The study aimed to estimate the lifetime risk of symptomatic knee osteoarthritis (OA) among participants of the Johnston County Osteoarthritis Project, a longitudinal study of black and white women and men aged 45 years and older in rural North Carolina. The lifetime risk of developing symptomatic knee OA was found to be 44.7% (95% CI 40.0–49.3%), with higher risks observed among those with a history of knee injury (56.8%) and obesity (60.5%). The analysis used logistic regression models with generalized estimating equations to account for repeated measures and correlated errors. The study highlights the significant public health burden of knee OA, particularly in obese individuals, and underscores the need for public health interventions to manage weight and reduce the risk of OA.The study aimed to estimate the lifetime risk of symptomatic knee osteoarthritis (OA) among participants of the Johnston County Osteoarthritis Project, a longitudinal study of black and white women and men aged 45 years and older in rural North Carolina. The lifetime risk of developing symptomatic knee OA was found to be 44.7% (95% CI 40.0–49.3%), with higher risks observed among those with a history of knee injury (56.8%) and obesity (60.5%). The analysis used logistic regression models with generalized estimating equations to account for repeated measures and correlated errors. The study highlights the significant public health burden of knee OA, particularly in obese individuals, and underscores the need for public health interventions to manage weight and reduce the risk of OA.