Tochigi Yuki, Suh Jin-Soo, Amendola Annunziato, Pedersen Douglas R, Saltzman Charles L
Orthopaedic Biomechanics Laboratory, University of Iowa, 2181 Westlawn, Iowa City, IA 52242-1100, USA.
Foot Ankle Int. 2006 Feb;27(2):82-7. doi: 10.1177/107110070602700202.
In ankles with end-stage osteoarthritis or with total ankle replacement (TAR), radiographic landmarks based on joint surface morphology usually are obscured and inadequate for radiographic measurement. Furthermore, because of difficulty in reproducibly positioning the ankle for a standing radiograph, any radiographic measure to accurately describe ankle alignment must tolerate perturbations of ankle positioning on clinical radiographs. To identify a radiographic measure of anteroposterior tibial-talar alignment that meets those requirements, three methods were compared to determine their sensitivity to perturbations in ankle positioning.
Ten cadaver ankles had lateral radiographs taken in varying ankle positions in nine prespecified positions in the transverse plane and in seven positions in the sagittal plane. The anteroposterior tibial-talar alignment was quantified by three methods. Sensitivities to changes of ankle position in each plane were then compared.
With 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), sensitivity to ankle positional changes in either plane was lowest, with errors associated with 10 degrees of ankle malpositioning being 2.2%. The posterior-tibial-line-to-talus ratio (P-T ratio: a similar ratio, but using the posterior longitudinal line of the tibial shaft) showed higher sensitivity in the transverse plane than the T-T ratio, though the associated errors in either plane were nearly comparable. The tibial-axis-to-lateral-process distance (T-L distance: the perpendicular distance from the tibial axis to the tip of the lateral talar process) showed highest sensitivity in both planes.
The T-T ratio tolerated perturbations of ankle positioning best among the tested measures. This measure is potentially applicable to clinical radiographic measurement when determining the anteroposterior tibial-talar alignment in ankles with articular degeneration or TAR. The P-T ratio also appears to have reasonable tolerance.
在终末期骨关节炎或全踝关节置换（TAR）的踝关节中，基于关节表面形态的放射学标志通常会被遮挡，不足以进行放射学测量。此外，由于难以在站立位X线片上可重复地定位踝关节，任何准确描述踝关节对线的放射学测量方法都必须能够容忍临床X线片上踝关节定位的偏差。为了确定一种满足这些要求的胫距前后对线的放射学测量方法，比较了三种方法以确定它们对踝关节定位偏差的敏感性。
对10个尸体踝关节在横断面上9个预先指定的位置以及矢状面上7个位置的不同踝关节位置拍摄侧位X线片。通过三种方法对胫距前后对线进行量化。然后比较每种平面中对踝关节位置变化的敏感性。
对于胫骨干中轴线与距骨长度之比（T-T比：胫骨干中轴线将距骨纵长分成的比例），在任一平面中对踝关节位置变化的敏感性最低，踝关节错位10度时的相关误差为2.2%。胫骨干后缘线与距骨长度之比（P-T比：类似的比例，但使用胫骨干后缘线）在横断面上比T-T比显示出更高的敏感性，尽管在任一平面中的相关误差几乎相当。胫骨干中轴线至外侧突距离（T-L距离：从胫骨干中轴线到距骨外侧突尖端的垂直距离）在两个平面中均显示出最高的敏感性。
在测试的测量方法中，T-T比对踝关节定位偏差的耐受性最佳。在确定患有关节退变或TAR的踝关节的胫距前后对线时，该测量方法可能适用于临床放射学测量。P-T比似乎也具有合理的耐受性。
