Osteoarthritis (OA) is the most common joint disorder in the United States, affecting approximately 10% of men and 13% of women aged 60 years or older. The prevalence is expected to increase due to population aging and the obesity epidemic. OA is characterized by a multifactorial etiology, influenced by both systemic and local factors. Key risk factors include old age, female gender, overweight and obesity, knee injury, repetitive joint use, bone density, muscle weakness, and joint laxity. Modifying these factors may reduce the risk of OA and prevent subsequent pain and disability. Radiographic, clinical, and genetic definitions of OA are used to describe its distribution and risk factors. The prevalence of radiographic knee OA varies across studies, ranging from 19.2% to 27.8% in adults aged 45 years or older. Symptomatic OA is defined by the presence of pain, aching, or stiffness in a joint with radiographic evidence of OA. Risk factors for symptomatic OA include gender, race/ethnicity, genetic predisposition, diet, obesity, injury, occupation, physical activity, mechanical factors, alignment, and laxity. Understanding these risk factors can help in the development of new interventions and preventive strategies.Osteoarthritis (OA) is the most common joint disorder in the United States, affecting approximately 10% of men and 13% of women aged 60 years or older. The prevalence is expected to increase due to population aging and the obesity epidemic. OA is characterized by a multifactorial etiology, influenced by both systemic and local factors. Key risk factors include old age, female gender, overweight and obesity, knee injury, repetitive joint use, bone density, muscle weakness, and joint laxity. Modifying these factors may reduce the risk of OA and prevent subsequent pain and disability. Radiographic, clinical, and genetic definitions of OA are used to describe its distribution and risk factors. The prevalence of radiographic knee OA varies across studies, ranging from 19.2% to 27.8% in adults aged 45 years or older. Symptomatic OA is defined by the presence of pain, aching, or stiffness in a joint with radiographic evidence of OA. Risk factors for symptomatic OA include gender, race/ethnicity, genetic predisposition, diet, obesity, injury, occupation, physical activity, mechanical factors, alignment, and laxity. Understanding these risk factors can help in the development of new interventions and preventive strategies.