Baverel L, Brilhault J, Odri G, Boissard M, Lintz François
CHU de Nantes, 1 place Alexis Ricordeau, Nantes, France.
CHRU de Tours, 37044 Tours, France.
Foot Ankle Surg. 2017 Mar;23(1):44-49. doi: 10.1016/j.fas.2016.02.003. Epub 2016 Mar 30.
Rotation is one of the variables explaining lack of reproducibility in assessing hindfoot alignment. The hypothesis for this study was that a mathematical model predicts how this modifies radiographic hindfoot alignment measurements.
A cadaveric lower limb, disjointed at knee level, was used. Sagittal and coronal planes were fixed using a custom clamp. Standard AP views were shot every five degrees and measured hindfoot alignments were compared to theoretical values obtained from a mathematical simulation.
Hindfoot angle was 7.04° at 0° rotation and 2.11° at -90°. Intra-class and inter-investigator correlation was 0.863. The t-test showed no significant difference (p=0.73). Intra-investigator correlation was 0.957. The R2 correlation index was 0.852.
The mathematical model accurately predicted the variations of the hindfoot angle which was maximum when the foot was aligned with the X-rays source. It then decreased when the foot rotated away, following a parabolic curve.
旋转是解释在评估后足对线时缺乏可重复性的变量之一。本研究的假设是，一个数学模型可以预测旋转如何改变X线后足对线测量结果。
使用一具在膝关节水平离断的尸体下肢。矢状面和冠状面用定制夹具固定。每隔5度拍摄标准前后位片，并将测量的后足对线与从数学模拟中获得的理论值进行比较。
旋转0°时后足角为7.04°，旋转-90°时为2.11°。组内及不同研究者间的相关性为0.863。t检验显示无显著差异（p=0.73）。研究者内相关性为0.957。R2相关指数为0.852。
该数学模型准确预测了后足角的变化，当足部与X线源对齐时后足角最大。当足部旋转离开时，后足角呈抛物线形下降。
