Three-dimensional morphometric analysis of cricoarytenoid subluxation

Objectives: To create a high-resolution three-dimensional (3D) reconstruction of a case of cricoarytenoid subluxation and perform quantitative analysis to understand its anatomy and functional consequence. Study Design: Computational, with image processing and analysis. Methods: High-resolution axial computed tomography images of the larynx of a patient with an anteriorly subluxed arytenoid were processed with custom MATLAB routines to create a versatile 3D reconstruction. The geometries of the subluxed and nonsubluxed arytenoids were quantitatively compared. Results: The anteriorly subluxed arytenoid has an inferoposteriorly displaced vocal process (VP), resulting in an elongated and inferiorly positioned vocal fold. The paradoxical posterior displacement of the VP with elongation of the vocal fold has not been described previously. Quantitative analysis reveals significant rotational components and a unidirectional translational component in anterior arytenoid subluxation. Conclusions: Quantitative 3D analysis yielded insight into the biomechanics of anterior arytenoid subluxation. Subluxation in this case appeared to involve more pure rotational than translational motion. Overrocking of the subluxed arytenoid can produce paradoxical elongation of the involved vocal fold.