Patient-specific 3D Models for Autogenous Ear Reconstruction.

Autogenous ear reconstruction remains one of the formidable procedures in plastic surgery. Precise 3-dimensional (3D) sculpting of the auricular construct is central to an operation, which requires countless patient experiences to hone one’s surgical skill. Current methods to autogenous ear construction entail tracing the contralateral (unaffected) ear, if available, and using this 2D outline as a surgical model. Unfortunately, these flat tracings have limitations as a model for one of the more elegant structures of the head and neck.

Our reconstructive team has leveraged departmentally available 3D photography, software platforms, and 3D printers to create sterilized patient-specific models for microtia reconstruction.[1] A 3D photograph of the unaffected ear (3dMD, Atlanta, Ga.) of a patient with unilateral microtia was uploaded into Amira (FEI Company, Hillsboro, Ore.) and transformed to a digital (.stl) model. After rendering the (.stl) model of the ear, it was imported into Blender (The Blender Foundation, Amsterdam, The Netherlands), where it was inverted along its vertical axis to create a working template of the contralateral ear. The depths of the scapha, triangular fossa, and cymba were deepened to accentuate these contours. Additional relief was added to the helical root to further define this structure. The final template was digitally separated to create the requisite auricular components for the Nagata technique reconstruction: helix; antihelical fold with the superior and inferior crus; base frame.[2] The patient had an intact tragus. The helix was digitally straightened to optimize its use as a surgical model. The completed auricular models were individually 3D printed (Builder Premium 3D Printer, Builder 3D Printers, Noordwijkerhout, The Netherlands) using a polylactic acid filament and sterilized following manufacturer’s specifications (121°C for 1 hour and 30-minute dry cycle).[3]

On the day of surgery, these sterilized, patient-specific 3D models were brought to the operating room and placed with the ear sculpting tools. The sterilized models were placed on the cartilage grafts and the forms and relief of the auricular model were easily appreciated and incorporated into the construct. Compared with the classic auricular tracings also present during this surgery (Fig. 1), these 3D printed models contained more detailed anatomic information which eliminated much of the guesswork from auricular reconstruction and resulted in a more efficient and precise operation (Fig. 2).

Fig. 1.

Classic auricular tracings alongside 3D printed models used during surgery.

Fig. 2.

Completed autogenous auricular construct with patient- specific 3D models.

The time of digital preparation was 5 hours. Total cost of manufacturing was $0.78. The cost of commercial manufacturing of similar constructs is approximately $3000. It is notable that we utilized hardware, expertise, and software platforms existing within our department, limiting cost to the polylactic acid filament. Surgeons who do not have access to these resources will not have the same degree of efficiency experienced by our group. However, we note that these resources are commonly present in academic medical centers and, therefore, are feasible starting points for the development of these models. 3D printers are becoming increasingly affordable, the filament is inexpensive, and the amount of digital manipulation needed to construct the presented models is straightforward. We believe this technique is feasible and reproducible by others and potentially in the community setting.