Mid-flexion instability (MFI) in total knee arthroplasty refers to a distinct clinical entity where the knee is stable at full extension and 90° of flexion, but unstable somewhere between these 2 points. The presentation of MFI is often vague, and studies defining objective clinical or intraoperative measurements are limited. In this review, we aim to properly define the condition, describe diagnostic criteria and risk factors contributing to MFI, review current implant design, and present outcomes of revision surgery performed for MFI. [Orthopedics. 20XX;XX(X):xx–xx.]

中文翻译：

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全膝关节置换术后屈曲中期不稳定：诊断、植入物设计和结果

全膝关节置换术中的屈曲中期不稳定 (MFI) 是指一种独特的临床实体，其中膝关节在完全伸展和 90° 屈曲时稳定，但在这两个点之间的某处不稳定。MFI 的表现通常很模糊，定义客观临床或术中测量的研究也很有限。在这篇综述中，我们的目标是正确定义该病症，描述导致 MFI 的诊断标准和风险因素，回顾当前的种植体设计，并介绍针对 MFI 进行的翻修手术的结果。[骨科。20XX;XX(X):xx–xx.]