Hu Dan, Howard David, Ren Lei
School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, United Kingdom; State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun, P.R. China.
School of Computing, Science and Engineering, University of Salford, Manchester, United Kingdom.
PLoS One. 2014 Apr 14;9(4):e94533. doi: 10.1371/journal.pone.0094533. eCollection 2014.
This study investigated the effects of the finger extensor mechanism on the bone-to-bone contact forces at the interphalangeal and metacarpal joints and also on the forces in the intrinsic and extrinsic muscles during finger pressing. This was done with finger postures ranging from very flexed to fully extended. The role of the finger extensor mechanism was investigated by using two alternative finger models, one which omitted the extensor mechanism and another which included it. A six-camera three-dimensional motion analysis system was used to capture the finger posture during maximum voluntary isometric pressing. The fingertip loads were recorded simultaneously using a force plate system. Two three-dimensional biomechanical finger models, a minimal model without extensor mechanism and a full model with extensor mechanism (tendon network), were used to calculate the joint bone-to-bone contact forces and the extrinsic and intrinsic muscle forces. If the full model is assumed to be realistic, then the results suggest some useful biomechanical advantages provided by the tendon network of the extensor mechanism. It was found that the forces in the intrinsic muscles (interosseus group and lumbrical) are significantly reduced by 22% to 61% due to the action of the extensor mechanism, with the greatest reductions in more flexed postures. The bone-to-bone contact force at the MCP joint is reduced by 10% to 41%. This suggests that the extensor mechanism may help to reduce the risk of injury at the finger joints and also to moderate the forces in intrinsic muscles. These apparent biomechanical advantages may be a result of the extensor mechanism's distinctive interconnected fibrous structure, through which the contraction of the intrinsic muscles as flexors of the MCP joint can generate extensions at the DIP and PIP joints.
本研究调查了手指伸肌机制在指间关节和掌指关节处的骨对骨接触力，以及在手指按压过程中对手内肌和手外肌力量的影响。研究通过从极度屈曲到完全伸展的手指姿势来进行。通过使用两种替代手指模型来研究手指伸肌机制的作用，一种模型省略了伸肌机制，另一种模型包含伸肌机制。使用六相机三维运动分析系统在最大自主等长按压过程中捕捉手指姿势。同时使用测力板系统记录指尖负荷。使用两个三维生物力学手指模型，一个是没有伸肌机制的简化模型，另一个是带有伸肌机制（肌腱网络）的完整模型，来计算关节骨对骨接触力以及手外肌和手内肌力量。如果假设完整模型是符合实际情况的，那么结果表明伸肌机制的肌腱网络具有一些有用的生物力学优势。研究发现，由于伸肌机制的作用，手内肌（骨间肌组和蚓状肌）的力量显著降低了22%至61%，在更屈曲的姿势下降低幅度最大。掌指关节处的骨对骨接触力降低了10%至41%。这表明伸肌机制可能有助于降低手指关节受伤的风险，还能调节手内肌的力量。这些明显可见生物力学优势可能是由于伸肌机制独特的相互连接的纤维结构，通过这种结构，作为掌指关节屈肌的手内肌收缩可在远侧指间关节和近侧指间关节产生伸展。
