de Cesar Netto Cesar, Silva Thiago, Li Shuyuan, Mansur Nacime Salomao, Auch Elijah, Dibbern Kevin, Femino John E, Baumfeld Daniel
Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA.
Hospital Madre Teresa, Orthopedics, Belo Horizonte, MG, Brazil.
Foot Ankle Int. 2020 Oct;41(10):1190-1197. doi: 10.1177/1071100720936603. Epub 2020 Jun 26.
Adult acquired flatfoot deformity (AAFD) is a complex 3-dimensional pathology characterized by peritalar subluxation (PTS) of the hindfoot. For many years, PTS was measured at the posterior facet of the subtalar joint. More recently, subluxation of the middle facet has been proposed as a more accurate and reliable marker of symptomatic AAFD, enabling earlier detection. The objective of this study was to compare the amount of subluxation between the medial and posterior facets in patients with AAFD.
In this institutional review board-approved retrospective comparative study, a total of 76 patients with AAFD (87 feet) who underwent standing weightbearing computed tomography (WBCT) as a standard baseline assessment of their foot deformity were analyzed. Two blinded fellowship-trained orthopedic foot and ankle surgeons with >10 years of experience measured subtalar joint subluxation (as a percentage of joint uncoverage) at the both posterior and middle facets. One of the readers also measured the foot and ankle offset (FAO). PTS measurements were performed at the sagittal midpoint of the articular facets using coronal plane WBCT images. Intra- and interobserver agreement was measured for PTS measurements using the intraclass correlation coefficient (ICC). The intermethod agreement between the posterior and middle facet subluxation was assessed using Spearman's correlation and bivariate analysis. Paired comparison of the measurements was performed using the Wilcoxon test. A multivariate analysis and a partition prediction model were used to assess influence of PTS measurements on FAO values. values of <.05 were considered significant.
ICCs for intra- and interobserver reliabilities were 0.97 and 0.93, respectively, for posterior and 0.99 and 0.97, respectively, for middle facet subluxation. The intermethod Spearman's correlation between subluxation of the posterior and middle facets was measured at 0.61. In a bivariate analysis, both measurements were found to be significantly and linearly correlated ( < .0001; = 0.42). Measurements of middle facet subluxation were found to be significantly higher than those for posterior facet subluxation, with a median difference (using the Hodges-Lehman factor) of 17.7% ( < .001; 95% CI, 10.9%-23.6%). We also found that for every 1% increase in posterior facet subluxation there was a corresponding 1.6-fold increase in middle facet subluxation. Only middle facet subluxation measurements were found to significantly influence FAO calculations ( = .003). The partition prediction model demonstrated that a middle facet subluxation value of 43.8% represented an important threshold for increased FAO.
This study is the first to compare WBCT measurements of subtalar joint subluxation at the posterior and middle facets as markers of PTS in patients with AAFD. We found a positive linear correlation between the measurements, with subluxation of the middle facet being significantly more pronounced than that of the posterior facet by an average of almost 18%. This suggests that middle facet subluxation may provide an earlier and more pronounced marker of progressive PTS in patients with AAFD.
Level III, retrospective comparative cohort study.
成人获得性平足畸形（AAFD）是一种复杂的三维病理状态，其特征为后足距下关节半脱位（PTS）。多年来，PTS是在距下关节后关节面进行测量的。最近，有人提出中关节面半脱位是有症状的AAFD更准确、更可靠的标志，能够实现早期检测。本研究的目的是比较AAFD患者内侧和后关节面的半脱位程度。
在这项经机构审查委员会批准的回顾性比较研究中，共分析了76例AAFD患者（87只脚），这些患者接受了站立位负重计算机断层扫描（WBCT）作为其足部畸形的标准基线评估。两名经过 fellowship 培训、经验超过10年且不知情的足踝外科骨科医生测量了距下关节后关节面和中关节面的半脱位情况（以关节覆盖不全的百分比表示）。其中一名读者还测量了足踝偏移（FAO）。使用冠状面WBCT图像在关节面的矢状中点进行PTS测量。使用组内相关系数（ICC）测量观察者内和观察者间PTS测量的一致性。使用Spearman相关性和双变量分析评估后关节面和中关节面半脱位之间的方法间一致性。使用Wilcoxon检验对测量值进行配对比较。采用多变量分析和分区预测模型评估PTS测量值对FAO值的影响。P值<.05被认为具有统计学意义。
观察者内和观察者间可靠性的ICC，后关节面半脱位分别为0.97和0.93，中关节面半脱位分别为0.99和0.97。后关节面和中关节面半脱位之间的方法间Spearman相关性为0.61。在双变量分析中，发现两种测量方法均具有显著的线性相关性（P<.0001；r = 0.42）。发现中关节面半脱位的测量值显著高于后关节面半脱位的测量值，中位数差异（使用Hodges-Lehman因子）为17.7%（P<.001；95%CI，10.9%-23.6%）。我们还发现，后关节面半脱位每增加1%，中关节面半脱位相应增加1.6倍。仅发现中关节面半脱位测量值对FAO计算有显著影响（P = .003）。分区预测模型表明，中关节面半脱位值43.8%代表FAO增加的重要阈值。
本研究首次比较了AAFD患者后关节面和中关节面距下关节半脱位的WBCT测量值，作为PTS的标志。我们发现测量值之间存在正线性相关性，中关节面半脱位比后关节面半脱位明显更显著，平均高出近18%。这表明中关节面半脱位可能为AAFD患者进行性PTS提供更早、更显著的标志。
III级，回顾性比较队列研究。
