Abstract: Objective To analyze the prevalence and influencing factors of knee osteoarthritis （KOA） in residents ≥ 40 years old in Zhangjiakou area. Methods The residents ≥ 40 years old in Zhangjiakou area were selected for questionnaire survey, their knee joints were examined with anteroposterior and lateral X‐ray. The prevalence of KOA was investigated, and the risk factors of KOA were analyzed with multivariate logistic regression. Results Among the 1 264 residents ≥ 40 years old in Zhangjiakou, 279 cases were finally diagnosed with KOA, and the prevalence rate was 22.07%. Multivariate logistic regression analysis showed that women （OR=2.248）, overweight/obesity （OR=1.389）, family history of KOA （OR=2.125）, history of knee surgery （OR=2.543）, combined diabetes （OR=3.426）, damp/dark living environment （OR=3.986）, and frequent stair climbing （OR=4.537） were independent risk factors for KOA in people ≥ 40 years old in Zhangjiakou area, and frequent eating seafood （OR=0.422） was a protective factor. Conclusions In Zhangjiakou, the prevalence rate of KOA is higher in residents ≥40 years old. Women, overweight/obese, family history of KOA, history of knee surgery, combined diabetes, damp/dark living environment, and frequent stair climbing residents should be considered as the high‐risk group for KOA prevention. It is recommended to ensure the consumption habit of seafood.

Key words: Knee osteoarthritis, Prevalence, Risk factor, Knee joint