A New Perspective on the Relation Between Obesity and Knee Osteoarthritis: Omentin

Objective: Knee osteoarthritis (KOA) is defined as a chronic degenerative joint disease. Obesity is a significant risk factor for KOA. Omentin is an adipose tissue-induced adipokine. The aim of the present study was to investigate the correlation between obesity and serum omentin levels in patients with KOA. Methods: This study included 60 patients with KOA, 34 obese individuals (O-KOA) and 26 nonobese individuals (NO-KOA) and 40 controls, 17 obese individuals (OC) and 23 nonobese individuals (NOC) matched in terms of age, sex, and body mass index (BMI) who were recruited from the same polyclinic. Blood samples and knee radiographs were obtained from all the subjects, and clinical features, BMI, and laboratory parameters were recorded. The Kellgren–Lawrence (KL) grade and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index were used to classify the radiographic and clinical findings, respectively. Serum omentin levels were determined using an ELISA. Results: Serum omentin levels in patients were significantly lower than those in the controls (p < 0.05). When the BMI values and KL scores were considered, serum omentin levels significantly decreased in severe O-KOA versus in mild-to-moderate O-KOA. There was no statistically significant decrease in severe NO-KOA versus mild-to-moderate NO-KOA. There was a significant negative correlation between the serum omentin level and BMI and WOMAC index. All findings were supported by a receiver operating characteristic curve analysis. Conclusions: Serum omentin levels were inversely related to obesity and the severity of KOA. The data indicate that omentin may be a new biomarker of KOA to our knowledge and may aid the diagnosis of early-stage O-KOA, if our findings are supported by further studies involving much more samples.