Martin Joel R, Paclet Florent, Latash Mark L, Zatsiorsky Vladimir M
Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.
Clin Biomech (Bristol). 2013 Feb;28(2):157-63. doi: 10.1016/j.clinbiomech.2012.11.004. Epub 2012 Dec 6.
Carpal tunnel syndrome is a disorder caused by increased pressure in the carpal tunnel associated with repetitive, stereotypical finger actions. Little is known about in vivo geometrical changes in the carpal tunnel caused by motion at the finger joints and exerting a fingertip force.
The hands and forearms of five subjects were scanned using a 3.0 T magnetic resonance imaging scanner. The metacarpophalangeal joint of the index finger was placed in: flexion, neutral and extension. For each joint posture subjects either produced no active force (passive condition) or exerted a flexion force to resist a load (~4.0 N) at the fingertip (active condition). Changes in the radii of curvature, position and transverse plane area of the flexor digitorum profundus tendons at the carpal tunnel level were measured.
The radius of curvature of the flexor digitorum profundus tendons, at the carpal tunnel level, was significantly affected by posture of the index finger metacarpophalangeal joint (P<0.05) and the radii was significantly different between fingers (P<0.05). Actively producing force caused a significant shift (P<0.05) in the flexor digitorum profundus tendons in the ventral (palmar) direction. No significant change in the area of an ellipse containing the flexor digitorum profundus tendons was observed between conditions.
The results show that relatively small changes in the posture and force production of a single finger can lead to significant changes in the geometry of all the flexor digitorum profundus tendons in the carpal tunnel. Additionally, voluntary force production at the fingertip increases the moment arm of the FDP tendons about the wrist joint.
腕管综合征是一种由腕管内压力升高引起的疾病，与重复性、刻板的手指动作有关。关于手指关节运动和施加指尖力导致的腕管内活体几何变化知之甚少。
使用3.0T磁共振成像扫描仪对5名受试者的手和前臂进行扫描。将食指的掌指关节置于：屈曲、中立和伸展位置。对于每个关节姿势，受试者要么不产生主动力（被动状态），要么施加屈曲力以抵抗指尖处的负荷（约4.0N）（主动状态）。测量腕管水平处指深屈肌腱的曲率半径、位置和横截面积的变化。
腕管水平处指深屈肌腱的曲率半径受食指掌指关节姿势的显著影响（P<0.05），且各手指间的半径有显著差异（P<0.05）。主动发力导致指深屈肌腱在腹侧（掌侧）方向发生显著移位（P<0.05）。不同状态下，包含指深屈肌腱的椭圆面积未见显著变化。
结果表明，单个手指姿势和力产生的相对较小变化可导致腕管内所有指深屈肌腱的几何形状发生显著变化。此外，指尖处的主动发力会增加指深屈肌腱绕腕关节的力臂。
