Inflammation Is More Distinct in Temporomandibular Joint Osteoarthritis Compared to the Knee Joint

Purpose: Most of the current understanding of articular cartilage maintenance and degradation is derived from large load-bearing synovial joints, in particular the knee joint. The aim of this study was to identify valuable degradation markers for cartilage degradation in the temporomandibular joint (TMJ) by comparing the relative concentrations of carboxyterminal telopeptides of collagen types I and II (CTX-I and CTX-II), cartilage oligomeric matrix protein (COMP), and prostaglandin E-2 (PGE(2)) in synovial fluid (SF) of TMJ and knee joints with cartilage degradation. Materials and Methods: In this cross-sectional comparative study, participants were recruited from the University Medical Center Groningen, The Netherlands. Patients with TMJ osteoarthritis were compared with patients with knee osteoarthritis. The outcome variables were the relative SF concentrations of CTX-I, CTX-II, COMP, and PGE(2). An independent samples Mann-Whitney U test was used to compare the relative concentrations. Results: Thirty consecutive patients (9 male, 21 female; mean age, 40.1 yr; standard deviation, 15.3 yr) with TMJ osteoarthritis and 31 consecutive patients (20 male, 11 female; mean age, 37.4 yr; standard deviation, 13.7 yr) who were scheduled for arthroscopy of the knee joint participated in this study. Significant differences were found between relative concentrations of COMP (P = .000) and PGE(2) (P = .005), and no significant differences were found between relative concentrations of CTX-I (P = .720) and CTX-II (P = .242). Conclusions: Relative SF concentrations of COMP and PGE(2) showed significant differences between the TMJ and the knee joint, suggesting that there are differences in pathophysiology and that the inflammatory component may be more distinct in the TMJ. (C) 2014 American Association of Oral and Maxillofacial Surgeons