Keir P J, Wells R P
Department of Kinesiology, York University, 364 Bethune College, 4700 Keele Street, North York, Toronto, Ontario, Canada.
Clin Biomech (Bristol). 1999 Nov;14(9):635-45. doi: 10.1016/s0268-0033(99)00012-1.
(1) To develop a methodology to determine the trajectories of the digital flexor tendons using MRI. (2) To examine changes in tendon trajectories due to wrist posture, with and without pinch force. (3) To calculate the radius of curvature of the flexor tendons and note implications for contact forces on the median nerve. (4) To assess the use of Landsmeer's models at the wrist.
Finger flexor tendon centroids were digitized from magnetic resonance images of the carpal tunnel and the tendon paths were determined analytically. Radii of curvature were calculated from the tendon paths.
Landsmeer's models of joint-tendon interaction (Landsmeer, 1961) have been used to determine moment arms and radius of curvature of the tendon paths about articulations. An explanation for a biomechanical cause of work-related carpal tunnel syndrome originated from these models.
Three healthy male participants had their right wrist scanned while splinted in four wrist postures (flexed to 20 degrees, 45 degrees, neutral, extended to 20 degrees ) with and without maintaining a 10 N pinch grip. 20-24 cross-sectional images were used for each condition.
Volar movement of the tendons was seen with wrist flexion and the opposite was true with extension. Tendon intersection angles were calculated between the tendon as it entered the carpal tunnel and as it exited the tunnel and were 50-65% of the wrist angle (R(2)=0.81-0.96). The radius of curvature was smallest (mean=82-127 mm) with an active pinch grip with the wrist splinted at 45 degrees of flexion (mean actual wrist angle 37 degrees ).
The radius of flexor tendon curvature is not constant as previously assumed and is larger than previous estimates. The addition of tendon force with the wrist flexed acts to reduce the radius of curvature which further increases the contact stress on the median nerve and other wrist structures. The use of MRI to determine the tendon paths has provided new insight into the relationships between the finger flexor tendons and other structures at the wrist.
These findings provide data for biomechanical models of the carpal tunnel and predict the possible pathophysiology of work-related carpal tunnel syndrome.
（1）开发一种利用磁共振成像（MRI）确定指屈肌腱轨迹的方法。（2）研究在有和没有捏力的情况下，腕部姿势对肌腱轨迹的影响。（3）计算屈肌腱的曲率半径，并注意其对正中神经接触力的影响。（4）评估兰斯米尔（Landsmeer）模型在腕部的应用。
从腕管的磁共振图像中数字化手指屈肌腱的质心，并通过分析确定肌腱路径。根据肌腱路径计算曲率半径。
兰斯米尔的关节 - 肌腱相互作用模型（Landsmeer，1961年）已被用于确定肌腱路径围绕关节的力臂和曲率半径。工作相关腕管综合征的生物力学原因的一种解释源于这些模型。
三名健康男性参与者在四种腕部姿势（屈曲20度、45度、中立位、伸展20度）下，有和没有保持10 N的捏握力时，对其右手腕进行扫描。每种情况使用20 - 24张横截面图像。
随着腕部屈曲，肌腱出现掌侧移动，伸展时则相反。计算了肌腱进入腕管和离开腕管时的肌腱交叉角度，该角度为腕部角度的50 - 65%（R² = 0.81 - 0.96）。在腕部固定于45度屈曲（实际平均腕部角度37度）并施加主动捏握力时，曲率半径最小（平均 = 82 - 127 mm）。
屈肌腱曲率半径并非如先前假设的那样恒定，且比先前估计的要大。腕部屈曲时增加肌腱力会减小曲率半径，这进一步增加了正中神经和其他腕部结构上的接触应力。利用MRI确定肌腱路径为手指屈肌腱与腕部其他结构之间的关系提供了新的见解。
这些发现为腕管的生物力学模型提供了数据，并预测了工作相关腕管综合征可能的病理生理学。
