Analysis of microarchitectural changes in a mouse temporomandibular joint osteoarthritis model

Objective: Little is known about the natural progression of the disease process of temporomandibular joint (TMJ) osteoarthritis (OA), which affects approximately 1% of the US population. The goal of this study was to examine the early microarchitectural and molecular changes in the condylar cartilage and subchondral bone in biglycan/fibromodulin (Bqn/Fmod) double-deficient mice, which develop TMJ-OA at 6 months. Methods: TMJs from 3-month-old (n = 44) and 9-month-old (n = 52) wild-type (WT n = 46) and Bgn/Fmod (n = SO) double-deficient mice were evaluated. Micro-CT analysis of the subchondral bone (n = 24), transmission electron microscopy for condylar cartilage fibril diameters (n = 26), and real-time PCR analysis for gene expression for bone and cartilage maturation markers (n = 45) was performed. Results: A statistically significant increase in collagen fibril diameter of the condylar cartilage and a decrease in expression of Parathyroid related protein in the mandibular condylar head were observed in the 3-month Bgn/Fmod double-deficient mice compared to WT controls. The 9-month Bqn/Fmod double-deficient mouse demonstrated an increase in bone volume and total volume in subchondral bone, and an increase in the expression of Collagen Type X and Aggrecan in the mandibular condylar head compared to the WT controls. Conclusion: We found that changes in the microarchitecture of the condylar cartilage preceded changes in the subchondral bone during CIA in the TMJ in Bqn/Fmod double-deficient mice. (C) 2009 Elsevier Ltd. All rights reserved.