Mogk Jeremy P M, Keir Peter J
School of Kinesiology & Health Science, York University, Toronto, Ontario, Canada.
J Biomech. 2007;40(10):2222-9. doi: 10.1016/j.jbiomech.2006.10.033. Epub 2006 Dec 12.
While deviated wrist postures have been linked to the development of carpal tunnel syndrome, the relative contributions of posture-related changes in size, shape and volume of the carpal tunnel contribute to median nerve compression are unclear. The purpose of this study was two-fold: (1) to reconstruct the carpal tunnel from MRI data in neutral and non-neutral (30 degrees extension, 30 degrees flexion) wrist postures, and (2) to evaluate errors associated with off-axis imaging. Three-dimensional reconstruction of the carpal tunnels of 8 volunteers from the university community revealed that the orientation of the carpal tunnel was not directly explained by external wrist angle. The average orientation of the carpal tunnel was extended in all postures, ranging from 25 degrees +/-9 degrees in extension, 13 degrees +/-5 degrees in neutral and 4 degrees +/-4 degrees in the flexed wrist. Changing the orientation of the imaging plane to be perpendicular to the reconstructed carpal tunnel revealed that axial images overestimated cross-sectional area by an average of nearly 10% in extension, 4% in neutral and less than 1% in flexion. Similarly, adjusting the imaging plane to be perpendicular to external wrist angle overestimated cross-sectional area by an average of 2% in extension, 4% in neutral and 24% in flexion. Distortion of the carpal tunnel shape also became evident with rotation of the imaging plane. The data suggest that correction for the orientation of the carpal tunnel itself to be more appropriate than relying on external wrist angle. Computerized reconstruction provided detailed anatomic visualization of the carpal tunnel, and has created the framework to develop a biomechanical model of the carpal tunnel. Similar reconstruction of the tissue structures passing through (median nerve and flexor tendons) and entering the carpal tunnel (muscle tissue) will enable evaluation and partitioning of median nerve injury mechanisms.
虽然手腕姿势异常与腕管综合征的发生有关，但腕管大小、形状和容积的姿势相关变化对正中神经压迫的相对作用尚不清楚。本研究的目的有两个：（1）从处于中立和非中立（伸展30度、屈曲30度）手腕姿势的MRI数据重建腕管，以及（2）评估与离轴成像相关的误差。对来自大学社区的8名志愿者的腕管进行三维重建显示，腕管的方向并不能直接由外部手腕角度来解释。腕管在所有姿势下的平均方向都是伸展的，伸展时为25度±9度，中立时为13度±5度，屈曲手腕时为4度±4度。将成像平面的方向改变为与重建的腕管垂直后发现，轴向图像在伸展时平均高估横截面积近10%，中立时高估4%，屈曲时高估不到1%。同样，将成像平面调整为与外部手腕角度垂直时，在伸展时平均高估横截面积2%，中立时高估4%，屈曲时高估24%。随着成像平面的旋转，腕管形状的变形也变得明显。数据表明，校正腕管本身的方向比依赖外部手腕角度更为合适。计算机重建提供了腕管详细的解剖可视化，并创建了开发腕管生物力学模型的框架。对穿过（正中神经和屈肌腱）和进入腕管（肌肉组织）的组织结构进行类似的重建，将能够评估和区分正中神经损伤机制。
