Deviated septum not only affects the ventilation function of the nasal cavity on the deviated side, but also affects the physiological function of the contralateral nasal cavity and the normal drainage of the sinuses, eventually causing a series of symptoms. The prevalence of nasal septal deviation varies widely in previous reports (16%-79%), and this difference may be related to the different criteria for judging nasal septal deviation and the subjects of investigation (such as ethnicity, age, gender, etc.). In particular, ethnicity is an issue, as Europeans have a longer anterior-posterior cranial diameter, high nasal bridge and longer airway space, while Asians have a shorter anterior-posterior cranial diameter and smaller nasal cavity. Therefore, the prevalence of septal deviation may be higher in Asians and should be given sufficient attention.
History of septum correction surgery
Corrective nasal septal surgery is the most effective means of correcting nasal septal deviation and is one of the most common procedures in otorhinolaryngology-head and neck surgery. It has been more than 100 years since Ingals first applied the submucosal resection of the nasal septum in 1882, but it was not until 1904 that Killian described the detailed method of this procedure, and it was widely adopted by Cottle (1950). In 1975, Smith modified it to “nasal-septal correction”, which extended the scope of orthopedic and reconstructive treatment to the entire septum and its extensions. With the introduction and development of nasal endoscopy in the 1970s, the development of nasal endoscopic septal 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 stent, which makes 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]. In recent years, a new concept of limited septoplasty has emerged, which can well manage posterior septal deviation and localized septal talipes (septal spurs) by removing only the curved part of cartilage and bone, maintaining the stiffness and scaffolding of the nasal septum.
Biomechanical analysis of septal deviation production
How to correct various forms of nasal septal deviation while preserving the cartilage and normal bone structure scaffolding of the septum and avoiding complications by relieving the stress relationships that lead to 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 septum gradually ossifies forward, with the order of ossification being from cephalad to 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 protrusions and, in severe cases, cristae, momentary protrusions, 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 reduced-tension septum correction surgery
In accordance with the biomechanical rules of nasal septal deviation, a new modified septum correction surgery is designed, i.e. three-line subtraction septum correction surgery. The features are as follows: most of the nasal septal cartilage and normal bony stent are preserved; only a small amount of cartilage and bone is removed from the area of the three tension lines to relieve the stresses that cause septal deviation. The surgical steps are as follows.
First, an “L”-shaped incision was made at the skin-mucosa junction of the nasal vestibule and extended toward the base of the nose, and the mucosa, mucous cartilage and cartilage were incised, leaving the contralateral mucous cartilage intact. Three core areas of tension formation were exposed: the caudal end of the square cartilage of the nasal septum, the union of the septal cartilage with the vertical plate of the sieve bone, and the junction of the lower end of the nasal septal cartilage with the plow bone, the nasal crest of the maxilla, or the nasal crest of the palate.
The first tension zone (A,B): the vertical cartilage strip at the caudal end of the square cartilage, about 2 mm; the second tension zone (C): the vertical cartilage strip at the anterior edge of the vertical plate of the sieve bone, where the septal cartilage joins the vertical plate of the sieve bone; the third tension zone (D): the deviated plow bone, the nasal crest of the maxilla and the nasal crest of the palate, and the horizontal cartilage strip at the base were removed. The septal square cartilage apical connection is formed, separating the left and right sides and freeing the anterior, posterior and inferior sides. If the cartilage is obviously deviated, several cuts can be made on the concave side of the cartilage along the direction of the depression, which can serve to straighten the cartilage; for severe high deviation of the vertical plate of the septum can be clamped with biting forceps to make it fracture without excision, and then the square cartilage is repositioned in the middle and the bilateral mucous cartilage membranes are buttressed. This procedure preserves the cartilage and bone of the deviation, which is the main difference from the traditional procedure.
Features of the three-line reduced septum correction surgery
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 septal stent, with the aim of reducing surgical complications while correcting the deviated septum. Its significance lies in.
① maintaining the thickness and stiffness of the septum, otherwise the mucosa heals together leading to mucosal atrophy and deformation, such as too large septal defect and septal flapping and whistling during whistling.
② help prevent the collapse of the nasal cone and tip, and prevent the contraction of the connective tissue of the mucous cartilage membrane layer.
③ Reduce the occurrence of nasal septal perforation.
Nasal resistance is mainly generated in the anterior nasal flap area. If the deviation is located within the functional nasal valve area and forms the smallest area of the entire nasal cavity, the nasal resistance will be much higher. Therefore, the management of anterior deviation of the septum is very important [20]. The three-wire subtraction septal correction procedure releases the tension on the anterior end of the square cartilage and restores it to the midline position, which is very effective in cases of anterior deviation in the nasal flap area and is the key point that distinguishes this procedure from other procedures such as limited septal correction.
The recovery after trilinear subtraction septum correction is different from previous surgeries. The nasal recovery is faster after the traditional complete removal of the septum bone, but if the cartilage structure is preserved or after the intraoperative fracture is performed there will be prolonged swelling and time for healing of the reservoir bone, so remain patient. Postoperative follow-up quality should be ensured to avoid nasal adhesions and stenosis and to administer reasonable medication.
Selection of the age of surgery
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 undergoing septal correction surgery have a higher likelihood of nasal collapse. It now appears that a number of children and adolescents have a completely deviated and obstructed nasal cavity on one side, and if they wait until 18 years of age, he will have a prolonged period of open mouth whistling causing altered compliance remodeling of the mandible, which in turn will negatively impact 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 of 3.1 years, a mild decrease in nasal dorsal length and nasal tip height was not considered clinically significant. Therefore, septal correction in children is not contraindicated as long as the normal nasal bony scaffold 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 ultimate 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 humanistic principles in functional recovery interventions. 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.