Obesity, together with aging and injury, is among the main risk factors for osteoarthritis. Obesity-related osteoarthritis can affect not only the weight-bearing joints, but also the hands, suggesting a role for circulating mediators released by the adipose tissue and known as adipokines. Thus, osteoarthritis may have a systemic metabolic component. Evidence from both epidemiological and biological studies support the concept of metabolic osteoarthritis, defined as a broad clinical phenotype that includes obesity-related osteoarthritis. Thus, osteoarthritis can be related to metabolic syndrome or to an accumulation of metabolic abnormalities. In addition, studies have demonstrated associations linking osteoarthritis to several components of the metabolic syndrome, such as hypertension and type 2 diabetes, independently from obesity or any of the other known risk factors for osteoarthritis. Both in vitro and in vitro findings indicate a deleterious effect of lipid and glucose abnormalities on cartilage homeostasis. Chronic low-grade inflammation is a feature shared by osteoarthritis and metabolic disorders and may contribute to the genesis of both. Thus, osteoarthritis is emerging as a disease that has a variety of phenotypes including a metabolic phenotype, in addition to the age-related and injury-related phenotypes.