A biomechanical study of the human cricoarytenoid joint.

OBJECTIVES/HYPOTHESIS: To develop a model to investigate the biomechanics of the cricoarytenoid joint and establish stiffness, laxity, and range of motion of the cricoarytenoid joint in adult human larynges. STUDY DESIGN: Laboratory investigation of freshly frozen larynges from adult humans, measuring the stiffness, laxity, and range of motion in intact and injured cricoarytenoid joints. METHODS: Eight normal-appearing frozen cadaver larynges from adult humans were studied. The cricoid cartilage was fixed to a load cell sensitive to forces in three dimensions. A probe was rigidly fixed to the arytenoid cartilage and attached to a frame to allow active rotation, rocking, and gliding of the arytenoid. A computer program simultaneously recorded forces generated by these motions and tracked the motion of the arytenoid in three dimensions. The joint was studied before and after injury to the posterior cricoarytenoid ligament, and the joint surfaces were digitized after completion of these studies. RESULTS: A successful method of evaluating the biomechanical properties of the cricoarytenoid joint was developed. Comparing intact and injured joints confirmed that laxity and range of motion increased during rocking, gliding, and rotational motion when the cricoarytenoid ligament had been divided. Stiffness measurements for rocking, rotation, and gliding also were documented. CONCLUSIONS: The model of study introduced in this report provides a significant and unique method of investigating the biomechanics of the cricoarytenoid joint, allowing insight into the basic joint characteristics and alteration in joint biomechanics related to injuries and surgical procedures. Dividing the cricoarytenoid ligament increases laxity and range of motion in sagittal rocking, gliding, and axial rotation. Secondary constraints on the joint provide significant stiffness of greater degrees of displacement. Further studies should provide insight into the significant secondary elements supporting the joint and into the mechanisms of cricoarytenoid injuries, as well as the effect of surgical procedures on the cricoarytenoid joint.