Metabolomics as a promising tool for early osteoarthritis diagnosis.

Osteoarthritis (OA) is the main cause of disability worldwide, due to progressive articular cartilage loss and degeneration. According to recent research, OA is more than just a degenerative disease due to some metabolic components associated to its pathogenesis. However, no biomarker has been identified to detect this disease at early stages or to track its development. Metabolomics is an emerging field and has the potential to detect many metabolites in a single spectrum using high resolution nuclear magnetic resonance (NMR) techniques or mass spectrometry (MS). NMR is a reproducible and reliable non-destructive analytical method. On the other hand, MS has a lower detection limit and is more destructive, but it is more sensitive. NMR and MS are useful for biological fluids, such as urine, blood plasma, serum, or synovial fluid, and have been used for metabolic profiling in dogs, mice, sheep, and humans. Thus, many metabolites have been listed as possibly associated to OA pathogenesis. The goal of this review is to provide an overview of the studies in animal models and humans, regarding the use of metabolomics as a tool for early osteoarthritis diagnosis. The concept of osteoarthritis as a metabolic disease and the importance of detecting a biomarker for its early diagnosis are highlighted. Then, some studies in plasma and synovial tissues are shown, and finally the application of metabolomics in the evaluation of synovial fluid is described.

Association between temporomandibular disorders and pain in other regions of the body.

The pain from temporomandibular disorder (TMD) is often associated with physical symptoms of other chronic pain disorders and comorbidities, such as generalised muscle and joint pain. However, this association is not widely studied. To evaluate the prevalence of comorbid pain in joints, specifically in the knees, hips, ankles, shoulders, wrists and elbows, in individuals with and without TMD. We evaluated 337 patients from a public hospital in the city of Rio de Janeiro, Brazil. The Research Diagnostic Criteria for TMD questionnaire were used for the diagnosis of TMD. To assess the presence of other joint pain, the patients were asked to answer questions considering: the presence of pain in the knee, hip, ankle, shoulder, wrist and elbow joints and time duration of pain. Individuals with TMD are 5·5 times more likely to present with other joint pain compared with those without the disorder. TMD muscle disorders were most associated with a higher number of pain at the other locations. There was a significant association between the presence of pain at the other locations, muscle (P < 0·001) and joint disorders (P = <0·001), as well as age advance, in TMD participants, showed to be a covariate factor for pain at the other locations. Individuals with TMD showed a high prevalence of pain in other joints of the body when compared with individuals without the disorder, and knee pain was the most prevalent pain complaint.