The Cricoarytenoid Joint Capsule and Its Relevance to Endotracheal Intubation Friedrich P. Paulsen, MD, Karl Jungmann, MD, and Bernhard N. Tillmann, MD Department of Anatomy, Christian Albrecht University of Kiel, Kiel, Germany Impaired movement of the cricoarytenoid joint with hoarseness and immobility of the vocal ligament may occur as a consequence of endotracheal intubation. Lit- tle is known about the cricoarytenoid joint capsule and its role in intubation. We investigated the joint capsules of 48 cricoarytenoid joints by means of gross anatomy microscopy, histology, and scanning electron micros- copy; 30 unfixed cadaver larynges were also subjected to attempts to simulate traumata such as those that may occur during intubation trials. The larynges were intu- bated with the arytenoid tip entering the lumen of the tracheal tube or extubated with the cuff of the tube only partially deflated. Subsequently, i.e., after dissecting the left and right cricoarytenoid joint from each larynx, the morphologic changes induced experimentally were analyzed by using histologic methods. The cricoaryte- noid joint was found to be lined by a wide joint capsule. Unexpectedly large and intensively vascularized syno- vial folds projected into the joint cavity. After simula- tion of intubation and extubation, histologic analysis revealed injuries to the synovial folds and joint surface impressions, but no trauma or rupture of the outer joint capsule. We conclude that laxity of the joint capsule and the large synovial folds are predisposing factors for in- tubation trauma of the cricoarytenoid joint, potentially leading to hemarthros and finally to cricoarytenoid joint dysfunction. Implications: The present study il- lustrates by morphological investigations and intuba- tion experiments that laxity of the joint capsule and large synovial folds are predisposing factors for intuba- tion trauma of the cricoarytenoid joint, potentially lead- ing to hemarthrosis and finally to cricoarytenoid joint dysfunction. (Anesth Analg 2000;90:180 –5) E ndotracheal intubation, laryngoscopy, bronchos- copy, and other invasive methods are often ap- plied to the respiratory tract, with the result that laryngeal complications are not uncommon. These complications include, for example, submucosal hemorrhage, granuloma formation, and subglottic edema or laryngitis with membrane formation and may be characterized by hoarseness or stridor. Other complications include impaired movement of one or both vocal folds caused by recurrent laryn- geal nerve damage, and/or cricoarytenoid joint (CAJ) dysfunction. The human CAJ can be involved in a number of different pathologic conditions. Trauma as described above, as well as joint diseases such as arthritis (1), osteoarthrosis (2) or rheumatoid arthritis (3) have all been reported to occur in the CAJ. Interestingly, and in contrast to the limb joints, publications elucidating the morphology of the CAJ capsule have, to date, been restricted to some investigations concerning the pos- terior CAJ ligament. Anatomically, the CAJ is a diarthrodial joint sup- ported by a wide joint capsule lined with synovia. The capsule is strengthened posteriorly by the cricoaryte- noid ligament. The structural arrangement of the joint allows two principal types of motion: a rocking or rotating movement around the axis of the joint, and a linear glide parallel to this axis (4). The function is to control the abduction, adduction, and length of the vocal cords, thereby facilitating respiration, protect the airway, and permit phonation. The present investigation analyzes the structure of the CAJ capsule and correlates the findings with the histology of the trauma associated with CAJ capsule damage that may occur after endotracheal intubation. We tried to simulate the forces induced by an endo- tracheal tube lumen extending into the CAJ capsule during intubation or extubation in unfixed human larynges. Results were discussed against the back- ground of the current understanding of CAJ dysfunc- tion subsequent to endotracheal intubation. Support was provided by a grant from the German Society of Otorhinolaryngology, Head and Neck Surgery. Accepted for publication September 20, 1999. Address correspondence and reprint requests to Dr. med. F. Paulsen, Department of Anatomy, Christian Albrecht University of Kiel, Olshausenstr. 40, 24098 Kiel, Germany. Address e-mail to fpaulsen@anat.uni-kiel.de. ©2000 by the International Anesthesia Research Society 180 Anesth Analg 2000;90:180–5 0003-2999/00