The nasal sill area is a key component of the alar ring, which needs to be considered by surgeons during the nasal base reconstruction procedure . Augmentation of this area is indicated when conditions, such as congenital asymmetrical nostrils, cleft lip and palate, malignancies, or traumatic lesions, occur .
The emphasis on the precise anatomical considerations in the sill area helps the surgeon to have a broader horizon to reach the optimal esthetic results. The alar ring is the most caudal area of the nose, which involves the edge of the nostril, extending to the alar base. It contains the alar cartilage with lateral and medial crura, as well as A1 to A4 accessory cartilages, positioned along the tail of the lateral crural cartilage  (Fig. 8). The boundaries of the nostril opening (alar ring) contains alar lobules, columellar base, and nostril sill . As an alar ring subunit, the nasal sill is a protuberant soft tissue bridge, extending from the base of the columella to the ala of the nose, separating the upper lip soft tissue from the nasal vestibule cephalocaudally . The nostril sill is situated approximately in the area of A3 and A4 cartilages. Also, the nostril sill can vary based in terms of width, height, and shape (Fig. 9).
In 1995, Irwin et al. categorized the nostril sill into three main types;
In Full/Sill-proper type, a protuberant area connects the columella and the ala. It is the most common variant with the greatest muscle and soft tissue thickness of all three .
In the Point type, the medial and lateral walls of the nostril sill approximate each other to form an apex.
In the Flat type, there is no soft tissue protuberance between the vestibule of the nose and the upper lip, with the least soft tissue thickness [31, 32] (Fig. 10).
The direct relationship between the nostril shape and sill area can be inferred from two measurable angles in this area. Figure 11 shows the angle between the longitudinal axis of the nostril and the horizontal plane, and the second angle is between the medially inclined nasal sill and the sagittal plane. An elliptical or pear-shaped nostril with a longitudinal axis angle of 45° has higher esthetic values . These angles can be considered and recorded in the patient’s preoperative analysis.
Muscle insertions of the nostril sill area include the depressor septi nasalis, myrtiformis, and dilator naris (DN) muscles, which originate from the maxilla and insert into the soft tissue and skin of the nares. The tela subcutanea cutis (TSC) that can be seen in this area (Figs. 12, 13, and 14) is a folded layer of dermis and subcutaneous tissue that connects the lateral and medial crura when seen from the basal view.
Other anatomical considerations in the sill area include the superficial and deep pitanguy’s ligaments, which extend caudally between the lower lateral cartilages and continue along the superficial orbicularis oris nasalis (SOON) and depressor septi nasalis (DSN) muscles, respectively (Fig. 15).
Our experience in the present study revealed that the proper symmetry and shape of the alar base and nostrils are dependent on the precise evaluation and further reconstruction of the nasal sill dimensions, especially in unilateral deformities where the normal shape of the sill is achieved similar to the normal side. In minor sill defects, muscle repositioning, specific suturing techniques, and small soft tissue grafts may result in the satisfactory elevation of the sill area ; however, in larger defects, composite grafts may be required to achieve the desired clinical outcomes .
Among esthetic rhinoplasty patients, those who require nasal tip modification and correction of gross septal deviation or perforation, as well as those who undergo esthetic rhinoplasty through an open approach, augmentation of the sill area can be performed using an open approach if needed (Fig. 1b). Also, in esthetic rhinoplasty patients, who require alar base reduction and have defects in the sill area, insertion of the sill graft through the alar base incision can be highly useful (Fig. 1c).
The review of published literature, addressing the concept of nasal sill augmentation, revealed that cleft palate patients require major corrections for sill defects (Table 2). Therefore, special attention must be paid to nasal sill reconstruction in these patients. However, nasal sill reconstruction in these patients is not usually performed as an independent procedure but as part of the cleft repair process. Dissection and repositioning of the orbicularis oris and depressor septi muscles is often the most preferred technique for sill augmentation in these patients [13, 23, 24]. Repositioning of the medial and lateral flaps of the upper lip during cleft closure is another method for reconstruction of the sill area . Although no major complications were reported for this method, the absence of graft can occasionally result in further depression of the sill area in the long term.
As mentioned earlier, no complications were detected among the participants of our study; however, infection, bleeding, ischemia, flap necrosis, complications associated with the harvesting procedure, graft deviation, obvious scar, excessive decrease in the nostril size, impaired ventilation, shortening of the upper lip, and sensory dysfunction are among potential complications, which require strict considerations, especially in the follow-up examinations [10, 20, 23, 25].
Earlobe-derived cartilage grafts do not offer satisfactory esthetic results in the sill area and are associated with complications in some cases . Instead, alveolar bone grafting in 18 unilateral cleft lip and palate patients with tension-free sutures produced optimal esthetic outcomes in the nasal sill area , with significant improvement in the width and height measures of the cleft site.
A review of previous studies showed that many of the published techniques are based on the transposition of flaps [13, 14, 18, 22,23,24]. The application of these techniques may be justified for patients with clefts or those with malignancies, where a part of the soft tissue is usually deficient. However, the use of these techniques in patients, who are diagnosed with simple congenital defects, seems extremely aggressive. On the other hand, the conservative design of our technique and the lack of extensive flaps provide an opportunity for nasal sill reconstruction in patients with congenital defects. In other words, the non-invasive design of our technique and providing a solution for nasal sill reconstruction in patients with congenital defects can be considered the most significant advantages of this study. However, the possibility of using our technique for patients with clefts, malignancies, or traumatic lesions cannot be rejected.
Recurrent asymmetry following graft deformity may be the most important limitation of this technique. Overall, ensuring that the graft is stable and fixed in its position can be very helpful in preventing the occurrence of this complication. However, in such cases, a secondary revision intervention is required.
In general, one of the advantages of this procedure is that it is not technique-sensitive, and it is easy to perform. Also, this technique is repeatable and does not produce a remarkable scar in the surgical site. On the other hand, its disadvantage is donor site morbidity.
In conclusion, based on the findings of the present study, our novel technique can be successfully used for reconstructing the nasal sill area, with minimal complications and morbidities in patients, who require esthetic rhinoplasty or have congenital defects, cleft lip deformities, malignancies, or traumatic lesions. It should be noted that in this technique, the proper symmetry and shape of the alar base and nostrils are dependent on the precise evaluation and further reconstruction of the nasal sill dimensions.