Custom Laser-Cut Silastic® Implants for Type I Thyroplasty in a Preclinical Model

Abstract

This study aimed to produce customized silicone elastomer implants of varied size and shape for optimization of type I thyroplasty procedures in a rabbit model. Computer-aided design models of different implant designs were designed and used to program laser cutting of a medical-grade Silastic® sheet. Laser-cut implants were produced rapidly and cost-efficiently. Surgical implantation demonstrated vocal fold medialization and phonation in 5 test subjects. This technique may provide a low-cost alternative or adjunct method to hand-carving or commercial implants.

Keywords: Implant; Laser cut; Silastic; Thyroplasty.

Fig. 1.. Development and Implementation Laser-cut silicone elastomer implants.

a. CAD representation of implants created using Tinkercad to create 4 distinct implant shapes and sizes. S1D1 (light blue): rectangular 1 mm × 1 mm × 2 mm; S1D2 (dark blue): rectangular 1 mm × 2 mm × 2 mm; S2D1 (light yellow): tetrahedral 1 mm × 1 mm × 2 mm; S2D2 (dark yellow): tetrahedral 1 mm × 2 mm × 2 mm. An Epilog Zing 24 laser-cutting used parameters from these CAD models to create implants from medical-grade silicone elastomer non-reinforced sheeting. b. Calipers were used to confirm dimensions of laser-cut implants and compare with CAD models for accuracy. Specific example demonstrates accuracy of width in a S1D1 rectangular 1 × 1 × 2 mm implant. c. ex vivo MRI image in axial view of unilaterally implanted rabbit vocal fold with S1D1 rectangular 1 × 1 × 2 mm implant. d. in vivo laryngoscopic image of unilateral implanted rabbit vocal fold with S1D1 rectangular 1 × 1 × 2 mm implant.

Fig. 2.. Vocal fold medialization from implant using one sample as an example.

Model reconstructions in axial orientation with anterior at the bottom of the field and posterior at the top of the field. a-b. Reconstruction of the larynx at paramedian before implantation; c. Reconstruction of the vocal fold cover layer at paramedian before implantation; d-e. model reconstruction of the larynx after implantation; f. model reconstruction of the vocal fold cover layer after implantation; g. vocal fold cover comparisons before and after implantation; h. definitions of quantitative parameters to evaluate vocal fold adduction.