Orthognathic surgery is a widely used procedure for functional and aesthetic improvement of skeletal class II and III facial deformity. During orthognathic surgery including Le Fort I osteotomy and maxillary repositioning, the position and shape of nasal soft tissues may be changed. For example, due to loosening of soft tissue attachment after muscle dissection, the interalar width (IAW) and alar base width may increment, and displacement of the nasal tip and nasal septum may be induced after maxillary repositioning [1-3].

To minimize nasal soft tissue deformation, alar base cinch suturing was introduced by Collins and Epker [4]. In this technique, fibroalveolar connective tissue on both sides of the alar base is identified, after which a transnasal suture is placed extraorally with nonabsorbable material from one alar base to the other and tightened over small rubber catheters. The original technique was modified by Ritto et al. [3], Shams and Motamedi [5], and Muradin et al. [6] among others [4,7]. The modified techniques are performed currently to manage non-aesthetic nasal deformation after maxillary osteotomy. The modified techniques of Shams and Motamedi [5] and Ritto et al. [3] have reduced skin complications and managed nasal soft tissue more delicately. Muradin et al. [6] introduced the modified technique that combined alar base cinch suturing with V–Y closure for effectively managing the widening of the alar base.

Gangneung-Wonju National University Dental Hospital, simplified alar base cinch suturing was performed during orthognathic surgery including Le Fort I osteotomy to minimize the horizontal nasal deformation. The aim of this study is to assess change in the IAW by comparing pre- and post-operative specific time point measurements.

Subjects

This study was approved by the Institutional Review Board of Gangneung-Wonju National University Dental Hospital (IRB No. GWNUDH-IRB2021-A011). According to the inclusion criteria, 5 male and 12 female patients with severe skeletal class III malocclusion were selected. The age of patients at the time of surgery was from 18 to 29 with an average of 21.8 years of age (Table 1).

Inclusion criteria were as follows:

(1) All patients underwent orthognathic surgery including Le Fort I osteotomy by identical operator in the time frame from 2019 to 2021. Informed consent including the agreement of publishment was provided to each patient before surgery. (2) All patients underwent alar base cinch suturing during the surgery. (3) The relevant IAW measurements were recorded at preoperative, postoperative and periodic follow-up time points and could be inquired on the operation chart and medical records, and sufficient follow-up data was available.

Method

All patients were measured for IAW at preoperative time point (T0). The IAW, which is the horizontal distance between both alare (Al), was measured in 0.5 mm increments using vernier calipers. Al means the most lateral point of ala nasi (Fig. 1).

Fig. 1. Measuring the distance between both alare (Al) using a vernier caliper.

During surgery, alar base cinch suturing was performed using absorbable 2-0 PDS (Johnson & Johnson International, New Brunswick, NJ, USA) after maxillary fixation by intermediate surgical stent and bioabsorbable osteofixation (Takiron Co., Ltd., Osaka, Japan) (Fig. 2). The 2-0 PDS penetrates from the intraoral submucosal part of the alar curvature, which means the folded area between the alar base and facial skin, to subcutaneous tissue. The suture holds the levator labii superioris alaque nasi muscle, alar part of nasalis muscle, fibroareolar tissue (Fig. 3). The opposite side is sutured similarly. The anterior nasal spine can be penetrated or not when knotting. The suture should be knotted under tension, and the knot buried in intraoral submucosal tissue. Alar base cinch suturing was overcorrected to 1–2 mm narrower than preoperative IAW.

Fig. 2. Alar base cinch suturing during orthognathic surgery including Le Fort I osteotomy. (A) Penetrating the levator labii superioris alaque nasi muscle, alar part of nasalis muscle, and submucosal tissues to hold the structures. (B) Approximating the muscles at the hole which was drilled below anterior nasal spine. (C) Suturing tautly for overcorrection of nasal width, which is combined with V–Y closure of the upper lip.

Fig. 3. Illustration of the alar base cinch suturing as used in this study. The 2-0 PDS penetrates from the intraoral submucosal part of the alar curvature to subcutaneous tissue. The suture should hold the target muscles. The opposite side is sutured similarly. Sutures should be knotted tensely, and the knot should be positioned on intraoral submucosal tissue.

IAW measurements were charted at time points of 1 day postoperative (T1), 1 week postoperative (T2), 1 month postoperative (T3), and 6 months postoperative (T4).

Statistical analysis

Statistical analysis was carried out using the NCSS 2021 statistical program (NCSS LLC, Kaysville, UT, USA). The equivalence of IAW measurement at T0 and T1, T2, T3, and T4 was analyzed by nonparametric two one-sided test (TOST) equivalence test. The equivalence margin was 0.5 mm. A p_equl-value <0.05 was considered significant. If the test result showed inequality, the difference between the relevant time point and T0 was carried out with nonparametric Wilcoxon signed rank test. A p-value <0.05 was considered statistically significant.

The raw data of the IAW measurements of each subject are presented in Table 2. Fig. 4 shows the distribution of IAW measurements. Test results are described in Table 3.

Fig. 4. Interalar width (IAW) measurements in all subjects over time. Distribution of IAW for all subjects at preoperative (T0), postoperative 1 day (T1), postoperative 1 week (T2), postoperative 1 month (T3), postoperative 6 months (T4).

Equivalence test of the measurements at T0 and at T1

According to the result using TOST, in the normal approximation of equivalence between T0 and T1, p-value (p_equl) was 0.098. Therefore, the equality between T0 and T1 could not be proved significantly.

Difference of the measurement at T0 and at T1

According to the result using Wilcoxon signed rank test, in the normal approximation of difference between T0 and T1, p-value was 0.0004. Therefore, a significant difference between T0 and T1 could be proven statistically.

Equivalence test of the measurement at T0 and at T2

According to the result using TOST, in the normal approximation of equivalence between T0 and T2, p-value (p_equl) was 0.03. Therefore, the equality between T0 and T2 could be proven statistically.

Equivalence test of the measurement at T0 and at T3

According to the result using TOST, in the normal approximation of equivalence between T0 and T3, p-value (p_equl) was 0.04. Therefore, the equality between T0 and T3 could be proven statistically.

Equivalence test of the measurement at T0 and at T4

According to the result using TOST, in the normal approximation of equivalence between T0 and T4, p-value (p_equl) was 0.04. Therefore, the equality between T0 and T4 could be proven statistically.

The major anatomical structures involved in the nasal profile after orthognathic surgery are as follows. First, the levator labii superioris alaque nasi muscle elevates the upper lip and wing of the nose. Second, the transverse part of nasalis muscle, known as “compressor naris”, depresses the nasal cartilage and pulls ala nasi to nasal septum. Third, the alar part of nasalis muscle is involved in horizontal enlargement of the nostril related with major complication in this study. Additionally, fibroareolar tissues around the nasal cartilage are also related to the nasal profile [8,9].

During the Le Fort I osteotomy procedure, the maxillary attachment of major nasal structures such as levator labii superioris alaque nasi muscle and nasalis muscle are dissected and retracted laterally. Therefore, the nasal horizontal profile after Le Fort I osteotomy may be bluntly deformed. In order to cope with this problem, we performed alar base cinch suturing on the basis of this anatomical background accurately. Our simplified technique of alar base cinch suturing holds the levator labii superioris alaque nasi muscle, the alar part of nasalis muscle, and fibroareolar tissues, and prevents unwanted nasal soft tissue deformation effectively.

Several studies have been conducted about nasal soft tissue changes after alar base cinch suturing in orthognathic surgery. In the study of Honrado et al. [10], which used a 3D digital imaging system on 32 patients for observing the nasal change after orthognathic surgery, postoperative IAW and internostril width increased over preoperative measurements, but these are not related with the amount of maxillary movement. In the study of Mani et al. [11], 100 patients underwent orthognathic surgery including Le Fort I osteotomy and anterior maxillary osteotomy and conventional alar base cinch suturing. Change in alar base width measurement before and after surgery was analyzed. A significant increase was not observed, which is similar to our study.

In the study of van Loon et al. [12], 36 patients who underwent orthognathic surgery including Le Fort I osteotomy were evaluated by cone-beam computed tomography and 2D stereophotogrammetry dataset before surgery and one year after surgery to evaluate the changes in nasal and upper lip soft tissues. The horizontal width of the nose increased significantly, and the volume of the nose increased also. Andin the study of Worasakwutiphong et al. [13], 38 patients with skeletal class III malocclusion with mandibular prognathism underwent orthognathic surgery including alar base cinch suturing. The change in nasal soft tissue after surgery was observed using three dimensional photogrammetry. Nasolabial angle and the size of the nostril increased, but the horizontal width of the nose was unchanged.

In previous studies, various techniques were used for analyzing the change in horizontal nasal soft tissue. The above studies compared preoperative measurements with postoperative measurements at fragmentary time points; so there were limits to observing the time dynamics of change in horizontal nasal profile. In this study, we used the IAW measurement as the finite criteria. The IAW measurements in our study were taken at the time points of postoperative 1 day (T1), 1 week (T2), 1 month (T3), and 6 months (T4) and were compared to the measurement of preoperative time point (T0) for evaluating the change of nasal horizontal soft tissue profile over time.

In this study, IAW in T1 was significantly decreased from T0 value, which means overcorrection was performed efficiently for preventing the widening of the alar base. IAW measurements equivalent to T0 were achieved in T2, T3, and T4, which means long-term effective postoperative nasal deformation was prevented by alar base cinch suturing. Relapse after surgery and other environmental factors should rightly be considered with postoperative nasal soft tissue deformation. However, significant error that could affect the outcome of this study was not observed. Therefore, we can suggest that changes in postoperative nasal horizontal soft tissue profile will not become problematic when alar base cinch suturing is performed effectively by holding relevant muscles and tissues.

The limitations in this study are that the sample size was small, nonparametric tests should be adopted indispensably, and the test result may have fallen into various biases. In order to improve these limitations, sample size should be enlarged by expanding the investigative operation. Next, the single index IAW measurement could be affected by measurement error, and may be limited in terms of reflecting a three-dimensional change in nasal soft tissue. Various indices such as alar base width, nostril width, and intercanthal width could be used to mitigate this single index limitation in follow-up studies.

In the present study, because alar base cinch suturing was performed effectively with orthognathic surgery including Le Fort I osteotomy, IAW measurement did not change significantly from preoperative to postoperative value. This effect continued consistently through the six-month postoperative time point, which represents long-term effect of alar base cinch suturing, considering the change of soft tissue.

None.

The authors declare that they have no competing interests.