Tochigi Yuki, Suh Jin-Soo, Amendola Annunziato, Saltzman Charles L
Orthopaedic Biomechanics Laboratory, University of Iowa, 2181 Westlawn, Iowa City, IA 52242-1100, USA.
Foot Ankle Int. 2006 Feb;27(2):88-92. doi: 10.1177/107110070602700203.
In ankles with end-stage osteoarthritis or after total ankle replacement (TAR), radiographic landmarks based on joint surface morphology usually are obscured and inadequate for measurement. Two methods for quantifying anteroposterior tibial-talar alignment without relying on those landmarks were identified in a corollary cadaver-based study. This study aimed to verify reliability and validity of those candidate measures.
On clinical radiographs of 33 nonarthritic and 35 arthritic ankles, the anteroposterior tibial-talar alignment was quantified by the two methods; the tibial-axis-to-talus ratio (T-T ratio: the ratio into which the midlongitudinal axis of the tibial shaft divides the longitudinal talar length) and the posterior-tibial-line-to-talus ratio (P-T ratio: a similar ratio, but using the posterior longitudinal line along the tibial shaft). Two observers performed every measurement twice to evaluate intraobserver and interobserver reliability of the candidate measures. For nonarthritic ankles, the anteroposterior tibial-talar alignment was further determined by a control measure that directly quantified orientation of the talar dome relative to the tibial shaft. Correlation of the T-T and P-T ratios with the control measure was then evaluated for validity.
Measurement of the T-T ratio with arthritic ankles was highly reproducible with the coefficients of determination (R(2)) greater than 0.95, for either interobserver or intraobserver. Correlation between this measure and the control measure was supported (R(2) = 0.60, p < 0.0001). Reliability of the P-T ratio also was strong (R(2) > 0.91), although both reliability and validity of this measure were relatively inferior to the T-T ratio.
The T-T ratio reliably and validly described the anteroposterior tibial-talar alignment on clinical radiographs, regardless of the condition of ankle joint surface. This measure appears to be a reliable radiographic measure for determining the magnitude of anteroposterior talar subluxation in ankles with articular degeneration or after TAR and can facilitate clinical investigations.
在终末期骨关节炎的踝关节或全踝关节置换（TAR）后，基于关节表面形态的放射学标志通常会被遮挡，不足以进行测量。在一项基于尸体的相关研究中，确定了两种不依赖这些标志来量化胫距前后位对线的方法。本研究旨在验证这些候选测量方法的可靠性和有效性。
在33例非关节炎和35例关节炎踝关节的临床X线片上，用这两种方法量化胫距前后位对线；胫骨干中轴线与距骨长度比（T-T比：胫骨干中轴线将距骨纵长分成的比例）和胫骨干后缘线与距骨长度比（P-T比：类似的比例，但使用沿胫骨干的后缘纵线）。两名观察者对每个测量值进行两次测量，以评估候选测量方法的观察者内和观察者间可靠性。对于非关节炎踝关节，通过一种直接量化距骨穹顶相对于胫骨干方向的对照测量方法进一步确定胫距前后位对线。然后评估T-T比和P-T比与对照测量方法的相关性以验证有效性。
对于关节炎踝关节，T-T比的测量具有高度可重复性，观察者间和观察者内的决定系数（R²）均大于0.95。该测量方法与对照测量方法之间的相关性得到证实（R² = 0.60，p < 0.0001）。P-T比的可靠性也很强（R² > 0.91），尽管该测量方法的可靠性和有效性均相对低于T-T比。
T-T比在临床X线片上可靠且有效地描述了胫距前后位对线，无论踝关节表面状况如何。该测量方法似乎是一种可靠的放射学测量方法，可用于确定关节退变的踝关节或TAR后距骨前后位半脱位的程度，并有助于临床研究。
