AN ANIMAL-MODEL FOR STUDYING MECHANISMS IN HUMAN TEMPOROMANDIBULAR-JOINT DISC DERANGEMENT

Purpose: A method for producing disc displacement is presented in whic h remodeling events in the disc and posterior attachment (PA) are simi lar to those occurring in patients suffering from disc displacement (D D). Method: Thirty-three adult New Zealand White rabbits were used in this study. A unilateral anterior DD was surgically induced in 18 anim als. Six animals were sham operated and nine animals served as control s. Results: Macroscopically, DD was associated with gross thickening o f the posterior band (PB), shortening of the disc anteroposteriorly, f lexure of the intermediate zone (IZ), and loss of the biconcave shape. Microscopically, dramatic internal structural changes were observed i n displaced discs, including extensive collagenous fiber reorganizatio n and changes in cell morphology associated with a generalized loss of metachromatic staining. As in humans, the disc displacement caused ab normal loading of the PA and remodeling of this tissue into a disc-lik e structure characterized by the appearance of coarse collagenous fibe r bundles and scattered chondrocytes surrounded by a matrix-containing cartilage-like glycosaminoglycans (GAGs). Conclusion: These pathoanat omic changes bear a remarkable similarity to those described in human disc derangements and support the use of this method as an experimenta l model for the study of remodeling events in human DD arthropathies.