Histological evaluation of osteochondral defects: consideration of animal models with emphasis on the rabbit, experimental setup, follow-up and applied methods.

Regardless of their etiology, cartilage defects of articular joints remain one of the unsolved problems in medicine. Therefore, numerous techniques to enhance cartilage repair are under clinical or experimental investigation. In any serious approach experimental investigation should precede human application. If the decision is made to implement an animal model, which one should be used? What is a good experimental animal for osteochondral defects? Can chondral defects be evaluated? What is the critical size of the defect? How long should the experiment last? Which histological techniques should be used? What are the pitfalls when evaluating osteochondral defects histologically? What is the best scoring system? All these questions will be addressed to provide concise information on this topic with particular attention being paid to the rabbit as an experimental animal. Biotechnological techniques of investigation are developing rapidly. Hence special emphasis is placed on principles and reliable morphological examination.