HISTOLOGIC EVALUATION OF AURICULAR CARTILAGE GRAFTS AFTER DISKECTOMY IN THE RABBIT CRANIOMANDIBULAR JOINT

Purpose: The clinical use of auricular cartilage grafting after discec tomy has been reported as a treatment in the terminal stage of interna l derangement of the temporomandibular joint (TMJ). Although the occur rence of fibrous adhesions has been observed in such grafted joints, t he exact tissue reaction to the graft is still not understood. The pur pose of this study was to evaluate the histologic changes after discec tomy and auricular cartilage grafting in the rabbit craniomandibular j oint (GMJ). Materials and Methods: Unilateral discectomy of the left C MJ was performed in 28 Japanese white rabbits, Auricular cartilage har vested from the ipsilateral ear was grafted as a disc replacement in 1 4 animals (Group C), and the other 14 underwent wound closure immediat ely after discectomy (Group B). Two other rabbits (Group A) served as nonsurgically treated controls. Two rabbits from each experimental gro up were killed at 2, 4, 6, 8, 10, 12, and 24 weeks postoperatively, Mi croscopic observation of the specimens was performed in the parasaggit al plane. Results: Complete resorption of the cartilage layer on the a rticular surface was observed within 4 weeks postoperatively in group B, Regeneration of a fibrous cartilage layer was observed in this grou p after 6 weeks, but the postoperative degenerative changes were so se vere that the surface of the condyle and eminence was flattened. In co ntrast, the degenerative changes were milder in group C, although the grafted cartilage showed perforation and fragmentation from the sixth postoperative week onward. The condylar shape and cartilage layer were well preserved at all times. Conclusions: These results suggest that the structure and function of the condyle may be preserved by auricula r cartilage grafting after discectomy. However, the problems of adhesi on and fragmentation need to be addressed.