(C-92) Nonsurgical Treatment for Nasal Septal Perforations by Utilizing 3D Printing for Individualized Silicone Prosthetic Closure

Nasal septal perforation is defined as a full-thickness defect through the nasal septum across the bilateral mucoperichondrial leaflets and the septal cartilage, most commonly occurring across the anterior cartilage. Nasal septal perforation was found to have a 2.05% prevalence rate in urban hospitals and has a variety of etiologies, symptoms, and both surgical and nonsurgical treatment options. 

As an alternative to surgical treatment, nasal septal buttons have been utilized as a prosthetic closure treatment. 3D printed, patient-specific silicone nasal septal buttons have been used as a nonsurgical treatment for nasal septal perforations including patients with large or irregular perforations. Custom-fitted silicone button prosthetics have been proven to be more effective and comfortable than commercial, uniformly shaped prosthetics for large and irregular perforations as it could fit exactly to the patient’s nasal anatomy, increasing their retention rate compared to that of commercial, non-patient-specific nasal septal buttons. Usage of patient CT (Computed Tomography) scans and 3D printing technology has been used to manufacture 342 patient-specific silicone buttons for nasal septum perforation closure at Mayo Clinic since 2013 and there have been developments and innovations to this process.

High-quality patient CT scans were transformed into a 3D digital model and were segmented using Analyze (Biomedical Imaging Resource; Mayo Clinic, Rochester, MN). Scans are initially loaded into Analyze 12.0 and saved to a database. After a 3D volume visualization of the CT scans, the volume is segmented to show the nasal septal perforation and surrounding tissue. The virtual model is then exported to an STL file and printed using a Stratasys Objet 260 Connex 3 Printer (Stratasys, Eden Prairie, MN). The 3D printed model can then be delivered to an engineering and prosthetics team such that a silicone prosthetic can be created. 

Upon arrival at the prosthetics department, the 3-D model is assessed and trimmed, if necessary, to expose the edges of the septal perforation more effectively for the casting process. The trimmed 3-D model is duplicated using dental impression materials made of dental compound. This duplication resulted in a cast that possessed the required durability to withstand the heat and pressure involved in creating the silastic prosthesis. The mold is placed in a press within a dry heat oven, where it remains overnight at 180°F. Afterward, the finished prosthesis was carefully removed. The prosthesis is positioned in close conformity to the template.  Subsequently, it undergoes thorough trimming, cleaning, and sterilization prior to insertion. 

Results: 

Since 2013, 342 patients were treated for nasal septal perforations at Mayo Clinic with a patient-specific, customized septal prosthesis. For 230 patients receiving a silicone button prosthetic from 2017 and onwards, perforation size and shape for each patient were measured using sagittal views of patient CT scans. 10 patients came back for additional treatment. The ages of these patients ranged from 11 and 81. 86 patients were male, and 144 patients were female. Metrics taken included perforation area, perimeter, and circularity. Circularity is measured by the ratio of the perimeter squared to the area divided by 4*pi. This value is equal to 1 for a perfect circle. 

For the 230 patients studied, the mean, median, and standard deviation perforation area were 658.1829, 191.67, and 1149.1 mm^2 respectively, and the mean, median, and standard deviation perforation circularity were 1.2308, 1.1793, and 0.1900 respectively. 

For a case series of 21 patients, the retention rate of the nasal septal prostheses was recorded to be 90% (19/21 patients chose to keep the prosthesis in place and reported a reduction in symptoms.  

Discussion: 

Mayo Clinic has implemented a process to fabricate nasal septal prosthetics by utilizing a 3D printing and silicone molding workflow to treat nasal septal perforations. Establishment and utilization of a point-of-care workflow process to manufacture patient-specific nasal septal prosthesis increases the accessibility of this nonsurgical treatment option to a larger variety of patients and a larger patient population. 

Patient-specific nasal septal prosthetics also serve the advantage of being able to treat large and irregular nasal septal perforations, which are difficult to attain successful surgical closure and non-patient-specific septal button closure on, as well as regular perforations. 

Conclusion: 

Patient-specific, customized nasal septal buttons have been shown to be extremely effective as a nonsurgical treatment option for nasal septal perforations through effective prosthetic closure and symptom reduction for a variety of perforation shapes and sizes. 3D printing and modeling technology can be utilized at the point of care to optimize the quality of patient care by improving the accessibility of patient-specific nasal septal buttons.