3D Printing in Otology: Printed Grommets Enhance Treatment of Ear Infections

Tailored to Each Patient

In a recent study published in the journal 3D Printing in Medicine, a research team from the University of Guadalajara in Mexico focused on the potential of 3D printing for tympanostomy, specifically in the production of personalized tympanostomy tubes, also known as grommets or spools.

These are used in treating recurrent middle ear infections, typically in children. The Eustachian tube does not function adequately at such times, necessitating assistance in ventilating the space behind the eardrum. Doctors create an opening through the eardrum into the external auditory canal and insert a tympanostomy tube, which ensures long-term and effective air circulation.

Grommets range in size from 2–3 mm and are used either for short-term or long-term treatment. In both cases, they are usually made from three basic biocompatible materials: fluoroplastic, silicone elastomer, and metal. Their design has recently undergone several innovations, such as a safety feature to prevent accidental deep insertion into the ear.

More Shapes and Sizes

According to the Mexican scientists, it might now be time to also improve the manufacturing process itself. They decided to test whether the continuously improving 3D printing technology could be used. Compared to conventionally manufactured tubes, 3D printing could allow easier production of a larger variety of shapes and sizes, which would best suit the diverse anatomy of children. Previous research has shown that greater accuracy significantly reduces the risk of complications and shortens the treatment duration.

The initial goal of the current study was to verify whether biocompatible PLA filament (polylactic acid), which is very commonly used in 3D printing in healthcare, would be suitable for this use. For example, small surgical clips or screws that gradually degrade in the patient's body over time are printed from it, eliminating the need for their removal. Similarly, conventionally manufactured grommets also fall out of the eardrum on their own.

The research itself took place in two phases. In the first, scientists used computer modeling to design various types of materials, structural solutions, and printing configurations. They then printed five different grommet models on three commonly available 3D printers. In the second phase, the scientists tested the functionality of the printed gromets in vivo, using ten healthy Wistar strain laboratory rats. Five of them had the printed grommets inserted into their ears, while the remaining five served as a reference group.

Material and Printer Technical Limits

During the first phase, however, the scientists began to encounter the technical limits of the material and printers used. 3D printers are not intended for printing such small objects from PLA filament. In some configurations, the printed grommets were fragile and easily deformed. It also seemed that the gradual degradation of the biopolymer was damaging the inner ear of the test animals. Due to the short observation period, it was unclear whether this mild to moderate damage was permanent or transient.

One of the subsequent recommendations of the research team is therefore careful configuration of the printing process, or possibly the use of a different type of material. An alternative could be biocompatible printing resins, which are used, for example, in dentistry. However, their use in the inner environment of the ear has not yet been thoroughly investigated and will thus require further research.

The need for further research and testing in the area of 3D printing otological tools is thus emphasized by the researchers in the conclusion of their study. If successful, the main benefits, according to them, could be the ability to customize implants according to the anatomical characteristics of individual patients, faster production, and reduced financial costs.

Editorial Team, Medscope.pro

Source:

Govea-Camacho L. H., Castillo-López I. Y., Carbajal-Castillo S. A. et al. 3D printed ventilation tubes and their effect on biological models. 3D Print Med 2024 Jul; 10 (1): 22, doi: 10.1186/s41205-024-00225-y.