3D printing from micro-CT images of the trochlea of the superior oblique muscle and its future applications

Abstract Purpose: To determine the detailed microstructure modeling of the trochlea of the superior oblique muscle (SOM) using micro-computed tomography (micro-CT) and to model a potential prototype for a trochlea implant using three-dimensional (3D) printing. Methods: We dissected 15 intact orbits of 15 embalmed cadavers. The trochleae of the SOM were detached from the periosteum. The specimens were stained by immersion in a 15% Lugol’s solution. Images were reconstructed using conventional scanner software. Measurement points were determined for the middle cross section. Points P1 and P2 were selected where the SOM adjoined the curvature of the inner trochlea. They defined the inner contact points of the SOM in the inner part of the trochlea curvature. On the back of the trochlea, points P3 and P4 were selected at the uppermost and lowest points in the inner parts of the straight trochlea, respectively. Origin O was defined on the arcuate line of P1P2 to generate the smallest-diameter circle consisting of P1, O, and P2. We then measured the angle from OP1 to OP2, and from OP3 to OP4. We also measured the distances OP1, OP2, OP3, and OP4 for the design of a potential trochlea implant prototype using 3D-printing and micro-CT-based modeling. Results: The distances OP1, OP2, OP3, and OP4 were 2.2±0.7, 1.4±0.5, 2.7±0.9, and 2.5±0.4 mm (mean±SD), respectively. The angles from OP1 to OP2, from OP2 to OP4 and from OP3 to OP4 were 100.7±14.4, 66.3±18.0, and 98.9±24.9 degrees, respectively. Conclusions: High-resolution CT is a powerful imaging technique for defining the true 3D geometry of a specimen and can potentially be used to create a 3D-printed trochlea implant.