Histology of surgically removed overgrown osteochondral rib grafts

Introduction: Osteochondral rib grafts are most commonly used for mandibular condylar replacements. However, when used in growing patients, unpredictable growth of the constructed condyle/ramus is a common complication. Clinically two types of overgrowth, linear or exuberant, have been described. Purpose: In order to investigate growth disorders associated with osteochondral rib grafts in children, overgrown grafts were examined histologically. Patients and Methods: The material consisted of seven samples (six patients) of osteochondral rib grafts, that had been removed due to overgrowth. Results: Examination revealed that the clinical type of overgrowth was not related to any specific micro architecture, which in itself, showed considerable variation. In three of the samples, a typical endochondral ossification zone was seen and in two others, signs of metaplasia, i.e. a gradual transformation of the cartilage cells into osteocytes, were noted. Conclusions: The study reveals that the clinical type of overgrowth, linear or exuberant, cannot be related to any typical histological finding. Furthermore, the findings suggest that local factors, such as mandibular movements and loading of the reconstructed condyle may have an effect on the structure of the osteochondral rib graft, and eventually on its growth. (C) 2002 European Association for Cranio-Maxillofacial Surgery. Published by Elsevier Science Ltd. All rights reserved.