Redefining the septal L-strut in septal surgery

Reconstruction of Palatal Defects Using a Composite Chondromucosal Nasoseptal Flap and Comparative Analysis

OBJECTIVE

The use of composite chondromucosal nasal septal flaps (ccNSF) has been demonstrated to be effective in cadaveric studies for the anterior skull base and the orbit. However, their application in the clinical setting remains unexplored. Our study aims to introduce a new method for treating palatal defects using ccNSF. Additionally, we studied the average NSF area and compared it to the average palate area.

METHODS

We collected 108 CT scans from the medical records of patients without head and neck pathologies from a tertiary medical institution. We quantified the quadrangular (septal) cartilage and palate areas. Furthermore, we included a clinical case in which we used the ccNSF for the palatal defect reconstruction. This was to compare the mean area between the palate and the septal cartilage.

RESULTS

The ccNSF covered the palatal defect without any significant complications for the first 9 months of follow-up. A total of 102 CT scans met the inclusion criteria and were measured. We found that the mean quadrangular cartilage had a length of 2.50 (±0.52) cm, a width of 2.28 (±0.51) cm, and an area of 5.43 (±1.68) cm2. The mean palate length was 2.73 (±0.44) cm, with a width of 3.13 (±0.34) cm, and area of 7.87 (±1.43) cm2.

CONCLUSIONS

The ccNSF proved successful in palatal defect reconstruction, resulting in positive outcomes and no major complications until the 9-month follow-up. The ccNSF is a useful flap that avoids the use of free flap transfer and its associated morbidities.

LEVEL OF EVIDENCE

4 Laryngoscope, 2024.

M-Shaped Auricular Cartilage Grafts for Correcting Short Nose Deformity in Asians: A Retrospective Study

BACKGROUND

The demand for rhinoplasty in Asia is growing annually, and short nose deformity has been one of the main reasons for the surgery due to its high incidence. There is an urgent need for rhinoplasty suitable for Asians because of their different facial features from Westerners. The M-shaped auricular cartilage rhinoplasty has been developed as a new method for correcting short nose deformity for Asians. This study aimed to evaluate the aesthetic and functional results of M-shaped auricular cartilage rhinoplasty compared to clinically commonly used rhinoplasty methods.

METHODS

A total of 45 patients were enrolled and divided into three groups of 15 patients: The first group underwent M-shaped auricular cartilage rhinoplasty, the second group underwent auricular-septal cartilage rhinoplasty, and the third group underwent overlapped auricular cartilage rhinoplasty. All of these patients underwent comprehensive rhinoplasty and had silicone or expanded polytetrafluoroethylene implants in the dorsum of their noses.

RESULTS

The patient score improvements on the three patient-reported outcome measures were higher in the M-shaped auricular cartilage rhinoplasty group (1.65/1.79/0.11) compared with the overlapped auricular cartilage rhinoplasty group (1.40/1.51/0.05), and the score improvements in the auricular-septal cartilage rhinoplasty group (2.04/1.98/0.28) were the highest.

CONCLUSIONS

This is a retrospective clinical study demonstrating the clinical efficacy of M-shaped auricular cartilage rhinoplasty. Compared with the overlapped auricular cartilage rhinoplasty, the effect of this novel M-shaped method is better. However, when compared to the auricular-septal cartilage rhinoplasty with septal extension and reinforcement using nasal septal cartilage, its effect is slightly worse.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The advanced concepts for septal l-strut re-designing in septorhinoplasty for better strength and stability by considering of center of gravity

PURPOSE

This study contributes to the multidisciplinary understanding of septal L-strut reshaping and introduces innovative surgical design concepts based on engineering principles of static equilibrium. The objective is to enhance structural strength and stability, ultimately leading to improved surgical outcomes.

METHOD

Finite element analysis is employed to model the three-dimensional septal cartilage in septoplasty. A significant contribution of this work is the introduction of an innovative redesigns for the septal L-strut structure. These redesigns represent the first-ever attempt to incorporate the center of gravity theory into the modeling of the septal L-strut.

RESULTS

Our findings emphasize the significance of attaining a lower center of gravity in the design of the septal L-strut, as it contributes to optimal core strength and stability. To achieve this, we recommend widening the caudal septum and shaping the interior fillet corner to its maximum size, taking into account its specific shape. Notably, the utilization of a standard 20x20 mm septal L-strut, the C-shaped technique, and the septal support graft technique provide superior strength due to enhanced basement support.

CONCLUSION

To enhance surgical outcomes in septal L-strut procedures, design modifications are proposed to improve strength and stability, resulting in optimized performance. Recommendations include widening the caudal septum and incorporating fillet shapes in the geometry to lower the center of gravity.

Use of nasal septal bone to straighten septal L-Strut in correction of east Asian short nose: A retrospective study

BACKGROUND

The perpendicular plate of ethmoid (PPE) was used to correct short noses in rhinoplasty in Asians, but the safe harvest of the plate and the assessment of its clinical application has been perplexing to plastic surgeons.

AIMS

To explore how to safely cut the perpendicular plate of ethmoid bone and evaluate its application effect.

PATIENTS/METHODS

A finite element model was established to guide the clinical operation. A total of 30 patients with short noses were selected. Among them, 15 patients used autologous septal cartilage to lengthen the nasal tip, and 15 patients used the PPE to strengthen the L-shape nasal septum. The differences in the esthetic parameters of the nose, complications, and patients' satisfaction were compared between the two groups.

RESULTS

Significant differences were noted in the nasal dorsal length (p = 0.001), Goode's ratio (p = 0.001), and nasofrontal angle (p = 0.003) after rhinoplasty, and no significant differences were noted in any of the esthetic parameters between the two groups. The symptoms of nasal obstruction in the experimental group were significantly lighter than those in the control group (p = 0.04). There was no statistically significant difference in the doctors' assessment of outcomes between the two groups (p = 0.48).

CONCLUSION

The safest region to harvest the PPE is in the middle and lower third. Rhinoplasty improves the esthetics of the patient's nose. The PPE used to strengthen the L-shape nasal septum structure has a smaller probability of nasal septal deviation with the time in Asian short noses.

An Advantageous Donor Site Alternative for Preparing Crushed Cartilage Graft: The Postero-inferior Part of the Septal Cartilage

Crushed cartilage is used in rhinoplasties and crushing carry the risk of devitalization. The most infero-posterior part of the septal cartilage has a rough surface compared with the smooth surface of the remaining parts. This cartilage may be more convenient for crushing with lesser pressure requirements, increasing the viability. Twenty-six patients underwent septorhinoplasty and the infero-posterior part of the septal cartilage was harvested. The rough cartilage was utilized in nine patients (excluded from the study). Seventeen patients were included in the study. The mean age of the patients was 28 (19-37y). Two pairs of grafts were utilized for histological study. In fifteen patients crushing experiment was performed. The smooth-surfaced cartilages were the control group, the rough-surfaced cartilages were the study group. For each case, grafts were reduced to the same dimensions and placed over millimetric-paper and photographed. The grafts were crushed simultaneously. The crushed cartilages were also placed on millimetric-paper and photographed. The data were evaluated statistically. The mean surface increment ratio was 2.26 ± 0.28 for the control and 2.94 ± 0.25 for the study group. The difference was statistically significant (p < 0.0048). In two specimen, after applying hematoxylin & eosin stain, the extracellular matrix of the rough cartilage specimen stained darker due to more abundant proteoglycan content. The rough septal cartilage widens more compared with the smooth cartilage under the same crushing pressure. Thus, the rough cartilage requires lesser pressure for widening which may increase the viability. The rough septal cartilage contains more proteoglycan which may explain its softness.

Bony Cartilaginous Graft in Unilateral Cleft Lip Rhinoplasty

BACKGROUND

Cleft rhinoplasty is a challenging form of nasal correction of both esthetic and functional deformities. The septal cartilage in many Asian patients are not sufficient and weak. Does a combination of the septal cartilage and the bony septum have both esthetic and functional benefits to secondary unilateral cleft rhinoplasty?

PATIENTS AND METHODS

Thirty patients with a unilateral cleft lip palate underwent open rhinoplasty from October 2018 to January 2021. After preserving a 10 mm L-strut, the posterior cartilaginous and bony septum were harvested as an integrative unit. The osteocartilaginous graft was used as a caudal septal extension graft and an extended spreader graft. Correcting the asymmetry of the tip and tip projection followed. The intraoperative harvested composite graft was analyzed. Acoustic rhinometry and the 3-dimensional anthropometric measurements of the external nose were assessed before and after surgery.

RESULTS

The osteocartilaginous unit was much larger than the cartilaginous part of this unit. The mean nasal tip height and the nasolabial angle increased significantly after surgery. The measurement of cross-sectional areas and volumes by acoustic rhinometry revealed that septorhinoplasty provided a significant increase in the function of both nasal cavities.

CONCLUSIONS

This septal bony cartilaginous graft is effective for cleft lip nasal deformity when correcting the deviated septum, creating a supporting frame to correct the nasal tip asymmetry, improving function.

Computational technology for nasal cartilage-related clinical research and application

Surgeons need to understand the effects of the nasal cartilage on facial morphology, the function of both soft tissues and hard tissues and nasal function when performing nasal surgery. In nasal cartilage-related surgery, the main goals for clinical research should include clarification of surgical goals, rationalization of surgical methods, precision and personalization of surgical design and preparation and improved convenience of doctor-patient communication. Computational technology has become an effective way to achieve these goals. Advances in three-dimensional (3D) imaging technology will promote nasal cartilage-related applications, including research on computational modelling technology, computational simulation technology, virtual surgery planning and 3D printing technology. These technologies are destined to revolutionize nasal surgery further. In this review, we summarize the advantages, latest findings and application progress of various computational technologies used in clinical nasal cartilage-related work and research. The application prospects of each technique are also discussed.

Beyond the L-Strut: Redefining the Biomechanics of Rhinoplasty Using Topographic Optimization Modeling

Rhinoplasty utilizes cartilage harvested from the nasal septum as autologous graft material. Traditional dogma espouses preservation of the "L-strut" of dorsal and caudal septum, which is less resistant to axial loading than virgin septum. Considering the 90° angle between dorsal and caudal limbs, the traditional L-strut also suffers from localized increases in internal stresses leading to premature septal "cracking," structural-scale deformation, or both. Deformation and failure of the L-strut leads to nasal deviation, saddle deformity, loss of tip support, or restriction of the nasal valve. The balance between cartilage yield and structural integrity is a topographical optimization problem. Guided by finite element (FE) modelling, recent efforts have yielded important modifications including the chamfering of right-angled corners to reduce stress concentrations and the preservation of a minimum width along the inferior portion of the caudal strut. However, all existing FE studies offer simplified assumptions to make the construct easier to model. This review article highlights advances in our understanding of septal engineering and identifies areas that require more work to further refine the balance between the competing interests of graft acquisition and the maintenance of nasal structural integrity.

Biomechanical analyses of common suspension sutures in primary cleft lip rhinoplasty

Background

For a better understanding of common suspension sutures during primary cleft lip nasal rhinoplasty, the biomechanical consequences of those sutures need to be demonstrated.

Methods

A finite element model of the infant specimen was established. The closure of cleft lip and four different specific suspension sutures were simulated by loading different forces on the model: 1. F1 to simulate the suture fastening both medial crura together; 2. F2 to simulate the suture which sewed both medial crura and the non-cleft-side upper lateral cartilage together; 3. F3 to simulate the suture elevating the alar cartilage cranially; 4. F4 to simulate the suture elevating the alar cartilage superiorly. The deformation and stress distribution consequent to each maneuver were analyzed in details.

Results

The deviation of columella was restored through the closure of cleft lip. Different suspension sutures had different biomechanical effects on the nasal structure. All suspension sutures had the function on elevating the alar cartilage. F2 had no function on restoring the collapse of the nasal tip. The suture which fastened both medial crura together leaded to the lowest stress on the skin envelope.

Conclusions

Each suspension suture had its characteristics respectively. The simulation suggested that F1, the suture which fastened both medial crura, could be the most potential maneuver for cleft lip rhinoplasty because it can symmetrically restore the shape of the nose without incurring a significant increase in stress.

Recapitulation of Unilateral Cleft Lip Nasal Deformity on Normal Nasal Structure: A Finite Element Model Analysis

Cleft lip nasal deformity has been challenging to plastic surgeons. A better understanding of the biomechanical aspect of the cleft nose would contribute to a better correction. In this study, finite element model of a normal nose was constructed and loaded with forces to recapitulate the unilateral cleft lip nasal deformity. Tether at the alar base was simulated by a laterally directed force at the lateral crus, and tether at the columella base by a posteriorly directed force at the medial crus. The equivalent von-Mises stress and the total deformation consequent to different patterns of loading were captured. In accordance with clinical observations, unilaterally loaded forces caused deformation on both sides of the nose. A correlation between the patterns of loading and different cleft lip nasal deformities was documented in detail. When set at the same force magnitude, tether at the columella base led to more extensive changes in the nasal morphology and higher level of stress than at the alar base. Clear identification of major pathological tethers in the nasolabial region might lead to more accurate and stable correction of cleft lip nasal deformities.

Biomechanical simulation of correcting primary unilateral cleft lip nasal deformity

For better outcomes of the primary correction of cleft lip nasal deformity, it is important to clarify the specific morphological and biomechanical consequences of major surgical maneuvers during cleft lip nose correction. In this study, a finite element model was established basing on the micro-MRI imaging of an infant specimen with unilateral complete cleft lip deformity. Alar base adduction was simulated as a medially-directed force on the lateral crus (F1); columella straightening was simulated as a laterally-directed force on the medial crus (F2); and nasal tip enhancement was simulated as an anteriorly-directed force on the intermediate crus (F3). The deformation and stress distribution consequent to each force vector or different force combinations were analyzed in details. Our biomechnical analyses suggested that W\when loaded alone, the three forces generated disparate morphological changes. The combination of different force loadings generated obviously different outcomes. F3 generated the most intensive stress when compared to F1 and F2. When F2 was loaded on top of F1-F3 combination, it further relieved nasal deviation without incurring significant increase in stress. Our simulation suggested that alar base adduction, columella straightening, and nasal tip elevation should all be included in a competent cleft lip nose correction.

Mechanical analyses of critical surgical maneuvers in the correction of cleft lip nasal deformity

The relapse of nasal deformity is a challenge for modern correction of cleft lip. A comprehensive understanding in the biomechanical perspective of both the formation and correction of the cleft lip nasal deformity would lead to improved stability of the corrective outcome. In this study, a finite element model of secondary cleft lip nasal deformity was constructed, on which two critical corrective maneuvers were mimicked in the form of force-loading. The intercrural suture was simulated by a force loaded at the intermediate crus of the alar cartilage directing anteriorly and medially, and the suture suspending the alar cartilage to the upper lateral cartilage was simulated by a force loaded at the lateral crus directing superiorly and medially. The equivalent von-mises stress and the total deformation consequent to different patterns of loading were captured. Our biomechanical analyses suggested that the intercrural suture at the nasal tip might be more effective in generating widespread morphological change than the suspension suture, but left much higher level of stress within the skin envelope if placed too high. Synergistic effect was observed between the two sutures in both the resultant deformation and stress. In addition, our simulations were partially supported by clinical photogrammetry data.

Advances in Technology for Functional Rhinoplasty: The Next Frontier

Advances in computer modeling and simulation technologies have the potential to provide facial plastic surgeons with information and tools that can aid in patient-specific surgical planning for rhinoplasty. Finite element modeling and computational fluid dynamics are modeling technologies that have been applied to the nose to study structural biomechanics and nasal airflow. Combining these technologies with patient-specific imaging data and symptom measures has the potential to alter the future landscape of nasal surgery.

Finite Element Model and Validation of Nasal Tip Deformation

Nasal tip mechanical stability is important for functional and cosmetic nasal airway surgery. Palpation of the nasal tip provides information on tip strength to the surgeon, though it is a purely subjective assessment. Providing a means to simulate nasal tip deformation with a validated model can offer a more objective approach in understanding the mechanics and nuances of the nasal tip support and eventual nasal mechanics as a whole. Herein we present validation of a finite element (FE) model of the nose using physical measurements recorded using an ABS plastic-silicone nasal phantom. Three-dimensional photogrammetry was used to capture the geometry of the phantom at rest and while under steady state load. The silicone used to make the phantom was mechanically tested and characterized using a linear elastic constitutive model. Surface point clouds of the silicone and FE model were compared for both the loaded and unloaded state. The average Hausdorff distance between actual measurements and FE simulations across the nose were 0.39 ± 1.04 mm and deviated up to 2 mm at the outermost boundaries of the model. FE simulation and measurements were in near complete agreement in the immediate vicinity of the nasal tip with millimeter accuracy. We have demonstrated validation of a two-component nasal FE model, which could be used to model more complex modes of deformation where direct measurement may be challenging. This is the first step in developing a nasal model to simulate nasal mechanics and ultimately the interaction between geometry and airflow.

Redefining the Septal L-Strut to Prevent Collapse

During septorhinoplasty, septal cartilage is frequently resected for various purposes but the L-strut is preserved. Numerous materials are inserted into the nasal dorsum during dorsal augmenation rhinoplasty without considering nasal structural safety. This study used a finite element method (FEM) to redefine the septal L-strut, to prevent collapse as pressure moved from the rhinion to the supratip breakpoint on the nasal dorsum and as the contact percentage between the caudal L-strut and the maxillary crest changed. We designed a 1-cm-wide L-strut model based on computed tomography data. At least 45% of the width of the L-strut in the inferior portion of the caudal strut must be preserved during septoplasty to stabilize the septum. In augmentation rhinoplasty, the caudal L-strut must either be preserved perfectly or reinforced to prevent collapse or distortion of the L-strut. The dorsal augmentation material must be fixed in an augmentation pocket to prevent movement of graft material toward the supratip breakpoint, which can disrupt the L-strut. We conducted a numerical analysis using a FEM to predict tissue/organ behavior and to help clinicians understand the reasons for target tissue/organ collapse and deformation.