Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA.
Department of Orthopedics and Traumatology, Paulista School of Medicine, Federal University of Sao Paulo, SP, Brazil.
Foot Ankle Int. 2022 Apr;43(4):582-589. doi: 10.1177/10711007211058154. Epub 2021 Dec 1.
Historical concept of flatfoot as posterior tibial tendon dysfunction (PTTD) has been questioned. Recently, the consensus group published a new classification system and recommended renaming PTTD to Progressive Collapsing Foot Deformity (PCFD). The new PCFD classification could be effective in providing comprehensive information on the deformity. To date, there has been no study reporting intra- and interobserver reliability and the frequency of each class in PCFD classification.
This was a single-center, retrospective study conducted from prospectively collected registry data. A consecutive cohort of PCFD patients evaluated from February 2015 to October 2020 was included, consisting of 92 feet in 84 patients. Classification of each patient was made using characteristic clinical and radiographic findings by 3 independent observers. Frequencies of each class and subclass were assessed. Intraobserver and inteobserver reliabilities were analyzed with Cohen kappa and Fleiss kappa, respectively.
Mean sample age was 54.4, 38% was male and 62% were female. 1ABC (25.4%) was the most common subclass, followed by 1AC (8.7%) and 1ABCD (6.9%). Only a small percentage of patients had isolated deformity. Class A was the most frequent component (89.5%), followed by C in 86.2% of the cases. Moderate interobserver reliability (Fleiss kappa = 0.561, < .001, 95% CI 0.528-0.594) was found for overall classification. Very good intraobserver reliability was found (Cohen kappa = 0.851, < .001, 95% CI 0.777-0.926).
Almost half (49.3%) of patients had a presentation dominantly involving the hindfoot (A) with various combinations of midfoot and/or forefoot deformity (B), (C) with or without subtalar joint involvement (D). The new system may cover all possible combinations of the PCFD, providing a comprehensive description and guiding treatment in a systematic and individualized manner, but this initial study suggests an opportunity to improve overall interobserver reliability.
Level III, retrospective diagnostic study.
平足（PTTD）的历史概念已受到质疑。最近，共识小组发布了一种新的分类系统，并建议将 PTTD 重新命名为进行性塌陷足畸形（PCFD）。新的 PCFD 分类系统可以有效地提供有关畸形的全面信息。迄今为止，尚无研究报告 PCFD 分类中观察者内和观察者间的可靠性以及各分类的频率。
这是一项单中心、回顾性研究，从前瞻性收集的登记数据中进行。纳入了 2015 年 2 月至 2020 年 10 月评估的连续 PCFD 患者队列，包括 84 例患者的 92 只脚。由 3 名独立观察者根据特征性临床和影像学发现对每位患者进行分类。评估了每个分类和子类别的频率。分别使用 Cohen kappa 和 Fleiss kappa 分析观察者内和观察者间的可靠性。
平均样本年龄为 54.4 岁，38%为男性，62%为女性。1ABC（25.4%）是最常见的子类，其次是 1AC（8.7%）和 1ABCD（6.9%）。只有一小部分患者有孤立性畸形。A 类是最常见的成分（89.5%），其次是 C 类（86.2%）。总体分类的观察者间可靠性中等（Fleiss kappa = 0.561， <.001，95%CI 0.528-0.594）。观察者内可靠性非常好（Cohen kappa = 0.851， <.001，95%CI 0.777-0.926）。
几乎一半（49.3%）的患者表现为后足（A）主要受累，伴中足和/或前足畸形（B）、（C）伴或不伴距下关节受累（D）。新系统可能涵盖 PCFD 的所有可能组合，以系统和个体化的方式提供全面的描述和指导治疗，但这项初步研究表明有机会提高总体观察者间可靠性。
三级，回顾性诊断研究。
