Objectives Knee injury and Osteoarthritis Outcome Score (KOOS)-Child is a modification of the adult KOOS aiming to evaluate knee injury, including ACL deficiency. However, the measurement properties of KOOS-Child have not been assessed in a cohort of children with ACL deficiency. We aimed to study the structure of KOOS-Child using modern test theory models (Rasch analysis and confirmatory factor analysis (CFA)). Methods Data were collected prospectively in a cohort of children with ACL deficiency at three time points: before-and-after ACL surgery, and at 1-year follow-up. For each subscale, structural validity through the fit of a CFA model was evaluated for 153 respondents. Modification indices were examined to find the model of best fit, confirmed using Rasch analysis. Responsiveness was reported for each subscale. Reliability was calculated for each item. Floor and ceiling effects, and Person-item distribution were reported. Results All subscales showed inadequate fit to a unidimensional CFA model. Rasch analysis confirmed these results. Adjusting the subscales improved model fit, although this was still quite poor, except for the quality of life subscale. With one exception, all items demonstrated ceiling effects. Person-item distribution confirmed this. Due to lack of fit, reliability was not reported. All subscales were able to detect change from baseline to 1-year follow-up. Conclusions KOOS-Child exhibits inadequate measurement properties in its current form for children with ACL deficiency. Suggestions to make the subscales fit the models better and improve accuracy of KOOS-Child are presented. However, the large ceiling effects observed may reduce sensitivity and induce type 2 errors. Data are available on reasonable request.

中文翻译：

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KOOS-Child 在 ACL 缺陷儿科患者队列中的结构有效性不足

目标 膝关节损伤和骨关节炎结果评分 (KOOS) - 儿童是对成人 KOOS 的修改，旨在评估膝关节损伤，包括 ACL 缺陷。然而，尚未在 ACL 缺陷儿童队列中评估 KOOS-Child 的测量特性。我们旨在使用现代测试理论模型（Rasch 分析和验证性因素分析 (CFA)）研究 KOOS-Child 的结构。方法 在三个时间点前瞻性地收集 ACL 缺陷儿童队列的数据：ACL 手术前后以及 1 年的随访。对于每个分量表，通过拟合 CFA 模型对 153 名受访者进行了结构有效性评估。检查修改指数以找到最佳拟合模型，并使用 Rasch 分析确认。报告了每个分量表的响应度。计算每个项目的可靠性。报告了地板和天花板效应，以及人-项目分布。结果 所有分量表都显示出不适合一维 CFA 模型。Rasch 分析证实了这些结果。调整子量表改善了模型拟合，尽管这仍然很差，除了生活质量子量表。除了一个例外，所有项目都表现出天花板效应。个人物品分布证实了这一点。由于缺乏拟合，未报告可靠性。所有分量表都能够检测到从基线到 1 年随访的变化。结论 KOOS-Child 目前的形式对 ACL 缺陷儿童的测量性能不足。提出了使分量表更好地拟合模型并提高 KOOS-Child 准确性的建议。然而，观察到的大上限效应可能会降低灵敏度并引发 2 类错误。可根据合理要求提供数据。