crest of the palate, forming a posterior deviation as well as a morphologically different nasal crest and talar eminence. Three-line subtraction septoplasty is different from septoplasty. Septoplasty is a new modified septoplasty procedure designed according to the biomechanical law of septal deviation, namely three-line subtraction septoplasty. Its features are as follows: most of the septal cartilage and normal bony scaffold are preserved; only a little cartilage and bone are partially removed from the area of the three tension lines to relieve the stresses that cause septal deviation. The vertical plate of the septum with severe high deviation can be fractured without resection by clamping with occlusal forceps, and then the square cartilage is repositioned medially and the bilateral mucous cartilage membranes are aligned. This procedure preserves the deviated cartilage and bone, which is the main difference from the traditional procedure. This procedure attempts to re-establish the concept of septal correction in accordance with the biomechanics of septal deviation. By releasing the core area where the three tensions are generated, the mutated stress relationship is corrected to normal and the new stress relationship causes the reshaping of the nasal septal stent with the aim of reducing surgical complications while correcting the deviated septum. Its significance is: (1) to maintain the thickness and hardness of the septum, otherwise the mucosa healing together will lead to mucosal atrophy and deformation, such as septal defect is too large, the septum produces flapping and whistling sound when breathing; (2) to help prevent the collapse of nasal cone and nasal tip, and can prevent the contraction of connective tissue of mucous cartilage membrane layer; (3) to reduce the occurrence of nasal septal perforation. The recovery after trilinear subtraction septum correction is different from previous surgeries. Nasal recovery is faster after traditional complete septal bone removal surgery, but it is important to maintain patience as there will be prolonged swelling and time for bone storage healing if cartilage structures are preserved or after intraoperative fracture is performed. Postoperative follow-up quality should be ensured to avoid nasal adhesions and stenosis and to administer reasonable medication. Selection of surgical age Over the years, due to the limitations of surgical concepts, we often locked septal correction surgery into an age limit, emphasizing that septal surgery should be performed after the age of 18. This old surgical concept has influenced several generations, believing that immature patients who undergo septum correction surgery have a higher possibility of nasal collapse. Nowadays it seems that a number of children and adolescents have a completely deviated and obstructed nasal cavity on one side, and if he waits until the age of 18, he will have a long-term open-mouth breathing causing altered compliance remodeling of the mandible, which in turn will have a negative impact on growth and development and increase the risk of developing obstructive sleep apnea hypoventilation syndrome in adulthood. El-Hakim et al. studied 26 children aged 4.5 to 15.5 years (mean age 9.5 years) who underwent corrective nasal septal surgery. After a mean follow-up period of 3.1 years, a mild decrease in nasal dorsal length and nasal tip height was not considered clinically significant. Therefore, septoplasty is not contraindicated for children as long as the normal nasal bony stent is preserved. Conclusion Nasal endoscopic septoplasty with the trilinear subtraction method is simple, easy, safe and reliable, with adequate correction of nasal septal deformity, which is conducive to the transformation of postoperative compensatory changes in the nasal cavity toward a physiological state and the eventual restoration of nasal-sinus physiological function. Although there are various characteristics and forms of nasal septal deviation, by removing the trilinear tension area and eliminating the tension between the septal cartilage and bone, it can simultaneously solve the anterior, posterior and high deviation of the nasal septum and local deformities such as crest and talus, which is in line with the biomechanical law of nasal septal deviation generation and raises the surgery to a minimally invasive level. Details determine success or failure, we should think about the subtleties in the process of structural remodeling and pay attention to the principle of humanization in functional recovery intervention. We should correctly understand the dialectical relationship between anatomical structure, physiological function and clinical symptoms, maximize the preservation of normal tissue structure, restore its basic physiological function, improve patients’ quality of life, and realize the purpose of minimally invasive surgical techniques.