It was observed that the degenerative changes in the condylar cartilage of the mice were significantly alleviated, suggesting that β-catenin is a key gene that triggers TMJOA, which can mediate osteoarthritis lesions by promoting the expression of Mmp13 and Adamts5. Transgenic mice with specifically activated β-CATENIN in chondrocytes also showed weakened Alcian blue staining of the mandibular condylar cartilage, reduced number of superficial chondrocytes, increased number of deep hypertrophic chondrocytes, and severe morphological defects on the joint surface. The gene discussed is MMP13; the disease is osteoarthritis.