Background: The aims of this study were to assess the anti-degenerative effects of pioglitazone and to compare these effects with those of methylprednisolone and hyaluronic acid on drug-induced osteoarthritis in rabbits' temporomandibular joint cartilage.
Material and methods: The experiment was conducted on 40 Californian white rabbits. Degenerative changes were induced by intra-articular injections of papain. Subsequently, all of the animals were randomly assigned to one of four groups: 1) a control group that received no medications; 2) a group treated with 4 intra-articular injections of 2 mg (0.2 ml) of hyaluronic acid at weekly intervals; 3) a group treated with 4 intra-articular injections of 2 mg (0.1 ml) of methylprednisolone at weekly intervals; 4) a group administered pioglitazone orally in daily doses of 2 mg/kg of body weight. Four weeks after the beginning of drug administration, the rabbits were sacrificed. Sagittal sections of the intra-articular cartilage (discs) and mandibular condyles were stained with hematoxylin and eosin by the PAS technique and with van Gieson's solution. Histologic examinations, as well as cartilage thickness and number of cell layers measurements, were performed.
Results: Histologic assessment in cases of arthritis-associated pathologies revealed that changes occurred most frequently in the control group and least frequently in the pioglitazone group. There were no differences in the histological structures of the intra-articular discs. Cartilage thickness measurements demonstrated the thinnest cartilage in group 2 and the thickest in group 3. Analysis of cell layer numbers showed the most numerous layers in the pioglitazone group and the least in the control group.
Conclusion: Pioglitazone and hyaluronic acid showed anti-degenerative properties compared to methylprednisolone in an animal model.