With the implementation of untargeted metabolomics method for the first time, obesity and osteoarthritis show significant associations and obesity is the reason behind having acidosis and oxidative stress among arthritic patients.

Fourteen osteoarthritic patients with obesity (OKOA), 14 non-obesity (NOKOA) and 15 control from orthopaedics and traumatology policlinic were selected and assessed for serum samples. Acetonitrile was used to denature the proteins, and then LC/Q-TOF/MS/MS method was applied to attain chromatographic separation of metabolites. Data was retrieved, classified and identified using the METLIN database. MATLAB2017a-PLS Toolbox 7.2 was used to execute cluster analysis.

The 274 (OKOA vs NOKOA) and 244 (patient vs control) m/z ratios were defined in accordance with LC/Q-TOF/MS/MS analysis. 36 and 41 m/z signal were separated for control vs patient group and NOKOA  vs OKOA, respectively. The OKOA vs NOKOA group exhibited 15 metabolites, and patient vs control group identified 21 different metabolites. The inflammatory group showed high levels of oxidative stress and acidosis, which were much higher during obesity. The only branched-chain amino acid (BCAA) molecule whose concentration has considerably varied among KOA patients was valine. The metabolomics method shows an important relationship between KOA and obesity.