A Refined and Clinically more Relevant, Preclinical Osteochondral Defect Model in Rabbits

Introduction: An osteochondral defect in the femoral trochlear groove of the rabbit is a well-described animal model to study cartilage regeneration and repair. Current models are performed via open arthrotomy. The objective of this study was to evaluate if the use of arthroscopy in this model will reduce the animal burden and also decrease the effects of the surgical approach on the study outcome.

Materials and Methods: Twelve New Zealand White Rabbits were used for this study. In six rabbits (group 1), an osteochondral defect was created in the medial trochlear ridge of the femur with arthroscopic technique. In the remaining six rabbits (group 2), the same defect was created via open arthrotomy. The effect of the surgical procedure on general condition and activity of the rabbits was monitored. After euthanasia and macroscopic evaluation of the operated stifle joint, the distal femora were fixed and processed for histology.

Results: Creation of a standardized defect was possible in 11 out of 12 rabbits. Clinically and on video evaluation no difference in behavior between the two groups was observed. In the macroscopic cartilage repair assessment ICRS group 1 reached a grade II; nearly normal, the score of Group 2 correlated with grade III; abnormal. Statistical results from the activity tracking and histology are pending.

Discussion/Conclusion: A standardized osteochondral defect in the trochlear ridge of the femur can be created arthroscopically in rabbits. Both rabbit groups showed normal behaviour after surgery. The macroscopic cartilage repair assessment ICRS showed a better overall repair in the arthroscopic group.

Acknowledgement: The study was financed by AO Trauma.