The fundamental thumb-tip force vectors produced by the muscles of the thumb
The fundamental thumb-tip force vectors produced by the muscles of the thumb
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DOI：
10.1016/j.orthres.2003.08.001
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发表时间：
2004-03-01
影响因子：
2.8
通讯作者：
Valero-Cuevas, FJ
中科院分区：
文献类型：
--
作者：
Pearlman, JL;Roach, SS;Valero-Cuevas, FJ
对每个拇指肌肉在拇指尖端产生的3D力矢量的大小和方向进行严格的描述，对于了解各种瘫痪和外科手术(如肌腱转移)挤压的生物力学后果是必要的。在这项研究中，我们描述了每个肌肉在拇指尖端产生的3D力矢量，并研究了这些拇指尖力矢量是否与肌腱张力成线性关系。在13具身体标本上，我们测量了每根肌腱作用于拇指产生的输出3D拇指尖力向量，以及两个常见的肌腱转移，作为输入肌腱张力的函数。在将手固定在刚性框架上后，我们将拇指配置为标准的按键或相反的捏合姿势，并将拇指尖端耦合到刚性固定的6自由度力/扭矩传感器上。直线致动器将张力施加到四块拇指外部肌肉的远端肌腱和六根尼龙绳上，这些张力再现了(I)四块内在拇指肌肉和(Ii)两种可选的肌腱移位术的动作路线，这些肌腱移位术通常用于恢复低位正中神经麻痹后的拇指对位。当我们测量拇指尖端的三维力矢量时，每个计算机控制的线性致动器将肌腱张力从预测的每条肌腱最大肌力的0增加到1/3，然后恢复到零。在测试/重新测试试验中，我们看到拇指尖力向量对安装程序非常敏感，但对关节表面位置的变化也很敏感。我们发现：(I)一些拇指尖力向量在意想不到的方向上作用(例如，对手的力向量平行于远端指骨)，(Ii)两个肌腱转移产生明显不同的力向量，以及(Iii)对于大多数肌肉，拇指尖力向量与肌腱张力不成线性关系--可能是由于负荷依赖的粘弹性肌腱路径、关节坐位和/或骨骼运动所致。我们的三维力矢量数据首次提供了所有拇指肌肉和两个肌腱转移产生的拇指尖力矢量的定量参考描述。我们的结论是，在生物力学模型中假设拇指尖端的力向量与肌腱张力成线性关系可能是不现实的，我们的数据表明，拇指可能是受载荷依赖的梯形运动影响的“浮动脚趾”。(C)2003年骨科研究会。爱思唯尔有限公司出版。保留所有权利。
A rigorous description of the magnitude and direction of the 3D force vector each thumb muscle produces at the thumb-tip is necessary to understand the biomechanical consequences to pinch of a variety of paralyses and surgical procedures (Such as tendon transfers). In this study, we characterized the 3D force vector each Muscle produces at the thumb-tip, and investigated if these thumb-tip force vectors scaled linearly with tendon tension. In 13 cadaver specimens, we measured the output 3D thumb-tip force vector produced by each tendon acting on the thumb, Plus two common tendon transfers, as a function of input tendon tension. After fixing the hand to a rigid frame, we mounted the thumb by configuring it in standardized key or opposition pinch posture and coupling the thumb-tip to a rigidly held 6 degree-of-freedom force/torque sensor. Linear actuators applied tension to the distal tendons of the four extrinsic thumb muscles, and to six Nylon cords reproducing the lines of action of (i) the four intrinsic thumb muscles and (ii) two alternative tendon transfers commonly used to restore thumb opposition following low median nerve palsy. Each computer-control led linear actuator ramped tendon tension from zero to 1/3 of predicted maximal muscle force expected at each tendon, and back to zero, while we measured the 3D force vector at the thumb-tip. In test/re-test trials, we saw thumb-tip force vectors were quite sensitive to mounting procedure, but also sensitive to variations in the seating of joint surfaces. We found that: (i) some thumb-tip force vectors act in unexpected directions (e.g., the opponens force vector is parallel to the distal phalanx), (ii) the two tendon transfers produced patently different force vectors, and (iii) for most muscles, thumb-tip force vectors do not scale linearly with tendon tension-likely due to load-dependent viscoelastic tendon paths, joint seating and/or bone motion. Our 3D force vector data provide the first quantitative reference descriptions of the thumb-tip force vectors produced by all thumb muscles and two tendon transfers. We conclude that it may not be realistic to assume in biomechanical models that thumb-tip force vectors scale linearly with tendon tensions, and that our data suggest the thumb may act as a "floating digit" affected by load-dependent trapezium motion. (C) 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.