Comparative study of osteoarthritis induced by monoiodoacetate and papain in rabbit temporomandibular joints: Macroscopic and microscopic analysis

Abstract

Background: Osteoarthritis (OA) is a chronic, progressive, degenerative pathology. Inducing OA in an animal model is useful for studying the pathology and testing the effectiveness of new treatments. The object of the present study was to determine the macroscopic and microscopic changes occurring in rabbit temporomandibular joints (TMJ) at 15, 30 and 45 days after induction of OA by monoiodoacetate (MIA) and papain. Materials and methods: Twenty two male rabbits were used in the experiment, divided into three groups: a control group (n = 4) and two experimental groups, MIA (n = 9) and papain (n = 9). The progress of the disease was analysed at 15, 30 and 45 days after induction of OA. Morphological and histological analyses were carried out of the joint disc and the mandibular condyle. Results: The most evident changes were expressed in the condyle and disc of joints with OA induced by MIA. The condyles presented deformation, fissures and loss of joint surface, the chondrocytes lost their morphology and organisation. In more advanced stages there was loss of the mid zone of the joint disc. Conclusions: The effects of papain were associated with condyle deformation, disorientation of the chondrocytes in the middle layer, and proliferation in deep zones; there was also an increase in the extracellular matrix. Both inductors generated changes in the TMJ and its joint surfaces; MIA was more effective and coincided more closely with the classic signs of the evolution of OA.