PURPOSE A few new criteria for early detection and prevention of early knee osteoarthritis (EKOA) have been proposed. However, its prevalence, risk factors, relationship with function and prognosis have not been clarified. The purpose of this study was to investigate the prevalence of EKOA and its risk factors in the Japanese general population. METHODS A total of 1104 volunteers (443 males, 661 females) who participated in the Iwaki cohort study in Japan were enrolled in this cross-sectional study. Their bilateral weight-bearing anterior-posterior knee radiographs were classified by Kellgren-Lawrence (KL) grade. EKOA (KL grade 0/1) was defined according to the following criteria: knee injury and osteoarthritis outcome score < 85%, joint line tenderness, and crepitus and its prevalence among age-sex groups was calculated. Logistic regression analyses were performed to determine the risk factors for EKOA. RESULTS Eight hundred and twenty-two participants had KL grade 0/1, and the EKOA prevalence was 9.5% in males and 15.0% in females (p = 0.011). The prevalence of EKOA increased with age. The highest prevalence was noted in females aged 50-59 years. Logistic regression analysis showed that the risk factors for EKOA were age (p < 0.001, odds ratio (OR) 1.1), female sex (p = 0.002, OR 2.5), high body mass index (p < 0.001, OR 1.2), and history of knee injury (p < 0.001, OR 21.7). CONCLUSIONS The highest EKOA prevalence was observed in middle adult females (50-59 years old). The risk factors for EKOA were female sex, ageing, obesity and knee injury history, which were extremely similar to those of definitive knee osteoarthritis. LEVEL OF EVIDENCE Level I in diagnostic studies-investigating a diagnostic test.

中文翻译：

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根据来自日本普通人群的大量样本研究得出的一组新的诊断标准，肥胖的中年成年女性中，早期膝骨关节炎的患病率最高。

目的已经提出了一些新的早期发现和预防早期膝骨关节炎的标准。但是，其患病率，危险因素，与功能的关系以及预后尚不清楚。这项研究的目的是调查日本普通人群中EKOA的患病率及其危险因素。方法参加本横断面研究的1104名志愿者（443名男性，661名女性）参加了日本的Iwaki队列研究。他们的双侧负重前后膝关节X线片按Kellgren-Lawrence（KL）等级分类。EKOA（KL 0/1级）是根据以下标准定义的：膝关节损伤和骨关节炎结局评分<85％，关节线压痛和刮pit，并计算了其在各年龄组之间的患病率。进行逻辑回归分析以确定EKOA的危险因素。结果822名参与者的KL等级为0/1，男性的EKOA患病率为9.5％，女性为15.0％（p = 0.011）。EKOA的患病率随年龄增长而增加。在50-59岁的女性中患病率最高。Logistic回归分析显示EKOA的危险因素为年龄（p <0.001，优势比（OR）1.1），女性（p = 0.002，OR 2.5），高体重指数（p <0.001，OR 1.2）和膝盖受伤的病史（p <0.001，或21.7）。结论在中年成年女性（50-59岁）中观察到EKOA患病率最高。EKOA的危险因素是女性，年龄，肥胖和膝盖受伤史，这与确定性膝骨关节炎极为相似。